X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Ftransaction.c;h=ded3fa836fc721a07932c54a6f741b89c8329066;hp=1086c5f037793d9df00269ff78b14ae2ad126e72;hb=e9989ef0758b3b660abf444d014c5b51a3a7c1b4;hpb=c5316eef05ab024c44224a165282e8df8ad30285

diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c
index 1086c5f0..ded3fa83 100644
--- a/ccan/tdb/transaction.c
+++ b/ccan/tdb/transaction.c
@@ -76,7 +76,7 @@
     to reduce this to 3 or even 2 with some more work.
 
   - check for a valid recovery record on open of the tdb, while the
-    global lock is held. Automatically recover from the transaction
+    open lock is held. Automatically recover from the transaction
     recovery area if needed, then continue with the open as
     usual. This allows for smooth crash recovery with no administrator
     intervention.
@@ -85,11 +85,21 @@
     still available, but no transaction recovery area is used and no
     fsync/msync calls are made.
 
-  - if TDB_NO_NESTING is passed to flags in tdb open then transaction
-    nesting is disabled. tdb_transaction_start() will then implicitely
-    cancel any pending transactions and always start a new transaction
-    context instead of nesting.
-
+  - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
+    tdb_add_flags() transaction nesting is enabled.
+    It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
+    The default is that transaction nesting is allowed.
+    Note: this default may change in future versions of tdb.
+
+    Beware. when transactions are nested a transaction successfully
+    completed with tdb_transaction_commit() can be silently unrolled later.
+
+  - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
+    tdb_add_flags() transaction nesting is disabled.
+    It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
+    An attempt create a nested transaction will fail with TDB_ERR_NESTING.
+    The default is that transaction nesting is allowed.
+    Note: this default may change in future versions of tdb.
 */
 
 
@@ -127,6 +137,9 @@ struct tdb_transaction {
 
 	/* old file size before transaction */
 	tdb_len_t old_map_size;
+
+	/* we should re-pack on commit */
+	bool need_repack;
 };
 
 
@@ -139,14 +152,6 @@ static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
 {
 	uint32_t blk;
 
-	/* Only a commit is allowed on a prepared transaction */
-	if (tdb->transaction->prepared) {
-		tdb->ecode = TDB_ERR_EINVAL;
-		TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n"));
-		tdb->transaction->transaction_error = 1;
-		return -1;
-	}
-
 	/* break it down into block sized ops */
 	while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 		tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
@@ -382,7 +387,8 @@ static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
 	if (len <= tdb->map_size) {
 		return 0;
 	}
-	return TDB_ERRCODE(TDB_ERR_IO, -1);
+	tdb->ecode = TDB_ERR_IO;
+	return -1;
 }
 
 /*
@@ -397,14 +403,26 @@ static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
 		return -1;
 	}
 
+	tdb->transaction->need_repack = true;
+
 	return 0;
 }
 
 /*
   brlock during a transaction - ignore them
 */
-static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset, 
-			      int rw_type, int lck_type, int probe, size_t len)
+static int transaction_brlock(struct tdb_context *tdb,
+			      int rw_type, tdb_off_t offset, size_t len,
+			      enum tdb_lock_flags flags)
+{
+	/* FIXME: We actually grab the open lock during a transaction. */
+	if (offset == OPEN_LOCK)
+		return tdb_brlock(tdb, rw_type, offset, len, flags);
+	return 0;
+}
+
+static int transaction_brunlock(struct tdb_context *tdb,
+				int rw_type, tdb_off_t offset, size_t len)
 {
 	return 0;
 }
@@ -415,7 +433,8 @@ static const struct tdb_methods transaction_methods = {
 	transaction_next_hash_chain,
 	transaction_oob,
 	transaction_expand_file,
-	transaction_brlock
+	transaction_brlock,
+	transaction_brunlock
 };
 
 /*
@@ -447,7 +466,8 @@ static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t
 	return 0;
 }
 
-int tdb_transaction_cancel_internal(struct tdb_context *tdb)
+/* ltype is F_WRLCK after prepare. */
+int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
 {
 	int i, ret = 0;
 
@@ -474,38 +494,24 @@ int tdb_transaction_cancel_internal(struct tdb_context *tdb)
 
 	if (tdb->transaction->magic_offset) {
 		const struct tdb_methods *methods = tdb->transaction->io_methods;
-		uint32_t zero = 0;
+		uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
 
 		/* remove the recovery marker */
-		if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
+		if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
 		transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
 			ret = -1;
 		}
 	}
 
