Use hash_make macros throughout the codebase

This shows how our code base looks when using the new APIs. This has
some typesafety, readability and maintanability benefits, but it also
introduces some backpatching problems. These backpatching problems
cannot be resolved by backporting the new hash_make macros, because some
of them require C11 (which we only require on master for now). I think
it's unlikely that we'll need to backpatch things in code that creates
hashtables though, so it could still be worth it to do this complete
refactor.

At the very least we should choose a few places where we use the new
macros to make sure they have coverage.

Author: JelteF

contrib/dblink/dblink.c

@@ -2540,13 +2540,9 @@ getConnectionByName(const char *name)
 static HTAB *
 createConnHash(void)
 {
-	HASHCTL		ctl;
-
-	ctl.keysize = NAMEDATALEN;
-	ctl.entrysize = sizeof(remoteConnHashEnt);
-
-	return hash_create("Remote Con hash", NUMCONN, &ctl,
-					   HASH_ELEM | HASH_STRINGS);
+	return hash_make_cxt(remoteConnHashEnt, name,
+						 "Remote Con hash", NUMCONN,
+						 TopMemoryContext);
 }
 
 static remoteConn *

contrib/pg_stat_statements/pg_stat_statements.c

@@ -517,7 +517,6 @@ static void
 pgss_shmem_startup(void)
 {
 	bool		found;
-	HASHCTL		info;
 	FILE	   *file = NULL;
 	FILE	   *qfile = NULL;
 	uint32		header;
@@ -557,12 +556,9 @@ pgss_shmem_startup(void)
 		pgss->stats.stats_reset = GetCurrentTimestamp();
 	}
 
-	info.keysize = sizeof(pgssHashKey);
-	info.entrysize = sizeof(pgssEntry);
-	pgss_hash = ShmemInitHash("pg_stat_statements hash",
-							  pgss_max, pgss_max,
-							  &info,
-							  HASH_ELEM | HASH_BLOBS);
+	pgss_hash = shmem_hash_make(pgssEntry, key,
+								"pg_stat_statements hash",
+								pgss_max, pgss_max);
 
 	LWLockRelease(AddinShmemInitLock);
 

contrib/pg_trgm/trgm_regexp.c

@@ -893,7 +893,6 @@ convertPgWchar(pg_wchar c, trgm_mb_char *result)
 static void
 transformGraph(TrgmNFA *trgmNFA)
 {
-	HASHCTL		hashCtl;
 	TrgmStateKey initkey;
 	TrgmState  *initstate;
 	ListCell   *lc;
@@ -905,13 +904,7 @@ transformGraph(TrgmNFA *trgmNFA)
 	trgmNFA->overflowed = false;
 
 	/* Create hashtable for states */
-	hashCtl.keysize = sizeof(TrgmStateKey);
-	hashCtl.entrysize = sizeof(TrgmState);
-	hashCtl.hcxt = CurrentMemoryContext;
-	trgmNFA->states = hash_create("Trigram NFA",
-								  1024,
-								  &hashCtl,
-								  HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+	trgmNFA->states = hash_make(TrgmState, stateKey, "Trigram NFA", 1024);
 	trgmNFA->nstates = 0;
 
 	/* Create initial state: ambiguous prefix, NFA's initial state */

contrib/postgres_fdw/connection.c

@@ -214,17 +214,13 @@ GetConnection(UserMapping *user, bool will_prep_stmt, PgFdwConnState **state)
 	/* First time through, initialize connection cache hashtable */
 	if (ConnectionHash == NULL)
 	{
-		HASHCTL		ctl;
-
 		if (pgfdw_we_get_result == 0)
 			pgfdw_we_get_result =
 				WaitEventExtensionNew("PostgresFdwGetResult");
 
-		ctl.keysize = sizeof(ConnCacheKey);
-		ctl.entrysize = sizeof(ConnCacheEntry);
-		ConnectionHash = hash_create("postgres_fdw connections", 8,
-									 &ctl,
-									 HASH_ELEM | HASH_BLOBS);
+		ConnectionHash = hash_make_cxt(ConnCacheEntry, key,
+									   "postgres_fdw connections", 8,
+									   TopMemoryContext);
 
 		/*
 		 * Register some callback functions that manage connection cleanup.

contrib/postgres_fdw/shippable.c

@@ -28,6 +28,7 @@
 #include "postgres_fdw.h"
 #include "utils/hsearch.h"
 #include "utils/inval.h"
+#include "utils/memutils.h"
 #include "utils/syscache.h"
 
 /* Hash table for caching the results of shippability lookups */
@@ -90,13 +91,10 @@ InvalidateShippableCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
 static void
 InitializeShippableCache(void)
 {
-	HASHCTL		ctl;
-
 	/* Create the hash table. */
-	ctl.keysize = sizeof(ShippableCacheKey);
-	ctl.entrysize = sizeof(ShippableCacheEntry);
-	ShippableCacheHash =
-		hash_create("Shippability cache", 256, &ctl, HASH_ELEM | HASH_BLOBS);
+	ShippableCacheHash = hash_make_cxt(ShippableCacheEntry, key,
+									   "Shippability cache", 256,
+									   TopMemoryContext);
 
