Add parallel pg_dump option.

New infrastructure is added which creates a set number of workers
(threads on Windows, forked processes on Unix). Jobs are then
handed out to these workers by the master process as needed.
pg_restore is adjusted to use this new infrastructure in place of the
old setup which created a new worker for each step on the fly. Parallel
dumps acquire a snapshot clone in order to stay consistent, if
available.

The parallel option is selected by the -j / --jobs command line
parameter of pg_dump.

Joachim Wieland, lightly editorialized by Andrew Dunstan.

1 files changed, 85 insertions, 0 deletions

diff --git a/src/bin/pg_dump/parallel.h b/src/bin/pg_dump/parallel.h
new file mode 100644
index 00000000000..858b2a09d24
--- /dev/null
+++ b/src/bin/pg_dump/parallel.h
@@ -0,0 +1,85 @@
+/*-------------------------------------------------------------------------
+ *
+ * parallel.h
+ *
+ *	Parallel support header file for the pg_dump archiver
+ *
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *	The author is not responsible for loss or damages that may
+ *	result from its use.
+ *
+ * IDENTIFICATION
+ *		src/bin/pg_dump/parallel.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "pg_backup_db.h"
+
+struct _archiveHandle;
+struct _tocEntry;
+
+typedef enum
+{
+	WRKR_TERMINATED = 0,
+	WRKR_IDLE,
+	WRKR_WORKING,
+	WRKR_FINISHED
+}	T_WorkerStatus;
+
+typedef enum T_Action
+{
+	ACT_DUMP,
+	ACT_RESTORE,
+}	T_Action;
+
+/* Arguments needed for a worker process */
+typedef struct ParallelArgs
+{
+	struct _archiveHandle *AH;
+	struct _tocEntry *te;
+}	ParallelArgs;
+
+/* State for each parallel activity slot */
+typedef struct ParallelSlot
+{
+	ParallelArgs *args;
+	T_WorkerStatus workerStatus;
+	int			status;
+	int			pipeRead;
+	int			pipeWrite;
+	int			pipeRevRead;
+	int			pipeRevWrite;
+#ifdef WIN32
+	uintptr_t	hThread;
+	unsigned int threadId;
+#else
+	pid_t		pid;
+#endif
+} ParallelSlot;
+
+#define NO_SLOT (-1)
+
+typedef struct ParallelState
+{
+	int			numWorkers;
+	ParallelSlot *parallelSlot;
+} ParallelState;
+
+extern int	GetIdleWorker(ParallelState *pstate);
+extern bool IsEveryWorkerIdle(ParallelState *pstate);
+extern void ListenToWorkers(struct _archiveHandle * AH, ParallelState *pstate, bool do_wait);
+extern int	ReapWorkerStatus(ParallelState *pstate, int *status);
+extern void EnsureIdleWorker(struct _archiveHandle * AH, ParallelState *pstate);
+extern void EnsureWorkersFinished(struct _archiveHandle * AH, ParallelState *pstate);
+
+extern ParallelState *ParallelBackupStart(struct _archiveHandle * AH,
+					RestoreOptions *ropt);
+extern void DispatchJobForTocEntry(struct _archiveHandle * AH,
+					   ParallelState *pstate,
+					   struct _tocEntry * te, T_Action act);
+extern void ParallelBackupEnd(struct _archiveHandle * AH, ParallelState *pstate);
+
+extern void checkAborting(struct _archiveHandle * AH);