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Improve performance of and reduce overheads of memory management 

Whenever we palloc a chunk of memory, traditionally, we prefix the
returned pointer with a pointer to the memory context to which the chunk
belongs.  This is required so that we're able to easily determine the
owning context when performing operations such as pfree() and repalloc().

For the AllocSet context, prior to this commit we additionally prefixed
the pointer to the owning context with the size of the chunk.  This made
the header 16 bytes in size.  This 16-byte overhead was required for all
AllocSet allocations regardless of the allocation size.

For the generation context, the problem was worse; in addition to the
pointer to the owning context and chunk size, we also stored a pointer to
the owning block so that we could track the number of freed chunks on a
block.

The slab allocator had a 16-byte chunk header.

The changes being made here reduce the chunk header size down to just 8
bytes for all 3 of our memory context types.  For small to medium sized
allocations, this significantly increases the number of chunks that we can
fit on a given block which results in much more efficient use of memory.

Additionally, this commit completely changes the rule that pointers to
palloc'd memory must be directly prefixed by a pointer to the owning
memory context and instead, we now insist that they're directly prefixed
by an 8-byte value where the least significant 3-bits are set to a value
to indicate which type of memory context the pointer belongs to.  Using
those 3 bits as an index (known as MemoryContextMethodID) to a new array
which stores the methods for each memory context type, we're now able to
pass the pointer given to functions such as pfree() and repalloc() to the
function specific to that context implementation to allow them to devise
their own methods of finding the memory context which owns the given
allocated chunk of memory.

The reason we're able to reduce the chunk header down to just 8 bytes is
because of the way we make use of the remaining 61 bits of the required
8-byte chunk header.  Here we also implement a general-purpose MemoryChunk
struct which makes use of those 61 remaining bits to allow the storage of
a 30-bit value which the MemoryContext is free to use as it pleases, and
also the number of bytes which must be subtracted from the chunk to get a
reference to the block that the chunk is stored on (also 30 bits).  The 1
additional remaining bit is to denote if the chunk is an "external" chunk
or not.  External here means that the chunk header does not store the
30-bit value or the block offset.  The MemoryContext can use these
external chunks at any time, but must use them if any of the two 30-bit
fields are not large enough for the value(s) that need to be stored in
them.  When the chunk is marked as external, it is up to the MemoryContext
to devise its own means to determine the block offset.

Using 3-bits for the MemoryContextMethodID does mean we're limiting
ourselves to only having a maximum of 8 different memory context types.
We could reduce the bit space for the 30-bit value a little to make way
for more than 3 bits, but it seems like it might be better to do that only
if we ever need more than 8 context types.  This would only be a problem
if some future memory context type which does not use MemoryChunk really
couldn't give up any of the 61 remaining bits in the chunk header.

With this MemoryChunk, each of our 3 memory context types can quickly
obtain a reference to the block any given chunk is located on.  AllocSet
is able to find the context to which the chunk is owned, by first
obtaining a reference to the block by subtracting the block offset as is
stored in the 'hdrmask' field and then referencing the block's 'aset'
field.  The Generation context uses the same method, but GenerationBlock
did not have a field pointing back to the owning context, so one is added
by this commit.

In aset.c and generation.c, all allocations larger than allocChunkLimit
are stored on dedicated blocks.  When there's just a single chunk on a
block like this, it's easy to find the block from the chunk, we just
subtract the size of the block header from the chunk pointer.  The size of
these chunks is also known as we store the endptr on the block, so we can
just subtract the pointer to the allocated memory from that.  Because we
can easily find the owning block and the size of the chunk for these
dedicated blocks, we just always use external chunks for allocation sizes
larger than allocChunkLimit.  For generation.c, this sidesteps the problem
of non-external MemoryChunks being unable to represent chunk sizes >= 1GB.
This is less of a problem for aset.c as we store the free list index in
the MemoryChunk's spare 30-bit field (the value of which will never be
close to using all 30-bits).  We can easily reverse engineer the chunk size
from this when needed.  Storing this saves AllocSetFree() from having to
make a call to AllocSetFreeIndex() to determine which free list to put the
newly freed chunk on.

For the slab allocator, this commit adds a new restriction that slab
chunks cannot be >= 1GB in size.  If there happened to be any users of
slab.c which used chunk sizes this large, they really should be using
AllocSet instead.

Here we also add a restriction that normal non-dedicated blocks cannot be
1GB or larger.  It's now not possible to pass a 'maxBlockSize' >= 1GB
during the creation of an AllocSet or Generation context.  Allocations can
still be larger than 1GB, it's just these will always be on dedicated
blocks (which do not have the 1GB restriction).

Author: Andres Freund, David Rowley
Discussion: https://postgr.es/m/CAApHDvpjauCRXcgcaL6+e3eqecEHoeRm9D-kcbuvBitgPnW=vw@mail.gmail.com
This commit is contained in:
David Rowley 2022-08-29 17:15:00 +12:00
parent d2169c9985
commit c6e0fe1f2a
10 changed files with 1055 additions and 617 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
src/backend/utils/mmgr/README
View File

@ -384,35 +384,55 @@ MemoryContext like the parent and child contexts, and the name of the
context.
This is essentially an abstract superclass, and the behavior is
determined by the "methods" pointer is its virtual function table
(struct MemoryContextMethods). Specific memory context types will use
derived structs having these fields as their first fields. All the
determined by the "methods" pointer which references which set of
MemoryContextMethods are to be used. Specific memory context types will
use derived structs having these fields as their first fields. All the
contexts of a specific type will have methods pointers that point to
the same static table of function pointers.
the corresponding element in the mcxt_methods[] array as defined in mcxt.c.
While operations like allocating from and resetting a context take the
relevant MemoryContext as a parameter, operations like free and
realloc are trickier. To make those work, we require all memory
context types to produce allocated chunks that are immediately,
without any padding, preceded by a pointer to the corresponding
MemoryContext.
without any padding, preceded by a uint64 value of which the least
significant 3 bits are set to the owning context's MemoryContextMethodID.
This allows the code to determine the correct MemoryContextMethods to
use by looking up the mcxt_methods[] array using the 3 bits as an index
into that array.
If a type of allocator needs additional information about its chunks,
like e.g. the size of the allocation, that information can in turn
precede the MemoryContext. This means the only overhead implied by
the memory context mechanism is a pointer to its context, so we're not
constraining context-type designers very much.
either be encoded into the remaining 61 bits of the preceding uint64 value
or if more space is required, additional values may be stored directly prior
to the uint64 value. It is up to the context implementation to manage this.
Given this, routines like pfree determine their corresponding context
with an operation like (although that is usually encapsulated in
GetMemoryChunkContext())
Given this, routines like pfree can determine which set of
MemoryContextMethods to call the free_p function for by calling
GetMemoryChunkMethodID() and finding the corresponding MemoryContextMethods
in the mcxt_methods[] array. For convenience, the MCXT_METHOD() macro is
provided, making the code as simple as:
MemoryContext context = *(MemoryContext*) (((char *) pointer) - sizeof(void *));
and then invoke the corresponding method for the context
context->methods->free_p(pointer);
void
pfree(void *pointer)
{
MCXT_METHOD(pointer, free_p)(pointer);
}
All of the current memory contexts make use of the MemoryChunk header type
which is defined in memutils_memorychunk.h. This suits all of the existing
context types well as it makes use of the remaining 61-bits of the uint64
header to efficiently encode the size of the chunk of memory (or freelist
index, in the case of aset.c) and the number of bytes which must be subtracted
from the chunk in order to obtain a reference to the block that the chunk
belongs to. 30 bits are used for each of these. If more than 30 bits are
required then the memory context must manage that itself. This can be done by
calling the MemoryChunkSetHdrMaskExternal() function on the given chunk.
Currently, each memory context type stores large allocations on dedicated
blocks (which always contain only a single chunk). For these, finding the
block is simple as we know that the chunk must be the first on the given
block, so the block is always at a fixed offset to the chunk. For these,
finding the size of the chunk is also simple as the block always stores an
endptr which we can use to calculate the size of the chunk.
More Control Over aset.c Behavior
---------------------------------

