/src/postgres/src/backend/utils/cache/catcache.c

Source
/*-------------------------------------------------------------------------
 *
 * catcache.c
 *    System catalog cache for tuples matching a key.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/cache/catcache.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heaptoast.h"
#include "access/relscan.h"
#include "access/table.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_type.h"
#include "common/hashfn.h"
#include "common/pg_prng.h"
#include "miscadmin.h"
#include "port/pg_bitutils.h"
#ifdef CATCACHE_STATS
#include "storage/ipc.h"    /* for on_proc_exit */
#endif
#include "storage/lmgr.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/datum.h"
#include "utils/fmgroids.h"
#include "utils/injection_point.h"
#include "utils/inval.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/resowner.h"
#include "utils/syscache.h"

/*
 * If a catcache invalidation is processed while we are in the middle of
 * creating a catcache entry (or list), it might apply to the entry we're
 * creating, making it invalid before it's been inserted to the catcache.  To
 * catch such cases, we have a stack of "create-in-progress" entries.  Cache
 * invalidation marks any matching entries in the stack as dead, in addition
 * to the actual CatCTup and CatCList entries.
 */
typedef struct CatCInProgress
{
  CatCache   *cache;      /* cache that the entry belongs to */
  uint32    hash_value;   /* hash of the entry; ignored for lists */
  bool    list;     /* is it a list entry? */
  bool    dead;     /* set when the entry is invalidated */
  struct CatCInProgress *next;
} CatCInProgress;

static CatCInProgress *catcache_in_progress_stack = NULL;

 /* #define CACHEDEBUG */ /* turns DEBUG elogs on */

/*
 * Given a hash value and the size of the hash table, find the bucket
 * in which the hash value belongs. Since the hash table must contain
 * a power-of-2 number of elements, this is a simple bitmask.
 */
#define HASH_INDEX(h, sz) ((Index) ((h) & ((sz) - 1)))


/*
 *    variables, macros and other stuff
 */

#ifdef CACHEDEBUG
#define CACHE_elog(...)       elog(__VA_ARGS__)
#else
#define CACHE_elog(...)
#endif

/* Cache management header --- pointer is NULL until created */
static CatCacheHeader *CacheHdr = NULL;

static inline HeapTuple SearchCatCacheInternal(CatCache *cache,
                         int nkeys,
                         Datum v1, Datum v2,
                         Datum v3, Datum v4);

static pg_noinline HeapTuple SearchCatCacheMiss(CatCache *cache,
                        int nkeys,
                        uint32 hashValue,
                        Index hashIndex,
                        Datum v1, Datum v2,
                        Datum v3, Datum v4);

static uint32 CatalogCacheComputeHashValue(CatCache *cache, int nkeys,
                       Datum v1, Datum v2, Datum v3, Datum v4);
static uint32 CatalogCacheComputeTupleHashValue(CatCache *cache, int nkeys,
                        HeapTuple tuple);
static inline bool CatalogCacheCompareTuple(const CatCache *cache, int nkeys,
                      const Datum *cachekeys,
                      const Datum *searchkeys);

#ifdef CATCACHE_STATS
static void CatCachePrintStats(int code, Datum arg);
#endif
static void CatCacheRemoveCTup(CatCache *cache, CatCTup *ct);
static void CatCacheRemoveCList(CatCache *cache, CatCList *cl);
static void RehashCatCache(CatCache *cp);
static void RehashCatCacheLists(CatCache *cp);
static void CatalogCacheInitializeCache(CatCache *cache);
static CatCTup *CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp,
                    Datum *arguments,
                    uint32 hashValue, Index hashIndex);

static void ReleaseCatCacheWithOwner(HeapTuple tuple, ResourceOwner resowner);
static void ReleaseCatCacheListWithOwner(CatCList *list, ResourceOwner resowner);
static void CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
               const Datum *keys);
static void CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
               const Datum *srckeys, Datum *dstkeys);


/*
 *          internal support functions
 */

/* ResourceOwner callbacks to hold catcache references */

static void ResOwnerReleaseCatCache(Datum res);
static char *ResOwnerPrintCatCache(Datum res);
static void ResOwnerReleaseCatCacheList(Datum res);
static char *ResOwnerPrintCatCacheList(Datum res);

static const ResourceOwnerDesc catcache_resowner_desc =
{
  /* catcache references */
  .name = "catcache reference",
  .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
  .release_priority = RELEASE_PRIO_CATCACHE_REFS,
  .ReleaseResource = ResOwnerReleaseCatCache,
  .DebugPrint = ResOwnerPrintCatCache
};

static const ResourceOwnerDesc catlistref_resowner_desc =
{
  /* catcache-list pins */
  .name = "catcache list reference",
  .release_phase = RESOURCE_RELEASE_AFTER_LOCKS,
  .release_priority = RELEASE_PRIO_CATCACHE_LIST_REFS,
  .ReleaseResource = ResOwnerReleaseCatCacheList,
  .DebugPrint = ResOwnerPrintCatCacheList
};

/* Convenience wrappers over ResourceOwnerRemember/Forget */
static inline void
ResourceOwnerRememberCatCacheRef(ResourceOwner owner, HeapTuple tuple)
{
  ResourceOwnerRemember(owner, PointerGetDatum(tuple), &catcache_resowner_desc);
}
static inline void
ResourceOwnerForgetCatCacheRef(ResourceOwner owner, HeapTuple tuple)
{
  ResourceOwnerForget(owner, PointerGetDatum(tuple), &catcache_resowner_desc);
}
static inline void
ResourceOwnerRememberCatCacheListRef(ResourceOwner owner, CatCList *list)
{
  ResourceOwnerRemember(owner, PointerGetDatum(list), &catlistref_resowner_desc);
}
static inline void
ResourceOwnerForgetCatCacheListRef(ResourceOwner owner, CatCList *list)
{
  ResourceOwnerForget(owner, PointerGetDatum(list), &catlistref_resowner_desc);
}


/*
 * Hash and equality functions for system types that are used as cache key
 * fields.  In some cases, we just call the regular SQL-callable functions for
 * the appropriate data type, but that tends to be a little slow, and the
 * speed of these functions is performance-critical.  Therefore, for data
 * types that frequently occur as catcache keys, we hard-code the logic here.
 * Avoiding the overhead of DirectFunctionCallN(...) is a substantial win, and
 * in certain cases (like int4) we can adopt a faster hash algorithm as well.
 */

static bool
chareqfast(Datum a, Datum b)
{
  return DatumGetChar(a) == DatumGetChar(b);
}

static uint32
charhashfast(Datum datum)
{
  return murmurhash32((int32) DatumGetChar(datum));
}

static bool
nameeqfast(Datum a, Datum b)
{
  char     *ca = NameStr(*DatumGetName(a));
  char     *cb = NameStr(*DatumGetName(b));

  /*
   * Catalogs only use deterministic collations, so ignore column collation
   * and use fast path.
   */
  return strncmp(ca, cb, NAMEDATALEN) == 0;
}

static uint32
namehashfast(Datum datum)
{
  char     *key = NameStr(*DatumGetName(datum));

  /*
   * Catalogs only use deterministic collations, so ignore column collation
   * and use fast path.
   */
  return hash_bytes((unsigned char *) key, strlen(key));
}

static bool
int2eqfast(Datum a, Datum b)
{
  return DatumGetInt16(a) == DatumGetInt16(b);
}

static uint32
int2hashfast(Datum datum)
{
  return murmurhash32((int32) DatumGetInt16(datum));
}

static bool
int4eqfast(Datum a, Datum b)
{
  return DatumGetInt32(a) == DatumGetInt32(b);
}

static uint32
int4hashfast(Datum datum)
{
  return murmurhash32((int32) DatumGetInt32(datum));
}

static bool
texteqfast(Datum a, Datum b)
{
  /*
   * Catalogs only use deterministic collations, so ignore column collation
   * and use "C" locale for efficiency.
   */
  return DatumGetBool(DirectFunctionCall2Coll(texteq, C_COLLATION_OID, a, b));
}

static uint32
texthashfast(Datum datum)
{
  /*
   * Catalogs only use deterministic collations, so ignore column collation
   * and use "C" locale for efficiency.
   */
  return DatumGetInt32(DirectFunctionCall1Coll(hashtext, C_COLLATION_OID, datum));
}

static bool
oidvectoreqfast(Datum a, Datum b)
{
  return DatumGetBool(DirectFunctionCall2(oidvectoreq, a, b));
}

static uint32
oidvectorhashfast(Datum datum)
{
  return DatumGetInt32(DirectFunctionCall1(hashoidvector, datum));
}

/* Lookup support functions for a type. */
static void
GetCCHashEqFuncs(Oid keytype, CCHashFN *hashfunc, RegProcedure *eqfunc, CCFastEqualFN *fasteqfunc)
{
  switch (keytype)
  {
    case BOOLOID:
      *hashfunc = charhashfast;
      *fasteqfunc = chareqfast;
      *eqfunc = F_BOOLEQ;
      break;
    case CHAROID:
      *hashfunc = charhashfast;
      *fasteqfunc = chareqfast;
      *eqfunc = F_CHAREQ;
      break;
    case NAMEOID:
      *hashfunc = namehashfast;
      *fasteqfunc = nameeqfast;
      *eqfunc = F_NAMEEQ;
      break;
    case INT2OID:
      *hashfunc = int2hashfast;
      *fasteqfunc = int2eqfast;
      *eqfunc = F_INT2EQ;
      break;
    case INT4OID:
      *hashfunc = int4hashfast;
      *fasteqfunc = int4eqfast;
      *eqfunc = F_INT4EQ;
      break;
    case TEXTOID:
      *hashfunc = texthashfast;
      *fasteqfunc = texteqfast;
      *eqfunc = F_TEXTEQ;
      break;
    case OIDOID:
    case REGPROCOID:
    case REGPROCEDUREOID:
    case REGOPEROID:
    case REGOPERATOROID:
    case REGCLASSOID:
    case REGTYPEOID:
    case REGCOLLATIONOID:
    case REGCONFIGOID:
    case REGDICTIONARYOID:
    case REGROLEOID:
    case REGNAMESPACEOID:
    case REGDATABASEOID:
      *hashfunc = int4hashfast;
      *fasteqfunc = int4eqfast;
      *eqfunc = F_OIDEQ;
      break;
    case OIDVECTOROID:
      *hashfunc = oidvectorhashfast;
      *fasteqfunc = oidvectoreqfast;
      *eqfunc = F_OIDVECTOREQ;
      break;
    default:
      elog(FATAL, "type %u not supported as catcache key", keytype);
      *hashfunc = NULL; /* keep compiler quiet */

