pg_buffercache_pages.c File Reference

#include "postgres.h"
#include "access/htup_details.h"
#include "access/relation.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "port/pg_numa.h"
#include "storage/buf_internals.h"
#include "storage/bufmgr.h"
#include "utils/rel.h"

Include dependency graph for pg_buffercache_pages.c:

Go to the source code of this file.

Data Structures
struct	BufferCachePagesRec
struct	BufferCachePagesContext
struct	BufferCacheNumaRec
struct	BufferCacheNumaContext

Macros
#define	NUM_BUFFERCACHE_PAGES_MIN_ELEM   8
#define	NUM_BUFFERCACHE_PAGES_ELEM   9
#define	NUM_BUFFERCACHE_SUMMARY_ELEM   5
#define	NUM_BUFFERCACHE_USAGE_COUNTS_ELEM   4
#define	NUM_BUFFERCACHE_EVICT_ELEM   2
#define	NUM_BUFFERCACHE_EVICT_RELATION_ELEM   3
#define	NUM_BUFFERCACHE_EVICT_ALL_ELEM   3
#define	NUM_BUFFERCACHE_NUMA_ELEM   3

Functions
	PG_MODULE_MAGIC_EXT (.name="pg_buffercache",.version=PG_VERSION)
	PG_FUNCTION_INFO_V1 (pg_buffercache_pages)
	PG_FUNCTION_INFO_V1 (pg_buffercache_numa_pages)
	PG_FUNCTION_INFO_V1 (pg_buffercache_summary)
	PG_FUNCTION_INFO_V1 (pg_buffercache_usage_counts)
	PG_FUNCTION_INFO_V1 (pg_buffercache_evict)
	PG_FUNCTION_INFO_V1 (pg_buffercache_evict_relation)
	PG_FUNCTION_INFO_V1 (pg_buffercache_evict_all)
Datum	pg_buffercache_pages (PG_FUNCTION_ARGS)
Datum	pg_buffercache_numa_pages (PG_FUNCTION_ARGS)
Datum	pg_buffercache_summary (PG_FUNCTION_ARGS)
Datum	pg_buffercache_usage_counts (PG_FUNCTION_ARGS)
static void	pg_buffercache_superuser_check (char *func_name)
Datum	pg_buffercache_evict (PG_FUNCTION_ARGS)
Datum	pg_buffercache_evict_relation (PG_FUNCTION_ARGS)
Datum	pg_buffercache_evict_all (PG_FUNCTION_ARGS)

Variables
static bool	firstNumaTouch = true

Macro Definition Documentation

NUM_BUFFERCACHE_EVICT_ALL_ELEM

#define NUM_BUFFERCACHE_EVICT_ALL_ELEM   3

Definition at line 27 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_EVICT_ELEM

#define NUM_BUFFERCACHE_EVICT_ELEM   2

Definition at line 25 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_EVICT_RELATION_ELEM

#define NUM_BUFFERCACHE_EVICT_RELATION_ELEM   3

Definition at line 26 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_NUMA_ELEM

#define NUM_BUFFERCACHE_NUMA_ELEM   3

Definition at line 29 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_PAGES_ELEM

#define NUM_BUFFERCACHE_PAGES_ELEM   9

Definition at line 22 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_PAGES_MIN_ELEM

#define NUM_BUFFERCACHE_PAGES_MIN_ELEM   8

Definition at line 21 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_SUMMARY_ELEM

#define NUM_BUFFERCACHE_SUMMARY_ELEM   5

Definition at line 23 of file pg_buffercache_pages.c.

NUM_BUFFERCACHE_USAGE_COUNTS_ELEM

#define NUM_BUFFERCACHE_USAGE_COUNTS_ELEM   4

Definition at line 24 of file pg_buffercache_pages.c.

Function Documentation

pg_buffercache_evict()

Datum pg_buffercache_evict

(

PG_FUNCTION_ARGS

)

Definition at line 664 of file pg_buffercache_pages.c.