539
src/backend/utils/mmgr/aset.c
View File

@ -49,6 +49,8 @@
#include "port/pg_bitutils.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_memorychunk.h"
#include "utils/memutils_internal.h"
/*--------------------
* Chunk freelist k holds chunks of size 1 << (k + ALLOC_MINBITS),
@ -66,7 +68,9 @@
* CAUTION: ALLOC_MINBITS must be large enough so that
* 1<<ALLOC_MINBITS is at least MAXALIGN,
* or we may fail to align the smallest chunks adequately.
* 8-byte alignment is enough on all currently known machines.
* 8-byte alignment is enough on all currently known machines. This 8-byte
* minimum also allows us to store a pointer to the next freelist item within
* the chunk of memory itself.
*
* With the current parameters, request sizes up to 8K are treated as chunks,
* larger requests go into dedicated blocks. Change ALLOCSET_NUM_FREELISTS
@ -98,10 +102,9 @@
*/
#define ALLOC_BLOCKHDRSZ MAXALIGN(sizeof(AllocBlockData))
#define ALLOC_CHUNKHDRSZ sizeof(struct AllocChunkData)
#define ALLOC_CHUNKHDRSZ sizeof(MemoryChunk)
typedef struct AllocBlockData *AllocBlock; /* forward reference */
typedef struct AllocChunkData *AllocChunk;
/*
* AllocPointer
@ -109,6 +112,30 @@ typedef struct AllocChunkData *AllocChunk;
*/
typedef void *AllocPointer;
/*
* AllocFreeListLink
* When pfreeing memory, if we maintain a freelist for the given chunk's
* size then we use a AllocFreeListLink to point to the current item in
* the AllocSetContext's freelist and then set the given freelist element
* to point to the chunk being freed.
*/
typedef struct AllocFreeListLink
{
MemoryChunk *next;
} AllocFreeListLink;
/*
* Obtain a AllocFreeListLink for the given chunk. Allocation sizes are
* always at least sizeof(AllocFreeListLink), so we reuse the pointer's memory
* itself to store the freelist link.
*/
#define GetFreeListLink(chkptr) \
(AllocFreeListLink *) ((char *) (chkptr) + ALLOC_CHUNKHDRSZ)
/* Determine the size of the chunk based on the freelist index */
#define GetChunkSizeFromFreeListIdx(fidx) \
((((Size) 1) << ALLOC_MINBITS) << (fidx))
/*
* AllocSetContext is our standard implementation of MemoryContext.
*
@ -123,7 +150,7 @@ typedef struct AllocSetContext
MemoryContextData header; /* Standard memory-context fields */
/* Info about storage allocated in this context: */
AllocBlock blocks; /* head of list of blocks in this set */
AllocChunk freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
MemoryChunk *freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
/* Allocation parameters for this context: */
Size initBlockSize; /* initial block size */
Size maxBlockSize; /* maximum block size */
@ -139,8 +166,8 @@ typedef AllocSetContext *AllocSet;
/*
* AllocBlock
* An AllocBlock is the unit of memory that is obtained by aset.c
* from malloc(). It contains one or more AllocChunks, which are
* the units requested by palloc() and freed by pfree(). AllocChunks
* from malloc(). It contains one or more MemoryChunks, which are
* the units requested by palloc() and freed by pfree(). MemoryChunks
* cannot be returned to malloc() individually, instead they are put
* on freelists by pfree() and re-used by the next palloc() that has
* a matching request size.
@ -158,48 +185,12 @@ typedef struct AllocBlockData
} AllocBlockData;
/*
* AllocChunk
* The prefix of each piece of memory in an AllocBlock
*
* Note: to meet the memory context APIs, the payload area of the chunk must
* be maxaligned, and the "aset" link must be immediately adjacent to the
* payload area (cf. GetMemoryChunkContext). We simplify matters for this
* module by requiring sizeof(AllocChunkData) to be maxaligned, and then
* we can ensure things work by adding any required alignment padding before
* the "aset" field. There is a static assertion below that the alignment
* is done correctly.
*/
typedef struct AllocChunkData
{
/* size is always the size of the usable space in the chunk */
Size size;
#ifdef MEMORY_CONTEXT_CHECKING
/* when debugging memory usage, also store actual requested size */
/* this is zero in a free chunk */
Size requested_size;
#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P)
#else
#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P)
#endif /* MEMORY_CONTEXT_CHECKING */
/* ensure proper alignment by adding padding if needed */
#if (ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
char padding[MAXIMUM_ALIGNOF - ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
#endif
/* aset is the owning aset if allocated, or the freelist link if free */
void *aset;
/* there must not be any padding to reach a MAXALIGN boundary here! */
} AllocChunkData;
/*
* Only the "aset" field should be accessed outside this module.
* Only the "hdrmask" field should be accessed outside this module.
* We keep the rest of an allocated chunk's header marked NOACCESS when using
* valgrind. But note that chunk headers that are in a freelist are kept
* accessible, for simplicity.
*/
#define ALLOCCHUNK_PRIVATE_LEN offsetof(AllocChunkData, aset)
#define ALLOCCHUNK_PRIVATE_LEN offsetof(MemoryChunk, hdrmask)
/*
* AllocPointerIsValid
@ -213,10 +204,13 @@ typedef struct AllocChunkData
*/
#define AllocSetIsValid(set) PointerIsValid(set)
#define AllocPointerGetChunk(ptr) \
((AllocChunk)(((char *)(ptr)) - ALLOC_CHUNKHDRSZ))
#define AllocChunkGetPointer(chk) \
((AllocPointer)(((char *)(chk)) + ALLOC_CHUNKHDRSZ))
/*
* We always store external chunks on a dedicated block. This makes fetching
* the block from an external chunk easy since it's always the first and only
* chunk on the block.
*/
#define ExternalChunkGetBlock(chunk) \
(AllocBlock) ((char *) chunk - ALLOC_BLOCKHDRSZ)
/*
* Rather than repeatedly creating and deleting memory contexts, we keep some
@ -260,42 +254,6 @@ static AllocSetFreeList context_freelists[2] =
}
};
/*
* These functions implement the MemoryContext API for AllocSet contexts.
*/
static void *AllocSetAlloc(MemoryContext context, Size size);
static void AllocSetFree(MemoryContext context, void *pointer);
static void *AllocSetRealloc(MemoryContext context, void *pointer, Size size);
static void AllocSetReset(MemoryContext context);
static void AllocSetDelete(MemoryContext context);
static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer);
static bool AllocSetIsEmpty(MemoryContext context);
static void AllocSetStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
static void AllocSetCheck(MemoryContext context);
#endif
/*
* This is the virtual function table for AllocSet contexts.
*/
static const MemoryContextMethods AllocSetMethods = {
AllocSetAlloc,
AllocSetFree,
AllocSetRealloc,
AllocSetReset,
AllocSetDelete,
AllocSetGetChunkSpace,
AllocSetIsEmpty,
AllocSetStats
#ifdef MEMORY_CONTEXT_CHECKING
,AllocSetCheck
#endif
};
/* ----------
* AllocSetFreeIndex -
@ -387,18 +345,24 @@ AllocSetContextCreateInternal(MemoryContext parent,
AllocSet set;
AllocBlock block;
/* Assert we padded AllocChunkData properly */
/* ensure MemoryChunk's size is properly maxaligned */
StaticAssertStmt(ALLOC_CHUNKHDRSZ == MAXALIGN(ALLOC_CHUNKHDRSZ),
"sizeof(AllocChunkData) is not maxaligned");
StaticAssertStmt(offsetof(AllocChunkData, aset) + sizeof(MemoryContext) ==
ALLOC_CHUNKHDRSZ,
"padding calculation in AllocChunkData is wrong");
"sizeof(MemoryChunk) is not maxaligned");
/* check we have enough space to store the freelist link */
StaticAssertStmt(sizeof(AllocFreeListLink) <= (1 << ALLOC_MINBITS),
"sizeof(AllocFreeListLink) larger than minimum allocation size");
/*
* First, validate allocation parameters. Once these were regular runtime
* test and elog's, but in practice Asserts seem sufficient because nobody
* varies their parameters at runtime. We somewhat arbitrarily enforce a
* minimum 1K block size.
* tests and elog's, but in practice Asserts seem sufficient because
* nobody varies their parameters at runtime. We somewhat arbitrarily
* enforce a minimum 1K block size. We restrict the maximum block size to
* MEMORYCHUNK_MAX_BLOCKOFFSET as MemoryChunks are limited to this in
* regards to addressing the offset between the chunk and the block that
* the chunk is stored on. We would be unable to store the offset between
* the chunk and block for any chunks that were beyond
* MEMORYCHUNK_MAX_BLOCKOFFSET bytes into the block if the block was to be
* larger than this.
*/
Assert(initBlockSize == MAXALIGN(initBlockSize) &&
initBlockSize >= 1024);
@ -409,6 +373,7 @@ AllocSetContextCreateInternal(MemoryContext parent,
(minContextSize == MAXALIGN(minContextSize) &&
minContextSize >= 1024 &&
minContextSize <= maxBlockSize));
Assert(maxBlockSize <= MEMORYCHUNK_MAX_BLOCKOFFSET);
/*
* Check whether the parameters match either available freelist. We do
@ -443,7 +408,7 @@ AllocSetContextCreateInternal(MemoryContext parent,
/* Reinitialize its header, installing correct name and parent */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
&AllocSetMethods,
MCTX_ASET_ID,
parent,
name);
@ -517,15 +482,20 @@ AllocSetContextCreateInternal(MemoryContext parent,
* requests that are all the maximum chunk size we will waste at most
* 1/8th of the allocated space.
*
* We have to have allocChunkLimit a power of two, because the requested
* and actually-allocated sizes of any chunk must be on the same side of
* the limit, else we get confused about whether the chunk is "big".
*
* Also, allocChunkLimit must not exceed ALLOCSET_SEPARATE_THRESHOLD.
*/
StaticAssertStmt(ALLOC_CHUNK_LIMIT == ALLOCSET_SEPARATE_THRESHOLD,
"ALLOC_CHUNK_LIMIT != ALLOCSET_SEPARATE_THRESHOLD");
/*
* Determine the maximum size that a chunk can be before we allocate an
* entire AllocBlock dedicated for that chunk. We set the absolute limit
* of that size as ALLOC_CHUNK_LIMIT but we reduce it further so that we
* can fit about ALLOC_CHUNK_FRACTION chunks this size on a maximally
* sized block. (We opt to keep allocChunkLimit a power-of-2 value
* primarily for legacy reasons rather than calculating it so that exactly
* ALLOC_CHUNK_FRACTION chunks fit on a maximally sized block.)
*/
set->allocChunkLimit = ALLOC_CHUNK_LIMIT;
while ((Size) (set->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
(Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))
@ -534,7 +504,7 @@ AllocSetContextCreateInternal(MemoryContext parent,
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
&AllocSetMethods,
MCTX_ASET_ID,
parent,
name);
@ -555,7 +525,7 @@ AllocSetContextCreateInternal(MemoryContext parent,
* thrash malloc() when a context is repeatedly reset after small allocations,
* which is typical behavior for per-tuple contexts.
*/
static void
void
AllocSetReset(MemoryContext context)
{
AllocSet set = (AllocSet) context;
@ -623,7 +593,7 @@ AllocSetReset(MemoryContext context)
*
* Unlike AllocSetReset, this *must* free all resources of the set.
*/
static void
void
AllocSetDelete(MemoryContext context)
{
AllocSet set = (AllocSet) context;
@ -717,12 +687,12 @@ AllocSetDelete(MemoryContext context)
* is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
* return space that is marked NOACCESS - AllocSetRealloc has to beware!
*/
static void *
void *
AllocSetAlloc(MemoryContext context, Size size)
{
AllocSet set = (AllocSet) context;
AllocBlock block;
AllocChunk chunk;
MemoryChunk *chunk;
int fidx;
Size chunk_size;
Size blksize;
@ -746,18 +716,20 @@ AllocSetAlloc(MemoryContext context, Size size)
block->aset = set;
block->freeptr = block->endptr = ((char *) block) + blksize;
chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
chunk->aset = set;
chunk->size = chunk_size;
chunk = (MemoryChunk *) (((char *) block) + ALLOC_BLOCKHDRSZ);
/* mark the MemoryChunk as externally managed */
MemoryChunkSetHdrMaskExternal(chunk, MCTX_ASET_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk_size)
set_sentinel(AllocChunkGetPointer(chunk), size);
set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) AllocChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/*
@ -780,13 +752,13 @@ AllocSetAlloc(MemoryContext context, Size size)
}
/* Ensure any padding bytes are marked NOACCESS. */
VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
return AllocChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
@ -799,37 +771,40 @@ AllocSetAlloc(MemoryContext context, Size size)
chunk = set->freelist[fidx];
if (chunk != NULL)
{
Assert(chunk->size >= size);
AllocFreeListLink *link = GetFreeListLink(chunk);
set->freelist[fidx] = (AllocChunk) chunk->aset;
Assert(fidx == MemoryChunkGetValue(chunk));
chunk->aset = (void *) set;
/* pop this chunk off the freelist */
VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
set->freelist[fidx] = link->next;
VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk->size)
set_sentinel(AllocChunkGetPointer(chunk), size);
if (size < GetChunkSizeFromFreeListIdx(fidx))
set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) AllocChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
chunk->size - size);
VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
GetChunkSizeFromFreeListIdx(fidx) - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
return AllocChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
* Choose the actual chunk size to allocate.
*/
chunk_size = (1 << ALLOC_MINBITS) << fidx;
chunk_size = GetChunkSizeFromFreeListIdx(fidx);
Assert(chunk_size >= size);
/*
@ -856,6 +831,7 @@ AllocSetAlloc(MemoryContext context, Size size)
*/
while (availspace >= ((1 << ALLOC_MINBITS) + ALLOC_CHUNKHDRSZ))
{
AllocFreeListLink *link;
Size availchunk = availspace - ALLOC_CHUNKHDRSZ;
int a_fidx = AllocSetFreeIndex(availchunk);
@ -864,29 +840,34 @@ AllocSetAlloc(MemoryContext context, Size size)
* freelist than the one we need to put this chunk on. The
* exception is when availchunk is exactly a power of 2.
*/
if (availchunk != ((Size) 1 << (a_fidx + ALLOC_MINBITS)))
if (availchunk != GetChunkSizeFromFreeListIdx(a_fidx))
{
a_fidx--;
Assert(a_fidx >= 0);
availchunk = ((Size) 1 << (a_fidx + ALLOC_MINBITS));
availchunk = GetChunkSizeFromFreeListIdx(a_fidx);
}
chunk = (AllocChunk) (block->freeptr);
chunk = (MemoryChunk *) (block->freeptr);
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
block->freeptr += (availchunk + ALLOC_CHUNKHDRSZ);
availspace -= (availchunk + ALLOC_CHUNKHDRSZ);
chunk->size = availchunk;
/* store the freelist index in the value field */
