* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.16 2003/03/04 21:51:21 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/freespace/freespace.c,v 1.17 2003/03/06 00:04:27 tgl Exp $
*
*
* NOTES:
* So the actual arithmetic is: for each relation compute myRequest as the
* number of chunks needed to hold its RRFS page count (not counting the
* first, guaranteed chunk); compute sumRequests as the sum of these values
- * over all relations; then for each relation figure its actual allocation
+ * over all relations; then for each relation figure its target allocation
* as
* 1 + round(spareChunks * myRequest / sumRequests)
* where spareChunks = totalChunks - numRels is the number of chunks we have
* a choice what to do with. We round off these numbers because truncating
* all of them would waste significant space. But because of roundoff, it's
* possible for the last few relations to get less space than they should;
- * the computed allocation must be checked against remaining available space.
+ * the target allocation must be checked against remaining available space.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include <errno.h>
#include <limits.h>
#include <math.h>
+#include <unistd.h>
+#include "miscadmin.h"
+#include "storage/fd.h"
#include "storage/freespace.h"
#include "storage/itemptr.h"
#include "storage/lwlock.h"
#define IndexFSMPageSetPageNum(ptr, pg) \
BlockIdSet(ptr, pg)
+/*----------
+ * During database shutdown, we store the contents of FSM into a disk file,
+ * which is re-read during startup. This way we don't have a startup
+ * transient condition where FSM isn't really functioning.
+ *
+ * The file format is:
+ * label "FSM\0"
+ * endian constant 0x01020304 for detecting endianness problems
+ * version#
+ * numRels
+ * -- for each rel, in *reverse* usage order:
+ * relfilenode
+ * isIndex
+ * avgRequest
+ * lastPageCount
+ * storedPages
+ * arena data array of storedPages FSMPageData or IndexFSMPageData
+ *----------
+ */
+
+/* Name of FSM cache file (relative to $PGDATA) */
+#define FSM_CACHE_FILENAME "global/pg_fsm.cache"
+
+/* Fixed values in header */
+#define FSM_CACHE_LABEL "FSM"
+#define FSM_CACHE_ENDIAN 0x01020304
+#define FSM_CACHE_VERSION 20030305
+
+/* File header layout */
+typedef struct FsmCacheFileHeader
+{
+ char label[4];
+ uint32 endian;
+ uint32 version;
+ int32 numRels;
+} FsmCacheFileHeader;
+
+/* Per-relation header */
+typedef struct FsmCacheRelHeader
+{
+ RelFileNode key; /* hash key (must be first) */
+ bool isIndex; /* if true, we store only page numbers */
+ uint32 avgRequest; /* moving average of space requests */
+ int32 lastPageCount; /* pages passed to RecordRelationFreeSpace */
+ int32 storedPages; /* # of pages stored in arena */
+} FsmCacheRelHeader;
+
/*
* Shared free-space-map objects
static FSMRelation *lookup_fsm_rel(RelFileNode *rel);
static FSMRelation *create_fsm_rel(RelFileNode *rel);
static void delete_fsm_rel(FSMRelation *fsmrel);
+static int realloc_fsm_rel(FSMRelation *fsmrel, int nPages, bool isIndex);
static void link_fsm_rel_usage(FSMRelation *fsmrel);
static void unlink_fsm_rel_usage(FSMRelation *fsmrel);
static void link_fsm_rel_storage(FSMRelation *fsmrel);
fsmrel = lookup_fsm_rel(rel);
if (fsmrel)
{
- int myRequest;
- int myAlloc;
int curAlloc;
int curAllocPages;
FSMPageData *newLocation;
- /*
- * Delete existing entries, and update request status.
- */
- fsmrel->storedPages = 0;
- FreeSpaceMap->sumRequests -= fsm_calc_request(fsmrel);
- fsmrel->lastPageCount = nPages;
- fsmrel->isIndex = false;
- myRequest = fsm_calc_request(fsmrel);
- FreeSpaceMap->sumRequests += myRequest;
- myAlloc = fsm_calc_target_allocation(myRequest);
- /*
- * Need to reallocate space if (a) my target allocation is more
- * than my current allocation, AND (b) my actual immediate need
- * (myRequest+1 chunks) is more than my current allocation.
- * Otherwise just store the new data in-place.