{
    Datum       result;
    TupleDesc   tupledesc;
    HeapTuple   tuple;
    Datum       values[NUM_BUFFERCACHE_EVICT_ELEM];
    bool        nulls[NUM_BUFFERCACHE_EVICT_ELEM] = {0};
 
    Buffer      buf = PG_GETARG_INT32(0);
    bool        buffer_flushed;
 
    if (get_call_result_type(fcinfo, NULL, &tupledesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");
 
    pg_buffercache_superuser_check("pg_buffercache_evict");
 
    if (buf < 1 || buf > NBuffers)
        elog(ERROR, "bad buffer ID: %d", buf);
 
    values[0] = BoolGetDatum(EvictUnpinnedBuffer(buf, &buffer_flushed));
    values[1] = BoolGetDatum(buffer_flushed);
 
    tuple = heap_form_tuple(tupledesc, values, nulls);
    result = HeapTupleGetDatum(tuple);
 
    PG_RETURN_DATUM(result);
}

References BoolGetDatum(), buf, elog, ERROR, EvictUnpinnedBuffer(), get_call_result_type(), heap_form_tuple(), HeapTupleGetDatum(), NBuffers, NUM_BUFFERCACHE_EVICT_ELEM, pg_buffercache_superuser_check(), PG_GETARG_INT32, PG_RETURN_DATUM, TYPEFUNC_COMPOSITE, and values.

pg_buffercache_evict_all()

Datum pg_buffercache_evict_all

(

PG_FUNCTION_ARGS

)

Definition at line 746 of file pg_buffercache_pages.c.

{
    Datum       result;
    TupleDesc   tupledesc;
    HeapTuple   tuple;
    Datum       values[NUM_BUFFERCACHE_EVICT_ALL_ELEM];
    bool        nulls[NUM_BUFFERCACHE_EVICT_ALL_ELEM] = {0};
 
    int32       buffers_evicted = 0;
    int32       buffers_flushed = 0;
    int32       buffers_skipped = 0;
 
    if (get_call_result_type(fcinfo, NULL, &tupledesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");
 
    pg_buffercache_superuser_check("pg_buffercache_evict_all");
 
    EvictAllUnpinnedBuffers(&buffers_evicted, &buffers_flushed,
                            &buffers_skipped);
 
    values[0] = Int32GetDatum(buffers_evicted);
    values[1] = Int32GetDatum(buffers_flushed);
    values[2] = Int32GetDatum(buffers_skipped);
 
    tuple = heap_form_tuple(tupledesc, values, nulls);
    result = HeapTupleGetDatum(tuple);
 
    PG_RETURN_DATUM(result);
}

References elog, ERROR, EvictAllUnpinnedBuffers(), get_call_result_type(), heap_form_tuple(), HeapTupleGetDatum(), Int32GetDatum(), NUM_BUFFERCACHE_EVICT_ALL_ELEM, pg_buffercache_superuser_check(), PG_RETURN_DATUM, TYPEFUNC_COMPOSITE, and values.

pg_buffercache_evict_relation()

Datum pg_buffercache_evict_relation

(

PG_FUNCTION_ARGS

)

Definition at line 696 of file pg_buffercache_pages.c.

{
    Datum       result;
    TupleDesc   tupledesc;
    HeapTuple   tuple;
    Datum       values[NUM_BUFFERCACHE_EVICT_RELATION_ELEM];
    bool        nulls[NUM_BUFFERCACHE_EVICT_RELATION_ELEM] = {0};
 
    Oid         relOid;
    Relation    rel;
 
    int32       buffers_evicted = 0;
    int32       buffers_flushed = 0;
    int32       buffers_skipped = 0;
 
    if (get_call_result_type(fcinfo, NULL, &tupledesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");
 
    pg_buffercache_superuser_check("pg_buffercache_evict_relation");
 
    relOid = PG_GETARG_OID(0);
 
    rel = relation_open(relOid, AccessShareLock);
 
    if (RelationUsesLocalBuffers(rel))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("relation uses local buffers, %s() is intended to be used for shared buffers only",
                        "pg_buffercache_evict_relation")));
 