      *eqfunc = InvalidOid;
      break;
  }
}

/*
 *    CatalogCacheComputeHashValue
 *
 * Compute the hash value associated with a given set of lookup keys
 */
static uint32
CatalogCacheComputeHashValue(CatCache *cache, int nkeys,
               Datum v1, Datum v2, Datum v3, Datum v4)
{
  uint32    hashValue = 0;
  uint32    oneHash;
  CCHashFN   *cc_hashfunc = cache->cc_hashfunc;

  CACHE_elog(DEBUG2, "CatalogCacheComputeHashValue %s %d %p",
         cache->cc_relname, nkeys, cache);

  switch (nkeys)
  {
    case 4:
      oneHash = (cc_hashfunc[3]) (v4);
      hashValue ^= pg_rotate_left32(oneHash, 24);
      pg_fallthrough;
    case 3:
      oneHash = (cc_hashfunc[2]) (v3);
      hashValue ^= pg_rotate_left32(oneHash, 16);
      pg_fallthrough;
    case 2:
      oneHash = (cc_hashfunc[1]) (v2);
      hashValue ^= pg_rotate_left32(oneHash, 8);
      pg_fallthrough;
    case 1:
      oneHash = (cc_hashfunc[0]) (v1);
      hashValue ^= oneHash;
      break;
    default:
      elog(FATAL, "wrong number of hash keys: %d", nkeys);
      break;
  }

  return hashValue;
}

/*
 *    CatalogCacheComputeTupleHashValue
 *
 * Compute the hash value associated with a given tuple to be cached
 */
static uint32
CatalogCacheComputeTupleHashValue(CatCache *cache, int nkeys, HeapTuple tuple)
{
  Datum   v1 = 0,
        v2 = 0,
        v3 = 0,
        v4 = 0;
  bool    isNull = false;
  int      *cc_keyno = cache->cc_keyno;
  TupleDesc cc_tupdesc = cache->cc_tupdesc;

  /* Now extract key fields from tuple, insert into scankey */
  switch (nkeys)
  {
    case 4:
      v4 = fastgetattr(tuple,
               cc_keyno[3],
               cc_tupdesc,
               &isNull);
      Assert(!isNull);
      pg_fallthrough;
    case 3:
      v3 = fastgetattr(tuple,
               cc_keyno[2],
               cc_tupdesc,
               &isNull);
      Assert(!isNull);
      pg_fallthrough;
    case 2:
      v2 = fastgetattr(tuple,
               cc_keyno[1],
               cc_tupdesc,
               &isNull);
      Assert(!isNull);
      pg_fallthrough;
    case 1:
      v1 = fastgetattr(tuple,
               cc_keyno[0],
               cc_tupdesc,
               &isNull);
      Assert(!isNull);
      break;
    default:
      elog(FATAL, "wrong number of hash keys: %d", nkeys);
      break;
  }

  return CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
}

/*
 *    CatalogCacheCompareTuple
 *
 * Compare a tuple to the passed arguments.
 */
static inline bool
CatalogCacheCompareTuple(const CatCache *cache, int nkeys,
             const Datum *cachekeys,
             const Datum *searchkeys)
{
  const CCFastEqualFN *cc_fastequal = cache->cc_fastequal;
  int     i;

  for (i = 0; i < nkeys; i++)
  {
    if (!(cc_fastequal[i]) (cachekeys[i], searchkeys[i]))
      return false;
  }
  return true;
}


#ifdef CATCACHE_STATS

static void
CatCachePrintStats(int code, Datum arg)
{
  slist_iter  iter;
  uint64    cc_searches = 0;
  uint64    cc_hits = 0;
  uint64    cc_neg_hits = 0;
  uint64    cc_newloads = 0;
  uint64    cc_invals = 0;
  uint64    cc_nlists = 0;
  uint64    cc_lsearches = 0;
  uint64    cc_lhits = 0;

  slist_foreach(iter, &CacheHdr->ch_caches)
  {
    CatCache   *cache = slist_container(CatCache, cc_next, iter.cur);

    if (cache->cc_ntup == 0 && cache->cc_searches == 0)
      continue;     /* don't print unused caches */
    elog(DEBUG2, "catcache %s/%u: %d tup, %" PRIu64 " srch, %" PRIu64 "+%"
       PRIu64 "=%" PRIu64 " hits, %" PRIu64 "+%" PRIu64 "=%"
       PRIu64 " loads, %" PRIu64 " invals, %d lists, %" PRIu64
       " lsrch, %" PRIu64 " lhits",
       cache->cc_relname,
       cache->cc_indexoid,
       cache->cc_ntup,
       cache->cc_searches,
       cache->cc_hits,
       cache->cc_neg_hits,
       cache->cc_hits + cache->cc_neg_hits,
       cache->cc_newloads,
       cache->cc_searches - cache->cc_hits - cache->cc_neg_hits - cache->cc_newloads,
       cache->cc_searches - cache->cc_hits - cache->cc_neg_hits,
       cache->cc_invals,
       cache->cc_nlist,
       cache->cc_lsearches,
       cache->cc_lhits);
    cc_searches += cache->cc_searches;
    cc_hits += cache->cc_hits;
    cc_neg_hits += cache->cc_neg_hits;
    cc_newloads += cache->cc_newloads;
    cc_invals += cache->cc_invals;
    cc_nlists += cache->cc_nlist;
    cc_lsearches += cache->cc_lsearches;
    cc_lhits += cache->cc_lhits;
  }
  elog(DEBUG2, "catcache totals: %d tup, %" PRIu64 " srch, %" PRIu64 "+%"
     PRIu64 "=%" PRIu64 " hits, %" PRIu64 "+%" PRIu64 "=%" PRIu64
     " loads, %" PRIu64 " invals, %" PRIu64 " lists, %" PRIu64
     " lsrch, %" PRIu64 " lhits",
     CacheHdr->ch_ntup,
     cc_searches,
     cc_hits,
     cc_neg_hits,
     cc_hits + cc_neg_hits,
     cc_newloads,
     cc_searches - cc_hits - cc_neg_hits - cc_newloads,
     cc_searches - cc_hits - cc_neg_hits,
     cc_invals,
     cc_nlists,
     cc_lsearches,
     cc_lhits);
}
#endif              /* CATCACHE_STATS */


/*
 *    CatCacheRemoveCTup
 *
 * Unlink and delete the given cache entry
 *
 * NB: if it is a member of a CatCList, the CatCList is deleted too.
 * Both the cache entry and the list had better have zero refcount.
 */
static void
CatCacheRemoveCTup(CatCache *cache, CatCTup *ct)
{
  Assert(ct->refcount == 0);
  Assert(ct->my_cache == cache);

  if (ct->c_list)
  {
    /*
     * The cleanest way to handle this is to call CatCacheRemoveCList,
     * which will recurse back to me, and the recursive call will do the
     * work.  Set the "dead" flag to make sure it does recurse.
     */
    ct->dead = true;
    CatCacheRemoveCList(cache, ct->c_list);
    return;         /* nothing left to do */
  }

  /* delink from linked list */
  dlist_delete(&ct->cache_elem);

  /*
   * Free keys when we're dealing with a negative entry, normal entries just
   * point into tuple, allocated together with the CatCTup.
   */
  if (ct->negative)
    CatCacheFreeKeys(cache->cc_tupdesc, cache->cc_nkeys,
             cache->cc_keyno, ct->keys);

  pfree(ct);

  --cache->cc_ntup;
  --CacheHdr->ch_ntup;
}

/*
 *    CatCacheRemoveCList
 *
 * Unlink and delete the given cache list entry
 *
 * NB: any dead member entries that become unreferenced are deleted too.
 */
static void
CatCacheRemoveCList(CatCache *cache, CatCList *cl)
{
  int     i;

  Assert(cl->refcount == 0);
  Assert(cl->my_cache == cache);

  /* delink from member tuples */
  for (i = cl->n_members; --i >= 0;)
  {
    CatCTup    *ct = cl->members[i];

    Assert(ct->c_list == cl);
    ct->c_list = NULL;
    /* if the member is dead and now has no references, remove it */
    if (
#ifndef CATCACHE_FORCE_RELEASE
      ct->dead &&
#endif
      ct->refcount == 0)
      CatCacheRemoveCTup(cache, ct);
  }

  /* delink from linked list */
  dlist_delete(&cl->cache_elem);

  /* free associated column data */
  CatCacheFreeKeys(cache->cc_tupdesc, cl->nkeys,
           cache->cc_keyno, cl->keys);

  pfree(cl);

