blinsert.c

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/*-------------------------------------------------------------------------
 *
 * blinsert.c
 *      Bloom index build and insert functions.
 *
 * Copyright (c) 2016-2017, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    contrib/bloom/blinsert.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/generic_xlog.h"
#include "catalog/index.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/indexfsm.h"
#include "storage/smgr.h"
#include "utils/memutils.h"
#include "utils/rel.h"

#include "bloom.h"

PG_MODULE_MAGIC;

/*
 * State of bloom index build.  We accumulate one page data here before
 * flushing it to buffer manager.
 */
typedef struct
{
    BloomState  blstate;        /* bloom index state */
    MemoryContext tmpCtx;       /* temporary memory context reset after each
                                 * tuple */
    char        data[BLCKSZ];   /* cached page */
    int64       count;          /* number of tuples in cached page */
} BloomBuildState;

/*
 * Flush page cached in BloomBuildState.
 */
static void
flushCachedPage(Relation index, BloomBuildState *buildstate)
{
    Page        page;
    Buffer      buffer = BloomNewBuffer(index);
    GenericXLogState *state;

    state = GenericXLogStart(index);
    page = GenericXLogRegisterBuffer(state, buffer, GENERIC_XLOG_FULL_IMAGE);
    memcpy(page, buildstate->data, BLCKSZ);
    GenericXLogFinish(state);
    UnlockReleaseBuffer(buffer);
}

/*
 * (Re)initialize cached page in BloomBuildState.
 */
static void
initCachedPage(BloomBuildState *buildstate)
{
    memset(buildstate->data, 0, BLCKSZ);
    BloomInitPage(buildstate->data, 0);
    buildstate->count = 0;
}

/*
 * Per-tuple callback from IndexBuildHeapScan.
 */
static void
bloomBuildCallback(Relation index, HeapTuple htup, Datum *values,
                   bool *isnull, bool tupleIsAlive, void *state)
{
    BloomBuildState *buildstate = (BloomBuildState *) state;
    MemoryContext oldCtx;
    BloomTuple *itup;

    oldCtx = MemoryContextSwitchTo(buildstate->tmpCtx);

    itup = BloomFormTuple(&buildstate->blstate, &htup->t_self, values, isnull);

    /* Try to add next item to cached page */
    if (BloomPageAddItem(&buildstate->blstate, buildstate->data, itup))
    {
        /* Next item was added successfully */
        buildstate->count++;
    }
    else
    {
        /* Cached page is full, flush it out and make a new one */
        flushCachedPage(index, buildstate);

        CHECK_FOR_INTERRUPTS();

        initCachedPage(buildstate);

        if (!BloomPageAddItem(&buildstate->blstate, buildstate->data, itup))
        {
            /* We shouldn't be here since we're inserting to the empty page */
            elog(ERROR, "could not add new bloom tuple to empty page");
        }
    }

    MemoryContextSwitchTo(oldCtx);
    MemoryContextReset(buildstate->tmpCtx);
}

/*
 * Build a new bloom index.
 */
IndexBuildResult *
blbuild(Relation heap, Relation index, IndexInfo *indexInfo)
{
    IndexBuildResult *result;
    double      reltuples;
    BloomBuildState buildstate;

    if (RelationGetNumberOfBlocks(index) != 0)
        elog(ERROR, "index \"%s\" already contains data",
             RelationGetRelationName(index));

    /* Initialize the meta page */
    BloomInitMetapage(index);

    /* Initialize the bloom build state */
    memset(&buildstate, 0, sizeof(buildstate));
    initBloomState(&buildstate.blstate, index);
    buildstate.tmpCtx = AllocSetContextCreate(CurrentMemoryContext,
                                              "Bloom build temporary context",
                                              ALLOCSET_DEFAULT_SIZES);
    initCachedPage(&buildstate);

    /* Do the heap scan */
    reltuples = IndexBuildHeapScan(heap, index, indexInfo, true,
                                   bloomBuildCallback, (void *) &buildstate);

    /*
     * There are could be some items in cached page.  Flush this page if
     * needed.
     */
    if (buildstate.count > 0)
        flushCachedPage(index, &buildstate);

    MemoryContextDelete(buildstate.tmpCtx);

    result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
    result->heap_tuples = result->index_tuples = reltuples;

    return result;
}

/*
 * Build an empty bloom index in the initialization fork.
 */
void
blbuildempty(Relation index)
{
    Page        metapage;

    /* Construct metapage. */
    metapage = (Page) palloc(BLCKSZ);
    BloomFillMetapage(index, metapage);

    /*
     * Write the page and log it.  It might seem that an immediate sync would
     * be sufficient to guarantee that the file exists on disk, but recovery
     * itself might remove it while replaying, for example, an
     * XLOG_DBASE_CREATE or XLOG_TBLSPC_CREATE record.  Therefore, we need
     * this even when wal_level=minimal.
     */
    PageSetChecksumInplace(metapage, BLOOM_METAPAGE_BLKNO);
    smgrwrite(index->rd_smgr, INIT_FORKNUM, BLOOM_METAPAGE_BLKNO,
              (char *) metapage, true);
    log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
                BLOOM_METAPAGE_BLKNO, metapage, false);

    /*
     * An immediate sync is required even if we xlog'd the page, because the
     * write did not go through shared_buffers and therefore a concurrent
     * checkpoint may have moved the redo pointer past our xlog record.
     */
    smgrimmedsync(index->rd_smgr, INIT_FORKNUM);
}