    EvictRelUnpinnedBuffers(rel, &buffers_evicted, &buffers_flushed,
                            &buffers_skipped);
 
    relation_close(rel, AccessShareLock);
 
    values[0] = Int32GetDatum(buffers_evicted);
    values[1] = Int32GetDatum(buffers_flushed);
    values[2] = Int32GetDatum(buffers_skipped);
 
    tuple = heap_form_tuple(tupledesc, values, nulls);
    result = HeapTupleGetDatum(tuple);
 
    PG_RETURN_DATUM(result);
}

References AccessShareLock, elog, ereport, errcode(), errmsg(), ERROR, EvictRelUnpinnedBuffers(), get_call_result_type(), heap_form_tuple(), HeapTupleGetDatum(), Int32GetDatum(), NUM_BUFFERCACHE_EVICT_RELATION_ELEM, pg_buffercache_superuser_check(), PG_GETARG_OID, PG_RETURN_DATUM, relation_close(), relation_open(), RelationUsesLocalBuffers, TYPEFUNC_COMPOSITE, and values.

pg_buffercache_numa_pages()

Datum pg_buffercache_numa_pages

(

PG_FUNCTION_ARGS

)

Definition at line 303 of file pg_buffercache_pages.c.

{
    FuncCallContext *funcctx;
    MemoryContext oldcontext;
    BufferCacheNumaContext *fctx;   /* User function context. */
    TupleDesc   tupledesc;
    TupleDesc   expected_tupledesc;
    HeapTuple   tuple;
    Datum       result;
 
    if (SRF_IS_FIRSTCALL())
    {
        int         i,
                    idx;
        Size        os_page_size;
        void      **os_page_ptrs;
        int        *os_page_status;
        uint64      os_page_count;
        int         pages_per_buffer;
        int         max_entries;
        volatile uint64 touch pg_attribute_unused();
        char       *startptr,
                   *endptr;
 
        if (pg_numa_init() == -1)
            elog(ERROR, "libnuma initialization failed or NUMA is not supported on this platform");
 
        /*
         * The database block size and OS memory page size are unlikely to be
         * the same. The block size is 1-32KB, the memory page size depends on
         * platform. On x86 it's usually 4KB, on ARM it's 4KB or 64KB, but
         * there are also features like THP etc. Moreover, we don't quite know
         * how the pages and buffers "align" in memory - the buffers may be
         * shifted in some way, using more memory pages than necessary.
         *
         * So we need to be careful about mapping buffers to memory pages. We
         * calculate the maximum number of pages a buffer might use, so that
         * we allocate enough space for the entries. And then we count the
         * actual number of entries as we scan the buffers.
         *
         * This information is needed before calling move_pages() for NUMA
         * node id inquiry.
         */
        os_page_size = pg_get_shmem_pagesize();
 
        /*
         * The pages and block size is expected to be 2^k, so one divides the
         * other (we don't know in which direction). This does not say
         * anything about relative alignment of pages/buffers.
         */
        Assert((os_page_size % BLCKSZ == 0) || (BLCKSZ % os_page_size == 0));
 
        /*
         * How many addresses we are going to query? Simply get the page for
         * the first buffer, and first page after the last buffer, and count
         * the pages from that.
         */
        startptr = (char *) TYPEALIGN_DOWN(os_page_size,
                                           BufferGetBlock(1));
        endptr = (char *) TYPEALIGN(os_page_size,
                                    (char *) BufferGetBlock(NBuffers) + BLCKSZ);
        os_page_count = (endptr - startptr) / os_page_size;
 