MemoryChunkSetHdrMask(chunk, block, a_fidx, MCTX_ASET_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = 0; /* mark it free */
chunk->requested_size = InvalidAllocSize; /* mark it free */
#endif
chunk->aset = (void *) set->freelist[a_fidx];
/* push this chunk onto the free list */
link = GetFreeListLink(chunk);
VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
link->next = set->freelist[a_fidx];
VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
set->freelist[a_fidx] = chunk;
}
/* Mark that we need to create a new block */
block = NULL;
}
@ -954,7 +935,7 @@ AllocSetAlloc(MemoryContext context, Size size)
/*
* OK, do the allocation
*/
chunk = (AllocChunk) (block->freeptr);
chunk = (MemoryChunk *) (block->freeptr);
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
@ -962,67 +943,68 @@ AllocSetAlloc(MemoryContext context, Size size)
block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
Assert(block->freeptr <= block->endptr);
chunk->aset = (void *) set;
chunk->size = chunk_size;
/* store the free list index in the value field */
MemoryChunkSetHdrMask(chunk, block, fidx, MCTX_ASET_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk->size)
set_sentinel(AllocChunkGetPointer(chunk), size);
if (size < chunk_size)
set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) AllocChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
return AllocChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
* AllocSetFree
* Frees allocated memory; memory is removed from the set.
*/
static void
AllocSetFree(MemoryContext context, void *pointer)
void
AllocSetFree(void *pointer)
{
AllocSet set = (AllocSet) context;
AllocChunk chunk = AllocPointerGetChunk(pointer);
AllocSet set;
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
if (MemoryChunkIsExternal(chunk))
{
AllocBlock block = ExternalChunkGetBlock(chunk);
set = block->aset;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < chunk->size)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
{
Size chunk_size = block->endptr - (char *) pointer;
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < chunk_size)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
}
#endif
if (chunk->size > set->allocChunkLimit)
{
/*
* Big chunks are certain to have been allocated as single-chunk
* blocks. Just unlink that block and return it to malloc().
*/
AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
/*
* Try to verify that we have a sane block pointer: it should
* reference the correct aset, and freeptr and endptr should point
* just past the chunk.
* Try to verify that we have a sane block pointer, the freeptr should
* match the endptr.
*/
if (block->aset != set ||
block->freeptr != block->endptr ||
block->freeptr != ((char *) block) +
(chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
if (block->freeptr != block->endptr)
elog(ERROR, "could not find block containing chunk %p", chunk);
/* OK, remove block from aset's list and free it */
@ -1033,7 +1015,7 @@ AllocSetFree(MemoryContext context, void *pointer)
if (block->next)
block->next->prev = block->prev;
context->mem_allocated -= block->endptr - ((char *) block);
set->header.mem_allocated -= block->endptr - ((char *) block);
#ifdef CLOBBER_FREED_MEMORY
wipe_mem(block, block->freeptr - ((char *) block));
@ -1042,20 +1024,37 @@ AllocSetFree(MemoryContext context, void *pointer)
}
else
{
/* Normal case, put the chunk into appropriate freelist */
int fidx = AllocSetFreeIndex(chunk->size);
int fidx = MemoryChunkGetValue(chunk);
AllocBlock block = MemoryChunkGetBlock(chunk);
AllocFreeListLink *link = GetFreeListLink(chunk);
chunk->aset = (void *) set->freelist[fidx];
#ifdef CLOBBER_FREED_MEMORY
wipe_mem(pointer, chunk->size);
#endif
set = block->aset;
#ifdef MEMORY_CONTEXT_CHECKING
/* Reset requested_size to 0 in chunks that are on freelist */
chunk->requested_size = 0;
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < GetChunkSizeFromFreeListIdx(fidx))
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
#endif
#ifdef CLOBBER_FREED_MEMORY
wipe_mem(pointer, GetChunkSizeFromFreeListIdx(fidx));
#endif
/* push this chunk onto the top of the free list */
VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
link->next = set->freelist[fidx];
VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
set->freelist[fidx] = chunk;
#ifdef MEMORY_CONTEXT_CHECKING
/*
* Reset requested_size to InvalidAllocSize in chunks that are on free
* list.
*/
chunk->requested_size = InvalidAllocSize;
#endif
}
}
@ -1071,57 +1070,48 @@ AllocSetFree(MemoryContext context, void *pointer)
* (In principle, we could use VALGRIND_GET_VBITS() to rediscover the old
* request size.)
*/
static void *
AllocSetRealloc(MemoryContext context, void *pointer, Size size)
void *
AllocSetRealloc(void *pointer, Size size)
{
AllocSet set = (AllocSet) context;
AllocChunk chunk = AllocPointerGetChunk(pointer);
AllocBlock block;
AllocSet set;
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
Size oldsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
oldsize = chunk->size;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < oldsize)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
#endif
if (oldsize > set->allocChunkLimit)
if (MemoryChunkIsExternal(chunk))
{
/*
* The chunk must have been allocated as a single-chunk block. Use
* realloc() to make the containing block bigger, or smaller, with
* minimum space wastage.
*/
AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
Size chksize;
Size blksize;
Size oldblksize;
/*
* Try to verify that we have a sane block pointer: it should
* reference the correct aset, and freeptr and endptr should point
* just past the chunk.
*/
if (block->aset != set ||
block->freeptr != block->endptr ||
block->freeptr != ((char *) block) +
(oldsize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
elog(ERROR, "could not find block containing chunk %p", chunk);
block = ExternalChunkGetBlock(chunk);
oldsize = block->endptr - (char *) pointer;
set = block->aset;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < oldsize)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
#endif
/*
* Even if the new request is less than set->allocChunkLimit, we stick
* with the single-chunk block approach. Therefore we need
* chunk->size to be bigger than set->allocChunkLimit, so we don't get
* confused about the chunk's status in future calls.
* Try to verify that we have a sane block pointer, the freeptr should
* match the endptr.
*/
chksize = Max(size, set->allocChunkLimit + 1);
chksize = MAXALIGN(chksize);
if (block->freeptr != block->endptr)
elog(ERROR, "could not find block containing chunk %p", chunk);
chksize = MAXALIGN(size);
/* Do the realloc */
blksize = chksize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
@ -1136,21 +1126,20 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
}
/* updated separately, not to underflow when (oldblksize > blksize) */
context->mem_allocated -= oldblksize;
context->mem_allocated += blksize;
set->header.mem_allocated -= oldblksize;
set->header.mem_allocated += blksize;
block->freeptr = block->endptr = ((char *) block) + blksize;
/* Update pointers since block has likely been moved */
chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
pointer = AllocChunkGetPointer(chunk);
chunk = (MemoryChunk *) (((char *) block) + ALLOC_BLOCKHDRSZ);
pointer = MemoryChunkGetPointer(chunk);
if (block->prev)
block->prev->next = block;
else
set->blocks = block;
if (block->next)
block->next->prev = block;
chunk->size = chksize;
#ifdef MEMORY_CONTEXT_CHECKING
#ifdef RANDOMIZE_ALLOCATED_MEMORY
@ -1172,9 +1161,8 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
#endif
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk->size)
if (size < chksize)
set_sentinel(pointer, size);
#else /* !MEMORY_CONTEXT_CHECKING */
@ -1195,12 +1183,24 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
return pointer;
}
block = MemoryChunkGetBlock(chunk);
oldsize = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk));
set = block->aset;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < oldsize)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
set->header.name, chunk);
#endif
/*
* Chunk sizes are aligned to power of 2 in AllocSetAlloc(). Maybe the
* allocated area already is >= the new size. (In particular, we will
* fall out here if the requested size is a decrease.)
*/
else if (oldsize >= size)
if (oldsize >= size)
{
#ifdef MEMORY_CONTEXT_CHECKING
Size oldrequest = chunk->requested_size;
@ -1289,34 +1289,59 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size)
memcpy(newPointer, pointer, oldsize);
/* free old chunk */
AllocSetFree((MemoryContext) set, pointer);
AllocSetFree(pointer);
return newPointer;
}
}
/*
* AllocSetGetChunkContext
* Return the MemoryContext that 'pointer' belongs to.
*/
MemoryContext
AllocSetGetChunkContext(void *pointer)
{
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
AllocBlock block;
AllocSet set;
if (MemoryChunkIsExternal(chunk))
block = ExternalChunkGetBlock(chunk);
else
block = (AllocBlock) MemoryChunkGetBlock(chunk);
set = block->aset;
return &set->header;
}
/*
* AllocSetGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
static Size
AllocSetGetChunkSpace(MemoryContext context, void *pointer)
Size
AllocSetGetChunkSpace(void *pointer)
{
AllocChunk chunk = AllocPointerGetChunk(pointer);
Size result;
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
result = chunk->size + ALLOC_CHUNKHDRSZ;
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
return result;
if (MemoryChunkIsExternal(chunk))
{
AllocBlock block = ExternalChunkGetBlock(chunk);
return block->endptr - (char *) chunk;
}
return GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk)) +
ALLOC_CHUNKHDRSZ;
}
/*
* AllocSetIsEmpty
* Is an allocset empty of any allocated space?
*/
static bool
bool
AllocSetIsEmpty(MemoryContext context)
{
/*
@ -1339,7 +1364,7 @@ AllocSetIsEmpty(MemoryContext context)
* totals: if not NULL, add stats about this context into *totals.
* print_to_stderr: print stats to stderr if true, elog otherwise.
*/
static void
void
AllocSetStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals, bool print_to_stderr)
@ -1363,13 +1388,21 @@ AllocSetStats(MemoryContext context,
}
for (fidx = 0; fidx < ALLOCSET_NUM_FREELISTS; fidx++)
{
AllocChunk chunk;
MemoryChunk *chunk = set->freelist[fidx];
for (chunk = set->freelist[fidx]; chunk != NULL;
chunk = (AllocChunk) chunk->aset)
while (chunk != NULL)
{
Size chksz = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk));
AllocFreeListLink *link = GetFreeListLink(chunk);
Assert(GetChunkSizeFromFreeListIdx(fidx) == chksz);
freechunks++;
freespace += chunk->size + ALLOC_CHUNKHDRSZ;
freespace += chksz + ALLOC_CHUNKHDRSZ;
VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
chunk = link->next;
VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
}
}
@ -1404,7 +1437,7 @@ AllocSetStats(MemoryContext context,
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
static void
void
AllocSetCheck(MemoryContext context)
{
AllocSet set = (AllocSet) context;
@ -1421,6 +1454,7 @@ AllocSetCheck(MemoryContext context)
long blk_used = block->freeptr - bpoz;
long blk_data = 0;
long nchunks = 0;
bool has_external_chunk = false;
if (set->keeper == block)
total_allocated += block->endptr - ((char *) set);
@ -1452,46 +1486,51 @@ AllocSetCheck(MemoryContext context)
*/
while (bpoz < block->freeptr)
{
AllocChunk chunk = (AllocChunk) bpoz;
MemoryChunk *chunk = (MemoryChunk *) bpoz;
Size chsize,
dsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
chsize = chunk->size; /* aligned chunk size */
if (MemoryChunkIsExternal(chunk))
{
chsize = block->endptr - (char *) MemoryChunkGetPointer(chunk); /* aligned chunk size */
has_external_chunk = true;
/* make sure this chunk consumes the entire block */
if (chsize + ALLOC_CHUNKHDRSZ != blk_used)
elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
name, chunk, block);
}
else
{
chsize = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk)); /* aligned chunk size */
/*
* Check the stored block offset correctly references this
* block.
*/
if (block != MemoryChunkGetBlock(chunk))
elog(WARNING, "problem in alloc set %s: bad block offset for chunk %p in block %p",
name, chunk, block);
}
dsize = chunk->requested_size; /* real data */
/*
* Check chunk size
*/
if (dsize > chsize)
/* an allocated chunk's requested size must be <= the chsize */
if (dsize != InvalidAllocSize && dsize > chsize)
elog(WARNING, "problem in alloc set %s: req size > alloc size for chunk %p in block %p",
name, chunk, block);
/* chsize must not be smaller than the first freelist's size */
if (chsize < (1 << ALLOC_MINBITS))
elog(WARNING, "problem in alloc set %s: bad size %zu for chunk %p in block %p",
name, chsize, chunk, block);
/* single-chunk block? */
if (chsize > set->allocChunkLimit &&
chsize + ALLOC_CHUNKHDRSZ != blk_used)
elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
name, chunk, block);
/*
* If chunk is allocated, check for correct aset pointer. (If it's
* free, the aset is the freelist pointer, which we can't check as
* easily...) Note this is an incomplete test, since palloc(0)
* produces an allocated chunk with requested_size == 0.
*/
if (dsize > 0 && chunk->aset != (void *) set)
elog(WARNING, "problem in alloc set %s: bogus aset link in block %p, chunk %p",
name, block, chunk);
/*
* Check for overwrite of padding space in an allocated chunk.
*/
if (chunk->aset == (void *) set && dsize < chsize &&
if (dsize != InvalidAllocSize && dsize < chsize &&
!sentinel_ok(chunk, ALLOC_CHUNKHDRSZ + dsize))
elog(WARNING, "problem in alloc set %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);
@ -1500,7 +1539,7 @@ AllocSetCheck(MemoryContext context)
* If chunk is allocated, disallow external access to private part
* of chunk header.
*/
if (chunk->aset == (void *) set)
if (dsize != InvalidAllocSize)
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
blk_data += chsize;
@ -1512,6 +1551,10 @@ AllocSetCheck(MemoryContext context)
if ((blk_data + (nchunks * ALLOC_CHUNKHDRSZ)) != blk_used)
elog(WARNING, "problem in alloc set %s: found inconsistent memory block %p",
name, block);
if (has_external_chunk && nchunks > 1)
elog(WARNING, "problem in alloc set %s: external chunk on non-dedicated block %p",
name, block);
}
Assert(total_allocated == context->mem_allocated);

