Ensure that all details of the ARC algorithm are hidden within freelist.c.
This refactoring does not change any algorithms or data structures, just remove visibility of the ARC datastructures from other source files.
This commit is contained in:
Tom Lane
parent
ad893a361d
commit
cc4f58f4cd
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.70 2004/12/31 22:00:49 pgsql Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.71 2005/02/03 23:29:11 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -73,7 +73,6 @@ long int LocalBufferFlushCount;
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* aborts, it should only unpin the buffers exactly the number of times it
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* has pinned them, so that it will not blow away buffers of another
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* backend.
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*
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*/
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@ -120,14 +119,17 @@ InitBufferPool(void)
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block = BufferBlocks;
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/*
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* link the buffers into a single linked list. This will become
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* the LIFO list of unused buffers returned by
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* StrategyGetBuffer().
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* Initialize all the buffer headers.
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*/
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for (i = 0; i < NBuffers; block += BLCKSZ, buf++, i++)
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{
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Assert(ShmemIsValid((unsigned long) block));
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/*
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* The bufNext fields link together all totally-unused buffers.
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* Subsequent management of this list is done by
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* StrategyGetBuffer().
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*/
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buf->bufNext = i + 1;
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CLEAR_BUFFERTAG(buf->tag);
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@ -142,7 +144,7 @@ InitBufferPool(void)
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buf->wait_backend_id = 0;
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}
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/* Correct last entry */
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/* Correct last entry of linked list */
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BufferDescriptors[NBuffers - 1].bufNext = -1;
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LWLockRelease(BufMgrLock);
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@ -178,7 +180,8 @@ InitBufferPoolAccess(void)
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/*
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* Convert shmem offsets into addresses as seen by this process. This
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* is just to speed up the BufferGetBlock() macro.
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* is just to speed up the BufferGetBlock() macro. It is OK to do this
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* without any lock since the data pointers never change.
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*/
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for (i = 0; i < NBuffers; i++)
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BufferBlockPointers[i] = (Block) MAKE_PTR(BufferDescriptors[i].data);
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@ -201,14 +204,8 @@ BufferShmemSize(void)
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/* size of data pages */
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size += NBuffers * MAXALIGN(BLCKSZ);
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/* size of buffer hash table */
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size += hash_estimate_size(NBuffers * 2, sizeof(BufferLookupEnt));
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/* size of the shared replacement strategy control block */
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size += MAXALIGN(sizeof(BufferStrategyControl));
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/* size of the ARC directory blocks */
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size += MAXALIGN(NBuffers * 2 * sizeof(BufferStrategyCDB));
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/* size of stuff controlled by freelist.c */
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size += StrategyShmemSize();
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return size;
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}
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@ -1,11 +1,11 @@
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/*-------------------------------------------------------------------------
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*
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* buf_table.c
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* routines for finding buffers in the buffer pool.
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* routines for mapping BufferTags to buffer indexes.
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*
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* NOTE: these days, what this table actually provides is a mapping from
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* BufferTags to CDB indexes, not directly to buffers. The function names
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* are thus slight misnomers.
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* NOTE: this module is called only by freelist.c, and the "buffer IDs"
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* it deals with are whatever freelist.c needs them to be; they may not be
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* directly equivalent to Buffer numbers.
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*
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* Note: all routines in this file assume that the BufMgrLock is held
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* by the caller, so no synchronization is needed.
