init

2026-04-07 13:35:22 +08:00
commit 0120fa9ce3
1530 changed files with 424864 additions and 0 deletions
--- a/pg_include/replication/walprotocol.h
+++ b/pg_include/replication/walprotocol.h
@@ -0,0 +1,116 @@
+/*-------------------------------------------------------------------------
+ *
+ * walprotocol.h
+ *	  Definitions relevant to the streaming WAL transmission protocol.
+ *
+ * Portions Copyright (c) 2010-2012, PostgreSQL Global Development Group
+ *
+ * src/include/replication/walprotocol.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALPROTOCOL_H
+#define _WALPROTOCOL_H
+
+#include "access/xlogdefs.h"
+#include "datatype/timestamp.h"
+
+
+/*
+ * All messages from WalSender must contain these fields to allow us to
+ * correctly calculate the replication delay.
+ */
+typedef struct
+{
+	/* Current end of WAL on the sender */
+	XLogRecPtr	walEnd;
+
+	/* Sender's system clock at the time of transmission */
+	TimestampTz sendTime;
+} WalSndrMessage;
+
+
+/*
+ * Header for a WAL data message (message type 'w').  This is wrapped within
+ * a CopyData message at the FE/BE protocol level.
+ *
+ * The header is followed by actual WAL data.  Note that the data length is
+ * not specified in the header --- it's just whatever remains in the message.
+ *
+ * walEnd and sendTime are not essential data, but are provided in case
+ * the receiver wants to adjust its behavior depending on how far behind
+ * it is.
+ */
+typedef struct
+{
+	/* WAL start location of the data included in this message */
+	XLogRecPtr	dataStart;
+
+	/* Current end of WAL on the sender */
+	XLogRecPtr	walEnd;
+
+	/* Sender's system clock at the time of transmission */
+	TimestampTz sendTime;
+} WalDataMessageHeader;
+
+/*
+ * Keepalive message from primary (message type 'k'). (lowercase k)
+ * This is wrapped within a CopyData message at the FE/BE protocol level.
+ *
+ * Note that the data length is not specified here.
+ */
+typedef WalSndrMessage PrimaryKeepaliveMessage;
+
+/*
+ * Reply message from standby (message type 'r').  This is wrapped within
+ * a CopyData message at the FE/BE protocol level.
+ *
+ * Note that the data length is not specified here.
+ */
+typedef struct
+{
+	/*
+	 * The xlog locations that have been written, flushed, and applied by
+	 * standby-side. These may be invalid if the standby-side is unable to or
+	 * chooses not to report these.
+	 */
+	XLogRecPtr	write;
+	XLogRecPtr	flush;
+	XLogRecPtr	apply;
+
+	/* Sender's system clock at the time of transmission */
+	TimestampTz sendTime;
+} StandbyReplyMessage;
+
+/*
+ * Hot Standby feedback from standby (message type 'h').  This is wrapped within
+ * a CopyData message at the FE/BE protocol level.
+ *
+ * Note that the data length is not specified here.
+ */
+typedef struct
+{
+	/*
+	 * The current xmin and epoch from the standby, for Hot Standby feedback.
+	 * This may be invalid if the standby-side does not support feedback, or
+	 * Hot Standby is not yet available.
+	 */
+	TransactionId xmin;
+	uint32		epoch;
+
+	/* Sender's system clock at the time of transmission */
+	TimestampTz sendTime;
+} StandbyHSFeedbackMessage;
+
+/*
+ * Maximum data payload in a WAL data message.	Must be >= XLOG_BLCKSZ.
+ *
+ * We don't have a good idea of what a good value would be; there's some
+ * overhead per message in both walsender and walreceiver, but on the other
+ * hand sending large batches makes walsender less responsive to signals
+ * because signals are checked only between messages.  128kB (with
+ * default 8k blocks) seems like a reasonable guess for now.
+ */
+#define MAX_SEND_SIZE (XLOG_BLCKSZ * 16)
+
+#endif   /* _WALPROTOCOL_H */