360
src/backend/utils/mmgr/generation.c
View File

@ -39,15 +39,16 @@
#include "port/pg_bitutils.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_memorychunk.h"
#include "utils/memutils_internal.h"
#define Generation_BLOCKHDRSZ MAXALIGN(sizeof(GenerationBlock))
#define Generation_CHUNKHDRSZ sizeof(GenerationChunk)
#define Generation_CHUNKHDRSZ sizeof(MemoryChunk)
#define Generation_CHUNK_FRACTION 8
typedef struct GenerationBlock GenerationBlock; /* forward reference */
typedef struct GenerationChunk GenerationChunk;
typedef void *GenerationPointer;
@ -77,11 +78,11 @@ typedef struct GenerationContext
/*
* GenerationBlock
* GenerationBlock is the unit of memory that is obtained by generation.c
* from malloc(). It contains zero or more GenerationChunks, which are
* the units requested by palloc() and freed by pfree(). GenerationChunks
* cannot be returned to malloc() individually, instead pfree()
* updates the free counter of the block and when all chunks in a block
* are free the whole block can be returned to malloc().
* from malloc(). It contains zero or more MemoryChunks, which are the
* units requested by palloc() and freed by pfree(). MemoryChunks cannot
* be returned to malloc() individually, instead pfree() updates the free
* counter of the block and when all chunks in a block are free the whole
* block can be returned to malloc().
*
* GenerationBlock is the header data for a block --- the usable space
* within the block begins at the next alignment boundary.
@ -89,6 +90,7 @@ typedef struct GenerationContext
struct GenerationBlock
{
dlist_node node; /* doubly-linked list of blocks */
GenerationContext *context; /* pointer back to the owning context */
Size blksize; /* allocated size of this block */
int nchunks; /* number of chunks in the block */
int nfree; /* number of free chunks */
@ -97,104 +99,36 @@ struct GenerationBlock
};
/*
* GenerationChunk
* The prefix of each piece of memory in a GenerationBlock
*
* Note: to meet the memory context APIs, the payload area of the chunk must
* be maxaligned, and the "context" link must be immediately adjacent to the
* payload area (cf. GetMemoryChunkContext). We simplify matters for this
* module by requiring sizeof(GenerationChunk) to be maxaligned, and then
* we can ensure things work by adding any required alignment padding before
* the pointer fields. There is a static assertion below that the alignment
* is done correctly.
*/
struct GenerationChunk
{
/* size is always the size of the usable space in the chunk */
Size size;
#ifdef MEMORY_CONTEXT_CHECKING
/* when debugging memory usage, also store actual requested size */
/* this is zero in a free chunk */
Size requested_size;
#define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P * 2)
#else
#define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P * 2)
#endif /* MEMORY_CONTEXT_CHECKING */
/* ensure proper alignment by adding padding if needed */
#if (GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
char padding[MAXIMUM_ALIGNOF - GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
#endif
GenerationBlock *block; /* block owning this chunk */
GenerationContext *context; /* owning context, or NULL if freed chunk */
/* there must not be any padding to reach a MAXALIGN boundary here! */
};
/*
* Only the "context" field should be accessed outside this module.
* Only the "hdrmask" field should be accessed outside this module.
* We keep the rest of an allocated chunk's header marked NOACCESS when using
* valgrind. But note that freed chunk headers are kept accessible, for
* simplicity.
*/
#define GENERATIONCHUNK_PRIVATE_LEN offsetof(GenerationChunk, context)
#define GENERATIONCHUNK_PRIVATE_LEN offsetof(MemoryChunk, hdrmask)
/*
* GenerationIsValid
* True iff set is valid allocation set.
*/
#define GenerationIsValid(set) PointerIsValid(set)
#define GenerationPointerGetChunk(ptr) \
((GenerationChunk *)(((char *)(ptr)) - Generation_CHUNKHDRSZ))
#define GenerationChunkGetPointer(chk) \
((GenerationPointer *)(((char *)(chk)) + Generation_CHUNKHDRSZ))
/*
* We always store external chunks on a dedicated block. This makes fetching
* the block from an external chunk easy since it's always the first and only
* chunk on the block.
*/
#define ExternalChunkGetBlock(chunk) \
(GenerationBlock *) ((char *) chunk - Generation_BLOCKHDRSZ)
/* Inlined helper functions */
static inline void GenerationBlockInit(GenerationBlock *block, Size blksize);
static inline void GenerationBlockInit(GenerationContext *context,
GenerationBlock *block,
Size blksize);
static inline bool GenerationBlockIsEmpty(GenerationBlock *block);
static inline void GenerationBlockMarkEmpty(GenerationBlock *block);
static inline Size GenerationBlockFreeBytes(GenerationBlock *block);
static inline void GenerationBlockFree(GenerationContext *set,
GenerationBlock *block);
/*
* These functions implement the MemoryContext API for Generation contexts.
*/
static void *GenerationAlloc(MemoryContext context, Size size);
static void GenerationFree(MemoryContext context, void *pointer);
static void *GenerationRealloc(MemoryContext context, void *pointer, Size size);
static void GenerationReset(MemoryContext context);
static void GenerationDelete(MemoryContext context);
static Size GenerationGetChunkSpace(MemoryContext context, void *pointer);
static bool GenerationIsEmpty(MemoryContext context);
static void GenerationStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
static void GenerationCheck(MemoryContext context);
#endif
/*
* This is the virtual function table for Generation contexts.
*/
static const MemoryContextMethods GenerationMethods = {
GenerationAlloc,
GenerationFree,
GenerationRealloc,
GenerationReset,
GenerationDelete,
GenerationGetChunkSpace,
GenerationIsEmpty,
GenerationStats
#ifdef MEMORY_CONTEXT_CHECKING
,GenerationCheck
#endif
};
/*
* Public routines
@ -223,17 +157,20 @@ GenerationContextCreate(MemoryContext parent,
GenerationContext *set;
GenerationBlock *block;
/* Assert we padded GenerationChunk properly */
/* ensure MemoryChunk's size is properly maxaligned */
StaticAssertStmt(Generation_CHUNKHDRSZ == MAXALIGN(Generation_CHUNKHDRSZ),
"sizeof(GenerationChunk) is not maxaligned");
StaticAssertStmt(offsetof(GenerationChunk, context) + sizeof(MemoryContext) ==
Generation_CHUNKHDRSZ,
"padding calculation in GenerationChunk is wrong");
"sizeof(MemoryChunk) is not maxaligned");
/*
* First, validate allocation parameters. Asserts seem sufficient because
* nobody varies their parameters at runtime. We somewhat arbitrarily
* enforce a minimum 1K block size.
* enforce a minimum 1K block size. We restrict the maximum block size to
* MEMORYCHUNK_MAX_BLOCKOFFSET as MemoryChunks are limited to this in
* regards to addressing the offset between the chunk and the block that
* the chunk is stored on. We would be unable to store the offset between
* the chunk and block for any chunks that were beyond
* MEMORYCHUNK_MAX_BLOCKOFFSET bytes into the block if the block was to be
* larger than this.
*/
Assert(initBlockSize == MAXALIGN(initBlockSize) &&
initBlockSize >= 1024);
@ -244,6 +181,7 @@ GenerationContextCreate(MemoryContext parent,
(minContextSize == MAXALIGN(minContextSize) &&
minContextSize >= 1024 &&
minContextSize <= maxBlockSize));
Assert(maxBlockSize <= MEMORYCHUNK_MAX_BLOCKOFFSET);
/* Determine size of initial block */
allocSize = MAXALIGN(sizeof(GenerationContext)) +
@ -278,7 +216,7 @@ GenerationContextCreate(MemoryContext parent,
block = (GenerationBlock *) (((char *) set) + MAXALIGN(sizeof(GenerationContext)));
/* determine the block size and initialize it */
firstBlockSize = allocSize - MAXALIGN(sizeof(GenerationContext));
GenerationBlockInit(block, firstBlockSize);
GenerationBlockInit(set, block, firstBlockSize);
/* add it to the doubly-linked list of blocks */
dlist_push_head(&set->blocks, &block->node);
@ -300,9 +238,14 @@ GenerationContextCreate(MemoryContext parent,
/*
* Compute the allocation chunk size limit for this context.
*
* Follows similar ideas as AllocSet, see aset.c for details ...
* Limit the maximum size a non-dedicated chunk can be so that we can fit
* at least Generation_CHUNK_FRACTION of chunks this big onto the maximum
* sized block. We must further limit this value so that it's no more
* than MEMORYCHUNK_MAX_VALUE. We're unable to have non-external chunks
* larger than that value as we store the chunk size in the MemoryChunk
* 'value' field in the call to MemoryChunkSetHdrMask().
*/
set->allocChunkLimit = maxBlockSize;
set->allocChunkLimit = Min(maxBlockSize, MEMORYCHUNK_MAX_VALUE);
while ((Size) (set->allocChunkLimit + Generation_CHUNKHDRSZ) >
(Size) ((Size) (maxBlockSize - Generation_BLOCKHDRSZ) / Generation_CHUNK_FRACTION))
set->allocChunkLimit >>= 1;
@ -310,7 +253,7 @@ GenerationContextCreate(MemoryContext parent,
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) set,
T_GenerationContext,
&GenerationMethods,
MCTX_GENERATION_ID,
parent,
name);
@ -326,7 +269,7 @@ GenerationContextCreate(MemoryContext parent,
* The code simply frees all the blocks in the context - we don't keep any
* keeper blocks or anything like that.
*/
static void
void
GenerationReset(MemoryContext context)
{
GenerationContext *set = (GenerationContext *) context;
@ -371,7 +314,7 @@ GenerationReset(MemoryContext context)
* GenerationDelete
* Free all memory which is allocated in the given context.
*/
static void
void
GenerationDelete(MemoryContext context)
{
/* Reset to release all releasable GenerationBlocks */
@ -393,12 +336,12 @@ GenerationDelete(MemoryContext context)
* is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
* return space that is marked NOACCESS - GenerationRealloc has to beware!
*/
static void *
void *
GenerationAlloc(MemoryContext context, Size size)
{
GenerationContext *set = (GenerationContext *) context;
GenerationBlock *block;
GenerationChunk *chunk;
MemoryChunk *chunk;
Size chunk_size = MAXALIGN(size);
Size required_size = chunk_size + Generation_CHUNKHDRSZ;
@ -414,6 +357,7 @@ GenerationAlloc(MemoryContext context, Size size)
context->mem_allocated += blksize;
/* block with a single (used) chunk */
block->context = set;
block->blksize = blksize;
block->nchunks = 1;
block->nfree = 0;
@ -421,33 +365,33 @@ GenerationAlloc(MemoryContext context, Size size)
/* the block is completely full */
block->freeptr = block->endptr = ((char *) block) + blksize;
chunk = (GenerationChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
chunk->block = block;
chunk->context = set;
chunk->size = chunk_size;
chunk = (MemoryChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
/* mark the MemoryChunk as externally managed */
