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pg_include/storage/ipc.h

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+/*-------------------------------------------------------------------------
+ *
+ * ipc.h
+ *	  POSTGRES inter-process communication definitions.
+ *
+ * This file is misnamed, as it no longer has much of anything directly
+ * to do with IPC.	The functionality here is concerned with managing
+ * exit-time cleanup for either a postmaster or a backend.
+ *
+ *
+ * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/ipc.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef IPC_H
+#define IPC_H
+
+typedef void (*pg_on_exit_callback) (int code, Datum arg);
+typedef void (*shmem_startup_hook_type) (void);
+
+/*----------
+ * API for handling cleanup that must occur during either ereport(ERROR)
+ * or ereport(FATAL) exits from a block of code.  (Typical examples are
+ * undoing transient changes to shared-memory state.)
+ *
+ *		PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
+ *		{
+ *			... code that might throw ereport(ERROR) or ereport(FATAL) ...
+ *		}
+ *		PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
+ *
+ * where the cleanup code is in a function declared per pg_on_exit_callback.
+ * The Datum value "arg" can carry any information the cleanup function
+ * needs.
+ *
+ * This construct ensures that cleanup_function() will be called during
+ * either ERROR or FATAL exits.  It will not be called on successful
+ * exit from the controlled code.  (If you want it to happen then too,
+ * call the function yourself from just after the construct.)
+ *
+ * Note: the macro arguments are multiply evaluated, so avoid side-effects.
+ *----------
+ */
+#define PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg)	\
+	do { \
+		on_shmem_exit(cleanup_function, arg); \
+		PG_TRY()
+
+#define PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg)	\
+		cancel_shmem_exit(cleanup_function, arg); \
+		PG_CATCH(); \
+		{ \
+			cancel_shmem_exit(cleanup_function, arg); \
+			cleanup_function (0, arg); \
+			PG_RE_THROW(); \
+		} \
+		PG_END_TRY(); \
+	} while (0)
+
+
+/* ipc.c */
+extern bool proc_exit_inprogress;
+
+extern void proc_exit(int code);
+extern void shmem_exit(int code);
+extern void on_proc_exit(pg_on_exit_callback function, Datum arg);
+extern void on_shmem_exit(pg_on_exit_callback function, Datum arg);
+extern void cancel_shmem_exit(pg_on_exit_callback function, Datum arg);
+extern void on_exit_reset(void);
+
+/* ipci.c */
+extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook;
+
+extern void CreateSharedMemoryAndSemaphores(bool makePrivate, int port);
+
+#endif   /* IPC_H */