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@ -16,7 +16,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.38 2004/12/31 22:00:49 pgsql Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_table.c,v 1.39 2005/02/03 23:29:11 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -26,12 +26,29 @@
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#include "storage/bufmgr.h"
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/* entry for buffer lookup hashtable */
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typedef struct
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{
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BufferTag key; /* Tag of a disk page */
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int id; /* Associated buffer ID */
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} BufferLookupEnt;
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static HTAB *SharedBufHash;
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/*
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* Estimate space needed for mapping hashtable
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* size is the desired hash table size (possibly more than NBuffers)
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*/
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int
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BufTableShmemSize(int size)
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{
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return hash_estimate_size(size, sizeof(BufferLookupEnt));
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}
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/*
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* Initialize shmem hash table for mapping buffers
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* size is the desired hash table size (2*NBuffers for ARC algorithm)
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* size is the desired hash table size (possibly more than NBuffers)
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*/
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void
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InitBufTable(int size)
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@ -56,7 +73,7 @@ InitBufTable(int size)
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/*
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* BufTableLookup
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* Lookup the given BufferTag; return CDB index, or -1 if not found
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* Lookup the given BufferTag; return buffer ID, or -1 if not found
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*/
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int
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BufTableLookup(BufferTag *tagPtr)
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@ -76,10 +93,10 @@ BufTableLookup(BufferTag *tagPtr)
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/*
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* BufTableInsert
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* Insert a hashtable entry for given tag and CDB index
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* Insert a hashtable entry for given tag and buffer ID
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*/
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void
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BufTableInsert(BufferTag *tagPtr, int cdb_id)
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BufTableInsert(BufferTag *tagPtr, int buf_id)
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{
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BufferLookupEnt *result;
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bool found;
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@ -92,15 +109,15 @@ BufTableInsert(BufferTag *tagPtr, int cdb_id)
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("out of shared memory")));
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if (found) /* found something else in the table? */
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if (found) /* found something already in the table? */
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elog(ERROR, "shared buffer hash table corrupted");
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result->id = cdb_id;
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result->id = buf_id;
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}
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/*
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* BufTableDelete
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* Delete the hashtable entry for given tag
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* Delete the hashtable entry for given tag (which must exist)
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*/
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void
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BufTableDelete(BufferTag *tagPtr)
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@ -3,6 +3,11 @@
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* freelist.c
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* routines for manipulating the buffer pool's replacement strategy.
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*
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* The name "freelist.c" is now a bit of a misnomer, since this module
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* controls not only the list of free buffers per se, but the entire
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* mechanism for looking up existing shared buffers and the strategy
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* for choosing replacement victims when needed.
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*
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* Note: all routines in this file assume that the BufMgrLock is held
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* by the caller, so no synchronization is needed.
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*
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@ -12,7 +17,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.49 2004/12/31 22:00:49 pgsql Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/freelist.c,v 1.50 2005/02/03 23:29:11 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -25,6 +30,51 @@
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#include "storage/bufmgr.h"
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/*
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* Definitions for the buffer replacement strategy
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*/
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#define STRAT_LIST_UNUSED (-1)
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#define STRAT_LIST_B1 0
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#define STRAT_LIST_T1 1
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#define STRAT_LIST_T2 2
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#define STRAT_LIST_B2 3
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#define STRAT_NUM_LISTS 4
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/*
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* The Cache Directory Block (CDB) of the Adaptive Replacement Cache (ARC)
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*/
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typedef struct
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{
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int prev; /* list links */
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int next;
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short list; /* ID of list it is currently in */
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bool t1_vacuum; /* t => present only because of VACUUM */
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TransactionId t1_xid; /* the xid this entry went onto T1 */
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BufferTag buf_tag; /* page identifier */
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int buf_id; /* currently assigned data buffer, or -1 */
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} BufferStrategyCDB;
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/*
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* The shared ARC control information.
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*/
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typedef struct
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{
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int target_T1_size; /* What T1 size are we aiming for */
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int listUnusedCDB; /* All unused StrategyCDB */
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int listHead[STRAT_NUM_LISTS]; /* ARC lists B1, T1, T2
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* and B2 */
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int listTail[STRAT_NUM_LISTS];
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int listSize[STRAT_NUM_LISTS];
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Buffer listFreeBuffers; /* List of unused buffers */
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long num_lookup; /* Some hit statistics */
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long num_hit[STRAT_NUM_LISTS];
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time_t stat_report;
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/* Array of CDB's starts here */
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BufferStrategyCDB cdb[1]; /* VARIABLE SIZE ARRAY */
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} BufferStrategyControl;
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/* GUC variable: time in seconds between statistics reports */
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int DebugSharedBuffers = 0;
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@ -812,6 +862,28 @@ StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
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}
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/*
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* StrategyShmemSize
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*
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* estimate the size of shared memory used by the freelist-related structures.
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*/
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int
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StrategyShmemSize(void)
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{
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int size = 0;
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/* size of CDB lookup hash table */
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size += BufTableShmemSize(NBuffers * 2);
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/* size of the shared replacement strategy control block */
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size += MAXALIGN(sizeof(BufferStrategyControl));
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/* size of the ARC directory blocks */
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size += MAXALIGN(NBuffers * 2 * sizeof(BufferStrategyCDB));
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return size;
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}
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/*
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* StrategyInitialize -- initialize the buffer cache replacement
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* strategy.
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.75 2004/12/31 22:03:42 pgsql Exp $
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* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.76 2005/02/03 23:29:19 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -17,8 +17,9 @@
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#include "storage/backendid.h"
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#include "storage/buf.h"
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#include "storage/lmgr.h"
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#include "storage/lwlock.h"
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#include "storage/shmem.h"
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#include "utils/rel.h"
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/*
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@ -40,10 +41,10 @@ typedef bits16 BufFlags;
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* Buffer tag identifies which disk block the buffer contains.