MemoryChunkSetHdrMaskExternal(chunk, MCTX_GENERATION_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk_size)
set_sentinel(GenerationChunkGetPointer(chunk), size);
set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* add the block to the list of allocated blocks */
dlist_push_head(&set->blocks, &block->node);
/* Ensure any padding bytes are marked NOACCESS. */
VALGRIND_MAKE_MEM_NOACCESS((char *) GenerationChunkGetPointer(chunk) + size,
VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
return GenerationChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
@ -516,7 +460,7 @@ GenerationAlloc(MemoryContext context, Size size)
context->mem_allocated += blksize;
/* initialize the new block */
GenerationBlockInit(block, blksize);
GenerationBlockInit(set, block, blksize);
/* add it to the doubly-linked list of blocks */
dlist_push_head(&set->blocks, &block->node);
@ -533,7 +477,7 @@ GenerationAlloc(MemoryContext context, Size size)
Assert(block != NULL);
Assert((block->endptr - block->freeptr) >= Generation_CHUNKHDRSZ + chunk_size);
chunk = (GenerationChunk *) block->freeptr;
chunk = (MemoryChunk *) block->freeptr;
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, Generation_CHUNKHDRSZ);
@ -543,29 +487,26 @@ GenerationAlloc(MemoryContext context, Size size)
Assert(block->freeptr <= block->endptr);
chunk->block = block;
chunk->context = set;
chunk->size = chunk_size;
MemoryChunkSetHdrMask(chunk, block, chunk_size, MCTX_GENERATION_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk->size)
set_sentinel(GenerationChunkGetPointer(chunk), size);
if (size < chunk_size)
set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
VALGRIND_MAKE_MEM_NOACCESS((char *) GenerationChunkGetPointer(chunk) + size,
VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
return GenerationChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
@ -574,8 +515,10 @@ GenerationAlloc(MemoryContext context, Size size)
* mem_allocated field.
*/
static inline void
GenerationBlockInit(GenerationBlock *block, Size blksize)
GenerationBlockInit(GenerationContext *context, GenerationBlock *block,
Size blksize)
{
block->context = context;
block->blksize = blksize;
block->nchunks = 0;
block->nfree = 0;
@ -661,36 +604,49 @@ GenerationBlockFree(GenerationContext *set, GenerationBlock *block)
* Update number of chunks in the block, and if all chunks in the block
* are now free then discard the block.
*/
static void
GenerationFree(MemoryContext context, void *pointer)
void
GenerationFree(void *pointer)
{
GenerationContext *set = (GenerationContext *) context;
GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
GenerationBlock *block;
GenerationContext *set;
#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
Size chunksize;
#endif
if (MemoryChunkIsExternal(chunk))
{
block = ExternalChunkGetBlock(chunk);
#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
chunksize = block->endptr - (char *) pointer;
#endif
}
else
{
block = MemoryChunkGetBlock(chunk);
#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
chunksize = MemoryChunkGetValue(chunk);
#endif
}
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
block = chunk->block;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (chunk->requested_size < chunk->size)
if (chunk->requested_size < chunksize)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
((MemoryContext) set)->name, chunk);
((MemoryContext) block->context)->name, chunk);
#endif
#ifdef CLOBBER_FREED_MEMORY
wipe_mem(pointer, chunk->size);
wipe_mem(pointer, chunksize);
#endif
/* Reset context to NULL in freed chunks */
chunk->context = NULL;
#ifdef MEMORY_CONTEXT_CHECKING
/* Reset requested_size to 0 in freed chunks */
chunk->requested_size = 0;
/* Reset requested_size to InvalidAllocSize in freed chunks */
chunk->requested_size = InvalidAllocSize;
#endif
block->nfree += 1;
@ -702,6 +658,8 @@ GenerationFree(MemoryContext context, void *pointer)
if (block->nfree < block->nchunks)
return;
set = block->context;
/* Don't try to free the keeper block, just mark it empty */
if (block == set->keeper)
{
@ -732,7 +690,7 @@ GenerationFree(MemoryContext context, void *pointer)
*/
dlist_delete(&block->node);
context->mem_allocated -= block->blksize;
set->header.mem_allocated -= block->blksize;
free(block);
}
@ -742,18 +700,30 @@ GenerationFree(MemoryContext context, void *pointer)
* and discard the old one. The only exception is when the new size fits
* into the old chunk - in that case we just update chunk header.
*/
static void *
GenerationRealloc(MemoryContext context, void *pointer, Size size)
void *
GenerationRealloc(void *pointer, Size size)
{
GenerationContext *set = (GenerationContext *) context;
GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
GenerationContext *set;
GenerationBlock *block;
GenerationPointer newPointer;
Size oldsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
oldsize = chunk->size;
if (MemoryChunkIsExternal(chunk))
{
block = ExternalChunkGetBlock(chunk);
oldsize = block->endptr - (char *) pointer;
}
else
{
block = MemoryChunkGetBlock(chunk);
oldsize = MemoryChunkGetValue(chunk);
}
set = block->context;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
@ -848,33 +818,57 @@ GenerationRealloc(MemoryContext context, void *pointer, Size size)
memcpy(newPointer, pointer, oldsize);
/* free old chunk */
GenerationFree((MemoryContext) set, pointer);
GenerationFree(pointer);
return newPointer;
}
/*
* GenerationGetChunkContext
* Return the MemoryContext that 'pointer' belongs to.
*/
MemoryContext
GenerationGetChunkContext(void *pointer)
{
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
GenerationBlock *block;
if (MemoryChunkIsExternal(chunk))
block = ExternalChunkGetBlock(chunk);
else
block = (GenerationBlock *) MemoryChunkGetBlock(chunk);
return &block->context->header;
}
/*
* GenerationGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
static Size
GenerationGetChunkSpace(MemoryContext context, void *pointer)
Size
GenerationGetChunkSpace(void *pointer)
{
GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
Size result;
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
Size chunksize;
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
result = chunk->size + Generation_CHUNKHDRSZ;
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
return result;
if (MemoryChunkIsExternal(chunk))
{
GenerationBlock *block = ExternalChunkGetBlock(chunk);
chunksize = block->endptr - (char *) pointer;
}
else
chunksize = MemoryChunkGetValue(chunk);
return Generation_CHUNKHDRSZ + chunksize;
}
/*
* GenerationIsEmpty
* Is a GenerationContext empty of any allocated space?
*/
static bool
bool
GenerationIsEmpty(MemoryContext context)
{
GenerationContext *set = (GenerationContext *) context;
@ -903,7 +897,7 @@ GenerationIsEmpty(MemoryContext context)
* XXX freespace only accounts for empty space at the end of the block, not
* space of freed chunks (which is unknown).
*/
static void
void
GenerationStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals, bool print_to_stderr)
@ -961,7 +955,7 @@ GenerationStats(MemoryContext context,
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
static void
void
GenerationCheck(MemoryContext context)
{
GenerationContext *gen = (GenerationContext *) context;
@ -976,6 +970,7 @@ GenerationCheck(MemoryContext context)
int nfree,
nchunks;
char *ptr;
bool has_external_chunk = false;
total_allocated += block->blksize;
@ -987,6 +982,11 @@ GenerationCheck(MemoryContext context)
elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p exceeds %d allocated",
name, block->nfree, block, block->nchunks);
/* check block belongs to the correct context */
if (block->context != gen)
elog(WARNING, "problem in Generation %s: bogus context link in block %p",
name, block);
/* Now walk through the chunks and count them. */
nfree = 0;
nchunks = 0;
@ -994,42 +994,47 @@ GenerationCheck(MemoryContext context)
while (ptr < block->freeptr)
{
GenerationChunk *chunk = (GenerationChunk *) ptr;
MemoryChunk *chunk = (MemoryChunk *) ptr;
GenerationBlock *chunkblock;
Size chunksize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
if (MemoryChunkIsExternal(chunk))
{
chunkblock = ExternalChunkGetBlock(chunk);
chunksize = block->endptr - (char *) MemoryChunkGetPointer(chunk);
has_external_chunk = true;
}
else
{
chunkblock = MemoryChunkGetBlock(chunk);
chunksize = MemoryChunkGetValue(chunk);
}
/* move to the next chunk */
ptr += (chunk->size + Generation_CHUNKHDRSZ);
ptr += (chunksize + Generation_CHUNKHDRSZ);
nchunks += 1;
/* chunks have both block and context pointers, so check both */
if (chunk->block != block)
if (chunkblock != block)
elog(WARNING, "problem in Generation %s: bogus block link in block %p, chunk %p",
name, block, chunk);
/*
* Check for valid context pointer. Note this is an incomplete
* test, since palloc(0) produces an allocated chunk with
* requested_size == 0.
*/
if ((chunk->requested_size > 0 && chunk->context != gen) ||
(chunk->context != gen && chunk->context != NULL))
elog(WARNING, "problem in Generation %s: bogus context link in block %p, chunk %p",
name, block, chunk);
/* now make sure the chunk size is correct */
if (chunk->size < chunk->requested_size ||
chunk->size != MAXALIGN(chunk->size))
elog(WARNING, "problem in Generation %s: bogus chunk size in block %p, chunk %p",
name, block, chunk);
/* is chunk allocated? */
if (chunk->context != NULL)
if (chunk->requested_size != InvalidAllocSize)
{
/* check sentinel, but only in allocated blocks */
if (chunk->requested_size < chunk->size &&
/* now make sure the chunk size is correct */
if (chunksize < chunk->requested_size ||
chunksize != MAXALIGN(chunksize))
elog(WARNING, "problem in Generation %s: bogus chunk size in block %p, chunk %p",
name, block, chunk);
/* check sentinel */
if (chunk->requested_size < chunksize &&
!sentinel_ok(chunk, Generation_CHUNKHDRSZ + chunk->requested_size))
elog(WARNING, "problem in Generation %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);
@ -1041,7 +1046,7 @@ GenerationCheck(MemoryContext context)
* If chunk is allocated, disallow external access to private part
* of chunk header.
*/
if (chunk->context != NULL)
if (chunk->requested_size != InvalidAllocSize)
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
}
@ -1056,6 +1061,11 @@ GenerationCheck(MemoryContext context)
if (nfree != block->nfree)
elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p does not match header %d",
name, nfree, block, block->nfree);
if (has_external_chunk && nchunks > 1)
elog(WARNING, "problem in Generation %s: external chunk on non-dedicated block %p",
name, block);
}
Assert(total_allocated == context->mem_allocated);

