Move the backup-block logic from XLogInsert to a new file, xloginsert.c.

xlog.c is huge, this makes it a little bit smaller, which is nice. Functions
related to putting together the WAL record are in xloginsert.c, and the
lower level stuff for managing WAL buffers and such are in xlog.c.

Also move the definition of XLogRecord to a separate header file. This
causes churn in the #includes of all the files that write WAL records, and
redo routines, but it avoids pulling in xlog.h into most places.

Reviewed by Michael Paquier, Alvaro Herrera, Andres Freund and Amit Kapila.

1 files changed, 4 insertions, 108 deletions

diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 0ae110f18b7..6f8b5f46e10 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -13,67 +13,11 @@
 
 #include "access/rmgr.h"
 #include "access/xlogdefs.h"
+#include "access/xloginsert.h"
+#include "access/xlogrecord.h"
 #include "datatype/timestamp.h"
 #include "lib/stringinfo.h"
-#include "storage/block.h"
-#include "storage/buf.h"
-#include "storage/relfilenode.h"
-#include "utils/pg_crc.h"
 
-/*
- * The overall layout of an XLOG record is:
- *		Fixed-size header (XLogRecord struct)
- *		rmgr-specific data
- *		BkpBlock
- *		backup block data
- *		BkpBlock
- *		backup block data
- *		...
- *
- * where there can be zero to four backup blocks (as signaled by xl_info flag
- * bits).  XLogRecord structs always start on MAXALIGN boundaries in the WAL
- * files, and we round up SizeOfXLogRecord so that the rmgr data is also
- * guaranteed to begin on a MAXALIGN boundary.  However, no padding is added
- * to align BkpBlock structs or backup block data.
- *
- * NOTE: xl_len counts only the rmgr data, not the XLogRecord header,
- * and also not any backup blocks.  xl_tot_len counts everything.  Neither
- * length field is rounded up to an alignment boundary.
- */
-typedef struct XLogRecord
-{
-	uint32		xl_tot_len;		/* total len of entire record */
-	TransactionId xl_xid;		/* xact id */
-	uint32		xl_len;			/* total len of rmgr data */
-	uint8		xl_info;		/* flag bits, see below */
-	RmgrId		xl_rmid;		/* resource manager for this record */
-	/* 2 bytes of padding here, initialize to zero */
-	XLogRecPtr	xl_prev;		/* ptr to previous record in log */
-	pg_crc32	xl_crc;			/* CRC for this record */
-
-	/* If MAXALIGN==8, there are 4 wasted bytes here */
-
-	/* ACTUAL LOG DATA FOLLOWS AT END OF STRUCT */
-
-} XLogRecord;
-
-#define SizeOfXLogRecord	MAXALIGN(sizeof(XLogRecord))
-
-#define XLogRecGetData(record)	((char*) (record) + SizeOfXLogRecord)
-
-/*
- * XLOG uses only low 4 bits of xl_info.  High 4 bits may be used by rmgr.
- */
-#define XLR_INFO_MASK			0x0F
-
-/*
- * If we backed up any disk blocks with the XLOG record, we use flag bits in
- * xl_info to signal it.  We support backup of up to 4 disk blocks per XLOG
- * record.
- */
-#define XLR_BKP_BLOCK_MASK		0x0F	/* all info bits used for bkp blocks */
-#define XLR_MAX_BKP_BLOCKS		4
-#define XLR_BKP_BLOCK(iblk)		(0x08 >> (iblk))		/* iblk in 0..3 */
 
 /* Sync methods */
 #define SYNC_METHOD_FSYNC		0
@@ -83,45 +27,6 @@ typedef struct XLogRecord
 #define SYNC_METHOD_OPEN_DSYNC	4		/* for O_DSYNC */
 extern int	sync_method;
 
