Import BSDDB 4.7.25 (as of svn r89086)

dbinc/txn.h

@@ -0,0 +1,239 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996,2008 Oracle.  All rights reserved.
+ *
+ * $Id: txn.h 63573 2008-05-23 21:43:21Z trent.nelson $
+ */
+
+#ifndef	_DB_TXN_H_
+#define	_DB_TXN_H_
+
+#include "dbinc/xa.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* Operation parameters to the delayed commit processing code. */
+typedef enum {
+	TXN_CLOSE,		/* Close a DB handle whose close had failed. */
+	TXN_REMOVE,		/* Remove a file. */
+	TXN_TRADE,		/* Trade lockers. */
+	TXN_TRADED		/* Already traded; downgrade lock. */
+} TXN_EVENT_T;
+
+struct __db_txnregion;	typedef struct __db_txnregion DB_TXNREGION;
+struct __txn_logrec;	typedef struct __txn_logrec DB_TXNLOGREC;
+
+/*
+ * !!!
+ * TXN_MINIMUM = (DB_LOCK_MAXID + 1) but this makes compilers complain.
+ */
+#define	TXN_MINIMUM	0x80000000
+#define	TXN_MAXIMUM	0xffffffff	/* Maximum number of txn ids. */
+#define	TXN_INVALID	0		/* Invalid transaction ID. */
+
+#define	DEF_MAX_TXNS	100		/* Default max transactions. */
+#define	TXN_NSLOTS	4		/* Initial slots to hold DB refs */
+
+/*
+ * Internal data maintained in shared memory for each transaction.
+ */
+typedef struct __txn_detail {
+	u_int32_t txnid;		/* current transaction id
+					   used to link free list also */
+	pid_t pid;			/* Process owning txn */
+	db_threadid_t tid;		/* Thread owning txn */
+
+	DB_LSN	last_lsn;		/* Last LSN written for this txn. */
+	DB_LSN	begin_lsn;		/* LSN of begin record. */
+	roff_t	parent;			/* Offset of transaction's parent. */
+	roff_t	name;			/* Offset of txn name. */
+
+	u_int32_t	nlog_dbs;	/* Number of databases used. */
+	u_int32_t	nlog_slots;	/* Number of allocated slots. */
+	roff_t		log_dbs;	/* Databases used. */
+
+	DB_LSN	read_lsn;		/* Read LSN for MVCC. */
+	DB_LSN	visible_lsn;		/* LSN at which this transaction's
+					   changes are visible. */
+	db_mutex_t	mvcc_mtx;	/* Version mutex. */
+	u_int32_t	mvcc_ref;	/* Number of buffers created by this
+					   transaction still in cache.  */
+
+	SH_TAILQ_HEAD(__tdkids)	kids;	/* Linked list of child txn detail. */
+	SH_TAILQ_ENTRY		klinks;
+
+	/* TXN_{ABORTED, COMMITTED PREPARED, RUNNING} */
+	u_int32_t status;		/* status of the transaction */
+
+#define	TXN_DTL_COLLECTED	0x1	/* collected during txn_recover */
+#define	TXN_DTL_RESTORED	0x2	/* prepared txn restored */
+#define	TXN_DTL_INMEMORY	0x4	/* uses in memory logs */
+	u_int32_t flags;
+
+	/* TXN_XA_{ABORTED, DEADLOCKED, ENDED, PREPARED, STARTED, SUSPENDED} */
+	SH_TAILQ_ENTRY	links;		/* active/free/snapshot list */
+
+	u_int32_t xa_status;		/* XA status */
+
+	/*
+	 * XID (xid_t) structure: because these fields are logged, the
+	 * sizes have to be explicit.
+	 */
+	u_int8_t xid[XIDDATASIZE];	/* XA global transaction id */
+	u_int32_t bqual;		/* bqual_length from XID */
+	u_int32_t gtrid;		/* gtrid_length from XID */
+	int32_t format;			/* XA format */
+	roff_t slots[TXN_NSLOTS];	/* Initial DB slot allocation. */
+} TXN_DETAIL;
+
+/*
+ * DB_TXNMGR --
+ *	The transaction manager encapsulates the transaction system.
+ */
+struct __db_txnmgr {
+	/*
+	 * These fields need to be protected for multi-threaded support.
+	 *
+	 * Lock list of active transactions (including the content of each
+	 * TXN_DETAIL structure on the list).
+	 */
+	db_mutex_t mutex;
+					/* List of active transactions. */
+	TAILQ_HEAD(_chain, __db_txn)	txn_chain;
+
+	u_int32_t n_discards;		/* Number of txns discarded. */
+
+	/* These fields are never updated after creation, so not protected. */
+	ENV	*env;			/* Environment. */
+	REGINFO	 reginfo;		/* Region information. */
+};
+
+/* Macros to lock/unlock the transaction region as a whole. */
+#define	TXN_SYSTEM_LOCK(env)						\
+	MUTEX_LOCK(env, ((DB_TXNREGION *)				\
+	    (env)->tx_handle->reginfo.primary)->mtx_region)
+#define	TXN_SYSTEM_UNLOCK(env)						\
+	MUTEX_UNLOCK(env, ((DB_TXNREGION *)				\
+	    (env)->tx_handle->reginfo.primary)->mtx_region)
+
+/*
+ * DB_TXNREGION --
+ *	The primary transaction data structure in the shared memory region.
