glibc/db2/include/log.h

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *	Sleepycat Software.  All rights reserved.
 *
 *	@(#)log.h	10.30 (Sleepycat) 10/11/98
 */

#ifndef _LOG_H_
#define	_LOG_H_

struct __fname;		typedef struct __fname FNAME;
struct __hdr;		typedef struct __hdr HDR;
struct __log;		typedef struct __log LOG;
struct __log_persist;	typedef struct __log_persist LOGP;

#ifndef MAXLFNAME
#define	LFPREFIX	"log."		/* Log file name prefix. */
#define	LFNAME		"log.%010d"	/* Log file name template. */
#define	LFNAME_V1	"log.%05d"	/* Log file name template, rev 1. */
#define	MAXLFNAME	2000000000	/* Maximum log file name. */
#endif
					/* Default log name. */
#define DB_DEFAULT_LOG_FILE	"__db_log.share"

#define	DEFAULT_MAX	(10 * MEGABYTE)	/* 10 Mb. */

/* Macros to lock/unlock the region and threads. */
#define	LOCK_LOGTHREAD(dblp)						\
	if (F_ISSET(dblp, DB_AM_THREAD))				\
		(void)__db_mutex_lock((dblp)->mutexp, -1)
#define	UNLOCK_LOGTHREAD(dblp)						\
	if (F_ISSET(dblp, DB_AM_THREAD))				\
		(void)__db_mutex_unlock((dblp)->mutexp, -1);
#define	LOCK_LOGREGION(dblp)						\
	(void)__db_mutex_lock(&((RLAYOUT *)(dblp)->lp)->lock,		\
	    (dblp)->reginfo.fd)
#define	UNLOCK_LOGREGION(dblp)						\
	(void)__db_mutex_unlock(&((RLAYOUT *)(dblp)->lp)->lock,		\
	    (dblp)->reginfo.fd)

/* Check for region catastrophic shutdown. */
#define	LOG_PANIC_CHECK(dblp) {						\
	if ((dblp)->lp->rlayout.panic)					\
		return (DB_RUNRECOVERY);				\
}

/*
 * The per-process table that maps log file-id's to DB structures.
 */
typedef	struct __db_entry {
	DB	 *dbp;			/* Associated DB structure. */
	u_int32_t refcount;		/* Reference counted. */
	int	  deleted;		/* File was not found during open. */
} DB_ENTRY;

/*
 * DB_LOG
 *	Per-process log structure.
 */
struct __db_log {
/* These fields need to be protected for multi-threaded support. */
	db_mutex_t	*mutexp;	/* Mutex for thread protection. */

	DB_ENTRY *dbentry;		/* Recovery file-id mapping. */
#define	DB_GROW_SIZE	64
	u_int32_t dbentry_cnt;		/* Entries.  Grows by DB_GROW_SIZE. */

/*
 * These fields are always accessed while the region lock is held, so they do
 * not have to be protected by the thread lock as well OR, they are only used
 * when threads are not being used, i.e. most cursor operations are disallowed
 * on threaded logs.
 */
	u_int32_t lfname;		/* Log file "name". */
	int	  lfd;			/* Log file descriptor. */

	DB_LSN	  c_lsn;		/* Cursor: current LSN. */
	DBT	  c_dbt;		/* Cursor: return DBT structure. */
	int	  c_fd;			/* Cursor: file descriptor. */
	u_int32_t c_off;		/* Cursor: previous record offset. */
	u_int32_t c_len;		/* Cursor: current record length. */

/* These fields are not protected. */
	LOG	 *lp;			/* Address of the shared LOG. */

	DB_ENV	 *dbenv;		/* Reference to error information. */
	REGINFO	  reginfo;		/* Region information. */

	void     *addr;			/* Address of shalloc() region. */

	char	 *dir;			/* Directory argument. */

/*
 * These fields are used by XA; since XA forbids threaded execution, these
 * do not have to be protected.
 */
	void 	*xa_info;		/* Committed transaction list that
					 * has to be carried between calls
					 * to xa_recover. */
	DB_LSN	xa_lsn;			/* Position of an XA recovery scan. */
	DB_LSN	xa_first;		/* LSN to which we need to roll back
					   for this XA recovery scan. */

	/*
	 * !!!
	 * Currently used to hold:
	 *	DB_AM_THREAD	(a DB flag)
	 *	DBC_RECOVER	(a DBC flag)
	 * If they are ever the same bits, we're in serious trouble.
	 */
#if DB_AM_THREAD == DBC_RECOVER
	DB_AM_THREAD, DBC_RECOVER, FLAG MISMATCH
#endif
	u_int32_t flags;
};

/*
 * HDR --
 *	Log record header.
 */
struct __hdr {
	u_int32_t prev;			/* Previous offset. */
	u_int32_t cksum;		/* Current checksum. */
	u_int32_t len;			/* Current length. */
};

struct __log_persist {
	u_int32_t magic;		/* DB_LOGMAGIC */
	u_int32_t version;		/* DB_LOGVERSION */

	u_int32_t lg_max;		/* Maximum file size. */
	int	  mode;			/* Log file mode. */
};

/*
 * LOG --
 *	Shared log region.  One of these is allocated in shared memory,
 *	and describes the log.
 */
struct __log {
	RLAYOUT	  rlayout;		/* General region information. */

	LOGP	  persist;		/* Persistent information. */

	SH_TAILQ_HEAD(__fq) fq;		/* List of file names. */

	/*
	 * The lsn LSN is the file offset that we're about to write and which
	 * we will return to the user.
	 */
	DB_LSN	  lsn;			/* LSN at current file offset. */

	/*
	 * The s_lsn LSN is the last LSN that we know is on disk, not just
	 * written, but synced.
	 */
	DB_LSN	  s_lsn;		/* LSN of the last sync. */

	u_int32_t len;			/* Length of the last record. */

	u_int32_t w_off;		/* Current write offset in the file. */

	DB_LSN	  chkpt_lsn;		/* LSN of the last checkpoint. */
	time_t	  chkpt;		/* Time of the last checkpoint. */

	DB_LOG_STAT stat;		/* Log statistics. */

	/*
	 * The f_lsn LSN is the LSN (returned to the user) that "owns" the
	 * first byte of the buffer.  If the record associated with the LSN
	 * spans buffers, it may not reflect the physical file location of
	 * the first byte of the buffer.
	 */
	DB_LSN	  f_lsn;		/* LSN of first byte in the buffer. */
	size_t	  b_off;		/* Current offset in the buffer. */
	u_int8_t buf[4 * 1024];		/* Log buffer. */
};

/*
 * FNAME --
 *	File name and id.
 */
struct __fname {
	SH_TAILQ_ENTRY q;		/* File name queue. */

	u_int16_t ref;			/* Reference count. */

	u_int32_t id;			/* Logging file id. */
	DBTYPE	  s_type;		/* Saved DB type. */

	size_t	  name_off;		/* Name offset. */
	u_int8_t  ufid[DB_FILE_ID_LEN];	/* Unique file id. */
};

/* File open/close register log record opcodes. */
#define	LOG_CHECKPOINT	1		/* Checkpoint: file name/id dump. */
#define	LOG_CLOSE	2		/* File close. */
#define	LOG_OPEN	3		/* File open. */

#include "log_auto.h"
#include "log_ext.h"
#endif /* _LOG_H_ */