-/*
- * The rmgr data to be written by XLogInsert() is defined by a chain of
- * one or more XLogRecData structs.  (Multiple structs would be used when
- * parts of the source data aren't physically adjacent in memory, or when
- * multiple associated buffers need to be specified.)
- *
- * If buffer is valid then XLOG will check if buffer must be backed up
- * (ie, whether this is first change of that page since last checkpoint).
- * If so, the whole page contents are attached to the XLOG record, and XLOG
- * sets XLR_BKP_BLOCK(N) bit in xl_info.  Note that the buffer must be pinned
- * and exclusive-locked by the caller, so that it won't change under us.
- * NB: when the buffer is backed up, we DO NOT insert the data pointed to by
- * this XLogRecData struct into the XLOG record, since we assume it's present
- * in the buffer.  Therefore, rmgr redo routines MUST pay attention to
- * XLR_BKP_BLOCK(N) to know what is actually stored in the XLOG record.
- * The N'th XLR_BKP_BLOCK bit corresponds to the N'th distinct buffer
- * value (ignoring InvalidBuffer) appearing in the rdata chain.
- *
- * When buffer is valid, caller must set buffer_std to indicate whether the
- * page uses standard pd_lower/pd_upper header fields.  If this is true, then
- * XLOG is allowed to omit the free space between pd_lower and pd_upper from
- * the backed-up page image.  Note that even when buffer_std is false, the
- * page MUST have an LSN field as its first eight bytes!
- *
- * Note: data can be NULL to indicate no rmgr data associated with this chain
- * entry.  This can be sensible (ie, not a wasted entry) if buffer is valid.
- * The implication is that the buffer has been changed by the operation being
- * logged, and so may need to be backed up, but the change can be redone using
- * only information already present elsewhere in the XLOG entry.
- */
-typedef struct XLogRecData
-{
-	char	   *data;			/* start of rmgr data to include */
-	uint32		len;			/* length of rmgr data to include */
-	Buffer		buffer;			/* buffer associated with data, if any */
-	bool		buffer_std;		/* buffer has standard pd_lower/pd_upper */
-	struct XLogRecData *next;	/* next struct in chain, or NULL */
-} XLogRecData;
-
 extern PGDLLIMPORT TimeLineID ThisTimeLineID;	/* current TLI */
 
 /*
@@ -281,28 +186,18 @@ typedef struct CheckpointStatsData
 
 extern CheckpointStatsData CheckpointStats;
 
-extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
-extern bool XLogCheckBufferNeedsBackup(Buffer buffer);
+extern XLogRecPtr XLogInsertRecord(XLogRecData *rdata, XLogRecPtr fpw_lsn);
 extern void XLogFlush(XLogRecPtr RecPtr);
 extern bool XLogBackgroundFlush(void);
 extern bool XLogNeedsFlush(XLogRecPtr RecPtr);
 extern int	XLogFileInit(XLogSegNo segno, bool *use_existent, bool use_lock);
 extern int	XLogFileOpen(XLogSegNo segno);
 
-extern XLogRecPtr log_newpage(RelFileNode *rnode, ForkNumber forkNum,
-			BlockNumber blk, char *page, bool page_std);
-extern XLogRecPtr log_newpage_buffer(Buffer buffer, bool page_std);
-extern XLogRecPtr XLogSaveBufferForHint(Buffer buffer, bool buffer_std);
-
 extern void CheckXLogRemoved(XLogSegNo segno, TimeLineID tli);
 extern XLogSegNo XLogGetLastRemovedSegno(void);
 extern void XLogSetAsyncXactLSN(XLogRecPtr record);
 extern void XLogSetReplicationSlotMinimumLSN(XLogRecPtr lsn);
 
-extern Buffer RestoreBackupBlock(XLogRecPtr lsn, XLogRecord *record,
-				   int block_index,
-				   bool get_cleanup_lock, bool keep_buffer);
-
 extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
 extern void xlog_desc(StringInfo buf, XLogRecord *record);
 extern const char *xlog_identify(uint8 info);
@@ -338,6 +233,7 @@ extern bool CreateRestartPoint(int flags);
 extern void XLogPutNextOid(Oid nextOid);
 extern XLogRecPtr XLogRestorePoint(const char *rpName);
 extern void UpdateFullPageWrites(void);
+extern void GetFullPageWriteInfo(XLogRecPtr *RedoRecPtr_p, bool *doPageWrites_p);
 extern XLogRecPtr GetRedoRecPtr(void);
 extern XLogRecPtr GetInsertRecPtr(void);
 extern XLogRecPtr GetFlushRecPtr(void);