        /* Used to determine the NUMA node for all OS pages at once */
        os_page_ptrs = palloc0(sizeof(void *) * os_page_count);
        os_page_status = palloc(sizeof(uint64) * os_page_count);
 
        /* Fill pointers for all the memory pages. */
        idx = 0;
        for (char *ptr = startptr; ptr < endptr; ptr += os_page_size)
        {
            os_page_ptrs[idx++] = ptr;
 
            /* Only need to touch memory once per backend process lifetime */
            if (firstNumaTouch)
                pg_numa_touch_mem_if_required(touch, ptr);
        }
 
        Assert(idx == os_page_count);
 
        elog(DEBUG1, "NUMA: NBuffers=%d os_page_count=" UINT64_FORMAT " "
             "os_page_size=%zu", NBuffers, os_page_count, os_page_size);
 
        /*
         * If we ever get 0xff back from kernel inquiry, then we probably have
         * bug in our buffers to OS page mapping code here.
         */
        memset(os_page_status, 0xff, sizeof(int) * os_page_count);
 
        /* Query NUMA status for all the pointers */
        if (pg_numa_query_pages(0, os_page_count, os_page_ptrs, os_page_status) == -1)
            elog(ERROR, "failed NUMA pages inquiry: %m");
 
        /* Initialize the multi-call context, load entries about buffers */
 
        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 = (BufferCacheNumaContext *) palloc(sizeof(BufferCacheNumaContext));
 
        if (get_call_result_type(fcinfo, NULL, &expected_tupledesc) != TYPEFUNC_COMPOSITE)
            elog(ERROR, "return type must be a row type");
 
        if (expected_tupledesc->natts != NUM_BUFFERCACHE_NUMA_ELEM)
            elog(ERROR, "incorrect number of output arguments");
 
        /* Construct a tuple descriptor for the result rows. */
        tupledesc = CreateTemplateTupleDesc(expected_tupledesc->natts);
        TupleDescInitEntry(tupledesc, (AttrNumber) 1, "bufferid",
                           INT4OID, -1, 0);
        TupleDescInitEntry(tupledesc, (AttrNumber) 2, "os_page_num",
                           INT8OID, -1, 0);
        TupleDescInitEntry(tupledesc, (AttrNumber) 3, "numa_node",
                           INT4OID, -1, 0);
 
        fctx->tupdesc = BlessTupleDesc(tupledesc);
 
        /*
         * Each buffer needs at least one entry, but it might be offset in
         * some way, and use one extra entry. So we allocate space for the
         * maximum number of entries we might need, and then count the exact
         * number as we're walking buffers. That way we can do it in one pass,
         * without reallocating memory.
         */
        pages_per_buffer = Max(1, BLCKSZ / os_page_size) + 1;
        max_entries = NBuffers * pages_per_buffer;
 
        /* Allocate entries for BufferCachePagesRec records. */
        fctx->record = (BufferCacheNumaRec *)
            MemoryContextAllocHuge(CurrentMemoryContext,
                                   sizeof(BufferCacheNumaRec) * max_entries);
 
        /* Return to original context when allocating transient memory */
        MemoryContextSwitchTo(oldcontext);
 
        if (firstNumaTouch)
            elog(DEBUG1, "NUMA: page-faulting the buffercache for proper NUMA readouts");
 
        /*
         * Scan through all the buffers, saving the relevant fields in the
         * fctx->record structure.
         *
         * We don't hold the partition locks, so we don't get a consistent
         * snapshot across all buffers, but we do grab the buffer header
         * locks, so the information of each buffer is self-consistent.
         *
         * This loop touches and stores addresses into os_page_ptrs[] as input
         * to one big move_pages(2) inquiry system call. Basically we ask for
         * all memory pages for NBuffers.
         */
        startptr = (char *) TYPEALIGN_DOWN(os_page_size, (char *) BufferGetBlock(1));
        idx = 0;
        for (i = 0; i < NBuffers; i++)
        {
            char       *buffptr = (char *) BufferGetBlock(i + 1);
            BufferDesc *bufHdr;
            uint32      buf_state;
            uint32      bufferid;
            int32       page_num;
            char       *startptr_buff,
                       *endptr_buff;
 