  --cache->cc_nlist;
}


/*
 *  CatCacheInvalidate
 *
 *  Invalidate entries in the specified cache, given a hash value.
 *
 *  We delete cache entries that match the hash value, whether positive
 *  or negative.  We don't care whether the invalidation is the result
 *  of a tuple insertion or a deletion.
 *
 *  We used to try to match positive cache entries by TID, but that is
 *  unsafe after a VACUUM FULL on a system catalog: an inval event could
 *  be queued before VACUUM FULL, and then processed afterwards, when the
 *  target tuple that has to be invalidated has a different TID than it
 *  did when the event was created.  So now we just compare hash values and
 *  accept the small risk of unnecessary invalidations due to false matches.
 *
 *  This routine is only quasi-public: it should only be used by inval.c.
 */
void
CatCacheInvalidate(CatCache *cache, uint32 hashValue)
{
  Index   hashIndex;
  dlist_mutable_iter iter;

  CACHE_elog(DEBUG2, "CatCacheInvalidate: called");

  /*
   * We don't bother to check whether the cache has finished initialization
   * yet; if not, there will be no entries in it so no problem.
   */

  /*
   * Invalidate *all* CatCLists in this cache; it's too hard to tell which
   * searches might still be correct, so just zap 'em all.
   */
  for (int i = 0; i < cache->cc_nlbuckets; i++)
  {
    dlist_head *bucket = &cache->cc_lbucket[i];

    dlist_foreach_modify(iter, bucket)
    {
      CatCList   *cl = dlist_container(CatCList, cache_elem, iter.cur);

      if (cl->refcount > 0)
        cl->dead = true;
      else
        CatCacheRemoveCList(cache, cl);
    }
  }

  /*
   * inspect the proper hash bucket for tuple matches
   */
  hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
  dlist_foreach_modify(iter, &cache->cc_bucket[hashIndex])
  {
    CatCTup    *ct = dlist_container(CatCTup, cache_elem, iter.cur);

    if (hashValue == ct->hash_value)
    {
      if (ct->refcount > 0 ||
        (ct->c_list && ct->c_list->refcount > 0))
      {
        ct->dead = true;
        /* list, if any, was marked dead above */
        Assert(ct->c_list == NULL || ct->c_list->dead);
      }
      else
        CatCacheRemoveCTup(cache, ct);
      CACHE_elog(DEBUG2, "CatCacheInvalidate: invalidated");
#ifdef CATCACHE_STATS
      cache->cc_invals++;
#endif
      /* could be multiple matches, so keep looking! */
    }
  }

  /* Also invalidate any entries that are being built */
  for (CatCInProgress *e = catcache_in_progress_stack; e != NULL; e = e->next)
  {
    if (e->cache == cache)
    {
      if (e->list || e->hash_value == hashValue)
        e->dead = true;
    }
  }
}

/* ----------------------------------------------------------------
 *             public functions
 * ----------------------------------------------------------------
 */


/*
 * Standard routine for creating cache context if it doesn't exist yet
 *
 * There are a lot of places (probably far more than necessary) that check
 * whether CacheMemoryContext exists yet and want to create it if not.
 * We centralize knowledge of exactly how to create it here.
 */
void
CreateCacheMemoryContext(void)
{
  /*
   * Purely for paranoia, check that context doesn't exist; caller probably
   * did so already.
   */
  if (!CacheMemoryContext)
    CacheMemoryContext = AllocSetContextCreate(TopMemoryContext,
                           "CacheMemoryContext",
                           ALLOCSET_DEFAULT_SIZES);
}


/*
 *    ResetCatalogCache
 *
 * Reset one catalog cache to empty.
 *
 * This is not very efficient if the target cache is nearly empty.
 * However, it shouldn't need to be efficient; we don't invoke it often.
 *
 * If 'debug_discard' is true, we are being called as part of
 * debug_discard_caches.  In that case, the cache is not reset for
 * correctness, but just to get more testing of cache invalidation.  We skip
 * resetting in-progress build entries in that case, or we'd never make any
 * progress.
 */
static void
ResetCatalogCache(CatCache *cache, bool debug_discard)
{
  dlist_mutable_iter iter;
  int     i;

  /* Remove each list in this cache, or at least mark it dead */
  for (i = 0; i < cache->cc_nlbuckets; i++)
  {
    dlist_head *bucket = &cache->cc_lbucket[i];

    dlist_foreach_modify(iter, bucket)
    {
      CatCList   *cl = dlist_container(CatCList, cache_elem, iter.cur);

      if (cl->refcount > 0)
        cl->dead = true;
      else
        CatCacheRemoveCList(cache, cl);
    }
  }

  /* Remove each tuple in this cache, or at least mark it dead */
  for (i = 0; i < cache->cc_nbuckets; i++)
  {
    dlist_head *bucket = &cache->cc_bucket[i];

    dlist_foreach_modify(iter, bucket)
    {
      CatCTup    *ct = dlist_container(CatCTup, cache_elem, iter.cur);

      if (ct->refcount > 0 ||
        (ct->c_list && ct->c_list->refcount > 0))
      {
        ct->dead = true;
        /* list, if any, was marked dead above */
        Assert(ct->c_list == NULL || ct->c_list->dead);
      }
      else
        CatCacheRemoveCTup(cache, ct);
#ifdef CATCACHE_STATS
      cache->cc_invals++;
#endif
    }
  }

  /* Also invalidate any entries that are being built */
  if (!debug_discard)
  {
    for (CatCInProgress *e = catcache_in_progress_stack; e != NULL; e = e->next)
    {
      if (e->cache == cache)
        e->dead = true;
    }
  }
}

/*
 *    ResetCatalogCaches
 *
 * Reset all caches when a shared cache inval event forces it
 */
void
ResetCatalogCaches(void)
{
  ResetCatalogCachesExt(false);
}

void
ResetCatalogCachesExt(bool debug_discard)
{
  slist_iter  iter;

  CACHE_elog(DEBUG2, "ResetCatalogCaches called");

  slist_foreach(iter, &CacheHdr->ch_caches)
  {
    CatCache   *cache = slist_container(CatCache, cc_next, iter.cur);

    ResetCatalogCache(cache, debug_discard);
  }

  CACHE_elog(DEBUG2, "end of ResetCatalogCaches call");
}

/*
 *    CatalogCacheFlushCatalog
 *
 *  Flush all catcache entries that came from the specified system catalog.
 *  This is needed after VACUUM FULL/CLUSTER on the catalog, since the
 *  tuples very likely now have different TIDs than before.  (At one point
 *  we also tried to force re-execution of CatalogCacheInitializeCache for
 *  the cache(s) on that catalog.  This is a bad idea since it leads to all
 *  kinds of trouble if a cache flush occurs while loading cache entries.
 *  We now avoid the need to do it by copying cc_tupdesc out of the relcache,
 *  rather than relying on the relcache to keep a tupdesc for us.  Of course
 *  this assumes the tupdesc of a cacheable system table will not change...)
 */
void
CatalogCacheFlushCatalog(Oid catId)
{
  slist_iter  iter;

  CACHE_elog(DEBUG2, "CatalogCacheFlushCatalog called for %u", catId);

  slist_foreach(iter, &CacheHdr->ch_caches)
  {
    CatCache   *cache = slist_container(CatCache, cc_next, iter.cur);

    /* Does this cache store tuples of the target catalog? */
    if (cache->cc_reloid == catId)
    {
      /* Yes, so flush all its contents */
      ResetCatalogCache(cache, false);

      /* Tell inval.c to call syscache callbacks for this cache */
      CallSyscacheCallbacks(cache->id, 0);
    }
  }

  CACHE_elog(DEBUG2, "end of CatalogCacheFlushCatalog call");
}

/*
 *    InitCatCache
 *
 *  This allocates and initializes a cache for a system catalog relation.
 *  Actually, the cache is only partially initialized to avoid opening the
 *  relation.  The relation will be opened and the rest of the cache
 *  structure initialized on the first access.
 */
#ifdef CACHEDEBUG
#define InitCatCache_DEBUG2 \
do { \
  elog(DEBUG2, "InitCatCache: rel=%u ind=%u id=%d nkeys=%d size=%d", \
     cp->cc_reloid, cp->cc_indexoid, cp->id, \
     cp->cc_nkeys, cp->cc_nbuckets); \
} while(0)
#else
#define InitCatCache_DEBUG2
#endif

CatCache *
InitCatCache(int id,
       Oid reloid,
       Oid indexoid,
       int nkeys,
       const int *key,
       int nbuckets)
{
  CatCache   *cp;
  MemoryContext oldcxt;
  int     i;

  /*
   * nbuckets is the initial number of hash buckets to use in this catcache.
   * It will be enlarged later if it becomes too full.
   *
   * nbuckets must be a power of two.  We check this via Assert rather than
   * a full runtime check because the values will be coming from constant
   * tables.
   *
   * If you're confused by the power-of-two check, see comments in
   * bitmapset.c for an explanation.
   */
  Assert(nbuckets > 0 && (nbuckets & -nbuckets) == nbuckets);

  /*
   * first switch to the cache context so our allocations do not vanish at
   * the end of a transaction
   */
  if (!CacheMemoryContext)
    CreateCacheMemoryContext();

  oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

  /*
   * if first time through, initialize the cache group header
   */
  if (CacheHdr == NULL)
  {
    CacheHdr = palloc_object(CatCacheHeader);
    slist_init(&CacheHdr->ch_caches);
    CacheHdr->ch_ntup = 0;
#ifdef CATCACHE_STATS
    /* set up to dump stats at backend exit */
    on_proc_exit(CatCachePrintStats, 0);
#endif
  }

  /*
   * Allocate a new cache structure, aligning to a cacheline boundary
   *
   * Note: we rely on zeroing to initialize all the dlist headers correctly
   */
  cp = (CatCache *) palloc_aligned(sizeof(CatCache), PG_CACHE_LINE_SIZE,
                   MCXT_ALLOC_ZERO);
  cp->cc_bucket = palloc0(nbuckets * sizeof(dlist_head));

