1 files changed, 67 insertions, 0 deletions
diff --git a/src/include/storage/sync.h b/src/include/storage/sync.h
new file mode 100644
index 0000000..fbdf34f
--- /dev/null
+++ b/src/include/storage/sync.h
@@ -0,0 +1,67 @@
+/*-------------------------------------------------------------------------
+ *
+ * sync.h
+ *	  File synchronization management code.
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/sync.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SYNC_H
+#define SYNC_H
+
+#include "storage/relfilenode.h"
+
+/*
+ * Type of sync request.  These are used to manage the set of pending
+ * requests to call a sync handler's sync or unlink functions at the next
+ * checkpoint.
+ */
+typedef enum SyncRequestType
+{
+	SYNC_REQUEST,				/* schedule a call of sync function */
+	SYNC_UNLINK_REQUEST,		/* schedule a call of unlink function */
+	SYNC_FORGET_REQUEST,		/* forget all calls for a tag */
+	SYNC_FILTER_REQUEST			/* forget all calls satisfying match fn */
+} SyncRequestType;
+
+/*
+ * Which set of functions to use to handle a given request.  The values of
+ * the enumerators must match the indexes of the function table in sync.c.
+ */
+typedef enum SyncRequestHandler
+{
+	SYNC_HANDLER_MD = 0,
+	SYNC_HANDLER_CLOG,
+	SYNC_HANDLER_COMMIT_TS,
+	SYNC_HANDLER_MULTIXACT_OFFSET,
+	SYNC_HANDLER_MULTIXACT_MEMBER,
+	SYNC_HANDLER_NONE
+} SyncRequestHandler;
+
+/*
+ * A tag identifying a file.  Currently it has the members required for md.c's
+ * usage, but sync.c has no knowledge of the internal structure, and it is
+ * liable to change as required by future handlers.
+ */
+typedef struct FileTag
+{
+	int16		handler;		/* SyncRequestHandler value, saving space */
+	int16		forknum;		/* ForkNumber, saving space */
+	RelFileNode rnode;
+	uint32		segno;
+} FileTag;
+
+extern void InitSync(void);
+extern void SyncPreCheckpoint(void);
+extern void SyncPostCheckpoint(void);
+extern void ProcessSyncRequests(void);
+extern void RememberSyncRequest(const FileTag *ftag, SyncRequestType type);
+extern void EnableSyncRequestForwarding(void);
+extern bool RegisterSyncRequest(const FileTag *ftag, SyncRequestType type,
+								bool retryOnError);
+
+#endif							/* SYNC_H */