test_tidstore.c

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/*--------------------------------------------------------------------------
 *
 * test_tidstore.c
 *      Test TidStore data structure.
 *
 * Note: all locking in this test module is useless since there is only
 * a single process to use the TidStore. It is meant to be an example of
 * usage.
 *
 * Copyright (c) 2024-2026, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/test/modules/test_tidstore/test_tidstore.c
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/tidstore.h"
#include "fmgr.h"
#include "storage/block.h"
#include "storage/itemptr.h"
#include "storage/lwlock.h"
#include "utils/array.h"
#include "utils/memutils.h"
 
PG_MODULE_MAGIC;
 
PG_FUNCTION_INFO_V1(test_create);
PG_FUNCTION_INFO_V1(do_set_block_offsets);
PG_FUNCTION_INFO_V1(check_set_block_offsets);
PG_FUNCTION_INFO_V1(test_is_full);
PG_FUNCTION_INFO_V1(test_destroy);
 
static TidStore *tidstore = NULL;
static size_t tidstore_empty_size;
 
/* array for verification of some tests */
typedef struct ItemArray
{
    ItemPointerData *insert_tids;
    ItemPointerData *lookup_tids;
    ItemPointerData *iter_tids;
    int         max_tids;
    int         num_tids;
} ItemArray;
 
static ItemArray items;
 
/* comparator routine for ItemPointer */
static int
itemptr_cmp(const void *left, const void *right)
{
    BlockNumber lblk,
                rblk;
    OffsetNumber loff,
                roff;
 
    lblk = ItemPointerGetBlockNumber((const ItemPointerData *) left);
    rblk = ItemPointerGetBlockNumber((const ItemPointerData *) right);
 
    if (lblk < rblk)
        return -1;
    if (lblk > rblk)
        return 1;
 
    loff = ItemPointerGetOffsetNumber((const ItemPointerData *) left);
    roff = ItemPointerGetOffsetNumber((const ItemPointerData *) right);
 
    if (loff < roff)
        return -1;
    if (loff > roff)
        return 1;
 
    return 0;
}
 
/*
 * Create a TidStore. If shared is false, the tidstore is created
 * on TopMemoryContext, otherwise on DSA. Although the tidstore
 * is created on DSA, only the same process can subsequently use
 * the tidstore. The tidstore handle is not shared anywhere.
*/
Datum
test_create(PG_FUNCTION_ARGS)
{
    bool        shared = PG_GETARG_BOOL(0);
    MemoryContext old_ctx;
 
    /* doesn't really matter, since it's just a hint */
    size_t      tidstore_max_size = 2 * 1024 * 1024;
    size_t      array_init_size = 1024;
 
    Assert(tidstore == NULL);
 
    /*
     * Create the TidStore on TopMemoryContext so that the same process use it
     * for subsequent tests.
     */
    old_ctx = MemoryContextSwitchTo(TopMemoryContext);
 
    if (shared)
    {
        int         tranche_id;
 
        tranche_id = LWLockNewTrancheId("test_tidstore");
 
        tidstore = TidStoreCreateShared(tidstore_max_size, tranche_id);
 
        /*
         * Remain attached until end of backend or explicitly detached so that
         * the same process use the tidstore for subsequent tests.
         */
        dsa_pin_mapping(TidStoreGetDSA(tidstore));
    }
    else
        /* VACUUM uses insert only, so we test the other option. */
        tidstore = TidStoreCreateLocal(tidstore_max_size, false);
 
    tidstore_empty_size = TidStoreMemoryUsage(tidstore);
 
    items.num_tids = 0;
    items.max_tids = array_init_size / sizeof(ItemPointerData);
    items.insert_tids = (ItemPointerData *) palloc0(array_init_size);
    items.lookup_tids = (ItemPointerData *) palloc0(array_init_size);
    items.iter_tids = (ItemPointerData *) palloc0(array_init_size);
 