  /*
   * Many catcaches never receive any list searches.  Therefore, we don't
   * allocate the cc_lbuckets till we get a list search.
   */
  cp->cc_lbucket = NULL;

  /*
   * initialize the cache's relation information for the relation
   * corresponding to this cache, and initialize some of the new cache's
   * other internal fields.  But don't open the relation yet.
   */
  cp->id = id;
  cp->cc_relname = "(not known yet)";
  cp->cc_reloid = reloid;
  cp->cc_indexoid = indexoid;
  cp->cc_relisshared = false; /* temporary */
  cp->cc_tupdesc = (TupleDesc) NULL;
  cp->cc_ntup = 0;
  cp->cc_nlist = 0;
  cp->cc_nbuckets = nbuckets;
  cp->cc_nlbuckets = 0;
  cp->cc_nkeys = nkeys;
  for (i = 0; i < nkeys; ++i)
  {
    Assert(AttributeNumberIsValid(key[i]));
    cp->cc_keyno[i] = key[i];
  }

  /*
   * new cache is initialized as far as we can go for now. print some
   * debugging information, if appropriate.
   */
  InitCatCache_DEBUG2;

  /*
   * add completed cache to top of group header's list
   */
  slist_push_head(&CacheHdr->ch_caches, &cp->cc_next);

  /*
   * back to the old context before we return...
   */
  MemoryContextSwitchTo(oldcxt);

  return cp;
}

/*
 * Enlarge a catcache, doubling the number of buckets.
 */
static void
RehashCatCache(CatCache *cp)
{
  dlist_head *newbucket;
  int     newnbuckets;
  int     i;

  elog(DEBUG1, "rehashing catalog cache id %d for %s; %d tups, %d buckets",
     cp->id, cp->cc_relname, cp->cc_ntup, cp->cc_nbuckets);

  /* Allocate a new, larger, hash table. */
  newnbuckets = cp->cc_nbuckets * 2;
  newbucket = (dlist_head *) MemoryContextAllocZero(CacheMemoryContext, newnbuckets * sizeof(dlist_head));

  /* Move all entries from old hash table to new. */
  for (i = 0; i < cp->cc_nbuckets; i++)
  {
    dlist_mutable_iter iter;

    dlist_foreach_modify(iter, &cp->cc_bucket[i])
    {
      CatCTup    *ct = dlist_container(CatCTup, cache_elem, iter.cur);
      int     hashIndex = HASH_INDEX(ct->hash_value, newnbuckets);

      dlist_delete(iter.cur);

      /*
       * Note that each item is pushed at the tail of the new bucket,
       * not its head.  This is consistent with the SearchCatCache*()
       * routines, where matching entries are moved at the front of the
       * list to speed subsequent searches.
       */
      dlist_push_tail(&newbucket[hashIndex], &ct->cache_elem);
    }
  }

  /* Switch to the new array. */
  pfree(cp->cc_bucket);
  cp->cc_nbuckets = newnbuckets;
  cp->cc_bucket = newbucket;
}

/*
 * Enlarge a catcache's list storage, doubling the number of buckets.
 */
static void
RehashCatCacheLists(CatCache *cp)
{
  dlist_head *newbucket;
  int     newnbuckets;
  int     i;

  elog(DEBUG1, "rehashing catalog cache id %d for %s; %d lists, %d buckets",
     cp->id, cp->cc_relname, cp->cc_nlist, cp->cc_nlbuckets);

  /* Allocate a new, larger, hash table. */
  newnbuckets = cp->cc_nlbuckets * 2;
  newbucket = (dlist_head *) MemoryContextAllocZero(CacheMemoryContext, newnbuckets * sizeof(dlist_head));

  /* Move all entries from old hash table to new. */
  for (i = 0; i < cp->cc_nlbuckets; i++)
  {
    dlist_mutable_iter iter;

    dlist_foreach_modify(iter, &cp->cc_lbucket[i])
    {
      CatCList   *cl = dlist_container(CatCList, cache_elem, iter.cur);
      int     hashIndex = HASH_INDEX(cl->hash_value, newnbuckets);

      dlist_delete(iter.cur);

      /*
       * Note that each item is pushed at the tail of the new bucket,
       * not its head.  This is consistent with the SearchCatCache*()
       * routines, where matching entries are moved at the front of the
       * list to speed subsequent searches.
       */
      dlist_push_tail(&newbucket[hashIndex], &cl->cache_elem);
    }
  }

  /* Switch to the new array. */
  pfree(cp->cc_lbucket);
  cp->cc_nlbuckets = newnbuckets;
  cp->cc_lbucket = newbucket;
}

/*
 *    ConditionalCatalogCacheInitializeCache
 *
 * Call CatalogCacheInitializeCache() if not yet done.
 */
pg_always_inline
static void
ConditionalCatalogCacheInitializeCache(CatCache *cache)
{
#ifdef USE_ASSERT_CHECKING
  /*
   * TypeCacheRelCallback() runs outside transactions and relies on TYPEOID
   * for hashing.  This isn't ideal.  Since lookup_type_cache() both
   * registers the callback and searches TYPEOID, reaching trouble likely
   * requires OOM at an unlucky moment.
   *
   * InvalidateAttoptCacheCallback() runs outside transactions and likewise
   * relies on ATTNUM.  InitPostgres() initializes ATTNUM, so it's reliable.
   */
  if (!(cache->id == TYPEOID || cache->id == ATTNUM) ||
    IsTransactionState())
    AssertCouldGetRelation();
  else
    Assert(cache->cc_tupdesc != NULL);
#endif

  if (unlikely(cache->cc_tupdesc == NULL))
    CatalogCacheInitializeCache(cache);
}

/*
 *    CatalogCacheInitializeCache
 *
 * This function does final initialization of a catcache: obtain the tuple
 * descriptor and set up the hash and equality function links.
 */
#ifdef CACHEDEBUG
#define CatalogCacheInitializeCache_DEBUG1 \
  elog(DEBUG2, "CatalogCacheInitializeCache: cache @%p rel=%u", cache, \
     cache->cc_reloid)

#define CatalogCacheInitializeCache_DEBUG2 \
do { \
    if (cache->cc_keyno[i] > 0) { \
      elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d, %u", \
        i+1, cache->cc_nkeys, cache->cc_keyno[i], \
         TupleDescAttr(tupdesc, cache->cc_keyno[i] - 1)->atttypid); \
    } else { \
      elog(DEBUG2, "CatalogCacheInitializeCache: load %d/%d w/%d", \
        i+1, cache->cc_nkeys, cache->cc_keyno[i]); \
    } \
} while(0)
#else
#define CatalogCacheInitializeCache_DEBUG1
#define CatalogCacheInitializeCache_DEBUG2
#endif

static void
CatalogCacheInitializeCache(CatCache *cache)
{
  Relation  relation;
  MemoryContext oldcxt;
  TupleDesc tupdesc;
  int     i;

  CatalogCacheInitializeCache_DEBUG1;

  relation = table_open(cache->cc_reloid, AccessShareLock);

  /*
   * switch to the cache context so our allocations do not vanish at the end
   * of a transaction
   */
  Assert(CacheMemoryContext != NULL);

  oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

  /*
   * copy the relcache's tuple descriptor to permanent cache storage
   */
  tupdesc = CreateTupleDescCopyConstr(RelationGetDescr(relation));

  /*
   * save the relation's name and relisshared flag, too (cc_relname is used
   * only for debugging purposes)
   */
  cache->cc_relname = pstrdup(RelationGetRelationName(relation));
  cache->cc_relisshared = RelationGetForm(relation)->relisshared;

  /*
   * return to the caller's memory context and close the rel
   */
  MemoryContextSwitchTo(oldcxt);

  table_close(relation, AccessShareLock);

  CACHE_elog(DEBUG2, "CatalogCacheInitializeCache: %s, %d keys",
         cache->cc_relname, cache->cc_nkeys);

  /*
   * initialize cache's key information
   */
  for (i = 0; i < cache->cc_nkeys; ++i)
  {
    Oid     keytype;
    RegProcedure eqfunc;

    CatalogCacheInitializeCache_DEBUG2;

    if (cache->cc_keyno[i] > 0)
    {
      Form_pg_attribute attr = TupleDescAttr(tupdesc,
                           cache->cc_keyno[i] - 1);

      keytype = attr->atttypid;
      /* cache key columns should always be NOT NULL */
      Assert(attr->attnotnull);
    }
    else
    {
      if (cache->cc_keyno[i] < 0)
        elog(FATAL, "sys attributes are not supported in caches");
      keytype = OIDOID;
    }

    GetCCHashEqFuncs(keytype,
             &cache->cc_hashfunc[i],
             &eqfunc,
             &cache->cc_fastequal[i]);

    /*
     * Do equality-function lookup (we assume this won't need a catalog
     * lookup for any supported type)
     */
    fmgr_info_cxt(eqfunc,
            &cache->cc_skey[i].sk_func,
            CacheMemoryContext);

    /* Initialize sk_attno suitably for HeapKeyTest() and heap scans */
    cache->cc_skey[i].sk_attno = cache->cc_keyno[i];

    /* Fill in sk_strategy as well --- always standard equality */
    cache->cc_skey[i].sk_strategy = BTEqualStrategyNumber;
    cache->cc_skey[i].sk_subtype = InvalidOid;
    /* If a catcache key requires a collation, it must be C collation */
    cache->cc_skey[i].sk_collation = C_COLLATION_OID;

