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Cosmetic improvements to freeze map code. 

Per post-commit review comments from Andres Freund, improve variable
names, comments, and in one place, slightly improve the code structure.

Masahiko Sawada
This commit is contained in:
Robert Haas 2016-06-03 08:43:41 -04:00
parent a3b30763cc
commit fdfaccfa79
3 changed files with 31 additions and 31 deletions
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34
src/backend/access/heap/visibilitymap.c
View File

@ -33,7 +33,7 @@
* is set, we know the condition is true, but if a bit is not set, it might or
* might not be true.
*
* Clearing both visibility map bits is not separately WAL-logged. The callers
* Clearing visibility map bits is not separately WAL-logged. The callers
* must make sure that whenever a bit is cleared, the bit is cleared on WAL
* replay of the updating operation as well.
*
@ -104,13 +104,16 @@
*/
#define MAPSIZE (BLCKSZ - MAXALIGN(SizeOfPageHeaderData))
/* Number of heap blocks we can represent in one byte */
#define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK)
/* Number of heap blocks we can represent in one visibility map page. */
#define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE)
/* Mapping from heap block number to the right bit in the visibility map */
#define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE)
#define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE)
#define HEAPBLK_TO_MAPBIT(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK)
#define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK)
/* tables for fast counting of set bits for visible and frozen */
static const uint8 number_of_ones_for_visible[256] = {
@ -156,7 +159,7 @@ static void vm_extend(Relation rel, BlockNumber nvmblocks);
/*
* visibilitymap_clear - clear all bits in visibility map
* visibilitymap_clear - clear all bits for one page in visibility map
*
* You must pass a buffer containing the correct map page to this function.
* Call visibilitymap_pin first to pin the right one. This function doesn't do
@ -167,8 +170,8 @@ visibilitymap_clear(Relation rel, BlockNumber heapBlk, Buffer buf)
{
BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk);
int mapByte = HEAPBLK_TO_MAPBYTE(heapBlk);
int mapBit = HEAPBLK_TO_MAPBIT(heapBlk);
uint8 mask = VISIBILITYMAP_VALID_BITS << mapBit;
int mapOffset = HEAPBLK_TO_OFFSET(heapBlk);
uint8 mask = VISIBILITYMAP_VALID_BITS << mapOffset;
char *map;
#ifdef TRACE_VISIBILITYMAP
@ -267,7 +270,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
{
BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk);
uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk);
uint8 mapBit = HEAPBLK_TO_MAPBIT(heapBlk);
uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk);
Page page;
uint8 *map;
@ -291,11 +294,11 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
map = (uint8 *)PageGetContents(page);
LockBuffer(vmBuf, BUFFER_LOCK_EXCLUSIVE);
if (flags != (map[mapByte] >> mapBit & VISIBILITYMAP_VALID_BITS))
if (flags != (map[mapByte] >> mapOffset & VISIBILITYMAP_VALID_BITS))
{
START_CRIT_SECTION();
map[mapByte] |= (flags << mapBit);
map[mapByte] |= (flags << mapOffset);
MarkBufferDirty(vmBuf);
if (RelationNeedsWAL(rel))
@ -338,8 +341,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
* earlier call to visibilitymap_pin or visibilitymap_get_status on the same
* relation. On return, *buf is a valid buffer with the map page containing
* the bit for heapBlk, or InvalidBuffer. The caller is responsible for
* releasing *buf after it's done testing and setting bits, and must pass flags
* for which it needs to check the value in visibility map.
* releasing *buf after it's done testing and setting bits.
*
* NOTE: This function is typically called without a lock on the heap page,
* so somebody else could change the bit just after we look at it. In fact,
@ -353,8 +355,9 @@ visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *buf)
{
BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk);
uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk);
uint8 mapBit = HEAPBLK_TO_MAPBIT(heapBlk);
uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk);
char *map;
uint8 result;
#ifdef TRACE_VISIBILITYMAP
elog(DEBUG1, "vm_get_status %s %d", RelationGetRelationName(rel), heapBlk);
@ -384,7 +387,8 @@ visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *buf)
* here, but for performance reasons we make it the caller's job to worry
* about that.
*/
return ((map[mapByte] >> mapBit) & VISIBILITYMAP_VALID_BITS);
result = ((map[mapByte] >> mapOffset) & VISIBILITYMAP_VALID_BITS);
return result;
}
/*
@ -456,7 +460,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks)
/* last remaining block, byte, and bit */
BlockNumber truncBlock = HEAPBLK_TO_MAPBLOCK(nheapblocks);
uint32 truncByte = HEAPBLK_TO_MAPBYTE(nheapblocks);
uint8 truncBit = HEAPBLK_TO_MAPBIT(nheapblocks);
uint8 truncOffset = HEAPBLK_TO_OFFSET(nheapblocks);
#ifdef TRACE_VISIBILITYMAP
elog(DEBUG1, "vm_truncate %s %d", RelationGetRelationName(rel), nheapblocks);
@ -478,7 +482,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks)
* because we don't get a chance to clear the bits if the heap is extended
* again.
*/
if (truncByte != 0 || truncBit != 0)
if (truncByte != 0 || truncOffset != 0)
{
Buffer mapBuffer;
Page page;
@ -511,7 +515,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks)
* ((1 << 7) - 1) = 01111111
*----
*/
map[truncByte] &= (1 << truncBit) - 1;
map[truncByte] &= (1 << truncOffset) - 1;
MarkBufferDirty(mapBuffer);
UnlockReleaseBuffer(mapBuffer);

