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pg_include/storage/sinval.h

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+/*-------------------------------------------------------------------------
+ *
+ * sinval.h
+ *	  POSTGRES shared cache invalidation communication definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/sinval.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SINVAL_H
+#define SINVAL_H
+
+#include "storage/relfilenode.h"
+
+
+/*
+ * We support several types of shared-invalidation messages:
+ *	* invalidate a specific tuple in a specific catcache
+ *	* invalidate all catcache entries from a given system catalog
+ *	* invalidate a relcache entry for a specific logical relation
+ *	* invalidate an smgr cache entry for a specific physical relation
+ *	* invalidate the mapped-relation mapping for a given database
+ * More types could be added if needed.  The message type is identified by
+ * the first "int8" field of the message struct.  Zero or positive means a
+ * specific-catcache inval message (and also serves as the catcache ID field).
+ * Negative values identify the other message types, as per codes below.
+ *
+ * Catcache inval events are initially driven by detecting tuple inserts,
+ * updates and deletions in system catalogs (see CacheInvalidateHeapTuple).
+ * An update can generate two inval events, one for the old tuple and one for
+ * the new, but this is reduced to one event if the tuple's hash key doesn't
+ * change.	Note that the inval events themselves don't actually say whether
+ * the tuple is being inserted or deleted.	Also, since we transmit only a
+ * hash key, there is a small risk of unnecessary invalidations due to chance
+ * matches of hash keys.
+ *
+ * Note that some system catalogs have multiple caches on them (with different
+ * indexes).  On detecting a tuple invalidation in such a catalog, separate
+ * catcache inval messages must be generated for each of its caches, since
+ * the hash keys will generally be different.
+ *
+ * Catcache and relcache invalidations are transactional, and so are sent
+ * to other backends upon commit.  Internally to the generating backend,
+ * they are also processed at CommandCounterIncrement so that later commands
+ * in the same transaction see the new state.  The generating backend also
+ * has to process them at abort, to flush out any cache state it's loaded
+ * from no-longer-valid entries.
+ *
+ * smgr and relation mapping invalidations are non-transactional: they are
+ * sent immediately when the underlying file change is made.
+ */
+
+typedef struct
+{
+	int8		id;				/* cache ID --- must be first */
+	Oid			dbId;			/* database ID, or 0 if a shared relation */
+	uint32		hashValue;		/* hash value of key for this catcache */
+} SharedInvalCatcacheMsg;
+
+#define SHAREDINVALCATALOG_ID	(-1)
+
+typedef struct
+{
+	int8		id;				/* type field --- must be first */
+	Oid			dbId;			/* database ID, or 0 if a shared catalog */
+	Oid			catId;			/* ID of catalog whose contents are invalid */
+} SharedInvalCatalogMsg;
+
+#define SHAREDINVALRELCACHE_ID	(-2)
+
+typedef struct
+{
+	int8		id;				/* type field --- must be first */
+	Oid			dbId;			/* database ID, or 0 if a shared relation */
+	Oid			relId;			/* relation ID */
+} SharedInvalRelcacheMsg;
+
+#define SHAREDINVALSMGR_ID		(-3)
+
+typedef struct
+{
+	/* note: field layout chosen to pack into 16 bytes */
+	int8		id;				/* type field --- must be first */
+	int8		backend_hi;		/* high bits of backend ID, if temprel */
+	uint16		backend_lo;		/* low bits of backend ID, if temprel */
+	RelFileNode rnode;			/* spcNode, dbNode, relNode */
+} SharedInvalSmgrMsg;
+
+#define SHAREDINVALRELMAP_ID	(-4)
+
+typedef struct
+{
+	int8		id;				/* type field --- must be first */
+	Oid			dbId;			/* database ID, or 0 for shared catalogs */
+} SharedInvalRelmapMsg;
+
+typedef union
+{
+	int8		id;				/* type field --- must be first */
+	SharedInvalCatcacheMsg cc;
+	SharedInvalCatalogMsg cat;
+	SharedInvalRelcacheMsg rc;
+	SharedInvalSmgrMsg sm;
+	SharedInvalRelmapMsg rm;
+} SharedInvalidationMessage;
+
+
+/* Counter of messages processed; don't worry about overflow. */
+extern uint64 SharedInvalidMessageCounter;
+
+
+extern void SendSharedInvalidMessages(const SharedInvalidationMessage *msgs,
+						  int n);
+extern void ReceiveSharedInvalidMessages(
+					  void (*invalFunction) (SharedInvalidationMessage *msg),
+							 void (*resetFunction) (void));
+
+/* signal handler for catchup events (PROCSIG_CATCHUP_INTERRUPT) */
+extern void HandleCatchupInterrupt(void);
+
+/*
+ * enable/disable processing of catchup events directly from signal handler.
+ * The enable routine first performs processing of any catchup events that
+ * have occurred since the last disable.
+ */
+extern void EnableCatchupInterrupt(void);
+extern bool DisableCatchupInterrupt(void);
+
+extern int xactGetCommittedInvalidationMessages(SharedInvalidationMessage **msgs,
+									 bool *RelcacheInitFileInval);
+extern void ProcessCommittedInvalidationMessages(SharedInvalidationMessage *msgs,
+									 int nmsgs, bool RelcacheInitFileInval,
+									 Oid dbid, Oid tsid);
+
+#endif   /* SINVAL_H */