    MemoryContextSwitchTo(old_ctx);
 
    PG_RETURN_VOID();
}
 
static void
sanity_check_array(ArrayType *ta)
{
    if (ARR_HASNULL(ta) && array_contains_nulls(ta))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                 errmsg("array must not contain nulls")));
 
    if (ARR_NDIM(ta) > 1)
        ereport(ERROR,
                (errcode(ERRCODE_DATA_EXCEPTION),
                 errmsg("argument must be empty or one-dimensional array")));
}
 
static void
check_tidstore_available(void)
{
    if (tidstore == NULL)
        elog(ERROR, "tidstore is not created");
}
 
static void
purge_from_verification_array(BlockNumber blkno)
{
    int         dst = 0;
 
    for (int src = 0; src < items.num_tids; src++)
        if (ItemPointerGetBlockNumber(&items.insert_tids[src]) != blkno)
            items.insert_tids[dst++] = items.insert_tids[src];
    items.num_tids = dst;
}
 
 
/* Set the given block and offsets pairs */
Datum
do_set_block_offsets(PG_FUNCTION_ARGS)
{
    BlockNumber blkno = PG_GETARG_INT64(0);
    ArrayType  *ta = PG_GETARG_ARRAYTYPE_P_COPY(1);
    OffsetNumber *offs;
    int         noffs;
 
    check_tidstore_available();
    sanity_check_array(ta);
 
    noffs = ArrayGetNItems(ARR_NDIM(ta), ARR_DIMS(ta));
    offs = ((OffsetNumber *) ARR_DATA_PTR(ta));
 
    /* Set TIDs in the store */
    TidStoreLockExclusive(tidstore);
    TidStoreSetBlockOffsets(tidstore, blkno, offs, noffs);
    TidStoreUnlock(tidstore);
 
    /* Remove the existing items of blkno from the verification array */
    purge_from_verification_array(blkno);
 
    /* Set TIDs in verification array */
    for (int i = 0; i < noffs; i++)
    {
        ItemPointer tid;
        int         idx = items.num_tids + i;
 
        /* Enlarge the TID arrays if necessary */
        if (idx >= items.max_tids)
        {
            items.max_tids *= 2;
            items.insert_tids = repalloc(items.insert_tids, sizeof(ItemPointerData) * items.max_tids);
            items.lookup_tids = repalloc(items.lookup_tids, sizeof(ItemPointerData) * items.max_tids);
            items.iter_tids = repalloc(items.iter_tids, sizeof(ItemPointerData) * items.max_tids);
        }
 
        tid = &(items.insert_tids[idx]);
        ItemPointerSet(tid, blkno, offs[i]);
    }
 
    /* Update statistics */
    items.num_tids += noffs;
 
    PG_RETURN_INT64(blkno);
}
 
/*
 * Verify TIDs in store against the array.
 */
Datum
check_set_block_offsets(PG_FUNCTION_ARGS)
{
    TidStoreIter *iter;
    TidStoreIterResult *iter_result;
    int         num_iter_tids = 0;
    int         num_lookup_tids = 0;
    BlockNumber prevblkno = 0;
 
    check_tidstore_available();
 
    /* lookup each member in the verification array */
    for (int i = 0; i < items.num_tids; i++)
        if (!TidStoreIsMember(tidstore, &items.insert_tids[i]))
            elog(ERROR, "missing TID with block %u, offset %u",
                 ItemPointerGetBlockNumber(&items.insert_tids[i]),
                 ItemPointerGetOffsetNumber(&items.insert_tids[i]));
 
    /*
     * Lookup all possible TIDs for each distinct block in the verification
     * array and save successful lookups in the lookup array.
     */
 
    for (int i = 0; i < items.num_tids; i++)
    {
        BlockNumber blkno = ItemPointerGetBlockNumber(&items.insert_tids[i]);
 
        if (i > 0 && blkno == prevblkno)
            continue;
 
        for (OffsetNumber offset = FirstOffsetNumber; offset < MaxOffsetNumber; offset++)
        {
            ItemPointerData tid;
 