    CACHE_elog(DEBUG2, "CatalogCacheInitializeCache %s %d %p",
           cache->cc_relname, i, cache);
  }

  /*
   * mark this cache fully initialized
   */
  cache->cc_tupdesc = tupdesc;
}

/*
 * InitCatCachePhase2 -- external interface for CatalogCacheInitializeCache
 *
 * One reason to call this routine is to ensure that the relcache has
 * created entries for all the catalogs and indexes referenced by catcaches.
 * Therefore, provide an option to open the index as well as fixing the
 * cache itself.  An exception is the indexes on pg_am, which we don't use
 * (cf. IndexScanOK).
 */
void
InitCatCachePhase2(CatCache *cache, bool touch_index)
{
  ConditionalCatalogCacheInitializeCache(cache);

  if (touch_index &&
    cache->id != AMOID &&
    cache->id != AMNAME)
  {
    Relation  idesc;

    /*
     * We must lock the underlying catalog before opening the index to
     * avoid deadlock, since index_open could possibly result in reading
     * this same catalog, and if anyone else is exclusive-locking this
     * catalog and index they'll be doing it in that order.
     */
    LockRelationOid(cache->cc_reloid, AccessShareLock);
    idesc = index_open(cache->cc_indexoid, AccessShareLock);

    /*
     * While we've got the index open, let's check that it's unique (and
     * not just deferrable-unique, thank you very much).  This is just to
     * catch thinkos in definitions of new catcaches, so we don't worry
     * about the pg_am indexes not getting tested.
     */
    Assert(idesc->rd_index->indisunique &&
         idesc->rd_index->indimmediate);

    index_close(idesc, AccessShareLock);
    UnlockRelationOid(cache->cc_reloid, AccessShareLock);
  }
}


/*
 *    IndexScanOK
 *
 *    This function checks for tuples that will be fetched by
 *    IndexSupportInitialize() during relcache initialization for
 *    certain system indexes that support critical syscaches.
 *    We can't use an indexscan to fetch these, else we'll get into
 *    infinite recursion.  A plain heap scan will work, however.
 *    Once we have completed relcache initialization (signaled by
 *    criticalRelcachesBuilt), we don't have to worry anymore.
 *
 *    Similarly, during backend startup we have to be able to use the
 *    pg_authid, pg_auth_members and pg_database syscaches for
 *    authentication even if we don't yet have relcache entries for those
 *    catalogs' indexes.
 */
static bool
IndexScanOK(CatCache *cache)
{
  switch (cache->id)
  {
    case INDEXRELID:

      /*
       * Rather than tracking exactly which indexes have to be loaded
       * before we can use indexscans (which changes from time to time),
       * just force all pg_index searches to be heap scans until we've
       * built the critical relcaches.
       */
      if (!criticalRelcachesBuilt)
        return false;
      break;

    case AMOID:
    case AMNAME:

      /*
       * Always do heap scans in pg_am, because it's so small there's
       * not much point in an indexscan anyway.  We *must* do this when
       * initially building critical relcache entries, but we might as
       * well just always do it.
       */
      return false;

    case AUTHNAME:
    case AUTHOID:
    case AUTHMEMMEMROLE:
    case DATABASEOID:
    case PARAMETERACLNAME:
    case PARAMETERACLOID:

      /*
       * Protect authentication lookups occurring before relcache has
       * collected entries for shared indexes.
       */
      if (!criticalSharedRelcachesBuilt)
        return false;
      break;

    default:
      break;
  }

  /* Normal case, allow index scan */
  return true;
}

/*
 *  SearchCatCache
 *
 *    This call searches a system cache for a tuple, opening the relation
 *    if necessary (on the first access to a particular cache).
 *
 *    The result is NULL if not found, or a pointer to a HeapTuple in
 *    the cache.  The caller must not modify the tuple, and must call
 *    ReleaseCatCache() when done with it.
 *
 * The search key values should be expressed as Datums of the key columns'
 * datatype(s).  (Pass zeroes for any unused parameters.)  As a special
 * exception, the passed-in key for a NAME column can be just a C string;
 * the caller need not go to the trouble of converting it to a fully
 * null-padded NAME.
 */
HeapTuple
SearchCatCache(CatCache *cache,
         Datum v1,
         Datum v2,
         Datum v3,
         Datum v4)
{
  return SearchCatCacheInternal(cache, cache->cc_nkeys, v1, v2, v3, v4);
}


/*
 * SearchCatCacheN() are SearchCatCache() versions for a specific number of
 * arguments. The compiler can inline the body and unroll loops, making them a
 * bit faster than SearchCatCache().
 */

HeapTuple
SearchCatCache1(CatCache *cache,
        Datum v1)
{
  return SearchCatCacheInternal(cache, 1, v1, 0, 0, 0);
}


HeapTuple
SearchCatCache2(CatCache *cache,
        Datum v1, Datum v2)
{
  return SearchCatCacheInternal(cache, 2, v1, v2, 0, 0);
}


HeapTuple
SearchCatCache3(CatCache *cache,
        Datum v1, Datum v2, Datum v3)
{
  return SearchCatCacheInternal(cache, 3, v1, v2, v3, 0);
}


HeapTuple
SearchCatCache4(CatCache *cache,
        Datum v1, Datum v2, Datum v3, Datum v4)
{
  return SearchCatCacheInternal(cache, 4, v1, v2, v3, v4);
}

/*
 * Work-horse for SearchCatCache/SearchCatCacheN.
 */
static inline HeapTuple
SearchCatCacheInternal(CatCache *cache,
             int nkeys,
             Datum v1,
             Datum v2,
             Datum v3,
             Datum v4)
{
  Datum   arguments[CATCACHE_MAXKEYS];
  uint32    hashValue;
  Index   hashIndex;
  dlist_iter  iter;
  dlist_head *bucket;
  CatCTup    *ct;

  Assert(cache->cc_nkeys == nkeys);

  /*
   * one-time startup overhead for each cache
   */
  ConditionalCatalogCacheInitializeCache(cache);

#ifdef CATCACHE_STATS
  cache->cc_searches++;
#endif

  /* Initialize local parameter array */
  arguments[0] = v1;
  arguments[1] = v2;
  arguments[2] = v3;
  arguments[3] = v4;

  /*
   * find the hash bucket in which to look for the tuple
   */
  hashValue = CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
  hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);

  /*
   * scan the hash bucket until we find a match or exhaust our tuples
   *
   * Note: it's okay to use dlist_foreach here, even though we modify the
   * dlist within the loop, because we don't continue the loop afterwards.
   */
  bucket = &cache->cc_bucket[hashIndex];
  dlist_foreach(iter, bucket)
  {
    ct = dlist_container(CatCTup, cache_elem, iter.cur);

    if (ct->dead)
      continue;     /* ignore dead entries */

    if (ct->hash_value != hashValue)
      continue;     /* quickly skip entry if wrong hash val */

    if (!CatalogCacheCompareTuple(cache, nkeys, ct->keys, arguments))
      continue;

    /*
     * We found a match in the cache.  Move it to the front of the list
     * for its hashbucket, in order to speed subsequent searches.  (The
     * most frequently accessed elements in any hashbucket will tend to be
     * near the front of the hashbucket's list.)
     */
    dlist_move_head(bucket, &ct->cache_elem);

    /*
     * If it's a positive entry, bump its refcount and return it. If it's
     * negative, we can report failure to the caller.
     */
    if (!ct->negative)
    {
      ResourceOwnerEnlarge(CurrentResourceOwner);
      ct->refcount++;
      ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple);

      CACHE_elog(DEBUG2, "SearchCatCache(%s): found in bucket %d",
             cache->cc_relname, hashIndex);

#ifdef CATCACHE_STATS
      cache->cc_hits++;
#endif

      return &ct->tuple;
    }
    else
    {
      CACHE_elog(DEBUG2, "SearchCatCache(%s): found neg entry in bucket %d",
             cache->cc_relname, hashIndex);

#ifdef CATCACHE_STATS
      cache->cc_neg_hits++;
#endif

      return NULL;
    }
  }

  return SearchCatCacheMiss(cache, nkeys, hashValue, hashIndex, v1, v2, v3, v4);
}

/*
 * Search the actual catalogs, rather than the cache.
 *
 * This is kept separate from SearchCatCacheInternal() to keep the fast-path
 * as small as possible.  To avoid that effort being undone by a helpful
 * compiler, try to explicitly forbid inlining.
 */
static pg_noinline HeapTuple
SearchCatCacheMiss(CatCache *cache,
           int nkeys,
           uint32 hashValue,
           Index hashIndex,
           Datum v1,
           Datum v2,
           Datum v3,
           Datum v4)
{
  ScanKeyData cur_skey[CATCACHE_MAXKEYS];
  Relation  relation;
  SysScanDesc scandesc;
  HeapTuple ntp;
  CatCTup    *ct;
  bool    stale;
  Datum   arguments[CATCACHE_MAXKEYS];

  /* Initialize local parameter array */
  arguments[0] = v1;
  arguments[1] = v2;
  arguments[2] = v3;
  arguments[3] = v4;

  /*
   * Tuple was not found in cache, so we have to try to retrieve it directly
   * from the relation.  If found, we will add it to the cache; if not
   * found, we will add a negative cache entry instead.
   *
   * NOTE: it is possible for recursive cache lookups to occur while reading
   * the relation --- for example, due to shared-cache-inval messages being
   * processed during table_open().  This is OK.  It's even possible for one
   * of those lookups to find and enter the very same tuple we are trying to
   * fetch here.  If that happens, we will enter a second copy of the tuple
   * into the cache.  The first copy will never be referenced again, and
   * will eventually age out of the cache, so there's no functional problem.
   * This case is rare enough that it's not worth expending extra cycles to
   * detect.
   *
   * Another case, which we *must* handle, is that the tuple could become
   * outdated during CatalogCacheCreateEntry's attempt to detoast it (since
   * AcceptInvalidationMessages can run during TOAST table access).  We do
   * not want to return already-stale catcache entries, so we loop around
   * and do the table scan again if that happens.
   */
  relation = table_open(cache->cc_reloid, AccessShareLock);