26
src/backend/commands/vacuumlazy.c
View File

@ -1192,9 +1192,9 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
}
/*
* If the page is marked as all-visible but not all-frozen, we should
* so mark it. Note that all_frozen is only valid if all_visible is
* true, so we must check both.
* If the all-visible page is turned out to be all-frozen but not marked,
* we should so mark it. Note that all_frozen is only valid if all_visible
* is true, so we must check both.
*/
else if (all_visible_according_to_vm && all_visible && all_frozen &&
!VM_ALL_FROZEN(onerel, blkno, &vmbuffer))
@ -2068,6 +2068,7 @@ heap_page_is_all_visible(Relation rel, Buffer buf,
if (ItemIdIsDead(itemid))
{
all_visible = false;
*all_frozen = false;
break;
}
@ -2087,6 +2088,7 @@ heap_page_is_all_visible(Relation rel, Buffer buf,
if (!HeapTupleHeaderXminCommitted(tuple.t_data))
{
all_visible = false;
*all_frozen = false;
break;
}
@ -2098,6 +2100,7 @@ heap_page_is_all_visible(Relation rel, Buffer buf,
if (!TransactionIdPrecedes(xmin, OldestXmin))
{
all_visible = false;
*all_frozen = false;
break;
}
@ -2116,23 +2119,16 @@ heap_page_is_all_visible(Relation rel, Buffer buf,
case HEAPTUPLE_RECENTLY_DEAD:
case HEAPTUPLE_INSERT_IN_PROGRESS:
case HEAPTUPLE_DELETE_IN_PROGRESS:
all_visible = false;
break;
{
all_visible = false;
*all_frozen = false;
break;
}
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
} /* scan along page */
/*
* We don't bother clearing *all_frozen when the page is discovered not to
* be all-visible, so do that now if necessary. The page might fail to be
* all-frozen for other reasons anyway, but if it's not all-visible, then
* it definitely isn't all-frozen.
*/
if (!all_visible)
*all_frozen = false;
return all_visible;
}

2
src/include/access/visibilitymap.h
View File

@ -19,8 +19,8 @@
#include "storage/buf.h"
#include "utils/relcache.h"
/* Number of bits for one heap page */
#define BITS_PER_HEAPBLOCK 2
#define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK)
/* Flags for bit map */
#define VISIBILITYMAP_ALL_VISIBLE 0x01