- */
- curAlloc = fsm_current_allocation(fsmrel);
- if (myAlloc > curAlloc && (myRequest+1) > curAlloc && nPages > 0)
- {
- /* Remove entry from storage list, and compact */
- unlink_fsm_rel_storage(fsmrel);
- compact_fsm_storage();
- /* Reattach to end of storage list */
- link_fsm_rel_storage(fsmrel);
- /* And allocate storage */
- fsmrel->firstChunk = FreeSpaceMap->usedChunks;
- FreeSpaceMap->usedChunks += myAlloc;
- curAlloc = myAlloc;
- /* Watch out for roundoff error */
- if (FreeSpaceMap->usedChunks > FreeSpaceMap->totalChunks)
- {
- FreeSpaceMap->usedChunks = FreeSpaceMap->totalChunks;
- curAlloc = FreeSpaceMap->totalChunks - fsmrel->firstChunk;
- }
- }
+ curAlloc = realloc_fsm_rel(fsmrel, nPages, false);
+ curAllocPages = curAlloc * CHUNKPAGES;
/*
* If the data fits in our current allocation, just copy it;
* otherwise must compress.
*/
newLocation = (FSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
- curAllocPages = curAlloc * CHUNKPAGES;
if (nPages <= curAllocPages)
{
int i;
fsmrel = lookup_fsm_rel(rel);
if (fsmrel)
{
- int myRequest;
- int myAlloc;
int curAlloc;
int curAllocPages;
int i;
IndexFSMPageData *newLocation;
- /*
- * Delete existing entries, and update request status.
- */
- fsmrel->storedPages = 0;
- FreeSpaceMap->sumRequests -= fsm_calc_request(fsmrel);
- fsmrel->lastPageCount = nPages;
- fsmrel->isIndex = true;
- myRequest = fsm_calc_request(fsmrel);
- FreeSpaceMap->sumRequests += myRequest;
- myAlloc = fsm_calc_target_allocation(myRequest);
- /*
- * Need to reallocate space if (a) my target allocation is more
- * than my current allocation, AND (b) my actual immediate need
- * (myRequest+1 chunks) is more than my current allocation.
- * Otherwise just store the new data in-place.
- */
- curAlloc = fsm_current_allocation(fsmrel);
- if (myAlloc > curAlloc && (myRequest+1) > curAlloc && nPages > 0)
- {
- /* Remove entry from storage list, and compact */
- unlink_fsm_rel_storage(fsmrel);
- compact_fsm_storage();
- /* Reattach to end of storage list */
- link_fsm_rel_storage(fsmrel);
- /* And allocate storage */
- fsmrel->firstChunk = FreeSpaceMap->usedChunks;
- FreeSpaceMap->usedChunks += myAlloc;
- curAlloc = myAlloc;
- /* Watch out for roundoff error */
- if (FreeSpaceMap->usedChunks > FreeSpaceMap->totalChunks)
- {
- FreeSpaceMap->usedChunks = FreeSpaceMap->totalChunks;
- curAlloc = FreeSpaceMap->totalChunks - fsmrel->firstChunk;
- }
- }
+ curAlloc = realloc_fsm_rel(fsmrel, nPages, true);
+ curAllocPages = curAlloc * INDEXCHUNKPAGES;
/*
* If the data fits in our current allocation, just copy it;
* otherwise must compress. But compression is easy: we merely
*/
newLocation = (IndexFSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
- curAllocPages = curAlloc * INDEXCHUNKPAGES;
if (nPages > curAllocPages)
nPages = curAllocPages;
(double) FreeSpaceShmemSize() / 1024.0);
}
+/*
+ * DumpFreeSpaceMap - dump contents of FSM into a disk file for later reload
+ *
+ * This is expected to be called during database shutdown, after updates to
+ * the FSM have stopped. We lock the FreeSpaceLock but that's purely pro
+ * forma --- if anyone else is still accessing FSM, there's a problem.