+ */
+struct __db_txnregion {
+	db_mutex_t	mtx_region;	/* Region mutex. */
+
+	u_int32_t	maxtxns;	/* maximum number of active TXNs */
+	u_int32_t	last_txnid;	/* last transaction id given out */
+	u_int32_t	cur_maxid;	/* current max unused id. */
+
+	db_mutex_t	mtx_ckp;	/* Single thread checkpoints. */
+	DB_LSN		last_ckp;	/* lsn of the last checkpoint */
+	time_t		time_ckp;	/* time of last checkpoint */
+
+	DB_TXN_STAT	stat;		/* Statistics for txns. */
+
+#define	TXN_IN_RECOVERY	 0x01		/* environment is being recovered */
+	u_int32_t	flags;
+					/* active TXN list */
+	SH_TAILQ_HEAD(__active) active_txn;
+	SH_TAILQ_HEAD(__mvcc) mvcc_txn;
+};
+
+/*
+ * DB_TXNLOGREC --
+ *	An in-memory, linked-list copy of a log record.
+ */
+struct __txn_logrec {
+	STAILQ_ENTRY(__txn_logrec) links;/* Linked list. */
+
+	u_int8_t data[1];		/* Log record. */
+};
+
+/*
+ * Log record types.  Note that these are *not* alphabetical.  This is
+ * intentional so that we don't change the meaning of values between
+ * software upgrades.
+ *
+ * EXPECTED, UNEXPECTED, IGNORE, and OK are used in the txnlist functions.
+ * Here is an explanation of how the statuses are used.
+ *
+ * TXN_OK
+ *	BEGIN records for transactions found on the txnlist during
+ *	OPENFILES (BEGIN records are those with a prev_lsn of 0,0)
+ *
+ * TXN_COMMIT
+ *	Transaction committed and should be rolled forward.
+ *
+ * TXN_ABORT
+ *	This transaction's changes must be undone.  Either there was
+ *	never a prepare or commit record for this transaction OR there
+ *	was a commit, but we are recovering to a timestamp or particular
+ *	LSN and that point is before this transaction's commit.
+ *
+ * TXN_PREPARE
+ *	Prepare record, but no commit record is in the log.
+ *
+ * TXN_IGNORE
+ *	Generic meaning is that this transaction should not be
+ *	processed during later recovery passes.  We use it in a
+ *	number of different manners:
+ *
+ *	1. We never saw its BEGIN record.  Therefore, the logs have
+ *	   been reclaimed and we *know* that this transaction doesn't
+ *	   need to be aborted, because in order for it to be
+ *	   reclaimed, there must have been a subsequent checkpoint
+ *	   (and any dirty pages for this transaction made it to
+ *	   disk).
+ *
+ *	2. This is a child transaction that created a database.
+ *	   For some reason, we don't want to recreate that database
+ *	   (i.e., it already exists or some other database created
+ *	   after it exists).
+ *
+ *	3. During recovery open of subdatabases, if the master check fails,
+ *	   we use a TXN_IGNORE on the create of the subdb in the nested
+ *	   transaction.
+ *
+ *	4. During a remove, the file with the name being removed isn't
+ *	   the file for which we are recovering a remove.
+ *
+ * TXN_EXPECTED
+ *	After a successful open during recovery, we update the
+ *	transaction's status to TXN_EXPECTED.  The open was done
+ *	in the parent, but in the open log record, we record the
+ *	child transaction's ID if we also did a create.  When there
+ *	is a valid ID in that field, we use it and mark the child's
+ *	status as TXN_EXPECTED (indicating that we don't need to redo
+ *	a create for this file).
+ *
+ *	When recovering a remove, if we don't find or can't open
+ *	the file, the child (which does the remove) gets marked
+ *	EXPECTED (indicating that we don't need to redo the remove).
+ *
+ * TXN_UNEXPECTED
+ *	During recovery, we attempted an open that should have succeeded
+ *	and we got ENOENT, so like with the EXPECTED case, we indicate
+ *	in the child that we got the UNEXPECTED return so that we do redo
+ *	the creating/deleting operation.
+ *
+ */
+#define	TXN_OK		0
+#define	TXN_COMMIT	1
+#define	TXN_PREPARE	2
+#define	TXN_ABORT	3
+#define	TXN_IGNORE	4
+#define	TXN_EXPECTED	5
+#define	TXN_UNEXPECTED	6
+
+#if defined(__cplusplus)
+}
+#endif
+
+#include "dbinc_auto/txn_auto.h"
+#include "dbinc_auto/txn_ext.h"
+#include "dbinc_auto/xa_ext.h"
+#endif /* !_DB_TXN_H_ */