            CHECK_FOR_INTERRUPTS();
 
            bufHdr = GetBufferDescriptor(i);
 
            /* Lock each buffer header before inspecting. */
            buf_state = LockBufHdr(bufHdr);
            bufferid = BufferDescriptorGetBuffer(bufHdr);
            UnlockBufHdr(bufHdr, buf_state);
 
            /* start of the first page of this buffer */
            startptr_buff = (char *) TYPEALIGN_DOWN(os_page_size, buffptr);
 
            /* end of the buffer (no need to align to memory page) */
            endptr_buff = buffptr + BLCKSZ;
 
            Assert(startptr_buff < endptr_buff);
 
            /* calculate ID of the first page for this buffer */
            page_num = (startptr_buff - startptr) / os_page_size;
 
            /* Add an entry for each OS page overlapping with this buffer. */
            for (char *ptr = startptr_buff; ptr < endptr_buff; ptr += os_page_size)
            {
                fctx->record[idx].bufferid = bufferid;
                fctx->record[idx].page_num = page_num;
                fctx->record[idx].numa_node = os_page_status[page_num];
 
                /* advance to the next entry/page */
                ++idx;
                ++page_num;
            }
        }
 
        Assert((idx >= os_page_count) && (idx <= max_entries));
 
        /* Set max calls and remember the user function context. */
        funcctx->max_calls = idx;
        funcctx->user_fctx = fctx;
 
        /* Remember this backend touched the pages */
        firstNumaTouch = false;
    }
 
    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_NUMA_ELEM];
        bool        nulls[NUM_BUFFERCACHE_NUMA_ELEM];
 
        values[0] = Int32GetDatum(fctx->record[i].bufferid);
        nulls[0] = false;
 
        values[1] = Int64GetDatum(fctx->record[i].page_num);
        nulls[1] = false;
 
        values[2] = Int32GetDatum(fctx->record[i].numa_node);
        nulls[2] = 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);
}

References Assert(), BlessTupleDesc(), BufferDescriptorGetBuffer(), BufferGetBlock(), BufferCacheNumaRec::bufferid, FuncCallContext::call_cntr, CHECK_FOR_INTERRUPTS, CreateTemplateTupleDesc(), CurrentMemoryContext, DEBUG1, elog, ERROR, firstNumaTouch, get_call_result_type(), GetBufferDescriptor(), heap_form_tuple(), HeapTupleGetDatum(), i, idx(), Int32GetDatum(), Int64GetDatum(), LockBufHdr(), Max, FuncCallContext::max_calls, MemoryContextAllocHuge(), MemoryContextSwitchTo(), FuncCallContext::multi_call_memory_ctx, TupleDescData::natts, NBuffers, NUM_BUFFERCACHE_NUMA_ELEM, BufferCacheNumaRec::numa_node, BufferCacheNumaRec::page_num, palloc(), palloc0(), pg_attribute_unused, pg_get_shmem_pagesize(), pg_numa_init(), pg_numa_query_pages(), pg_numa_touch_mem_if_required, BufferCacheNumaContext::record, SRF_FIRSTCALL_INIT, SRF_IS_FIRSTCALL, SRF_PERCALL_SETUP, SRF_RETURN_DONE, SRF_RETURN_NEXT, BufferCacheNumaContext::tupdesc, TupleDescInitEntry(), TYPEALIGN, TYPEALIGN_DOWN, TYPEFUNC_COMPOSITE, UINT64_FORMAT, UnlockBufHdr(), FuncCallContext::user_fctx, and values.

pg_buffercache_pages()

Datum pg_buffercache_pages

(

PG_FUNCTION_ARGS

)

Definition at line 110 of file pg_buffercache_pages.c.

