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/*-------------------------------------------------------------------------
*
* pg_freespacemap.c
* display some contents of the free space map.
*
* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.3 2006/04/26 22:41:18 momjian Exp $
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "funcapi.h"
#include "catalog/pg_type.h"
#include "storage/freespace.h"
#include "utils/relcache.h"
#define NUM_FREESPACE_PAGES_ELEM 5
#if defined(WIN32) || defined(__CYGWIN__)
/* Need DLLIMPORT for some things that are not so marked in main headers */
extern DLLIMPORT int MaxFSMPages;
extern DLLIMPORT volatile uint32 InterruptHoldoffCount;
#endif
Datum pg_freespacemap(PG_FUNCTION_ARGS);
/*
* Record structure holding the to be exposed free space data.
*/
typedef struct
{
uint32 reltablespace;
uint32 reldatabase;
uint32 relfilenode;
uint32 relblocknumber;
uint32 bytes;
bool isindex;
} FreeSpacePagesRec;
/*
* Function context for data persisting over repeated calls.
*/
typedef struct
{
AttInMetadata *attinmeta;
FreeSpacePagesRec *record;
char *values[NUM_FREESPACE_PAGES_ELEM];
} FreeSpacePagesContext;
/*
* Function returning data from the Free Space Map (FSM).
*/
PG_FUNCTION_INFO_V1(pg_freespacemap);
Datum
pg_freespacemap(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
Datum result;
MemoryContext oldcontext;
FreeSpacePagesContext *fctx; /* User function context. */
TupleDesc tupledesc;
HeapTuple tuple;
FSMHeader *FreeSpaceMap; /* FSM main structure. */
FSMRelation *fsmrel; /* Individual relation. */
if (SRF_IS_FIRSTCALL())
{
uint32 i;
uint32 numPages; /* Max possible no. of pages in map. */
int nPages; /* Mapped pages for a relation. */
/*
* Get the free space map data structure.
*/
FreeSpaceMap = GetFreeSpaceMap();
numPages = MaxFSMPages;
funcctx = SRF_FIRSTCALL_INIT();
/* Switch context when allocating stuff to be used in later calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Construct a tuple to return. */
tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_PAGES_ELEM, false);
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "reltablespace",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "reldatabase",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "relfilenode",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "relblocknumber",
INT8OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "bytes",
INT4OID, -1, 0);
/* Generate attribute metadata needed later to produce tuples */
funcctx->attinmeta = TupleDescGetAttInMetadata(tupledesc);
/*
* Create a function context for cross-call persistence and initialize
* the counters.
*/
fctx = (FreeSpacePagesContext *) palloc(sizeof(FreeSpacePagesContext));
funcctx->user_fctx = fctx;
/* Set an upper bound on the calls */
funcctx->max_calls = numPages;
/* Allocate numPages worth of FreeSpacePagesRec records, this is also
* an upper bound.
*/
fctx->record = (FreeSpacePagesRec *) palloc(sizeof(FreeSpacePagesRec) * numPages);
/* allocate the strings for tuple formation */
fctx->values[0] = (char *) palloc(3 * sizeof(uint32) + 1);
fctx->values[1] = (char *) palloc(3 * sizeof(uint32) + 1);
fctx->values[2] = (char *) palloc(3 * sizeof(uint32) + 1);
fctx->values[3] = (char *) palloc(3 * sizeof(uint32) + 1);
fctx->values[4] = (char *) palloc(3 * sizeof(uint32) + 1);
/* Return to original context when allocating transient memory */
MemoryContextSwitchTo(oldcontext);
/*
* Lock free space map and scan though all the relations,
* for each relation, gets all its mapped pages.
*/
LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
i = 0;
for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
{
if (fsmrel->isIndex)
{ /* Index relation. */
IndexFSMPageData *page;
page = (IndexFSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
{
fctx->record[i].reltablespace = fsmrel->key.spcNode;
fctx->record[i].reldatabase = fsmrel->key.dbNode;
fctx->record[i].relfilenode = fsmrel->key.relNode;
fctx->record[i].relblocknumber = IndexFSMPageGetPageNum(page);
fctx->record[i].bytes = 0;
fctx->record[i].isindex = true;
page++;
i++;
}
}
else
{ /* Heap relation. */
FSMPageData *page;
page = (FSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
{
fctx->record[i].reltablespace = fsmrel->key.spcNode;
fctx->record[i].reldatabase = fsmrel->key.dbNode;
fctx->record[i].relfilenode = fsmrel->key.relNode;
fctx->record[i].relblocknumber = FSMPageGetPageNum(page);
fctx->record[i].bytes = FSMPageGetSpace(page);
fctx->record[i].isindex = false;
page++;
i++;
}
}
}
/* Set the real no. of calls as we know it now! */
funcctx->max_calls = i;
/* Release free space map. */
LWLockRelease(FreeSpaceLock);
}
funcctx = SRF_PERCALL_SETUP();
/* Get the saved state */
fctx = funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
uint32 i = funcctx->call_cntr;
char *values[NUM_FREESPACE_PAGES_ELEM];
int j;
/*
* Use a temporary values array, initially pointing to fctx->values,
* so it can be reassigned w/o losing the storage for subsequent
* calls.
*/
for (j = 0; j < NUM_FREESPACE_PAGES_ELEM; j++)
{
values[j] = fctx->values[j];
}
sprintf(values[0], "%u", fctx->record[i].reltablespace);
sprintf(values[1], "%u", fctx->record[i].reldatabase);
sprintf(values[2], "%u", fctx->record[i].relfilenode);
sprintf(values[3], "%u", fctx->record[i].relblocknumber);
/*
* Set (free) bytes to NULL for an index relation.
*/
if (fctx->record[i].isindex == true)
{
values[4] = NULL;
}
else
{
sprintf(values[4], "%u", fctx->record[i].bytes);
}
/* Build and return the tuple. */
tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
SRF_RETURN_DONE(funcctx);
}
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