Header And Logo
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#include "postgres.h"#include "access/htup_details.h"#include "catalog/pg_type.h"#include "funcapi.h"#include "storage/buf_internals.h"#include "storage/bufmgr.h"
Go to the source code of this file.
Data Structures | |
| struct | BufferCachePagesRec |
| struct | BufferCachePagesContext |
Defines | |
| #define | NUM_BUFFERCACHE_PAGES_ELEM 8 |
Functions | |
| Datum | pg_buffercache_pages (PG_FUNCTION_ARGS) |
| PG_FUNCTION_INFO_V1 (pg_buffercache_pages) | |
Variables | |
| PG_MODULE_MAGIC | |
| #define NUM_BUFFERCACHE_PAGES_ELEM 8 |
Definition at line 18 of file pg_buffercache_pages.c.
Referenced by pg_buffercache_pages().
| Datum pg_buffercache_pages | ( | PG_FUNCTION_ARGS | ) |
Definition at line 59 of file pg_buffercache_pages.c.
References BlessTupleDesc(), buftag::blockNum, BufferCachePagesRec::blocknum, BM_DIRTY, BM_TAG_VALID, BM_VALID, BoolGetDatum, BOOLOID, BufferDescriptorGetBuffer, BufferDescriptors, BufferCachePagesRec::bufferid, FuncCallContext::call_cntr, CreateTemplateTupleDesc(), RelFileNode::dbNode, FirstBufMappingLock, sbufdesc::flags, buftag::forkNum, BufferCachePagesRec::forknum, heap_form_tuple(), HeapTupleGetDatum, i, Int16GetDatum, INT2OID, Int32GetDatum, INT4OID, Int64GetDatum(), INT8OID, InvalidBlockNumber, BufferCachePagesRec::isdirty, BufferCachePagesRec::isvalid, LockBufHdr, LW_SHARED, LWLockAcquire(), LWLockRelease(), FuncCallContext::max_calls, MemoryContextSwitchTo(), FuncCallContext::multi_call_memory_ctx, NBuffers, NUM_BUFFERCACHE_PAGES_ELEM, ObjectIdGetDatum, OIDOID, palloc(), BufferCachePagesContext::record, BufferCachePagesRec::reldatabase, BufferCachePagesRec::relfilenode, RelFileNode::relNode, BufferCachePagesRec::reltablespace, buftag::rnode, RelFileNode::spcNode, SRF_FIRSTCALL_INIT, SRF_IS_FIRSTCALL, SRF_PERCALL_SETUP, SRF_RETURN_DONE, SRF_RETURN_NEXT, sbufdesc::tag, BufferCachePagesContext::tupdesc, TupleDescInitEntry(), UnlockBufHdr, sbufdesc::usage_count, BufferCachePagesRec::usagecount, FuncCallContext::user_fctx, and values.
{
FuncCallContext *funcctx;
Datum result;
MemoryContext oldcontext;
BufferCachePagesContext *fctx; /* User function context. */
TupleDesc tupledesc;
HeapTuple tuple;
if (SRF_IS_FIRSTCALL())
{
int i;
volatile BufferDesc *bufHdr;
funcctx = SRF_FIRSTCALL_INIT();
/* Switch context when allocating stuff to be used in later calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Create a user function context for cross-call persistence */
fctx = (BufferCachePagesContext *) palloc(sizeof(BufferCachePagesContext));
/* Construct a tuple descriptor for the result rows. */
tupledesc = CreateTemplateTupleDesc(NUM_BUFFERCACHE_PAGES_ELEM, false);
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "bufferid",
INT4OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "relfilenode",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "reltablespace",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "reldatabase",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "relforknumber",
INT2OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 6, "relblocknumber",
INT8OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 7, "isdirty",
BOOLOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 8, "usage_count",
INT2OID, -1, 0);
fctx->tupdesc = BlessTupleDesc(tupledesc);
/* Allocate NBuffers worth of BufferCachePagesRec records. */
fctx->record = (BufferCachePagesRec *) palloc(sizeof(BufferCachePagesRec) * NBuffers);
/* Set max calls and remember the user function context. */
funcctx->max_calls = NBuffers;
funcctx->user_fctx = fctx;
/* Return to original context when allocating transient memory */
MemoryContextSwitchTo(oldcontext);
/*
* To get a consistent picture of the buffer state, we must lock all
* partitions of the buffer map. Needless to say, this is horrible
* for concurrency. Must grab locks in increasing order to avoid
* possible deadlocks.
