Introduce Streaming Replication.

This includes two new kinds of postmaster processes, walsenders and
walreceiver. Walreceiver is responsible for connecting to the primary server
and streaming WAL to disk, while walsender runs in the primary server and
streams WAL from disk to the client.

Documentation still needs work, but the basics are there. We will probably
pull the replication section to a new chapter later on, as well as the
sections describing file-based replication. But let's do that as a separate
patch, so that it's easier to see what has been added/changed. This patch
also adds a new section to the chapter about FE/BE protocol, documenting the
protocol used by walsender/walreceivxer.

Bump catalog version because of two new functions,
pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for
monitoring the progress of replication.

Fujii Masao, with additional hacking by me

1 files changed, 70 insertions, 0 deletions

diff --git a/src/include/replication/walreceiver.h b/src/include/replication/walreceiver.h
new file mode 100644
index 0000000000..7651a696a0
--- /dev/null
+++ b/src/include/replication/walreceiver.h
@@ -0,0 +1,70 @@
+/*-------------------------------------------------------------------------
+ *
+ * walreceiver.h
+ *	  Exports from replication/walreceiverfuncs.c.
+ *
+ * Portions Copyright (c) 2010-2010, PostgreSQL Global Development Group
+ *
+ * $PostgreSQL: pgsql/src/include/replication/walreceiver.h,v 1.1 2010/01/15 09:19:09 heikki Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALRECEIVER_H
+#define _WALRECEIVER_H
+
+#include "storage/spin.h"
+
+/*
+ * MAXCONNINFO: maximum size of a connection string.
+ *
+ * XXX: Should this move to pg_config_manual.h?
+ */
+#define MAXCONNINFO		1024
+
+/*
+ * Values for WalRcv->walRcvState.
+ */
+typedef enum
+{
+	WALRCV_NOT_STARTED,
+	WALRCV_RUNNING,		/* walreceiver has been started */
+	WALRCV_STOPPING,	/* requested to stop, but still running */
+	WALRCV_STOPPED		/* stopped and mustn't start up again */
+} WalRcvState;
+
+/* Shared memory area for management of walreceiver process */
+typedef struct
+{
+	/*
+	 * connection string; is used for walreceiver to connect with
+	 * the primary.
+	 */
+	char	conninfo[MAXCONNINFO];
+
+	/*
+	 * PID of currently active walreceiver process, and the current state.
+	 */
+	pid_t	pid;
+	WalRcvState walRcvState;
+
+	/*
+	 * receivedUpto-1 is the last byte position that has been already
+	 * received. When startup process starts the walreceiver, it sets this
+	 * to the point where it wants the streaming to begin. After that,
+	 * walreceiver updates this whenever it flushes the received WAL.
+	 */
+	XLogRecPtr	receivedUpto;
+
+	slock_t	mutex;		/* locks shared variables shown above */
+} WalRcvData;
+
+extern WalRcvData *WalRcv;
+
+extern Size WalRcvShmemSize(void);
+extern void WalRcvShmemInit(void);
+extern bool WalRcvInProgress(void);
+extern XLogRecPtr WaitNextXLogAvailable(XLogRecPtr recptr, bool *finished);
+extern void RequestXLogStreaming(XLogRecPtr recptr, const char *conninfo);
+extern XLogRecPtr GetWalRcvWriteRecPtr(void);
+
+#endif   /* _WALRECEIVER_H */