93
src/backend/utils/mmgr/mcxt.c
View File

@ -29,12 +29,57 @@
#include "utils/fmgrprotos.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_internal.h"
/*****************************************************************************
* GLOBAL MEMORY *
*****************************************************************************/
static const MemoryContextMethods mcxt_methods[] = {
/* aset.c */
[MCTX_ASET_ID].alloc = AllocSetAlloc,
[MCTX_ASET_ID].free_p = AllocSetFree,
[MCTX_ASET_ID].realloc = AllocSetRealloc,
[MCTX_ASET_ID].reset = AllocSetReset,
[MCTX_ASET_ID].delete_context = AllocSetDelete,
[MCTX_ASET_ID].get_chunk_context = AllocSetGetChunkContext,
[MCTX_ASET_ID].get_chunk_space = AllocSetGetChunkSpace,
[MCTX_ASET_ID].is_empty = AllocSetIsEmpty,
[MCTX_ASET_ID].stats = AllocSetStats,
#ifdef MEMORY_CONTEXT_CHECKING
[MCTX_ASET_ID].check = AllocSetCheck,
#endif
/* generation.c */
[MCTX_GENERATION_ID].alloc = GenerationAlloc,
[MCTX_GENERATION_ID].free_p = GenerationFree,
[MCTX_GENERATION_ID].realloc = GenerationRealloc,
[MCTX_GENERATION_ID].reset = GenerationReset,
[MCTX_GENERATION_ID].delete_context = GenerationDelete,
[MCTX_GENERATION_ID].get_chunk_context = GenerationGetChunkContext,
[MCTX_GENERATION_ID].get_chunk_space = GenerationGetChunkSpace,
[MCTX_GENERATION_ID].is_empty = GenerationIsEmpty,
[MCTX_GENERATION_ID].stats = GenerationStats,
#ifdef MEMORY_CONTEXT_CHECKING
[MCTX_GENERATION_ID].check = GenerationCheck,
#endif
/* slab.c */
[MCTX_SLAB_ID].alloc = SlabAlloc,
[MCTX_SLAB_ID].free_p = SlabFree,
[MCTX_SLAB_ID].realloc = SlabRealloc,
[MCTX_SLAB_ID].reset = SlabReset,
[MCTX_SLAB_ID].delete_context = SlabDelete,
[MCTX_SLAB_ID].get_chunk_context = SlabGetChunkContext,
[MCTX_SLAB_ID].get_chunk_space = SlabGetChunkSpace,
[MCTX_SLAB_ID].is_empty = SlabIsEmpty,
[MCTX_SLAB_ID].stats = SlabStats
#ifdef MEMORY_CONTEXT_CHECKING
,[MCTX_SLAB_ID].check = SlabCheck
#endif
};
/*
* CurrentMemoryContext
* Default memory context for allocations.
@ -73,6 +118,13 @@ static void MemoryContextStatsPrint(MemoryContext context, void *passthru,
#define AssertNotInCriticalSection(context) \
Assert(CritSectionCount == 0 || (context)->allowInCritSection)
/*
* Call the given function in the MemoryContextMethods for the memory context
* type that 'pointer' belongs to.
*/
#define MCXT_METHOD(pointer, method) \
mcxt_methods[GetMemoryChunkMethodID(pointer)].method
/*****************************************************************************
* EXPORTED ROUTINES *
@ -422,6 +474,17 @@ MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
context->allowInCritSection = allow;
}
/*
* GetMemoryChunkContext
* Given a currently-allocated chunk, determine the MemoryContext that
* the chunk belongs to.
*/
MemoryContext
GetMemoryChunkContext(void *pointer)
{
return MCXT_METHOD(pointer, get_chunk_context) (pointer);
}
/*
* GetMemoryChunkSpace
* Given a currently-allocated chunk, determine the total space
@ -433,9 +496,7 @@ MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
Size
GetMemoryChunkSpace(void *pointer)
{
MemoryContext context = GetMemoryChunkContext(pointer);
return context->methods->get_chunk_space(context, pointer);
return MCXT_METHOD(pointer, get_chunk_space) (pointer);
}
/*
@ -804,7 +865,7 @@ MemoryContextContains(MemoryContext context, void *pointer)
*
* node: the as-yet-uninitialized common part of the context header node.
* tag: NodeTag code identifying the memory context type.
* methods: context-type-specific methods (usually statically allocated).
* method_id: MemoryContextMethodID of the context-type being created.
* parent: parent context, or NULL if this will be a top-level context.
* name: name of context (must be statically allocated).
*
@ -814,7 +875,7 @@ MemoryContextContains(MemoryContext context, void *pointer)
void
MemoryContextCreate(MemoryContext node,
NodeTag tag,
const MemoryContextMethods *methods,
MemoryContextMethodID method_id,
MemoryContext parent,
const char *name)
{
@ -824,7 +885,7 @@ MemoryContextCreate(MemoryContext node,
/* Initialize all standard fields of memory context header */
node->type = tag;
node->isReset = true;
node->methods = methods;
node->methods = &mcxt_methods[method_id];
node->parent = parent;
node->firstchild = NULL;
node->mem_allocated = 0;
@ -1174,9 +1235,11 @@ palloc_extended(Size size, int flags)
void
pfree(void *pointer)
{
#ifdef USE_VALGRIND
MemoryContext context = GetMemoryChunkContext(pointer);
#endif
context->methods->free_p(context, pointer);
MCXT_METHOD(pointer, free_p) (pointer);
VALGRIND_MEMPOOL_FREE(context, pointer);
}
@ -1187,7 +1250,9 @@ pfree(void *pointer)
void *
repalloc(void *pointer, Size size)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
#endif
void *ret;
if (!AllocSizeIsValid(size))
@ -1198,15 +1263,17 @@ repalloc(void *pointer, Size size)
/* isReset must be false already */
Assert(!context->isReset);
ret = context->methods->realloc(context, pointer, size);
ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
MemoryContext cxt = GetMemoryChunkContext(pointer);
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
size, context->name)));
size, cxt->name)));
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
@ -1257,7 +1324,9 @@ MemoryContextAllocHuge(MemoryContext context, Size size)
void *
repalloc_huge(void *pointer, Size size)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
#endif
void *ret;
if (!AllocHugeSizeIsValid(size))
@ -1268,15 +1337,17 @@ repalloc_huge(void *pointer, Size size)
/* isReset must be false already */
Assert(!context->isReset);
ret = context->methods->realloc(context, pointer, size);
ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
MemoryContext cxt = GetMemoryChunkContext(pointer);
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
size, context->name)));
size, cxt->name)));
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);

198
src/backend/utils/mmgr/slab.c
View File

@ -55,6 +55,8 @@
#include "lib/ilist.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_memorychunk.h"
#include "utils/memutils_internal.h"
/*
* SlabContext is a specialized implementation of MemoryContext.
@ -90,75 +92,23 @@ typedef struct SlabBlock
dlist_node node; /* doubly-linked list */
int nfree; /* number of free chunks */
int firstFreeChunk; /* index of the first free chunk in the block */
SlabContext *slab; /* owning context */
} SlabBlock;
/*
* SlabChunk
* The prefix of each piece of memory in a SlabBlock
*
* Note: to meet the memory context APIs, the payload area of the chunk must
* be maxaligned, and the "slab" link must be immediately adjacent to the
* payload area (cf. GetMemoryChunkContext). Since we support no machines on
* which MAXALIGN is more than twice sizeof(void *), this happens without any
* special hacking in this struct declaration. But there is a static
* assertion below that the alignment is done correctly.
*/
typedef struct SlabChunk
{
SlabBlock *block; /* block owning this chunk */
SlabContext *slab; /* owning context */
/* there must not be any padding to reach a MAXALIGN boundary here! */
} SlabChunk;
#define Slab_CHUNKHDRSZ sizeof(MemoryChunk)
#define SlabPointerGetChunk(ptr) \
((SlabChunk *)(((char *)(ptr)) - sizeof(SlabChunk)))
((MemoryChunk *)(((char *)(ptr)) - sizeof(MemoryChunk)))
#define SlabChunkGetPointer(chk) \
((void *)(((char *)(chk)) + sizeof(SlabChunk)))
((void *)(((char *)(chk)) + sizeof(MemoryChunk)))
#define SlabBlockGetChunk(slab, block, idx) \
((SlabChunk *) ((char *) (block) + sizeof(SlabBlock) \
((MemoryChunk *) ((char *) (block) + sizeof(SlabBlock) \
+ (idx * slab->fullChunkSize)))
#define SlabBlockStart(block) \
((char *) block + sizeof(SlabBlock))
#define SlabChunkIndex(slab, block, chunk) \
(((char *) chunk - SlabBlockStart(block)) / slab->fullChunkSize)
/*
* These functions implement the MemoryContext API for Slab contexts.
*/
static void *SlabAlloc(MemoryContext context, Size size);
static void SlabFree(MemoryContext context, void *pointer);
static void *SlabRealloc(MemoryContext context, void *pointer, Size size);
static void SlabReset(MemoryContext context);
static void SlabDelete(MemoryContext context);
static Size SlabGetChunkSpace(MemoryContext context, void *pointer);
static bool SlabIsEmpty(MemoryContext context);
static void SlabStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
static void SlabCheck(MemoryContext context);
#endif
/*
* This is the virtual function table for Slab contexts.
*/
static const MemoryContextMethods SlabMethods = {
SlabAlloc,
SlabFree,
SlabRealloc,
SlabReset,
SlabDelete,
SlabGetChunkSpace,
SlabIsEmpty,
SlabStats
#ifdef MEMORY_CONTEXT_CHECKING
,SlabCheck
#endif
};
/*
* SlabContextCreate
* Create a new Slab context.
@ -168,8 +118,7 @@ static const MemoryContextMethods SlabMethods = {
* blockSize: allocation block size
* chunkSize: allocation chunk size
*
* The chunkSize may not exceed:
* MAXALIGN_DOWN(SIZE_MAX) - MAXALIGN(sizeof(SlabBlock)) - sizeof(SlabChunk)
* The MAXALIGN(chunkSize) may not exceed MEMORYCHUNK_MAX_VALUE
*/
MemoryContext
SlabContextCreate(MemoryContext parent,
@ -184,19 +133,17 @@ SlabContextCreate(MemoryContext parent,
SlabContext *slab;
int i;
/* Assert we padded SlabChunk properly */
StaticAssertStmt(sizeof(SlabChunk) == MAXALIGN(sizeof(SlabChunk)),
"sizeof(SlabChunk) is not maxaligned");
StaticAssertStmt(offsetof(SlabChunk, slab) + sizeof(MemoryContext) ==
sizeof(SlabChunk),
"padding calculation in SlabChunk is wrong");
/* ensure MemoryChunk's size is properly maxaligned */
StaticAssertStmt(Slab_CHUNKHDRSZ == MAXALIGN(Slab_CHUNKHDRSZ),
"sizeof(MemoryChunk) is not maxaligned");
Assert(MAXALIGN(chunkSize) <= MEMORYCHUNK_MAX_VALUE);
/* Make sure the linked list node fits inside a freed chunk */
if (chunkSize < sizeof(int))
chunkSize = sizeof(int);
/* chunk, including SLAB header (both addresses nicely aligned) */
fullChunkSize = sizeof(SlabChunk) + MAXALIGN(chunkSize);
fullChunkSize = Slab_CHUNKHDRSZ + MAXALIGN(chunkSize);
/* Make sure the block can store at least one chunk. */
if (blockSize < fullChunkSize + sizeof(SlabBlock))
@ -265,7 +212,7 @@ SlabContextCreate(MemoryContext parent,
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) slab,
T_SlabContext,
&SlabMethods,
MCTX_SLAB_ID,
parent,
name);
@ -279,7 +226,7 @@ SlabContextCreate(MemoryContext parent,
* The code simply frees all the blocks in the context - we don't keep any
* keeper blocks or anything like that.
*/
static void
void
SlabReset(MemoryContext context)
{
int i;
@ -322,7 +269,7 @@ SlabReset(MemoryContext context)
* SlabDelete
* Free all memory which is allocated in the given context.
*/
static void
void
SlabDelete(MemoryContext context)
{
/* Reset to release all the SlabBlocks */
@ -336,12 +283,12 @@ SlabDelete(MemoryContext context)
* Returns pointer to allocated memory of given size or NULL if
* request could not be completed; memory is added to the slab.
*/
static void *
void *
SlabAlloc(MemoryContext context, Size size)
{
SlabContext *slab = castNode(SlabContext, context);
SlabBlock *block;
SlabChunk *chunk;
MemoryChunk *chunk;
int idx;
Assert(slab);
@ -370,6 +317,7 @@ SlabAlloc(MemoryContext context, Size size)
block->nfree = slab->chunksPerBlock;
block->firstFreeChunk = 0;
block->slab = slab;
/*
* Put all the chunks on a freelist. Walk the chunks and point each
@ -378,7 +326,7 @@ SlabAlloc(MemoryContext context, Size size)
for (idx = 0; idx < slab->chunksPerBlock; idx++)
{
chunk = SlabBlockGetChunk(slab, block, idx);
*(int32 *) SlabChunkGetPointer(chunk) = (idx + 1);
*(int32 *) MemoryChunkGetPointer(chunk) = (idx + 1);
}
/*
@ -426,8 +374,8 @@ SlabAlloc(MemoryContext context, Size size)
* Remove the chunk from the freelist head. The index of the next free
* chunk is stored in the chunk itself.
*/
VALGRIND_MAKE_MEM_DEFINED(SlabChunkGetPointer(chunk), sizeof(int32));
block->firstFreeChunk = *(int32 *) SlabChunkGetPointer(chunk);
VALGRIND_MAKE_MEM_DEFINED(MemoryChunkGetPointer(chunk), sizeof(int32));
block->firstFreeChunk = *(int32 *) MemoryChunkGetPointer(chunk);
Assert(block->firstFreeChunk >= 0);
Assert(block->firstFreeChunk <= slab->chunksPerBlock);
@ -464,47 +412,47 @@ SlabAlloc(MemoryContext context, Size size)
slab->minFreeChunks = 0;
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, sizeof(SlabChunk));
chunk->block = block;
chunk->slab = slab;
VALGRIND_MAKE_MEM_UNDEFINED(chunk, Slab_CHUNKHDRSZ);
MemoryChunkSetHdrMask(chunk, block, MAXALIGN(slab->chunkSize),
MCTX_SLAB_ID);
#ifdef MEMORY_CONTEXT_CHECKING
/* slab mark to catch clobber of "unused" space */
if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
{
set_sentinel(SlabChunkGetPointer(chunk), size);
set_sentinel(MemoryChunkGetPointer(chunk), size);
VALGRIND_MAKE_MEM_NOACCESS(((char *) chunk) +
sizeof(SlabChunk) + slab->chunkSize,
Slab_CHUNKHDRSZ + slab->chunkSize,
slab->fullChunkSize -
(slab->chunkSize + sizeof(SlabChunk)));
(slab->chunkSize + Slab_CHUNKHDRSZ));
}
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
randomize_mem((char *) SlabChunkGetPointer(chunk), size);
randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
Assert(slab->nblocks * slab->blockSize == context->mem_allocated);
return SlabChunkGetPointer(chunk);
return MemoryChunkGetPointer(chunk);
}
/*
* SlabFree
* Frees allocated memory; memory is removed from the slab.
*/
static void
SlabFree(MemoryContext context, void *pointer)
void
SlabFree(void *pointer)
{
int idx;
SlabContext *slab = castNode(SlabContext, context);
SlabChunk *chunk = SlabPointerGetChunk(pointer);
SlabBlock *block = chunk->block;
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
SlabBlock *block = MemoryChunkGetBlock(chunk);
SlabContext *slab = block->slab;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
if (!sentinel_ok(pointer, slab->chunkSize))
elog(WARNING, "detected write past chunk end in %s %p",
slab->header.name, chunk);
@ -560,13 +508,13 @@ SlabFree(MemoryContext context, void *pointer)
{
free(block);
slab->nblocks--;
context->mem_allocated -= slab->blockSize;
slab->header.mem_allocated -= slab->blockSize;
}
else
dlist_push_head(&slab->freelist[block->nfree], &block->node);
Assert(slab->nblocks >= 0);
Assert(slab->nblocks * slab->blockSize == context->mem_allocated);
Assert(slab->nblocks * slab->blockSize == slab->header.mem_allocated);
}
/*
@ -582,13 +530,14 @@ SlabFree(MemoryContext context, void *pointer)
* rather pointless - Slab is meant for chunks of constant size, and moreover
* realloc is usually used to enlarge the chunk.
*/
static void *
SlabRealloc(MemoryContext context, void *pointer, Size size)
void *
SlabRealloc(void *pointer, Size size)
{
SlabContext *slab = castNode(SlabContext, context);
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
SlabBlock *block = MemoryChunkGetBlock(chunk);
SlabContext *slab = block->slab;
Assert(slab);
/* can't do actual realloc with slab, but let's try to be gentle */
if (size == slab->chunkSize)
return pointer;
@ -597,15 +546,33 @@ SlabRealloc(MemoryContext context, void *pointer, Size size)
return NULL; /* keep compiler quiet */
}
/*
* SlabGetChunkContext
* Return the MemoryContext that 'pointer' belongs to.
*/
MemoryContext
SlabGetChunkContext(void *pointer)
{
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
SlabBlock *block = MemoryChunkGetBlock(chunk);
SlabContext *slab = block->slab;
Assert(slab != NULL);
return &slab->header;
}
/*
* SlabGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
static Size
SlabGetChunkSpace(MemoryContext context, void *pointer)
Size
SlabGetChunkSpace(void *pointer)
{
SlabContext *slab = castNode(SlabContext, context);
MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
SlabBlock *block = MemoryChunkGetBlock(chunk);
SlabContext *slab = block->slab;
Assert(slab);
@ -616,7 +583,7 @@ SlabGetChunkSpace(MemoryContext context, void *pointer)
* SlabIsEmpty
* Is an Slab empty of any allocated space?
*/
static bool
bool
SlabIsEmpty(MemoryContext context)
{
SlabContext *slab = castNode(SlabContext, context);
@ -635,7 +602,7 @@ SlabIsEmpty(MemoryContext context)
* totals: if not NULL, add stats about this context into *totals.
* print_to_stderr: print stats to stderr if true, elog otherwise.
*/
static void
void
SlabStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
@ -697,7 +664,7 @@ SlabStats(MemoryContext context,
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
static void
void
SlabCheck(MemoryContext context)
{
int i;
@ -728,6 +695,11 @@ SlabCheck(MemoryContext context)
elog(WARNING, "problem in slab %s: number of free chunks %d in block %p does not match freelist %d",
name, block->nfree, block, i);
/* make sure the slab pointer correctly points to this context */
if (block->slab != slab)
elog(WARNING, "problem in slab %s: bogus slab link in block %p",
name, block);
/* reset the bitmap of free chunks for this block */
memset(slab->freechunks, 0, (slab->chunksPerBlock * sizeof(bool)));
idx = block->firstFreeChunk;
@ -742,7 +714,7 @@ SlabCheck(MemoryContext context)
nfree = 0;
while (idx < slab->chunksPerBlock)
{
SlabChunk *chunk;
MemoryChunk *chunk;
/* count the chunk as free, add it to the bitmap */
nfree++;
@ -750,8 +722,8 @@ SlabCheck(MemoryContext context)
/* read index of the next free chunk */
chunk = SlabBlockGetChunk(slab, block, idx);
VALGRIND_MAKE_MEM_DEFINED(SlabChunkGetPointer(chunk), sizeof(int32));
idx = *(int32 *) SlabChunkGetPointer(chunk);
VALGRIND_MAKE_MEM_DEFINED(MemoryChunkGetPointer(chunk), sizeof(int32));
idx = *(int32 *) MemoryChunkGetPointer(chunk);
}
for (j = 0; j < slab->chunksPerBlock; j++)
@ -759,19 +731,19 @@ SlabCheck(MemoryContext context)
/* non-zero bit in the bitmap means chunk the chunk is used */
if (!slab->freechunks[j])
{
SlabChunk *chunk = SlabBlockGetChunk(slab, block, j);
MemoryChunk *chunk = SlabBlockGetChunk(slab, block, j);
SlabBlock *chunkblock = (SlabBlock *) MemoryChunkGetBlock(chunk);
/* chunks have both block and slab pointers, so check both */
if (chunk->block != block)
/*
* check the chunk's blockoffset correctly points back to
* the block
*/
if (chunkblock != block)
elog(WARNING, "problem in slab %s: bogus block link in block %p, chunk %p",
name, block, chunk);
if (chunk->slab != slab)
elog(WARNING, "problem in slab %s: bogus slab link in block %p, chunk %p",
name, block, chunk);
/* there might be sentinel (thanks to alignment) */
if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
if (!sentinel_ok(chunk, slab->chunkSize))
elog(WARNING, "problem in slab %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);