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*
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* Note: the BufferTag data must be sufficient to determine where to write the
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* block, even during a "blind write" with no relcache entry. It's possible
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* that the backend flushing the buffer doesn't even believe the relation is
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* visible yet (its xact may have started before the xact that created the
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* rel). The storage manager must be able to cope anyway.
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* block, without reference to pg_class or pg_tablespace entries. It's
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* possible that the backend flushing the buffer doesn't even believe the
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* relation is visible yet (its xact may have started before the xact that
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* created the rel). The storage manager must be able to cope anyway.
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*
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* Note: if there's any pad bytes in the struct, INIT_BUFFERTAG will have
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* to be fixed to zero them, since this struct is used as a hash key.
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@ -107,58 +108,12 @@ typedef struct sbufdesc
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#define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
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/* entry for buffer lookup hashtable */
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typedef struct
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{
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BufferTag key; /* Tag of a disk page */
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int id; /* CDB id of associated CDB */
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} BufferLookupEnt;
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/*
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* Definitions for the buffer replacement strategy
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*/
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#define STRAT_LIST_UNUSED (-1)
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#define STRAT_LIST_B1 0
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#define STRAT_LIST_T1 1
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#define STRAT_LIST_T2 2
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#define STRAT_LIST_B2 3
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#define STRAT_NUM_LISTS 4
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/*
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* The Cache Directory Block (CDB) of the Adaptive Replacement Cache (ARC)
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*/
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typedef struct
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{
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int prev; /* list links */
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int next;
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short list; /* ID of list it is currently in */
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bool t1_vacuum; /* t => present only because of VACUUM */
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TransactionId t1_xid; /* the xid this entry went onto T1 */
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BufferTag buf_tag; /* page identifier */
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int buf_id; /* currently assigned data buffer, or -1 */
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} BufferStrategyCDB;
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/*
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* The shared ARC control information.
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*/
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typedef struct
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{
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int target_T1_size; /* What T1 size are we aiming for */
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int listUnusedCDB; /* All unused StrategyCDB */
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int listHead[STRAT_NUM_LISTS]; /* ARC lists B1, T1, T2
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* and B2 */
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int listTail[STRAT_NUM_LISTS];
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int listSize[STRAT_NUM_LISTS];
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Buffer listFreeBuffers; /* List of unused buffers */
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long num_lookup; /* Some hit statistics */
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long num_hit[STRAT_NUM_LISTS];
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time_t stat_report;
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/* Array of CDB's starts here */
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BufferStrategyCDB cdb[1]; /* VARIABLE SIZE ARRAY */
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} BufferStrategyControl;
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/* in bufmgr.c */
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extern BufferDesc *BufferDescriptors;
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/* in localbuf.c */
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extern BufferDesc *LocalBufferDescriptors;
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/* counters in buf_init.c */
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extern long int ReadBufferCount;
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@ -170,11 +125,9 @@ extern long int LocalBufferFlushCount;
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/*
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* Bufmgr Interface:
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* Internal routines: only called by bufmgr
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*/
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/* Internal routines: only called by bufmgr */
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/* freelist.c */
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extern BufferDesc *StrategyBufferLookup(BufferTag *tagPtr, bool recheck,
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int *cdb_found_index);
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@ -185,20 +138,17 @@ extern void StrategyInvalidateBuffer(BufferDesc *buf);
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extern void StrategyHintVacuum(bool vacuum_active);
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extern int StrategyDirtyBufferList(BufferDesc **buffers, BufferTag *buftags,
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int max_buffers);
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extern int StrategyShmemSize(void);
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extern void StrategyInitialize(bool init);
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/* buf_table.c */
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extern int BufTableShmemSize(int size);
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extern void InitBufTable(int size);
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extern int BufTableLookup(BufferTag *tagPtr);
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extern void BufTableInsert(BufferTag *tagPtr, int cdb_id);
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extern void BufTableInsert(BufferTag *tagPtr, int buf_id);
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extern void BufTableDelete(BufferTag *tagPtr);
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/* bufmgr.c */
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extern BufferDesc *BufferDescriptors;
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/* localbuf.c */
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extern BufferDesc *LocalBufferDescriptors;
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extern BufferDesc *LocalBufferAlloc(Relation reln, BlockNumber blockNum,
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bool *foundPtr);
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extern void WriteLocalBuffer(Buffer buffer, bool release);
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Reference in New Issue