/*
 * Insert new tuple to the bloom index.
 */
bool
blinsert(Relation index, Datum *values, bool *isnull,
         ItemPointer ht_ctid, Relation heapRel,
         IndexUniqueCheck checkUnique,
         IndexInfo *indexInfo)
{
    BloomState  blstate;
    BloomTuple *itup;
    MemoryContext oldCtx;
    MemoryContext insertCtx;
    BloomMetaPageData *metaData;
    Buffer      buffer,
                metaBuffer;
    Page        page,
                metaPage;
    BlockNumber blkno = InvalidBlockNumber;
    OffsetNumber nStart;
    GenericXLogState *state;

    insertCtx = AllocSetContextCreate(CurrentMemoryContext,
                                      "Bloom insert temporary context",
                                      ALLOCSET_DEFAULT_SIZES);

    oldCtx = MemoryContextSwitchTo(insertCtx);

    initBloomState(&blstate, index);
    itup = BloomFormTuple(&blstate, ht_ctid, values, isnull);

    /*
     * At first, try to insert new tuple to the first page in notFullPage
     * array.  If successful, we don't need to modify the meta page.
     */
    metaBuffer = ReadBuffer(index, BLOOM_METAPAGE_BLKNO);
    LockBuffer(metaBuffer, BUFFER_LOCK_SHARE);
    metaData = BloomPageGetMeta(BufferGetPage(metaBuffer));

    if (metaData->nEnd > metaData->nStart)
    {
        Page        page;

        blkno = metaData->notFullPage[metaData->nStart];
        Assert(blkno != InvalidBlockNumber);

        /* Don't hold metabuffer lock while doing insert */
        LockBuffer(metaBuffer, BUFFER_LOCK_UNLOCK);

        buffer = ReadBuffer(index, blkno);
        LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);

        state = GenericXLogStart(index);
        page = GenericXLogRegisterBuffer(state, buffer, 0);

        /*
         * We might have found a page that was recently deleted by VACUUM.  If
         * so, we can reuse it, but we must reinitialize it.
         */
        if (PageIsNew(page) || BloomPageIsDeleted(page))
            BloomInitPage(page, 0);

        if (BloomPageAddItem(&blstate, page, itup))
        {
            /* Success!  Apply the change, clean up, and exit */
            GenericXLogFinish(state);
            UnlockReleaseBuffer(buffer);
            ReleaseBuffer(metaBuffer);
            MemoryContextSwitchTo(oldCtx);
            MemoryContextDelete(insertCtx);
            return false;
        }

        /* Didn't fit, must try other pages */
        GenericXLogAbort(state);
        UnlockReleaseBuffer(buffer);
    }
    else
    {
        /* No entries in notFullPage */
        LockBuffer(metaBuffer, BUFFER_LOCK_UNLOCK);
    }

    /*
     * Try other pages in notFullPage array.  We will have to change nStart in
     * metapage.  Thus, grab exclusive lock on metapage.
     */
    LockBuffer(metaBuffer, BUFFER_LOCK_EXCLUSIVE);

    /* nStart might have changed while we didn't have lock */
    nStart = metaData->nStart;

    /* Skip first page if we already tried it above */
    if (nStart < metaData->nEnd &&
        blkno == metaData->notFullPage[nStart])
        nStart++;

    /*
     * This loop iterates for each page we try from the notFullPage array, and
     * will also initialize a GenericXLogState for the fallback case of having
     * to allocate a new page.
     */
    for (;;)
    {
        state = GenericXLogStart(index);

        /* get modifiable copy of metapage */
        metaPage = GenericXLogRegisterBuffer(state, metaBuffer, 0);
        metaData = BloomPageGetMeta(metaPage);

        if (nStart >= metaData->nEnd)
            break;              /* no more entries in notFullPage array */

        blkno = metaData->notFullPage[nStart];
        Assert(blkno != InvalidBlockNumber);

        buffer = ReadBuffer(index, blkno);
        LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
        page = GenericXLogRegisterBuffer(state, buffer, 0);

        /* Basically same logic as above */
        if (PageIsNew(page) || BloomPageIsDeleted(page))
            BloomInitPage(page, 0);

        if (BloomPageAddItem(&blstate, page, itup))
        {
            /* Success!  Apply the changes, clean up, and exit */
            metaData->nStart = nStart;
            GenericXLogFinish(state);
            UnlockReleaseBuffer(buffer);
            UnlockReleaseBuffer(metaBuffer);
            MemoryContextSwitchTo(oldCtx);
            MemoryContextDelete(insertCtx);
            return false;
        }

        /* Didn't fit, must try other pages */
        GenericXLogAbort(state);
        UnlockReleaseBuffer(buffer);
        nStart++;
    }

    /*
     * Didn't find place to insert in notFullPage array.  Allocate new page.
     * (XXX is it good to do this while holding ex-lock on the metapage??)
     */
    buffer = BloomNewBuffer(index);

    page = GenericXLogRegisterBuffer(state, buffer, GENERIC_XLOG_FULL_IMAGE);
    BloomInitPage(page, 0);

    if (!BloomPageAddItem(&blstate, page, itup))
    {
        /* We shouldn't be here since we're inserting to an empty page */
        elog(ERROR, "could not add new bloom tuple to empty page");
    }

    /* Reset notFullPage array to contain just this new page */
    metaData->nStart = 0;
    metaData->nEnd = 1;
    metaData->notFullPage[0] = BufferGetBlockNumber(buffer);

    /* Apply the changes, clean up, and exit */
    GenericXLogFinish(state);

    UnlockReleaseBuffer(buffer);
    UnlockReleaseBuffer(metaBuffer);

    MemoryContextSwitchTo(oldCtx);
    MemoryContextDelete(insertCtx);

    return false;
}