            ItemPointerSet(&tid, blkno, offset);
 
            TidStoreLockShare(tidstore);
            if (TidStoreIsMember(tidstore, &tid))
                ItemPointerSet(&items.lookup_tids[num_lookup_tids++], blkno, offset);
            TidStoreUnlock(tidstore);
        }
 
        prevblkno = blkno;
    }
 
    /* Collect TIDs stored in the tidstore, in order */
 
    TidStoreLockShare(tidstore);
    iter = TidStoreBeginIterate(tidstore);
    while ((iter_result = TidStoreIterateNext(iter)) != NULL)
    {
        OffsetNumber offsets[MaxOffsetNumber];
        int         num_offsets;
 
        num_offsets = TidStoreGetBlockOffsets(iter_result, offsets, lengthof(offsets));
        Assert(num_offsets <= lengthof(offsets));
        for (int i = 0; i < num_offsets; i++)
            ItemPointerSet(&(items.iter_tids[num_iter_tids++]), iter_result->blkno,
                           offsets[i]);
    }
    TidStoreEndIterate(iter);
    TidStoreUnlock(tidstore);
 
    /*
     * Sort verification and lookup arrays and test that all arrays are the
     * same.
     */
 
    if (num_lookup_tids != items.num_tids)
        elog(ERROR, "should have %d TIDs, have %d", items.num_tids, num_lookup_tids);
    if (num_iter_tids != items.num_tids)
        elog(ERROR, "should have %d TIDs, have %d", items.num_tids, num_iter_tids);
 
    qsort(items.insert_tids, items.num_tids, sizeof(ItemPointerData), itemptr_cmp);
    qsort(items.lookup_tids, items.num_tids, sizeof(ItemPointerData), itemptr_cmp);
    for (int i = 0; i < items.num_tids; i++)
    {
        if (itemptr_cmp(&items.insert_tids[i], &items.iter_tids[i]) != 0)
            elog(ERROR, "TID iter array doesn't match verification array, got (%u,%u) expected (%u,%u)",
                 ItemPointerGetBlockNumber(&items.iter_tids[i]),
                 ItemPointerGetOffsetNumber(&items.iter_tids[i]),
                 ItemPointerGetBlockNumber(&items.insert_tids[i]),
                 ItemPointerGetOffsetNumber(&items.insert_tids[i]));
        if (itemptr_cmp(&items.insert_tids[i], &items.lookup_tids[i]) != 0)
            elog(ERROR, "TID lookup array doesn't match verification array, got (%u,%u) expected (%u,%u)",
                 ItemPointerGetBlockNumber(&items.lookup_tids[i]),
                 ItemPointerGetOffsetNumber(&items.lookup_tids[i]),
                 ItemPointerGetBlockNumber(&items.insert_tids[i]),
                 ItemPointerGetOffsetNumber(&items.insert_tids[i]));
    }
 
    PG_RETURN_VOID();
}
 
/*
 * In real world use, we care if the memory usage is greater than
 * some configured limit. Here we just want to verify that
 * TidStoreMemoryUsage is not broken.
 */
Datum
test_is_full(PG_FUNCTION_ARGS)
{
    bool        is_full;
 
    check_tidstore_available();
 
    is_full = (TidStoreMemoryUsage(tidstore) > tidstore_empty_size);
 
    PG_RETURN_BOOL(is_full);
}
 
/* Free the tidstore */
Datum
test_destroy(PG_FUNCTION_ARGS)
{
    check_tidstore_available();
 
    TidStoreDestroy(tidstore);
    tidstore = NULL;
    items.num_tids = 0;
    pfree(items.insert_tids);
    pfree(items.lookup_tids);
    pfree(items.iter_tids);
 
    PG_RETURN_VOID();
}