{
    FuncCallContext *funcctx;
    Datum       result;
    MemoryContext oldcontext;
    BufferCachePagesContext *fctx;  /* User function context. */
    TupleDesc   tupledesc;
    TupleDesc   expected_tupledesc;
    HeapTuple   tuple;
 
    if (SRF_IS_FIRSTCALL())
    {
        int         i;
 
        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));
 
        /*
         * To smoothly support upgrades from version 1.0 of this extension
         * transparently handle the (non-)existence of the pinning_backends
         * column. We unfortunately have to get the result type for that... -
         * we can't use the result type determined by the function definition
         * without potentially crashing when somebody uses the old (or even
         * wrong) function definition though.
         */
        if (get_call_result_type(fcinfo, NULL, &expected_tupledesc) != TYPEFUNC_COMPOSITE)
            elog(ERROR, "return type must be a row type");
 
        if (expected_tupledesc->natts < NUM_BUFFERCACHE_PAGES_MIN_ELEM ||
            expected_tupledesc->natts > NUM_BUFFERCACHE_PAGES_ELEM)
            elog(ERROR, "incorrect number of output arguments");
 
        /* Construct a tuple descriptor for the result rows. */
        tupledesc = CreateTemplateTupleDesc(expected_tupledesc->natts);
        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);
 
        if (expected_tupledesc->natts == NUM_BUFFERCACHE_PAGES_ELEM)
            TupleDescInitEntry(tupledesc, (AttrNumber) 9, "pinning_backends",
                               INT4OID, -1, 0);
 
        fctx->tupdesc = BlessTupleDesc(tupledesc);
 
        /* Allocate NBuffers worth of BufferCachePagesRec records. */
        fctx->record = (BufferCachePagesRec *)
            MemoryContextAllocHuge(CurrentMemoryContext,
                                   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);
 
        /*
         * Scan through all the buffers, saving the relevant fields in the
         * fctx->record structure.
         *
         * We don't hold the partition locks, so we don't get a consistent
         * snapshot across all buffers, but we do grab the buffer header
         * locks, so the information of each buffer is self-consistent.
         */
        for (i = 0; i < NBuffers; i++)
        {
            BufferDesc *bufHdr;
            uint32      buf_state;
 
            bufHdr = GetBufferDescriptor(i);
            /* Lock each buffer header before inspecting. */
            buf_state = LockBufHdr(bufHdr);
 
            fctx->record[i].bufferid = BufferDescriptorGetBuffer(bufHdr);
            fctx->record[i].relfilenumber = BufTagGetRelNumber(&bufHdr->tag);
            fctx->record[i].reltablespace = bufHdr->tag.spcOid;
            fctx->record[i].reldatabase = bufHdr->tag.dbOid;
            fctx->record[i].forknum = BufTagGetForkNum(&bufHdr->tag);
            fctx->record[i].blocknum = bufHdr->tag.blockNum;
            fctx->record[i].usagecount = BUF_STATE_GET_USAGECOUNT(buf_state);
            fctx->record[i].pinning_backends = BUF_STATE_GET_REFCOUNT(buf_state);
 
            if (buf_state & BM_DIRTY)
                fctx->record[i].isdirty = true;
            else
                fctx->record[i].isdirty = false;
 
            /* Note if the buffer is valid, and has storage created */
            if ((buf_state & BM_VALID) && (buf_state & BM_TAG_VALID))
                fctx->record[i].isvalid = true;
            else
                fctx->record[i].isvalid = false;
 
            UnlockBufHdr(bufHdr, buf_state);
        }
    }
 
    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;
            /* unused for v1.0 callers, but the array is always long enough */
            nulls[8] = true;
        }
        else
        {
            values[1] = ObjectIdGetDatum(fctx->record[i].relfilenumber);
            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;
            /* unused for v1.0 callers, but the array is always long enough */
            values[8] = Int32GetDatum(fctx->record[i].pinning_backends);
            nulls[8] = 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);
}

