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pg_include/replication/walreceiver.h

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+/*-------------------------------------------------------------------------
+ *
+ * walreceiver.h
+ *	  Exports from replication/walreceiverfuncs.c.
+ *
+ * Portions Copyright (c) 2010-2012, PostgreSQL Global Development Group
+ *
+ * src/include/replication/walreceiver.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALRECEIVER_H
+#define _WALRECEIVER_H
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "storage/spin.h"
+#include "pgtime.h"
+
+extern int	wal_receiver_status_interval;
+extern bool hot_standby_feedback;
+
+/*
+ * MAXCONNINFO: maximum size of a connection string.
+ *
+ * XXX: Should this move to pg_config_manual.h?
+ */
+#define MAXCONNINFO		1024
+
+/* Can we allow the standby to accept replication connection from another standby? */
+#define AllowCascadeReplication() (EnableHotStandby && max_wal_senders > 0)
+
+/*
+ * Values for WalRcv->walRcvState.
+ */
+typedef enum
+{
+	WALRCV_STOPPED,				/* stopped and mustn't start up again */
+	WALRCV_STARTING,			/* launched, but the process hasn't
+								 * initialized yet */
+	WALRCV_RUNNING,				/* walreceiver is running */
+	WALRCV_STOPPING				/* requested to stop, but still running */
+} WalRcvState;
+
+/* Shared memory area for management of walreceiver process */
+typedef struct
+{
+	/*
+	 * PID of currently active walreceiver process, its current state and
+	 * start time (actually, the time at which it was requested to be
+	 * started).
+	 */
+	pid_t		pid;
+	WalRcvState walRcvState;
+	pg_time_t	startTime;
+
+	/*
+	 * receiveStart is the first byte position that will be received. When
+	 * startup process starts the walreceiver, it sets receiveStart to the
+	 * point where it wants the streaming to begin.
+	 */
+	XLogRecPtr	receiveStart;
+
+	/*
+	 * receivedUpto-1 is the last byte position that has already been
+	 * received.  At the first startup of walreceiver, receivedUpto is set to
+	 * receiveStart. After that, walreceiver updates this whenever it flushes
+	 * the received WAL to disk.
+	 */
+	XLogRecPtr	receivedUpto;
+
+	/*
+	 * latestChunkStart is the starting byte position of the current "batch"
+	 * of received WAL.  It's actually the same as the previous value of
+	 * receivedUpto before the last flush to disk.	Startup process can use
+	 * this to detect whether it's keeping up or not.
+	 */
+	XLogRecPtr	latestChunkStart;
+
+	/*
+	 * Time of send and receive of any message received.
+	 */
+	TimestampTz lastMsgSendTime;
+	TimestampTz lastMsgReceiptTime;
+
+	/*
+	 * Latest reported end of WAL on the sender
+	 */
+	XLogRecPtr	latestWalEnd;
+	TimestampTz latestWalEndTime;
+
+	/*
+	 * connection string; is used for walreceiver to connect with the primary.
+	 */
+	char		conninfo[MAXCONNINFO];
+
+	slock_t		mutex;			/* locks shared variables shown above */
+} WalRcvData;
+
+extern WalRcvData *WalRcv;
+
+/* libpqwalreceiver hooks */
+typedef bool (*walrcv_connect_type) (char *conninfo, XLogRecPtr startpoint);
+extern PGDLLIMPORT walrcv_connect_type walrcv_connect;
+
+typedef bool (*walrcv_receive_type) (int timeout, unsigned char *type,
+												 char **buffer, int *len);
+extern PGDLLIMPORT walrcv_receive_type walrcv_receive;
+
+typedef void (*walrcv_send_type) (const char *buffer, int nbytes);
+extern PGDLLIMPORT walrcv_send_type walrcv_send;
+
+typedef void (*walrcv_disconnect_type) (void);
+extern PGDLLIMPORT walrcv_disconnect_type walrcv_disconnect;
+
+/* prototypes for functions in walreceiver.c */
+extern void WalReceiverMain(void);
+
+/* prototypes for functions in walreceiverfuncs.c */
+extern Size WalRcvShmemSize(void);
+extern void WalRcvShmemInit(void);
+extern void ShutdownWalRcv(void);
+extern bool WalRcvInProgress(void);
+extern void RequestXLogStreaming(XLogRecPtr recptr, const char *conninfo);
+extern XLogRecPtr GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart);
+extern int	GetReplicationApplyDelay(void);
+extern int	GetReplicationTransferLatency(void);
+
+#endif   /* _WALRECEIVER_H */