  /*
   * Ok, need to make a lookup in the relation, copy the scankey and fill
   * out any per-call fields.
   */
  memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * nkeys);
  cur_skey[0].sk_argument = v1;
  cur_skey[1].sk_argument = v2;
  cur_skey[2].sk_argument = v3;
  cur_skey[3].sk_argument = v4;

  do
  {
    scandesc = systable_beginscan(relation,
                    cache->cc_indexoid,
                    IndexScanOK(cache),
                    NULL,
                    nkeys,
                    cur_skey);

    ct = NULL;
    stale = false;

    while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
    {
      ct = CatalogCacheCreateEntry(cache, ntp, NULL,
                     hashValue, hashIndex);
      /* upon failure, we must start the scan over */
      if (ct == NULL)
      {
        stale = true;
        break;
      }
      /* immediately set the refcount to 1 */
      ResourceOwnerEnlarge(CurrentResourceOwner);
      ct->refcount++;
      ResourceOwnerRememberCatCacheRef(CurrentResourceOwner, &ct->tuple);
      break;       /* assume only one match */
    }

    systable_endscan(scandesc);
  } while (stale);

  table_close(relation, AccessShareLock);

  /*
   * If tuple was not found, we need to build a negative cache entry
   * containing a fake tuple.  The fake tuple has the correct key columns,
   * but nulls everywhere else.
   *
   * In bootstrap mode, we don't build negative entries, because the cache
   * invalidation mechanism isn't alive and can't clear them if the tuple
   * gets created later.  (Bootstrap doesn't do UPDATEs, so it doesn't need
   * cache inval for that.)
   */
  if (ct == NULL)
  {
    if (IsBootstrapProcessingMode())
      return NULL;

    ct = CatalogCacheCreateEntry(cache, NULL, arguments,
                   hashValue, hashIndex);

    /* Creating a negative cache entry shouldn't fail */
    Assert(ct != NULL);

    CACHE_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples",
           cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup);
    CACHE_elog(DEBUG2, "SearchCatCache(%s): put neg entry in bucket %d",
           cache->cc_relname, hashIndex);

    /*
     * We are not returning the negative entry to the caller, so leave its
     * refcount zero.
     */

    return NULL;
  }

  CACHE_elog(DEBUG2, "SearchCatCache(%s): Contains %d/%d tuples",
         cache->cc_relname, cache->cc_ntup, CacheHdr->ch_ntup);
  CACHE_elog(DEBUG2, "SearchCatCache(%s): put in bucket %d",
         cache->cc_relname, hashIndex);

#ifdef CATCACHE_STATS
  cache->cc_newloads++;
#endif

  return &ct->tuple;
}

/*
 *  ReleaseCatCache
 *
 *  Decrement the reference count of a catcache entry (releasing the
 *  hold grabbed by a successful SearchCatCache).
 *
 *  NOTE: if compiled with -DCATCACHE_FORCE_RELEASE then catcache entries
 *  will be freed as soon as their refcount goes to zero.  In combination
 *  with aset.c's CLOBBER_FREED_MEMORY option, this provides a good test
 *  to catch references to already-released catcache entries.
 */
void
ReleaseCatCache(HeapTuple tuple)
{
  ReleaseCatCacheWithOwner(tuple, CurrentResourceOwner);
}

static void
ReleaseCatCacheWithOwner(HeapTuple tuple, ResourceOwner resowner)
{
  CatCTup    *ct = (CatCTup *) (((char *) tuple) -
                  offsetof(CatCTup, tuple));

  /* Safety checks to ensure we were handed a cache entry */
  Assert(ct->ct_magic == CT_MAGIC);
  Assert(ct->refcount > 0);

  ct->refcount--;
  if (resowner)
    ResourceOwnerForgetCatCacheRef(resowner, &ct->tuple);

  if (
#ifndef CATCACHE_FORCE_RELEASE
    ct->dead &&
#endif
    ct->refcount == 0 &&
    (ct->c_list == NULL || ct->c_list->refcount == 0))
    CatCacheRemoveCTup(ct->my_cache, ct);
}


/*
 *  GetCatCacheHashValue
 *
 *    Compute the hash value for a given set of search keys.
 *
 * The reason for exposing this as part of the API is that the hash value is
 * exposed in cache invalidation operations, so there are places outside the
 * catcache code that need to be able to compute the hash values.
 */
uint32
GetCatCacheHashValue(CatCache *cache,
           Datum v1,
           Datum v2,
           Datum v3,
           Datum v4)
{
  /*
   * one-time startup overhead for each cache
   */
  ConditionalCatalogCacheInitializeCache(cache);

  /*
   * calculate the hash value
   */
  return CatalogCacheComputeHashValue(cache, cache->cc_nkeys, v1, v2, v3, v4);
}


/*
 *  SearchCatCacheList
 *
 *    Generate a list of all tuples matching a partial key (that is,
 *    a key specifying just the first K of the cache's N key columns).
 *
 *    It doesn't make any sense to specify all of the cache's key columns
 *    here: since the key is unique, there could be at most one match, so
 *    you ought to use SearchCatCache() instead.  Hence this function takes
 *    one fewer Datum argument than SearchCatCache() does.
 *
 *    The caller must not modify the list object or the pointed-to tuples,
 *    and must call ReleaseCatCacheList() when done with the list.
 */
CatCList *
SearchCatCacheList(CatCache *cache,
           int nkeys,
           Datum v1,
           Datum v2,
           Datum v3)
{
  Datum   v4 = 0;     /* dummy last-column value */
  Datum   arguments[CATCACHE_MAXKEYS];
  uint32    lHashValue;
  Index   lHashIndex;
  dlist_iter  iter;
  dlist_head *lbucket;
  CatCList   *cl;
  CatCTup    *ct;
  List     *volatile ctlist;
  ListCell   *ctlist_item;
  int     nmembers;
  bool    ordered;
  HeapTuple ntp;
  MemoryContext oldcxt;
  int     i;
  CatCInProgress *save_in_progress;
  CatCInProgress in_progress_ent;

  /*
   * one-time startup overhead for each cache
   */
  ConditionalCatalogCacheInitializeCache(cache);

  Assert(nkeys > 0 && nkeys < cache->cc_nkeys);

#ifdef CATCACHE_STATS
  cache->cc_lsearches++;
#endif

  /* Initialize local parameter array */
  arguments[0] = v1;
  arguments[1] = v2;
  arguments[2] = v3;
  arguments[3] = v4;

  /*
   * If we haven't previously done a list search in this cache, create the
   * bucket header array; otherwise, consider whether it's time to enlarge
   * it.
   */
  if (cache->cc_lbucket == NULL)
  {
    /* Arbitrary initial size --- must be a power of 2 */
    int     nbuckets = 16;

    cache->cc_lbucket = (dlist_head *)
      MemoryContextAllocZero(CacheMemoryContext,
                   nbuckets * sizeof(dlist_head));
    /* Don't set cc_nlbuckets if we get OOM allocating cc_lbucket */
    cache->cc_nlbuckets = nbuckets;
  }
  else
  {
    /*
     * If the hash table has become too full, enlarge the buckets array.
     * Quite arbitrarily, we enlarge when fill factor > 2.
     */
    if (cache->cc_nlist > cache->cc_nlbuckets * 2)
      RehashCatCacheLists(cache);
  }

  /*
   * Find the hash bucket in which to look for the CatCList.
   */
  lHashValue = CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
  lHashIndex = HASH_INDEX(lHashValue, cache->cc_nlbuckets);

  /*
   * scan the items until we find a match or exhaust our list
   *
   * Note: it's okay to use dlist_foreach here, even though we modify the
   * dlist within the loop, because we don't continue the loop afterwards.
   */
  lbucket = &cache->cc_lbucket[lHashIndex];
  dlist_foreach(iter, lbucket)
  {
    cl = dlist_container(CatCList, cache_elem, iter.cur);

    if (cl->dead)
      continue;     /* ignore dead entries */

    if (cl->hash_value != lHashValue)
      continue;     /* quickly skip entry if wrong hash val */

    /*
     * see if the cached list matches our key.
     */
    if (cl->nkeys != nkeys)
      continue;

    if (!CatalogCacheCompareTuple(cache, nkeys, cl->keys, arguments))
      continue;

    /*
     * We found a matching list.  Move the list to the front of the list
     * for its hashbucket, so as to speed subsequent searches.  (We do not
     * move the members to the fronts of their hashbucket lists, however,
     * since there's no point in that unless they are searched for
     * individually.)
     */
    dlist_move_head(lbucket, &cl->cache_elem);

    /* Bump the list's refcount and return it */
    ResourceOwnerEnlarge(CurrentResourceOwner);
    cl->refcount++;
    ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl);

    CACHE_elog(DEBUG2, "SearchCatCacheList(%s): found list",
           cache->cc_relname);

#ifdef CATCACHE_STATS
    cache->cc_lhits++;
#endif

    return cl;
  }

  /*
   * List was not found in cache, so we have to build it by reading the
   * relation.  For each matching tuple found in the relation, use an
   * existing cache entry if possible, else build a new one.
   *
   * We have to bump the member refcounts temporarily to ensure they won't
   * get dropped from the cache while loading other members. We use a PG_TRY
   * block to ensure we can undo those refcounts if we get an error before
   * we finish constructing the CatCList.  ctlist must be valid throughout
   * the PG_TRY block.
   */
  ctlist = NIL;