7
src/include/nodes/memnodes.h
View File

@ -59,11 +59,12 @@ typedef struct MemoryContextMethods
{
void *(*alloc) (MemoryContext context, Size size);
/* call this free_p in case someone #define's free() */
void (*free_p) (MemoryContext context, void *pointer);
void *(*realloc) (MemoryContext context, void *pointer, Size size);
void (*free_p) (void *pointer);
void *(*realloc) (void *pointer, Size size);
void (*reset) (MemoryContext context);
void (*delete_context) (MemoryContext context);
Size (*get_chunk_space) (MemoryContext context, void *pointer);
MemoryContext (*get_chunk_context) (void *pointer);
Size (*get_chunk_space) (void *pointer);
bool (*is_empty) (MemoryContext context);
void (*stats) (MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,

51
src/include/utils/memutils.h
View File

@ -41,8 +41,11 @@
#define AllocSizeIsValid(size) ((Size) (size) <= MaxAllocSize)
/* Must be less than SIZE_MAX */
#define MaxAllocHugeSize (SIZE_MAX / 2)
#define InvalidAllocSize SIZE_MAX
#define AllocHugeSizeIsValid(size) ((Size) (size) <= MaxAllocHugeSize)
@ -79,6 +82,7 @@ extern void MemoryContextDeleteChildren(MemoryContext context);
extern void MemoryContextSetIdentifier(MemoryContext context, const char *id);
extern void MemoryContextSetParent(MemoryContext context,
MemoryContext new_parent);
extern MemoryContext GetMemoryChunkContext(void *pointer);
extern Size GetMemoryChunkSpace(void *pointer);
extern MemoryContext MemoryContextGetParent(MemoryContext context);
extern bool MemoryContextIsEmpty(MemoryContext context);
@ -98,53 +102,6 @@ extern bool MemoryContextContains(MemoryContext context, void *pointer);
#define MemoryContextCopyAndSetIdentifier(cxt, id) \
MemoryContextSetIdentifier(cxt, MemoryContextStrdup(cxt, id))
/*
* GetMemoryChunkContext
* Given a currently-allocated chunk, determine the context
* it belongs to.
*
* All chunks allocated by any memory context manager are required to be
* preceded by the corresponding MemoryContext stored, without padding, in the
* preceding sizeof(void*) bytes. A currently-allocated chunk must contain a
* backpointer to its owning context. The backpointer is used by pfree() and
* repalloc() to find the context to call.
*/
#ifndef FRONTEND
static inline MemoryContext
GetMemoryChunkContext(void *pointer)
{
MemoryContext context;
/*
* Try to detect bogus pointers handed to us, poorly though we can.
* Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
* allocated chunk.
*/
Assert(pointer != NULL);
Assert(pointer == (void *) MAXALIGN(pointer));
/*
* OK, it's probably safe to look at the context.
*/
context = *(MemoryContext *) (((char *) pointer) - sizeof(void *));
AssertArg(MemoryContextIsValid(context));
return context;
}
#endif
/*
* This routine handles the context-type-independent part of memory
* context creation. It's intended to be called from context-type-
* specific creation routines, and noplace else.
*/
extern void MemoryContextCreate(MemoryContext node,
NodeTag tag,
const MemoryContextMethods *methods,
MemoryContext parent,
const char *name);
extern void HandleLogMemoryContextInterrupt(void);
extern void ProcessLogMemoryContextInterrupt(void);

127
src/include/utils/memutils_internal.h Normal file
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@ -0,0 +1,127 @@
/*-------------------------------------------------------------------------
*
* memutils_internal.h
* This file contains declarations for memory allocation utility
* functions for internal use.
*
*
* Portions Copyright (c) 2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/memutils_internal.h
*
*-------------------------------------------------------------------------
*/
#ifndef MEMUTILS_INTERNAL_H
#define MEMUTILS_INTERNAL_H
#include "utils/memutils.h"
/* These functions implement the MemoryContext API for AllocSet context. */
extern void *AllocSetAlloc(MemoryContext context, Size size);
extern void AllocSetFree(void *pointer);
extern void *AllocSetRealloc(void *pointer, Size size);
extern void AllocSetReset(MemoryContext context);
extern void AllocSetDelete(MemoryContext context);
extern MemoryContext AllocSetGetChunkContext(void *pointer);
extern Size AllocSetGetChunkSpace(void *pointer);
extern bool AllocSetIsEmpty(MemoryContext context);
extern void AllocSetStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void AllocSetCheck(MemoryContext context);
#endif
/* These functions implement the MemoryContext API for Generation context. */
extern void *GenerationAlloc(MemoryContext context, Size size);
extern void GenerationFree(void *pointer);
extern void *GenerationRealloc(void *pointer, Size size);
extern void GenerationReset(MemoryContext context);
extern void GenerationDelete(MemoryContext context);
extern MemoryContext GenerationGetChunkContext(void *pointer);
extern Size GenerationGetChunkSpace(void *pointer);
extern bool GenerationIsEmpty(MemoryContext context);
extern void GenerationStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void GenerationCheck(MemoryContext context);
#endif
/* These functions implement the MemoryContext API for Slab context. */
extern void *SlabAlloc(MemoryContext context, Size size);
extern void SlabFree(void *pointer);
extern void *SlabRealloc(void *pointer, Size size);
extern void SlabReset(MemoryContext context);
extern void SlabDelete(MemoryContext context);
extern MemoryContext SlabGetChunkContext(void *pointer);
extern Size SlabGetChunkSpace(void *pointer);
extern bool SlabIsEmpty(MemoryContext context);
extern void SlabStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void SlabCheck(MemoryContext context);
#endif
/*
* MemoryContextMethodID
* A unique identifier for each MemoryContext implementation which
* indicates the index into the mcxt_methods[] array. See mcxt.c.
*/
typedef enum MemoryContextMethodID
{
MCTX_ASET_ID,
MCTX_GENERATION_ID,
MCTX_SLAB_ID,
} MemoryContextMethodID;
/*
* The number of bits that 8-byte memory chunk headers can use to encode the
* MemoryContextMethodID.
*/
#define MEMORY_CONTEXT_METHODID_BITS 3
#define MEMORY_CONTEXT_METHODID_MASK \
UINT64CONST((1 << MEMORY_CONTEXT_METHODID_BITS) - 1)
/*
* This routine handles the context-type-independent part of memory
* context creation. It's intended to be called from context-type-
* specific creation routines, and noplace else.
*/
extern void MemoryContextCreate(MemoryContext node,
NodeTag tag,
MemoryContextMethodID method_id,
MemoryContext parent,
const char *name);
/*
* GetMemoryChunkMethodID
* Return the MemoryContextMethodID from the uint64 chunk header which
* directly precedes 'pointer'.
*/
static inline MemoryContextMethodID
GetMemoryChunkMethodID(void *pointer)
{
uint64 header;
/*
* Try to detect bogus pointers handed to us, poorly though we can.
* Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
* allocated chunk.
*/
Assert(pointer != NULL);
Assert(pointer == (void *) MAXALIGN(pointer));
header = *((uint64 *) ((char *) pointer - sizeof(uint64)));
return (MemoryContextMethodID) (header & MEMORY_CONTEXT_METHODID_MASK);
}
#endif /* MEMUTILS_INTERNAL_H */