References BlessTupleDesc(), BufferCachePagesRec::blocknum, buftag::blockNum, BM_DIRTY, BM_TAG_VALID, BM_VALID, BoolGetDatum(), BUF_STATE_GET_REFCOUNT, BUF_STATE_GET_USAGECOUNT, BufferDescriptorGetBuffer(), BufferCachePagesRec::bufferid, BufTagGetForkNum(), BufTagGetRelNumber(), FuncCallContext::call_cntr, CreateTemplateTupleDesc(), CurrentMemoryContext, buftag::dbOid, elog, ERROR, BufferCachePagesRec::forknum, get_call_result_type(), GetBufferDescriptor(), heap_form_tuple(), HeapTupleGetDatum(), i, Int16GetDatum(), Int32GetDatum(), Int64GetDatum(), InvalidBlockNumber, BufferCachePagesRec::isdirty, BufferCachePagesRec::isvalid, LockBufHdr(), FuncCallContext::max_calls, MemoryContextAllocHuge(), MemoryContextSwitchTo(), FuncCallContext::multi_call_memory_ctx, TupleDescData::natts, NBuffers, NUM_BUFFERCACHE_PAGES_ELEM, NUM_BUFFERCACHE_PAGES_MIN_ELEM, ObjectIdGetDatum(), palloc(), BufferCachePagesRec::pinning_backends, BufferCachePagesContext::record, BufferCachePagesRec::reldatabase, BufferCachePagesRec::relfilenumber, BufferCachePagesRec::reltablespace, buftag::spcOid, SRF_FIRSTCALL_INIT, SRF_IS_FIRSTCALL, SRF_PERCALL_SETUP, SRF_RETURN_DONE, SRF_RETURN_NEXT, BufferDesc::tag, BufferCachePagesContext::tupdesc, TupleDescInitEntry(), TYPEFUNC_COMPOSITE, UnlockBufHdr(), BufferCachePagesRec::usagecount, FuncCallContext::user_fctx, and values.

pg_buffercache_summary()

Datum pg_buffercache_summary

(

PG_FUNCTION_ARGS

)

Definition at line 542 of file pg_buffercache_pages.c.

{
    Datum       result;
    TupleDesc   tupledesc;
    HeapTuple   tuple;
    Datum       values[NUM_BUFFERCACHE_SUMMARY_ELEM];
    bool        nulls[NUM_BUFFERCACHE_SUMMARY_ELEM];
 
    int32       buffers_used = 0;
    int32       buffers_unused = 0;
    int32       buffers_dirty = 0;
    int32       buffers_pinned = 0;
    int64       usagecount_total = 0;
 
    if (get_call_result_type(fcinfo, NULL, &tupledesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");
 
    for (int i = 0; i < NBuffers; i++)
    {
        BufferDesc *bufHdr;
        uint32      buf_state;
 
        /*
         * This function summarizes the state of all headers. Locking the
         * buffer headers wouldn't provide an improved result as the state of
         * the buffer can still change after we release the lock and it'd
         * noticeably increase the cost of the function.
         */
        bufHdr = GetBufferDescriptor(i);
        buf_state = pg_atomic_read_u32(&bufHdr->state);
 
        if (buf_state & BM_VALID)
        {
            buffers_used++;
            usagecount_total += BUF_STATE_GET_USAGECOUNT(buf_state);
 
            if (buf_state & BM_DIRTY)
                buffers_dirty++;
        }
        else
            buffers_unused++;
 
        if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
            buffers_pinned++;
    }
 
    memset(nulls, 0, sizeof(nulls));
    values[0] = Int32GetDatum(buffers_used);
    values[1] = Int32GetDatum(buffers_unused);
    values[2] = Int32GetDatum(buffers_dirty);
    values[3] = Int32GetDatum(buffers_pinned);
 
    if (buffers_used != 0)
        values[4] = Float8GetDatum((double) usagecount_total / buffers_used);
    else
        nulls[4] = true;
 