  /*
   * Cache invalidation can happen while we're building the list.
   * CatalogCacheCreateEntry() handles concurrent invalidation of individual
   * tuples, but it's also possible that a new entry is concurrently added
   * that should be part of the list we're building.  Register an
   * "in-progress" entry that will receive the invalidation, until we have
   * built the final list entry.
   */
  save_in_progress = catcache_in_progress_stack;
  in_progress_ent.next = catcache_in_progress_stack;
  in_progress_ent.cache = cache;
  in_progress_ent.hash_value = lHashValue;
  in_progress_ent.list = true;
  in_progress_ent.dead = false;
  catcache_in_progress_stack = &in_progress_ent;

  PG_TRY();
  {
    ScanKeyData cur_skey[CATCACHE_MAXKEYS];
    Relation  relation;
    SysScanDesc scandesc;
    bool    first_iter = true;

    relation = table_open(cache->cc_reloid, AccessShareLock);

    /*
     * Ok, need to make a lookup in the relation, copy the scankey and
     * fill out any per-call fields.
     */
    memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * cache->cc_nkeys);
    cur_skey[0].sk_argument = v1;
    cur_skey[1].sk_argument = v2;
    cur_skey[2].sk_argument = v3;
    cur_skey[3].sk_argument = v4;

    /*
     * Scan the table for matching entries.  If an invalidation arrives
     * mid-build, we will loop back here to retry.
     */
    do
    {
      /*
       * If we are retrying, release refcounts on any items created on
       * the previous iteration.  We dare not try to free them if
       * they're now unreferenced, since an error while doing that would
       * result in the PG_CATCH below doing extra refcount decrements.
       * Besides, we'll likely re-adopt those items in the next
       * iteration, so it's not worth complicating matters to try to get
       * rid of them.
       */
      foreach(ctlist_item, ctlist)
      {
        ct = (CatCTup *) lfirst(ctlist_item);
        Assert(ct->c_list == NULL);
        Assert(ct->refcount > 0);
        ct->refcount--;
      }
      /* Reset ctlist in preparation for new try */
      ctlist = NIL;
      in_progress_ent.dead = false;

      scandesc = systable_beginscan(relation,
                      cache->cc_indexoid,
                      IndexScanOK(cache),
                      NULL,
                      nkeys,
                      cur_skey);

      /* The list will be ordered iff we are doing an index scan */
      ordered = (scandesc->irel != NULL);

      /* Injection point to help testing the recursive invalidation case */
      if (first_iter)
      {
        INJECTION_POINT("catcache-list-miss-systable-scan-started", NULL);
        first_iter = false;
      }

      while (HeapTupleIsValid(ntp = systable_getnext(scandesc)) &&
           !in_progress_ent.dead)
      {
        uint32    hashValue;
        Index   hashIndex;
        bool    found = false;
        dlist_head *bucket;

        /*
         * See if there's an entry for this tuple already.
         */
        ct = NULL;
        hashValue = CatalogCacheComputeTupleHashValue(cache, cache->cc_nkeys, ntp);
        hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);

        bucket = &cache->cc_bucket[hashIndex];
        dlist_foreach(iter, bucket)
        {
          ct = dlist_container(CatCTup, cache_elem, iter.cur);

          if (ct->dead || ct->negative)
            continue; /* ignore dead and negative entries */

          if (ct->hash_value != hashValue)
            continue; /* quickly skip entry if wrong hash val */

          if (!ItemPointerEquals(&(ct->tuple.t_self), &(ntp->t_self)))
            continue; /* not same tuple */

          /*
           * Found a match, but can't use it if it belongs to
           * another list already
           */
          if (ct->c_list)
            continue;

          found = true;
          break;   /* A-OK */
        }

        if (!found)
        {
          /* We didn't find a usable entry, so make a new one */
          ct = CatalogCacheCreateEntry(cache, ntp, NULL,
                         hashValue, hashIndex);

          /* upon failure, we must start the scan over */
          if (ct == NULL)
          {
            in_progress_ent.dead = true;
            break;
          }
        }

        /* Careful here: add entry to ctlist, then bump its refcount */
        /* This way leaves state correct if lappend runs out of memory */
        ctlist = lappend(ctlist, ct);
        ct->refcount++;
      }

      systable_endscan(scandesc);
    } while (in_progress_ent.dead);

    table_close(relation, AccessShareLock);

    /* Make sure the resource owner has room to remember this entry. */
    ResourceOwnerEnlarge(CurrentResourceOwner);

    /* Now we can build the CatCList entry. */
    oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
    nmembers = list_length(ctlist);
    cl = (CatCList *)
      palloc(offsetof(CatCList, members) + nmembers * sizeof(CatCTup *));

    /* Extract key values */
    CatCacheCopyKeys(cache->cc_tupdesc, nkeys, cache->cc_keyno,
             arguments, cl->keys);
    MemoryContextSwitchTo(oldcxt);

    /*
     * We are now past the last thing that could trigger an elog before we
     * have finished building the CatCList and remembering it in the
     * resource owner.  So it's OK to fall out of the PG_TRY, and indeed
     * we'd better do so before we start marking the members as belonging
     * to the list.
     */
  }
  PG_CATCH();
  {
    Assert(catcache_in_progress_stack == &in_progress_ent);
    catcache_in_progress_stack = save_in_progress;

    foreach(ctlist_item, ctlist)
    {
      ct = (CatCTup *) lfirst(ctlist_item);
      Assert(ct->c_list == NULL);
      Assert(ct->refcount > 0);
      ct->refcount--;
      if (
#ifndef CATCACHE_FORCE_RELEASE
        ct->dead &&
#endif
        ct->refcount == 0 &&
        (ct->c_list == NULL || ct->c_list->refcount == 0))
        CatCacheRemoveCTup(cache, ct);
    }

    PG_RE_THROW();
  }
  PG_END_TRY();
  Assert(catcache_in_progress_stack == &in_progress_ent);
  catcache_in_progress_stack = save_in_progress;

  cl->cl_magic = CL_MAGIC;
  cl->my_cache = cache;
  cl->refcount = 0;     /* for the moment */
  cl->dead = false;
  cl->ordered = ordered;
  cl->nkeys = nkeys;
  cl->hash_value = lHashValue;
  cl->n_members = nmembers;

  i = 0;
  foreach(ctlist_item, ctlist)
  {
    cl->members[i++] = ct = (CatCTup *) lfirst(ctlist_item);
    Assert(ct->c_list == NULL);
    ct->c_list = cl;
    /* release the temporary refcount on the member */
    Assert(ct->refcount > 0);
    ct->refcount--;
    /* mark list dead if any members already dead */
    if (ct->dead)
      cl->dead = true;
  }
  Assert(i == nmembers);

  /*
   * Add the CatCList to the appropriate bucket, and count it.
   */
  dlist_push_head(lbucket, &cl->cache_elem);

  cache->cc_nlist++;

  /* Finally, bump the list's refcount and return it */
  cl->refcount++;
  ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl);

  CACHE_elog(DEBUG2, "SearchCatCacheList(%s): made list of %d members",
         cache->cc_relname, nmembers);

  return cl;
}

/*
 *  ReleaseCatCacheList
 *
 *  Decrement the reference count of a catcache list.
 */
void
ReleaseCatCacheList(CatCList *list)
{
  ReleaseCatCacheListWithOwner(list, CurrentResourceOwner);
}

static void
ReleaseCatCacheListWithOwner(CatCList *list, ResourceOwner resowner)
{
  /* Safety checks to ensure we were handed a cache entry */
  Assert(list->cl_magic == CL_MAGIC);
  Assert(list->refcount > 0);
  list->refcount--;
  if (resowner)
    ResourceOwnerForgetCatCacheListRef(resowner, list);

  if (
#ifndef CATCACHE_FORCE_RELEASE
    list->dead &&
#endif
    list->refcount == 0)
    CatCacheRemoveCList(list->my_cache, list);
}


/*
 * CatalogCacheCreateEntry
 *    Create a new CatCTup entry, copying the given HeapTuple and other
 *    supplied data into it.  The new entry initially has refcount 0.
 *
 * To create a normal cache entry, ntp must be the HeapTuple just fetched
 * from scandesc, and "arguments" is not used.  To create a negative cache
 * entry, pass NULL for ntp; then "arguments" is the cache keys to use.
 * In either case, hashValue/hashIndex are the hash values computed from
 * the cache keys.
 *
 * Returns NULL if we attempt to detoast the tuple and observe that it
 * became stale.  (This cannot happen for a negative entry.)  Caller must
 * retry the tuple lookup in that case.
 */
static CatCTup *
CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
            uint32 hashValue, Index hashIndex)
{
  CatCTup    *ct;
  MemoryContext oldcxt;

  if (ntp)
  {
    int     i;
    HeapTuple dtp = NULL;

    /*
     * The invalidation of the in-progress entry essentially never happens
     * during our regression tests, and there's no easy way to force it to
     * fail for testing purposes.  To ensure we have test coverage for the
     * retry paths in our callers, make debug builds randomly fail about
     * 0.1% of the times through this code path, even when there's no
     * toasted fields.
     */
#ifdef USE_ASSERT_CHECKING
    if (pg_prng_uint32(&pg_global_prng_state) <= (PG_UINT32_MAX / 1000))
      return NULL;
#endif

    /*
     * If there are any out-of-line toasted fields in the tuple, expand
     * them in-line.  This saves cycles during later use of the catcache
     * entry, and also protects us against the possibility of the toast
     * tuples being freed before we attempt to fetch them, in case of
     * something using a slightly stale catcache entry.
     */
    if (HeapTupleHasExternal(ntp))
    {
      CatCInProgress *save_in_progress;
      CatCInProgress in_progress_ent;