 	/* Set up invalidation callback on pg_foreign_server. */
 	CacheRegisterSyscacheCallback(FOREIGNSERVEROID,

contrib/tablefunc/tablefunc.c

@@ -705,24 +705,17 @@ static HTAB *
 load_categories_hash(char *cats_sql, MemoryContext per_query_ctx)
 {
 	HTAB	   *crosstab_hash;
-	HASHCTL		ctl;
 	int			ret;
 	uint64		proc;
 	MemoryContext SPIcontext;
 
-	/* initialize the category hash table */
-	ctl.keysize = MAX_CATNAME_LEN;
-	ctl.entrysize = sizeof(crosstab_HashEnt);
-	ctl.hcxt = per_query_ctx;
-
 	/*
-	 * use INIT_CATS, defined above as a guess of how many hash table entries
-	 * to create, initially
+	 * Initialize the category hash table. Use INIT_CATS, defined above as a
+	 * guess of how many hash table entries to create, initially.
 	 */
-	crosstab_hash = hash_create("crosstab hash",
-								INIT_CATS,
-								&ctl,
-								HASH_ELEM | HASH_STRINGS | HASH_CONTEXT);
+	crosstab_hash = hash_make_cxt(crosstab_HashEnt, internal_catname,
+								  "crosstab hash", INIT_CATS,
+								  per_query_ctx);
 
 	/* Connect to SPI manager */
 	SPI_connect();

src/backend/access/common/heaptuple.c

@@ -125,18 +125,9 @@ missing_match(const void *key1, const void *key2, Size keysize)
 static void
 init_missing_cache(void)
 {
-	HASHCTL		hash_ctl;
-
-	hash_ctl.keysize = sizeof(missing_cache_key);
-	hash_ctl.entrysize = sizeof(missing_cache_key);
-	hash_ctl.hcxt = TopMemoryContext;
-	hash_ctl.hash = missing_hash;
-	hash_ctl.match = missing_match;
 	missing_cache =
-		hash_create("Missing Values Cache",
-					32,
-					&hash_ctl,
-					HASH_ELEM | HASH_CONTEXT | HASH_FUNCTION | HASH_COMPARE);
+		hashset_make_fn_cxt(missing_cache_key, "Missing Values Cache", 32,
+							missing_hash, missing_match, TopMemoryContext);
 }
 
 /* ----------------------------------------------------------------

src/backend/access/gist/gistbuild.c

@@ -1515,15 +1515,8 @@ typedef struct
 static void
 gistInitParentMap(GISTBuildState *buildstate)
 {
-	HASHCTL		hashCtl;
-
-	hashCtl.keysize = sizeof(BlockNumber);
-	hashCtl.entrysize = sizeof(ParentMapEntry);
-	hashCtl.hcxt = CurrentMemoryContext;
-	buildstate->parentMap = hash_create("gistbuild parent map",
-										1024,
-										&hashCtl,
-										HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+	buildstate->parentMap = hash_make(ParentMapEntry, childblkno,
+									  "gistbuild parent map", 1024);
 }
 
 static void

src/backend/access/gist/gistbuildbuffers.c

@@ -44,7 +44,6 @@ GISTBuildBuffers *
 gistInitBuildBuffers(int pagesPerBuffer, int levelStep, int maxLevel)
 {
 	GISTBuildBuffers *gfbb;
-	HASHCTL		hashCtl;
 
 	gfbb = palloc(sizeof(GISTBuildBuffers));
 	gfbb->pagesPerBuffer = pagesPerBuffer;
@@ -72,13 +71,8 @@ gistInitBuildBuffers(int pagesPerBuffer, int levelStep, int maxLevel)
 	 * nodeBuffersTab hash is association between index blocks and it's
 	 * buffers.
 	 */
-	hashCtl.keysize = sizeof(BlockNumber);
-	hashCtl.entrysize = sizeof(GISTNodeBuffer);
-	hashCtl.hcxt = CurrentMemoryContext;
-	gfbb->nodeBuffersTab = hash_create("gistbuildbuffers",
-									   1024,
-									   &hashCtl,
-									   HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+	gfbb->nodeBuffersTab = hash_make(GISTNodeBuffer, nodeBlocknum,
+									 "gistbuildbuffers", 1024);
 
 	gfbb->bufferEmptyingQueue = NIL;
 

src/backend/access/hash/hashpage.c

@@ -1356,7 +1356,6 @@ void
 _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
 				   uint32 maxbucket, uint32 highmask, uint32 lowmask)
 {
-	HASHCTL		hash_ctl;
 	HTAB	   *tidhtab;
 	Buffer		bucket_nbuf = InvalidBuffer;
 	Buffer		nbuf;
@@ -1367,16 +1366,8 @@ _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
 	Bucket		nbucket;
 	bool		found;
 
-	/* Initialize hash tables used to track TIDs */
-	hash_ctl.keysize = sizeof(ItemPointerData);
-	hash_ctl.entrysize = sizeof(ItemPointerData);
-	hash_ctl.hcxt = CurrentMemoryContext;
-
-	tidhtab =
-		hash_create("bucket ctids",
-					256,		/* arbitrary initial size */
-					&hash_ctl,
-					HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+	/* Initialize hash tables used to track TIDs (with arbitrary initial size) */
+	tidhtab = hashset_make(ItemPointerData, "bucket ctids", 256);
 
 	bucket_nblkno = nblkno = _hash_get_newblock_from_oldbucket(rel, obucket);