Persiste pgstat file in PS to include it in basebackup and so do not loose this information on compute restart

Author: Konstantin Knizhnik

src/backend/access/heap/rewriteheap.c

@@ -785,36 +785,6 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
  * ------------------------------------------------------------------------
  */
 
-/*
- * NEON: we need to persist mapping file in WAL
- */
-static void
-wallog_mapping_file(char const* path, int fd)
-{
-	char	prefix[MAXPGPATH];
-	snprintf(prefix, sizeof(prefix), "neon-file:%s", path);
-	if (fd < 0)
-	{
-		elog(DEBUG1, "neon: deleting contents of rewrite file %s", path);
-		/* unlink file */
-		LogLogicalMessage(prefix, NULL, 0, false);
-	}
-	else
-	{
-		off_t size = lseek(fd, 0, SEEK_END);
-		char* buf;
-		elog(DEBUG1, "neon: writing contents of rewrite file %s, size %ld", path, (long)size);
-		if (size < 0)
-			elog(ERROR, "Failed to get size of mapping file: %m");
-		buf = palloc((size_t)size);
-		lseek(fd, 0, SEEK_SET);
-		if (read(fd, buf, (size_t)size) != size)
-			elog(ERROR, "Failed to read mapping file: %m");
-		LogLogicalMessage(prefix, buf, (size_t)size, false);
-		pfree(buf);
-	}
-}
-
 /*
  * Do preparations for logging logical mappings during a rewrite if
  * necessary. If we detect that we don't need to log anything we'll prevent
@@ -950,7 +920,7 @@ logical_heap_rewrite_flush_mappings(RewriteState state)
 					 errmsg("could not write to file \"%s\", wrote %d of %d: %m", src->path,
 							written, len)));
 		src->off += len;
-		wallog_mapping_file(src->path, FileGetRawDesc(src->vfd));
+		wallog_file_descriptor(src->path, FileGetRawDesc(src->vfd));
 
 		XLogBeginInsert();
 		XLogRegisterData((char *) (&xlrec), sizeof(xlrec));
@@ -1201,7 +1171,7 @@ heap_xlog_logical_rewrite(XLogReaderState *r)
 				 errmsg("could not fsync file \"%s\": %m", path)));
 	pgstat_report_wait_end();
 
-	wallog_mapping_file(path, fd);
+	wallog_file_descriptor(path, fd);
 
 	if (CloseTransientFile(fd) != 0)
 		ereport(ERROR,
@@ -1280,7 +1250,7 @@ CheckPointLogicalRewriteHeap(void)
 				ereport(ERROR,
 						(errcode_for_file_access(),
 						 errmsg("could not remove file \"%s\": %m", path)));
-			wallog_mapping_file(path, -1);
+			wallog_file_descriptor(path, -1);
 		}
 		else
 		{
@@ -1309,7 +1279,7 @@ CheckPointLogicalRewriteHeap(void)
 						 errmsg("could not fsync file \"%s\": %m", path)));
 			pgstat_report_wait_end();
 
-			wallog_mapping_file(path, fd);
+			wallog_file_descriptor(path, fd);
 
 			if (CloseTransientFile(fd) != 0)
 				ereport(ERROR,

src/backend/replication/logical/message.c

@@ -31,6 +31,8 @@
 
 #include "postgres.h"
 
+#include <unistd.h>
+
 #include "access/xact.h"
 #include "access/xloginsert.h"
 #include "miscadmin.h"
@@ -87,3 +89,51 @@ logicalmsg_redo(XLogReaderState *record)
 
 	/* This is only interesting for logical decoding, see decode.c. */
 }
+
+/*
+ * NEON: persist file in WAL to save it in persistent storage.
+ * If fd < 0, then remote entry from page server.
+ */
+void
+wallog_file_descriptor(char const* path, int fd)
+{
+	char	prefix[MAXPGPATH];
+	snprintf(prefix, sizeof(prefix), "neon-file:%s", path);
+	if (fd < 0)
+	{
+		elog(DEBUG1, "neon: deleting contents of rewrite file %s", path);
+		/* unlink file */
+		LogLogicalMessage(prefix, NULL, 0, false);
+	}
+	else
+	{
+		off_t size = lseek(fd, 0, SEEK_END);
+		char* buf;
+		elog(DEBUG1, "neon: writing contents of rewrite file %s, size %ld", path, (long)size);
+		if (size < 0)
+			elog(ERROR, "Failed to get size of mapping file: %m");
+		buf = palloc((size_t)size);
+		lseek(fd, 0, SEEK_SET);
+		if (read(fd, buf, (size_t)size) != size)
+			elog(ERROR, "Failed to read mapping file: %m");
+		LogLogicalMessage(prefix, buf, (size_t)size, false);
+		pfree(buf);
+	}
+}
+
+void
+wallog_file(char const* path)
+{
+	int fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
+	if (fd < 0)
+	{
+		ereport(LOG,
+				(errcode_for_file_access(),
+				 errmsg("could not create file \"%s\": %m", path)));
+	}
+	else
+	{
+		wallog_file_descriptor(path, fd);
+		CloseTransientFile(fd);
+	}
+}

src/backend/utils/activity/pgstat.c

@@ -98,6 +98,7 @@
 #include "lib/dshash.h"
 #include "pgstat.h"
 #include "port/atomics.h"
+#include "replication/message.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
 #include "storage/lwlock.h"
@@ -1462,6 +1463,7 @@ pgstat_write_statsfile(void)
 						tmpfile, statfile)));
 		unlink(tmpfile);
 	}
+	wallog_file(statfile);
 }
 
 /* helpers for pgstat_read_statsfile() */

src/include/replication/message.h

@@ -32,6 +32,9 @@ typedef struct xl_logical_message
 extern XLogRecPtr LogLogicalMessage(const char *prefix, const char *message,
 									size_t size, bool transactional);
 
+extern void wallog_file(char const* path);
+extern void wallog_file_descriptor(char const* path, int fd);
+
 /* RMGR API */
 #define XLOG_LOGICAL_MESSAGE	0x00
 extern void logicalmsg_redo(XLogReaderState *record);