1 files changed, 236 insertions, 0 deletions
diff --git a/src/backend/utils/cache/spccache.c b/src/backend/utils/cache/spccache.c
new file mode 100644
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--- /dev/null
+++ b/src/backend/utils/cache/spccache.c
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+/*-------------------------------------------------------------------------
+ *
+ * spccache.c
+ *	  Tablespace cache management.
+ *
+ * We cache the parsed version of spcoptions for each tablespace to avoid
+ * needing to reparse on every lookup.  Right now, there doesn't appear to
+ * be a measurable performance gain from doing this, but that might change
+ * in the future as we add more options.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/cache/spccache.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/reloptions.h"
+#include "catalog/pg_tablespace.h"
+#include "commands/tablespace.h"
+#include "miscadmin.h"
+#include "optimizer/optimizer.h"
+#include "storage/bufmgr.h"
+#include "utils/catcache.h"
+#include "utils/hsearch.h"
+#include "utils/inval.h"
+#include "utils/spccache.h"
+#include "utils/syscache.h"
+
+
+/* Hash table for information about each tablespace */
+static HTAB *TableSpaceCacheHash = NULL;
+
+typedef struct
+{
+	Oid			oid;			/* lookup key - must be first */
+	TableSpaceOpts *opts;		/* options, or NULL if none */
+} TableSpaceCacheEntry;
+
+
+/*
+ * InvalidateTableSpaceCacheCallback
+ *		Flush all cache entries when pg_tablespace is updated.
+ *
+ * When pg_tablespace is updated, we must flush the cache entry at least
+ * for that tablespace.  Currently, we just flush them all.  This is quick
+ * and easy and doesn't cost much, since there shouldn't be terribly many
+ * tablespaces, nor do we expect them to be frequently modified.
+ */
+static void
+InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
+{
+	HASH_SEQ_STATUS status;
+	TableSpaceCacheEntry *spc;
+
+	hash_seq_init(&status, TableSpaceCacheHash);
+	while ((spc = (TableSpaceCacheEntry *) hash_seq_search(&status)) != NULL)
+	{
+		if (spc->opts)
+			pfree(spc->opts);
+		if (hash_search(TableSpaceCacheHash,
+						(void *) &spc->oid,
+						HASH_REMOVE,
+						NULL) == NULL)
+			elog(ERROR, "hash table corrupted");
+	}
+}
+
+/*
+ * InitializeTableSpaceCache
+ *		Initialize the tablespace cache.
+ */
+static void
+InitializeTableSpaceCache(void)
+{
+	HASHCTL		ctl;
+
+	/* Initialize the hash table. */
+	ctl.keysize = sizeof(Oid);
+	ctl.entrysize = sizeof(TableSpaceCacheEntry);
+	TableSpaceCacheHash =
+		hash_create("TableSpace cache", 16, &ctl,
+					HASH_ELEM | HASH_BLOBS);
+
+	/* Make sure we've initialized CacheMemoryContext. */
+	if (!CacheMemoryContext)
+		CreateCacheMemoryContext();
+
+	/* Watch for invalidation events. */
+	CacheRegisterSyscacheCallback(TABLESPACEOID,
+								  InvalidateTableSpaceCacheCallback,
+								  (Datum) 0);
+}
+
+/*
+ * get_tablespace
+ *		Fetch TableSpaceCacheEntry structure for a specified table OID.
+ *
+ * Pointers returned by this function should not be stored, since a cache
+ * flush will invalidate them.
+ */
+static TableSpaceCacheEntry *
+get_tablespace(Oid spcid)
+{
+	TableSpaceCacheEntry *spc;
+	HeapTuple	tp;
+	TableSpaceOpts *opts;
+
+	/*
+	 * Since spcid is always from a pg_class tuple, InvalidOid implies the
+	 * default.
+	 */
+	if (spcid == InvalidOid)
+		spcid = MyDatabaseTableSpace;
+
+	/* Find existing cache entry, if any. */
+	if (!TableSpaceCacheHash)
+		InitializeTableSpaceCache();
+	spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
+											   (void *) &spcid,
+											   HASH_FIND,
+											   NULL);
+	if (spc)
+		return spc;
+
+	/*
+	 * Not found in TableSpace cache.  Check catcache.  If we don't find a
+	 * valid HeapTuple, it must mean someone has managed to request tablespace
+	 * details for a non-existent tablespace.  We'll just treat that case as
+	 * if no options were specified.
+	 */
+	tp = SearchSysCache1(TABLESPACEOID, ObjectIdGetDatum(spcid));
+	if (!HeapTupleIsValid(tp))
+		opts = NULL;
+	else
+	{
+		Datum		datum;
+		bool		isNull;
+
+		datum = SysCacheGetAttr(TABLESPACEOID,
+								tp,
+								Anum_pg_tablespace_spcoptions,
+								&isNull);
+		if (isNull)
+			opts = NULL;
+		else
+		{
+			bytea	   *bytea_opts = tablespace_reloptions(datum, false);
+
+			opts = MemoryContextAlloc(CacheMemoryContext, VARSIZE(bytea_opts));
+			memcpy(opts, bytea_opts, VARSIZE(bytea_opts));
+		}
+		ReleaseSysCache(tp);
+	}
+
+	/*
+	 * Now create the cache entry.  It's important to do this only after
+	 * reading the pg_tablespace entry, since doing so could cause a cache
+	 * flush.
+	 */
+	spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
+											   (void *) &spcid,
+											   HASH_ENTER,
+											   NULL);
+	spc->opts = opts;
+	return spc;
+}
+
+/*
+ * get_tablespace_page_costs
+ *		Return random and/or sequential page costs for a given tablespace.
+ *
+ *		This value is not locked by the transaction, so this value may
+ *		be changed while a SELECT that has used these values for planning
+ *		is still executing.
+ */
+void
+get_tablespace_page_costs(Oid spcid,
+						  double *spc_random_page_cost,
+						  double *spc_seq_page_cost)
+{
+	TableSpaceCacheEntry *spc = get_tablespace(spcid);
+
+	Assert(spc != NULL);
+
+	if (spc_random_page_cost)
+	{
+		if (!spc->opts || spc->opts->random_page_cost < 0)
+			*spc_random_page_cost = random_page_cost;
+		else
+			*spc_random_page_cost = spc->opts->random_page_cost;
+	}
+
+	if (spc_seq_page_cost)
+	{
+		if (!spc->opts || spc->opts->seq_page_cost < 0)
+			*spc_seq_page_cost = seq_page_cost;
+		else
+			*spc_seq_page_cost = spc->opts->seq_page_cost;
+	}
+}
+
+/*
+ * get_tablespace_io_concurrency
+ *
+ *		This value is not locked by the transaction, so this value may
+ *		be changed while a SELECT that has used these values for planning
+ *		is still executing.
+ */
+int
+get_tablespace_io_concurrency(Oid spcid)
+{
+	TableSpaceCacheEntry *spc = get_tablespace(spcid);
+
+	if (!spc->opts || spc->opts->effective_io_concurrency < 0)
+		return effective_io_concurrency;
+	else
+		return spc->opts->effective_io_concurrency;
+}
+
+/*
+ * get_tablespace_maintenance_io_concurrency
+ */
+int
+get_tablespace_maintenance_io_concurrency(Oid spcid)
+{
+	TableSpaceCacheEntry *spc = get_tablespace(spcid);
+
+	if (!spc->opts || spc->opts->maintenance_io_concurrency < 0)
+		return maintenance_io_concurrency;
+	else
+		return spc->opts->maintenance_io_concurrency;
+}