*/
for (i = 0; i < NUM_BUFFER_PARTITIONS; i++)
LWLockAcquire(FirstBufMappingLock + i, LW_SHARED);
/*
* Scan though all the buffers, saving the relevant fields in the
* fctx->record structure.
*/
for (i = 0, bufHdr = BufferDescriptors; i < NBuffers; i++, bufHdr++)
{
/* Lock each buffer header before inspecting. */
LockBufHdr(bufHdr);
fctx->record[i].bufferid = BufferDescriptorGetBuffer(bufHdr);
fctx->record[i].relfilenode = bufHdr->tag.rnode.relNode;
fctx->record[i].reltablespace = bufHdr->tag.rnode.spcNode;
fctx->record[i].reldatabase = bufHdr->tag.rnode.dbNode;
fctx->record[i].forknum = bufHdr->tag.forkNum;
fctx->record[i].blocknum = bufHdr->tag.blockNum;
fctx->record[i].usagecount = bufHdr->usage_count;
if (bufHdr->flags & BM_DIRTY)
fctx->record[i].isdirty = true;
else
fctx->record[i].isdirty = false;
/* Note if the buffer is valid, and has storage created */
if ((bufHdr->flags & BM_VALID) && (bufHdr->flags & BM_TAG_VALID))
fctx->record[i].isvalid = true;
else
fctx->record[i].isvalid = false;
UnlockBufHdr(bufHdr);
}
/*
* And release locks. We do this in reverse order for two reasons:
* (1) Anyone else who needs more than one of the locks will be trying
* to lock them in increasing order; we don't want to release the
* other process until it can get all the locks it needs. (2) This
* avoids O(N^2) behavior inside LWLockRelease.
*/
for (i = NUM_BUFFER_PARTITIONS; --i >= 0;)
LWLockRelease(FirstBufMappingLock + i);
}
funcctx = SRF_PERCALL_SETUP();
/* Get the saved state */
fctx = funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
uint32 i = funcctx->call_cntr;
Datum values[NUM_BUFFERCACHE_PAGES_ELEM];
bool nulls[NUM_BUFFERCACHE_PAGES_ELEM];
values[0] = Int32GetDatum(fctx->record[i].bufferid);
nulls[0] = false;
/*
* Set all fields except the bufferid to null if the buffer is unused
* or not valid.
*/
if (fctx->record[i].blocknum == InvalidBlockNumber ||
fctx->record[i].isvalid == false)
{
nulls[1] = true;
nulls[2] = true;
nulls[3] = true;
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
nulls[7] = true;
}
else
{
values[1] = ObjectIdGetDatum(fctx->record[i].relfilenode);
nulls[1] = false;
values[2] = ObjectIdGetDatum(fctx->record[i].reltablespace);
nulls[2] = false;
values[3] = ObjectIdGetDatum(fctx->record[i].reldatabase);
nulls[3] = false;
values[4] = ObjectIdGetDatum(fctx->record[i].forknum);
nulls[4] = false;
values[5] = Int64GetDatum((int64) fctx->record[i].blocknum);
nulls[5] = false;
values[6] = BoolGetDatum(fctx->record[i].isdirty);
nulls[6] = false;
values[7] = Int16GetDatum(fctx->record[i].usagecount);
nulls[7] = false;
}
/* Build and return the tuple. */
tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
SRF_RETURN_DONE(funcctx);
}
| PG_FUNCTION_INFO_V1 | ( | pg_buffercache_pages | ) |
Definition at line 20 of file pg_buffercache_pages.c.
1.7.1