+ */
+void
+DumpFreeSpaceMap(void)
+{
+ FILE *fp;
+ char cachefilename[MAXPGPATH];
+ FsmCacheFileHeader header;
+ FSMRelation *fsmrel;
+
+ /* Try to create file */
+ snprintf(cachefilename, sizeof(cachefilename), "%s/%s",
+ DataDir, FSM_CACHE_FILENAME);
+
+ unlink(cachefilename); /* in case it exists w/wrong permissions */
+
+ fp = AllocateFile(cachefilename, PG_BINARY_W);
+ if (fp == NULL)
+ {
+ elog(LOG, "Failed to write %s: %m", cachefilename);
+ return;
+ }
+
+ LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
+
+ /* Write file header */
+ MemSet(&header, 0, sizeof(header));
+ strcpy(header.label, FSM_CACHE_LABEL);
+ header.endian = FSM_CACHE_ENDIAN;
+ header.version = FSM_CACHE_VERSION;
+ header.numRels = FreeSpaceMap->numRels;
+ if (fwrite(&header, 1, sizeof(header), fp) != sizeof(header))
+ goto write_failed;
+
+ /* For each relation, in order from least to most recently used... */
+ for (fsmrel = FreeSpaceMap->usageListTail;
+ fsmrel != NULL;
+ fsmrel = fsmrel->priorUsage)
+ {
+ FsmCacheRelHeader relheader;
+ int nPages;
+
+ /* Write relation header */
+ MemSet(&relheader, 0, sizeof(relheader));
+ relheader.key = fsmrel->key;
+ relheader.isIndex = fsmrel->isIndex;
+ relheader.avgRequest = fsmrel->avgRequest;
+ relheader.lastPageCount = fsmrel->lastPageCount;
+ relheader.storedPages = fsmrel->storedPages;
+ if (fwrite(&relheader, 1, sizeof(relheader), fp) != sizeof(relheader))
+ goto write_failed;
+
+ /* Write the per-page data directly from the arena */
+ nPages = fsmrel->storedPages;
+ if (nPages > 0)
+ {
+ Size len;
+ char *data;
+
+ if (fsmrel->isIndex)
+ len = nPages * sizeof(IndexFSMPageData);
+ else
+ len = nPages * sizeof(FSMPageData);
+ data = (char *)
+ (FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
+ if (fwrite(data, 1, len, fp) != len)
+ goto write_failed;
+ }
+ }
+
+ /* Clean up */
+ LWLockRelease(FreeSpaceLock);
+
+ FreeFile(fp);
+
+ return;
+
+write_failed:
+ elog(LOG, "Failed to write %s: %m", cachefilename);
+
+ /* Clean up */
+ LWLockRelease(FreeSpaceLock);
+
+ FreeFile(fp);
+
+ /* Remove busted cache file */
+ unlink(cachefilename);
+}
+
+/*
+ * LoadFreeSpaceMap - load contents of FSM from a disk file
+ *
+ * This is expected to be called during database startup, before any FSM
+ * updates begin. We lock the FreeSpaceLock but that's purely pro
+ * forma --- if anyone else is accessing FSM yet, there's a problem.
+ *
+ * Notes: no complaint is issued if no cache file is found. If the file is
+ * found, it is deleted after reading. Thus, if we crash without a clean
+ * shutdown, the next cycle of life starts with no FSM data. To do otherwise,
+ * we'd need to do significantly more validation in this routine, because of
+ * the likelihood that what is in the dump file would be out-of-date, eg
+ * there might be entries for deleted or truncated rels.
+ */
+void
+LoadFreeSpaceMap(void)
+{
+ FILE *fp;
+ char cachefilename[MAXPGPATH];
+ FsmCacheFileHeader header;
+ int relno;
+
+ /* Try to open file */
+ snprintf(cachefilename, sizeof(cachefilename), "%s/%s",
+ DataDir, FSM_CACHE_FILENAME);
+
+ fp = AllocateFile(cachefilename, PG_BINARY_R);
+ if (fp == NULL)
+ {
+ if (errno != ENOENT)
+ elog(LOG, "Failed to read %s: %m", cachefilename);
+ return;
+ }
+
+ LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
+
+ /* Read and verify file header */
+ if (fread(&header, 1, sizeof(header), fp) != sizeof(header) ||
+ strcmp(header.label, FSM_CACHE_LABEL) != 0 ||
+ header.endian != FSM_CACHE_ENDIAN ||
+ header.version != FSM_CACHE_VERSION ||
+ header.numRels < 0)
+ {
+ elog(LOG, "Bogus file header in %s", cachefilename);
+ goto read_failed;
+ }
+
+ /* For each relation, in order from least to most recently used... */
+ for (relno = 0; relno < header.numRels; relno++)
+ {
+ FsmCacheRelHeader relheader;
+ Size len;
+ char *data;
+ FSMRelation *fsmrel;
+ int nPages;
+ int curAlloc;
+ int curAllocPages;
+
+ /* Read and verify relation header, as best we can */
+ if (fread(&relheader, 1, sizeof(relheader), fp) != sizeof(relheader) ||
+ (relheader.isIndex != false && relheader.isIndex != true) ||
+ relheader.avgRequest >= BLCKSZ ||
+ relheader.lastPageCount < 0 ||
+ relheader.storedPages < 0)
+ {
+ elog(LOG, "Bogus rel header in %s", cachefilename);
+ goto read_failed;
+ }
+
+ /* Make sure lastPageCount doesn't exceed current MaxFSMPages */
+ if (relheader.lastPageCount > MaxFSMPages)
+ relheader.lastPageCount = MaxFSMPages;
+
+ /* Read the per-page data */
+ nPages = relheader.storedPages;
+ if (relheader.isIndex)
+ len = nPages * sizeof(IndexFSMPageData);
+ else
+ len = nPages * sizeof(FSMPageData);
+ data = (char *) palloc(len + 1); /* +1 to avoid palloc(0) */
+ if (fread(data, 1, len, fp) != len)
+ {
+ elog(LOG, "Premature EOF in %s", cachefilename);
+ pfree(data);
+ goto read_failed;
+ }
+
+ /*
+ * Okay, create the FSM entry and insert data into it. Since the
+ * rels were stored in reverse usage order, at the end of the loop
+ * they will be correctly usage-ordered in memory; and if
+ * MaxFSMRelations is less than it used to be, we will correctly
+ * drop the least recently used ones.