    /* Build and return the tuple. */
    tuple = heap_form_tuple(tupledesc, values, nulls);
    result = HeapTupleGetDatum(tuple);
 
    PG_RETURN_DATUM(result);
}

References BM_DIRTY, BM_VALID, BUF_STATE_GET_REFCOUNT, BUF_STATE_GET_USAGECOUNT, elog, ERROR, Float8GetDatum(), get_call_result_type(), GetBufferDescriptor(), heap_form_tuple(), HeapTupleGetDatum(), i, Int32GetDatum(), NBuffers, NUM_BUFFERCACHE_SUMMARY_ELEM, pg_atomic_read_u32(), PG_RETURN_DATUM, BufferDesc::state, TYPEFUNC_COMPOSITE, and values.

pg_buffercache_superuser_check()

static void pg_buffercache_superuser_check ( char *  func_name )

static

Definition at line 651 of file pg_buffercache_pages.c.

{
    if (!superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be superuser to use %s()",
                        func_name)));
}

References ereport, errcode(), errmsg(), ERROR, and superuser().

Referenced by pg_buffercache_evict(), pg_buffercache_evict_all(), and pg_buffercache_evict_relation().

pg_buffercache_usage_counts()

Datum pg_buffercache_usage_counts

(

PG_FUNCTION_ARGS

)

Definition at line 607 of file pg_buffercache_pages.c.

{
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    int         usage_counts[BM_MAX_USAGE_COUNT + 1] = {0};
    int         dirty[BM_MAX_USAGE_COUNT + 1] = {0};
    int         pinned[BM_MAX_USAGE_COUNT + 1] = {0};
    Datum       values[NUM_BUFFERCACHE_USAGE_COUNTS_ELEM];
    bool        nulls[NUM_BUFFERCACHE_USAGE_COUNTS_ELEM] = {0};
 
    InitMaterializedSRF(fcinfo, 0);
 
    for (int i = 0; i < NBuffers; i++)
    {
        BufferDesc *bufHdr = GetBufferDescriptor(i);
        uint32      buf_state = pg_atomic_read_u32(&bufHdr->state);
        int         usage_count;
 
        usage_count = BUF_STATE_GET_USAGECOUNT(buf_state);
        usage_counts[usage_count]++;
 
        if (buf_state & BM_DIRTY)
            dirty[usage_count]++;
 
        if (BUF_STATE_GET_REFCOUNT(buf_state) > 0)
            pinned[usage_count]++;
    }
 
    for (int i = 0; i < BM_MAX_USAGE_COUNT + 1; i++)
    {
        values[0] = Int32GetDatum(i);
        values[1] = Int32GetDatum(usage_counts[i]);
        values[2] = Int32GetDatum(dirty[i]);
        values[3] = Int32GetDatum(pinned[i]);
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
 
    return (Datum) 0;
}

References BM_MAX_USAGE_COUNT.

PG_FUNCTION_INFO_V1() [1/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_evict

)

PG_FUNCTION_INFO_V1() [2/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_evict_all

)

PG_FUNCTION_INFO_V1() [3/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_evict_relation

)

PG_FUNCTION_INFO_V1() [4/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_numa_pages

)

PG_FUNCTION_INFO_V1() [5/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_pages

)

PG_FUNCTION_INFO_V1() [6/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_summary

)

PG_FUNCTION_INFO_V1() [7/7]

PG_FUNCTION_INFO_V1

(

pg_buffercache_usage_counts

)

PG_MODULE_MAGIC_EXT()

PG_MODULE_MAGIC_EXT	(	.	name = "pg_buffercache",
		.	version = PG_VERSION
	)

Variable Documentation

firstNumaTouch

bool firstNumaTouch = true

static

Definition at line 106 of file pg_buffercache_pages.c.

Referenced by pg_buffercache_numa_pages().