237
src/include/utils/memutils_memorychunk.h Normal file
View File

@ -0,0 +1,237 @@
/*-------------------------------------------------------------------------
*
* memutils_memorychunk.h
* Here we define a struct named MemoryChunk which implementations of
* MemoryContexts may use as a header for chunks of memory they allocate.
*
* MemoryChunk provides a lightweight header that a MemoryContext can use to
* store a reference back to the block the which the given chunk is allocated
* on and also an additional 30-bits to store another value such as the size
* of the allocated chunk.
*
* Although MemoryChunks are used by each of our MemoryContexts, future
* implementations may choose to implement their own method for storing chunk
* headers. The only requirement is that the header ends with an 8-byte value
* which the least significant 3-bits of are set to the MemoryContextMethodID
* of the given context.
*
* By default, a MemoryChunk is 8 bytes in size, however, when
* MEMORY_CONTEXT_CHECKING is defined the header becomes 16 bytes in size due
* to the additional requested_size field. The MemoryContext may use this
* field for whatever they wish, but it is intended to be used for additional
* checks which are only done in MEMORY_CONTEXT_CHECKING builds.
*
* The MemoryChunk contains a uint64 field named 'hdrmask'. This field is
* used to encode 4 separate pieces of information. Starting with the least
* significant bits of 'hdrmask', the bit space is reserved as follows:
*
* 1. 3-bits to indicate the MemoryContextMethodID as defined by
* MEMORY_CONTEXT_METHODID_MASK
* 2. 1-bit to denote an "external" chunk (see below)
* 3. 30-bits reserved for the MemoryContext to use for anything it
* requires. Most MemoryContext likely want to store the size of the
* chunk here.
* 4. 30-bits for the number of bytes that must be subtracted from the chunk
* to obtain the address of the block that the chunk is stored on.
*
* In some cases, for example when memory allocations become large, it's
* possible fields 3 and 4 above are not large enough to store the values
* required for the chunk. In this case, the MemoryContext can choose to mark
* the chunk as "external" by calling the MemoryChunkSetExternal() function.
* When this is done, fields 3 and 4 are unavailable for use by the
* MemoryContext and it's up to the MemoryContext itself to devise its own
* method for getting the reference to the block.
*
* Interface:
*
* MemoryChunkSetHdrMask:
* Used to set up a non-external MemoryChunk.
*
* MemoryChunkSetHdrMaskExternal:
* Used to set up an externally managed MemoryChunk.
*
* MemoryChunkIsExternal:
* Determine if the given MemoryChunk is externally managed, i.e.
* MemoryChunkSetHdrMaskExternal() was called on the chunk.
*
* MemoryChunkGetValue:
* For non-external chunks, return the stored 30-bit value as it was set
* in the call to MemoryChunkSetHdrMask().
*
* MemoryChunkGetBlock:
* For non-external chunks, return a pointer to the block as it was set
* in the call to MemoryChunkSetHdrMask().
*
* Also exports:
* MEMORYCHUNK_MAX_VALUE
* MEMORYCHUNK_MAX_BLOCKOFFSET
* PointerGetMemoryChunk
* MemoryChunkGetPointer
*
* Portions Copyright (c) 2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/memutils_memorychunk.h
*
*-------------------------------------------------------------------------
*/
#ifndef MEMUTILS_MEMORYCHUNK_H
#define MEMUTILS_MEMORYCHUNK_H
#include "utils/memutils_internal.h"
/*
* The maximum allowed value that MemoryContexts can store in the value
* field. Must be 1 less than a power of 2.
*/
#define MEMORYCHUNK_MAX_VALUE UINT64CONST(0x3FFFFFFF)
/*
* The maximum distance in bytes that a MemoryChunk can be offset from the
* block that is storing the chunk. Must be 1 less than a power of 2.
*/
#define MEMORYCHUNK_MAX_BLOCKOFFSET UINT64CONST(0x3FFFFFFF)
/* define the least significant base-0 bit of each portion of the hdrmask */
#define MEMORYCHUNK_EXTERNAL_BASEBIT MEMORY_CONTEXT_METHODID_BITS
#define MEMORYCHUNK_VALUE_BASEBIT (MEMORYCHUNK_EXTERNAL_BASEBIT + 1)
#define MEMORYCHUNK_BLOCKOFFSET_BASEBIT (MEMORYCHUNK_VALUE_BASEBIT + 30)
/*
* A magic number for storing in the free bits of an external chunk. This
* must mask out the bits used for storing the MemoryContextMethodID and the
* external bit.
*/
#define MEMORYCHUNK_MAGIC (UINT64CONST(0xB1A8DB858EB6EFBA) >> \
MEMORYCHUNK_VALUE_BASEBIT << \
MEMORYCHUNK_VALUE_BASEBIT)
typedef struct MemoryChunk
{
#ifdef MEMORY_CONTEXT_CHECKING
Size requested_size;
#endif
/* bitfield for storing details about the chunk */
uint64 hdrmask; /* must be last */
} MemoryChunk;
/* Get the MemoryChunk from the pointer */
#define PointerGetMemoryChunk(p) \
((MemoryChunk *) ((char *) (p) - sizeof(MemoryChunk)))
/* Get the pointer from the MemoryChunk */
#define MemoryChunkGetPointer(c) \
((void *) ((char *) (c) + sizeof(MemoryChunk)))
/* private macros for making the inline functions below more simple */
#define HdrMaskIsExternal(hdrmask) \
((hdrmask) & (((uint64) 1) << MEMORYCHUNK_EXTERNAL_BASEBIT))
#define HdrMaskGetValue(hdrmask) \
(((hdrmask) >> MEMORYCHUNK_VALUE_BASEBIT) & MEMORYCHUNK_MAX_VALUE)
/*
* We should have used up all the bits here, so the compiler is likely to
* optimize out the & MEMORYCHUNK_MAX_BLOCKOFFSET.
*/
#define HdrMaskBlockOffset(hdrmask) \
(((hdrmask) >> MEMORYCHUNK_BLOCKOFFSET_BASEBIT) & MEMORYCHUNK_MAX_BLOCKOFFSET)
/* For external chunks only, check the magic number matches */
#define HdrMaskCheckMagic(hdrmask) \
(MEMORYCHUNK_MAGIC == \
((hdrmask) >> MEMORYCHUNK_VALUE_BASEBIT << MEMORYCHUNK_VALUE_BASEBIT))
/*
* MemoryChunkSetHdrMask
* Store the given 'block', 'chunk_size' and 'methodid' in the given
* MemoryChunk.
*
* The number of bytes between 'block' and 'chunk' must be <=
* MEMORYCHUNK_MAX_BLOCKOFFSET.
* 'value' must be <= MEMORYCHUNK_MAX_VALUE.
*/
static inline void
MemoryChunkSetHdrMask(MemoryChunk *chunk, void *block,
Size value, MemoryContextMethodID methodid)
{
Size blockoffset = (char *) chunk - (char *) block;
Assert((char *) chunk > (char *) block);
Assert(blockoffset <= MEMORYCHUNK_MAX_BLOCKOFFSET);
Assert(value <= MEMORYCHUNK_MAX_VALUE);
Assert(methodid <= MEMORY_CONTEXT_METHODID_MASK);
chunk->hdrmask = (((uint64) blockoffset) << MEMORYCHUNK_BLOCKOFFSET_BASEBIT) |
(((uint64) value) << MEMORYCHUNK_VALUE_BASEBIT) |
methodid;
}
/*
* MemoryChunkSetHdrMaskExternal
* Set 'chunk' as an externally managed chunk. Here we only record the
* MemoryContextMethodID and set the external chunk bit.
*/
static inline void
MemoryChunkSetHdrMaskExternal(MemoryChunk *chunk,
MemoryContextMethodID methodid)
{
Assert(methodid <= MEMORY_CONTEXT_METHODID_MASK);
chunk->hdrmask = MEMORYCHUNK_MAGIC | (((uint64) 1) << MEMORYCHUNK_EXTERNAL_BASEBIT) |
methodid;
}
/*
* MemoryChunkIsExternal
* Return true if 'chunk' is marked as external.
*/
static inline bool
MemoryChunkIsExternal(MemoryChunk *chunk)
{
/*
* External chunks should always store MEMORYCHUNK_MAGIC in the upper
* portion of the hdrmask, check that nothing has stomped on that.
*/
Assert(!HdrMaskIsExternal(chunk->hdrmask) ||
HdrMaskCheckMagic(chunk->hdrmask));
return HdrMaskIsExternal(chunk->hdrmask);
}
/*
* MemoryChunkGetValue
* For non-external chunks, returns the value field as it was set in
* MemoryChunkSetHdrMask.
*/
static inline Size
MemoryChunkGetValue(MemoryChunk *chunk)
{
Assert(!HdrMaskIsExternal(chunk->hdrmask));
return HdrMaskGetValue(chunk->hdrmask);
}
/*
* MemoryChunkGetBlock
* For non-external chunks, returns the pointer to the block as was set
* in MemoryChunkSetHdrMask.
*/
static inline void *
MemoryChunkGetBlock(MemoryChunk *chunk)
{
Assert(!HdrMaskIsExternal(chunk->hdrmask));
return (void *) ((char *) chunk - HdrMaskBlockOffset(chunk->hdrmask));
}
/* cleanup all internal definitions */
#undef MEMORYCHUNK_EXTERNAL_BASEBIT
#undef MEMORYCHUNK_VALUE_BASEBIT
#undef MEMORYCHUNK_BLOCKOFFSET_BASEBIT
#undef MEMORYCHUNK_MAGIC
#undef HdrMaskIsExternal
#undef HdrMaskGetValue
#undef HdrMaskBlockOffset
#undef HdrMaskCheckMagic
#endif /* MEMUTILS_MEMORYCHUNK_H */

6
src/tools/pgindent/typedefs.list
View File

@ -56,7 +56,7 @@ AggregateInstrumentation
AlenState
Alias
AllocBlock
AllocChunk
AllocFreeListLink
AllocPointer
AllocSet
AllocSetContext
@ -947,7 +947,6 @@ GatherState
Gene
GeneratePruningStepsContext
GenerationBlock
GenerationChunk
GenerationContext
GenerationPointer
GenericCosts
@ -1522,12 +1521,14 @@ MemoizeKey
MemoizePath
MemoizeState
MemoizeTuple
MemoryChunk
MemoryContext
MemoryContextCallback
MemoryContextCallbackFunction
MemoryContextCounters
MemoryContextData
MemoryContextMethods
MemoryContextMethodID
MemoryStatsPrintFunc
MergeAction
MergeActionState
@ -2530,7 +2531,6 @@ SingleBoundSortItem
Size
SkipPages
SlabBlock
SlabChunk
SlabContext
SlabSlot
SlotNumber