      /*
       * The tuple could become stale while we are doing toast table
       * access (since AcceptInvalidationMessages can run then).  The
       * invalidation will mark our in-progress entry as dead.
       */
      save_in_progress = catcache_in_progress_stack;
      in_progress_ent.next = catcache_in_progress_stack;
      in_progress_ent.cache = cache;
      in_progress_ent.hash_value = hashValue;
      in_progress_ent.list = false;
      in_progress_ent.dead = false;
      catcache_in_progress_stack = &in_progress_ent;

      PG_TRY();
      {
        dtp = toast_flatten_tuple(ntp, cache->cc_tupdesc);
      }
      PG_FINALLY();
      {
        Assert(catcache_in_progress_stack == &in_progress_ent);
        catcache_in_progress_stack = save_in_progress;
      }
      PG_END_TRY();

      if (in_progress_ent.dead)
      {
        heap_freetuple(dtp);
        return NULL;
      }
    }
    else
      dtp = ntp;

    /* Allocate memory for CatCTup and the cached tuple in one go */
    ct = (CatCTup *)
      MemoryContextAlloc(CacheMemoryContext,
                 MAXALIGN(sizeof(CatCTup)) + dtp->t_len);
    ct->tuple.t_len = dtp->t_len;
    ct->tuple.t_self = dtp->t_self;
    ct->tuple.t_tableOid = dtp->t_tableOid;
    ct->tuple.t_data = (HeapTupleHeader)
      (((char *) ct) + MAXALIGN(sizeof(CatCTup)));
    /* copy tuple contents */
    memcpy((char *) ct->tuple.t_data,
         (const char *) dtp->t_data,
         dtp->t_len);

    if (dtp != ntp)
      heap_freetuple(dtp);

    /* extract keys - they'll point into the tuple if not by-value */
    for (i = 0; i < cache->cc_nkeys; i++)
    {
      Datum   atp;
      bool    isnull;

      atp = heap_getattr(&ct->tuple,
                 cache->cc_keyno[i],
                 cache->cc_tupdesc,
                 &isnull);
      Assert(!isnull);
      ct->keys[i] = atp;
    }
  }
  else
  {
    /* Set up keys for a negative cache entry */
    oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
    ct = palloc_object(CatCTup);

    /*
     * Store keys - they'll point into separately allocated memory if not
     * by-value.
     */
    CatCacheCopyKeys(cache->cc_tupdesc, cache->cc_nkeys, cache->cc_keyno,
             arguments, ct->keys);
    MemoryContextSwitchTo(oldcxt);
  }

  /*
   * Finish initializing the CatCTup header, and add it to the cache's
   * linked list and counts.
   */
  ct->ct_magic = CT_MAGIC;
  ct->my_cache = cache;
  ct->c_list = NULL;
  ct->refcount = 0;     /* for the moment */
  ct->dead = false;
  ct->negative = (ntp == NULL);
  ct->hash_value = hashValue;

  dlist_push_head(&cache->cc_bucket[hashIndex], &ct->cache_elem);

  cache->cc_ntup++;
  CacheHdr->ch_ntup++;

  /*
   * If the hash table has become too full, enlarge the buckets array. Quite
   * arbitrarily, we enlarge when fill factor > 2.
   */
  if (cache->cc_ntup > cache->cc_nbuckets * 2)
    RehashCatCache(cache);

  return ct;
}

/*
 * Helper routine that frees keys stored in the keys array.
 */
static void
CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, const int *attnos, const Datum *keys)
{
  int     i;

  for (i = 0; i < nkeys; i++)
  {
    int     attnum = attnos[i];

    /* system attribute are not supported in caches */
    Assert(attnum > 0);

    if (!TupleDescCompactAttr(tupdesc, attnum - 1)->attbyval)
      pfree(DatumGetPointer(keys[i]));
  }
}

/*
 * Helper routine that copies the keys in the srckeys array into the dstkeys
 * one, guaranteeing that the datums are fully allocated in the current memory
 * context.
 */
static void
CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
         const Datum *srckeys, Datum *dstkeys)
{
  int     i;

  /*
   * XXX: memory and lookup performance could possibly be improved by
   * storing all keys in one allocation.
   */

  for (i = 0; i < nkeys; i++)
  {
    int     attnum = attnos[i];
    Form_pg_attribute att = TupleDescAttr(tupdesc, attnum - 1);
    Datum   src = srckeys[i];
    NameData  srcname;

    /*
     * Must be careful in case the caller passed a C string where a NAME
     * is wanted: convert the given argument to a correctly padded NAME.
     * Otherwise the memcpy() done by datumCopy() could fall off the end
     * of memory.
     */
    if (att->atttypid == NAMEOID)
    {
      namestrcpy(&srcname, DatumGetCString(src));
      src = NameGetDatum(&srcname);
    }

    dstkeys[i] = datumCopy(src,
                 att->attbyval,
                 att->attlen);
  }
}

/*
 *  PrepareToInvalidateCacheTuple()
 *
 *  This is part of a rather subtle chain of events, so pay attention:
 *
 *  When a tuple is inserted or deleted, it cannot be flushed from the
 *  catcaches immediately, for reasons explained at the top of cache/inval.c.
 *  Instead we have to add entry(s) for the tuple to a list of pending tuple
 *  invalidations that will be done at the end of the command or transaction.
 *
 *  The lists of tuples that need to be flushed are kept by inval.c.  This
 *  routine is a helper routine for inval.c.  Given a tuple belonging to
 *  the specified relation, find all catcaches it could be in, compute the
 *  correct hash value for each such catcache, and call the specified
 *  function to record the cache id and hash value in inval.c's lists.
 *  SysCacheInvalidate will be called later, if appropriate,
 *  using the recorded information.
 *
 *  For an insert or delete, tuple is the target tuple and newtuple is NULL.
 *  For an update, we are called just once, with tuple being the old tuple
 *  version and newtuple the new version.  We should make two list entries
 *  if the tuple's hash value changed, but only one if it didn't.
 *
 *  Note that it is irrelevant whether the given tuple is actually loaded
 *  into the catcache at the moment.  Even if it's not there now, it might
 *  be by the end of the command, or there might be a matching negative entry
 *  to flush --- or other backends' caches might have such entries --- so
 *  we have to make list entries to flush it later.
 *
 *  Also note that it's not an error if there are no catcaches for the
 *  specified relation.  inval.c doesn't know exactly which rels have
 *  catcaches --- it will call this routine for any tuple that's in a
 *  system relation.
 */
void
PrepareToInvalidateCacheTuple(Relation relation,
                HeapTuple tuple,
                HeapTuple newtuple,
                void (*function) (int, uint32, Oid, void *),
                void *context)
{
  slist_iter  iter;
  Oid     reloid;

  CACHE_elog(DEBUG2, "PrepareToInvalidateCacheTuple: called");

  /*
   * sanity checks
   */
  Assert(RelationIsValid(relation));
  Assert(HeapTupleIsValid(tuple));
  Assert(function);
  Assert(CacheHdr != NULL);

  reloid = RelationGetRelid(relation);

  /* ----------------
   *  for each cache
   *     if the cache contains tuples from the specified relation
   *       compute the tuple's hash value(s) in this cache,
   *       and call the passed function to register the information.
   * ----------------
   */

  slist_foreach(iter, &CacheHdr->ch_caches)
  {
    CatCache   *ccp = slist_container(CatCache, cc_next, iter.cur);
    uint32    hashvalue;
    Oid     dbid;

    if (ccp->cc_reloid != reloid)
      continue;

    /* Just in case cache hasn't finished initialization yet... */
    ConditionalCatalogCacheInitializeCache(ccp);

    hashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, tuple);
    dbid = ccp->cc_relisshared ? (Oid) 0 : MyDatabaseId;

    (*function) (ccp->id, hashvalue, dbid, context);

    if (newtuple)
    {
      uint32    newhashvalue;

      newhashvalue = CatalogCacheComputeTupleHashValue(ccp, ccp->cc_nkeys, newtuple);

      if (newhashvalue != hashvalue)
        (*function) (ccp->id, newhashvalue, dbid, context);
    }
  }
}

/* ResourceOwner callbacks */

static void
ResOwnerReleaseCatCache(Datum res)
{
  ReleaseCatCacheWithOwner((HeapTuple) DatumGetPointer(res), NULL);
}

static char *
ResOwnerPrintCatCache(Datum res)
{
  HeapTuple tuple = (HeapTuple) DatumGetPointer(res);
  CatCTup    *ct = (CatCTup *) (((char *) tuple) -
                  offsetof(CatCTup, tuple));

  /* Safety check to ensure we were handed a cache entry */
  Assert(ct->ct_magic == CT_MAGIC);

  return psprintf("cache %s (%d), tuple %u/%u has count %d",
          ct->my_cache->cc_relname, ct->my_cache->id,
          ItemPointerGetBlockNumber(&(tuple->t_self)),
          ItemPointerGetOffsetNumber(&(tuple->t_self)),
          ct->refcount);
}

static void
ResOwnerReleaseCatCacheList(Datum res)
{
  ReleaseCatCacheListWithOwner((CatCList *) DatumGetPointer(res), NULL);
}

static char *
ResOwnerPrintCatCacheList(Datum res)
{
  CatCList   *list = (CatCList *) DatumGetPointer(res);

  return psprintf("cache %s (%d), list %p has count %d",
          list->my_cache->cc_relname, list->my_cache->id,
          list, list->refcount);
}

Coverage Report

Created: 2026-08-13 07:12