+ */
+ fsmrel = create_fsm_rel(&relheader.key);
+ fsmrel->avgRequest = relheader.avgRequest;
+
+ curAlloc = realloc_fsm_rel(fsmrel, relheader.lastPageCount,
+ relheader.isIndex);
+ if (relheader.isIndex)
+ {
+ IndexFSMPageData *newLocation;
+
+ curAllocPages = curAlloc * INDEXCHUNKPAGES;
+ /*
+ * If the data fits in our current allocation, just copy it;
+ * otherwise must compress. But compression is easy: we merely
+ * forget extra pages.
+ */
+ newLocation = (IndexFSMPageData *)
+ (FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
+ if (nPages > curAllocPages)
+ nPages = curAllocPages;
+ memcpy(newLocation, data, nPages * sizeof(IndexFSMPageData));
+ fsmrel->storedPages = nPages;
+ }
+ else
+ {
+ FSMPageData *newLocation;
+
+ curAllocPages = curAlloc * CHUNKPAGES;
+ /*
+ * If the data fits in our current allocation, just copy it;
+ * otherwise must compress.
+ */
+ newLocation = (FSMPageData *)
+ (FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
+ if (nPages <= curAllocPages)
+ {
+ memcpy(newLocation, data, nPages * sizeof(FSMPageData));
+ fsmrel->storedPages = nPages;
+ }
+ else
+ {
+ pack_existing_pages(newLocation, curAllocPages,
+ (FSMPageData *) data, nPages);
+ fsmrel->storedPages = curAllocPages;
+ }
+ }
+
+ pfree(data);
+ }
+
+read_failed:
+
+ /* Clean up */
+ LWLockRelease(FreeSpaceLock);
+
+ FreeFile(fp);
+
+ /* Remove cache file before it can become stale; see notes above */
+ unlink(cachefilename);
+}
+
/*
* Internal routines. These all assume the caller holds the FreeSpaceLock.
}
/*
+ * Reallocate space for a FSMRelation.
+ *
+ * This is shared code for RecordRelationFreeSpace and RecordIndexFreeSpace.
+ * The return value is the actual new allocation, in chunks.
+ */
+static int
+realloc_fsm_rel(FSMRelation *fsmrel, int nPages, bool isIndex)
+{
+ int myRequest;
+ int myAlloc;
+ int curAlloc;
+
+ /*
+ * Delete any existing entries, and update request status.
+ */
+ fsmrel->storedPages = 0;
+ FreeSpaceMap->sumRequests -= fsm_calc_request(fsmrel);
+ fsmrel->lastPageCount = nPages;
+ fsmrel->isIndex = isIndex;
+ myRequest = fsm_calc_request(fsmrel);
+ FreeSpaceMap->sumRequests += myRequest;
+ myAlloc = fsm_calc_target_allocation(myRequest);
+ /*
+ * Need to reallocate space if (a) my target allocation is more
+ * than my current allocation, AND (b) my actual immediate need
+ * (myRequest+1 chunks) is more than my current allocation.
+ * Otherwise just store the new data in-place.
+ */
+ curAlloc = fsm_current_allocation(fsmrel);
+ if (myAlloc > curAlloc && (myRequest+1) > curAlloc && nPages > 0)
+ {
+ /* Remove entry from storage list, and compact */
+ unlink_fsm_rel_storage(fsmrel);
+ compact_fsm_storage();
+ /* Reattach to end of storage list */
+ link_fsm_rel_storage(fsmrel);
+ /* And allocate storage */
+ fsmrel->firstChunk = FreeSpaceMap->usedChunks;
+ FreeSpaceMap->usedChunks += myAlloc;
+ curAlloc = myAlloc;
+ /* Watch out for roundoff error */
+ if (FreeSpaceMap->usedChunks > FreeSpaceMap->totalChunks)
+ {
+ FreeSpaceMap->usedChunks = FreeSpaceMap->totalChunks;
+ curAlloc = FreeSpaceMap->totalChunks - fsmrel->firstChunk;
+ }
+ }
+ return curAlloc;
+}
+
+/*
* Link a FSMRelation into the LRU list (always at the head).
*/
static void
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