-	/* remove any global lock created during the transaction */
-	if (tdb->global_lock.count != 0) {
-		tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
-		tdb->global_lock.count = 0;
-	}
-
-	/* remove any locks created during the transaction */
-	if (tdb->num_locks != 0) {
-		for (i=0;i<tdb->num_lockrecs;i++) {
-			tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
-				   F_UNLCK,F_SETLKW, 0, 1);
-		}
-		tdb->num_locks = 0;
-		tdb->num_lockrecs = 0;
-		SAFE_FREE(tdb->lockrecs);
-	}
+	/* This also removes the OPEN_LOCK, if we have it. */
+	tdb_release_extra_locks(tdb);
 
 	/* restore the normal io methods */
 	tdb->methods = tdb->transaction->io_methods;
 
-	tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
-	tdb_transaction_unlock(tdb);
+	tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
+	tdb_transaction_unlock(tdb, F_WRLCK);
 	SAFE_FREE(tdb->transaction->hash_heads);
 	SAFE_FREE(tdb->transaction);
 	
@@ -527,19 +533,18 @@ int tdb_transaction_start(struct tdb_context *tdb)
 
 	/* cope with nested tdb_transaction_start() calls */
 	if (tdb->transaction != NULL) {
-		tdb_trace(tdb, "tdb_transaction_start");
-		if (!tdb->flags & TDB_NO_NESTING) {
-			tdb->transaction->nesting++;
-			TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", 
-				 tdb->transaction->nesting));
-			return 0;
-		} else {
-			tdb_transaction_cancel_internal(tdb);
-			TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n"));
+		if (!(tdb->flags & TDB_ALLOW_NESTING)) {
+			tdb->ecode = TDB_ERR_NESTING;
+			return -1;
 		}
+		tdb_trace(tdb, "tdb_transaction_start");
+		tdb->transaction->nesting++;
+		TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", 
+			 tdb->transaction->nesting));
+		return 0;
 	}
 
-	if (tdb->num_locks != 0 || tdb->global_lock.count) {
+	if (tdb_have_extra_locks(tdb)) {
 		/* the caller must not have any locks when starting a
 		   transaction as otherwise we'll be screwed by lack
 		   of nested locks in posix */
@@ -578,7 +583,7 @@ int tdb_transaction_start(struct tdb_context *tdb)
 	
 	/* get a read lock from the freelist to the end of file. This
 	   is upgraded to a write lock during the commit */
-	if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
+	if (tdb_brlock(tdb, F_RDLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
 		tdb->ecode = TDB_ERR_LOCK;
 		goto fail;
@@ -614,8 +619,8 @@ int tdb_transaction_start(struct tdb_context *tdb)
 	return 0;
 	
 fail:
-	tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
-	tdb_transaction_unlock(tdb);
+	tdb_brunlock(tdb, F_RDLCK, FREELIST_TOP, 0);
+	tdb_transaction_unlock(tdb, F_WRLCK);
 	SAFE_FREE(tdb->transaction->blocks);
 	SAFE_FREE(tdb->transaction->hash_heads);
 	SAFE_FREE(tdb->transaction);
@@ -627,9 +632,12 @@ fail:
   cancel the current transaction
 */
 int tdb_transaction_cancel(struct tdb_context *tdb)
-{	
+{
+	int ltype = F_RDLCK;
 	tdb_trace(tdb, "tdb_transaction_cancel");
-	return tdb_transaction_cancel_internal(tdb);
+	if (tdb->transaction && tdb->transaction->prepared)
+		ltype = F_WRLCK;
+	return _tdb_transaction_cancel(tdb, ltype);
 }
 
 /*
@@ -668,7 +676,7 @@ static int tdb_recovery_allocate(struct tdb_context *tdb,
 				 tdb_off_t *recovery_offset,
 				 tdb_len_t *recovery_max_size)
 {
-	struct list_struct rec;
+	struct tdb_record rec;
 	const struct tdb_methods *methods = tdb->transaction->io_methods;
 	tdb_off_t recovery_head;
 
@@ -754,7 +762,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	tdb_len_t recovery_size;
 	unsigned char *data, *p;
 	const struct tdb_methods *methods = tdb->transaction->io_methods;
-	struct list_struct *rec;
+	struct tdb_record *rec;
 	tdb_off_t recovery_offset, recovery_max_size;
 	tdb_off_t old_map_size = tdb->transaction->old_map_size;
 	uint32_t magic, tailer;
@@ -774,10 +782,10 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 		return -1;
 	}
 
-	rec = (struct list_struct *)data;
+	rec = (struct tdb_record *)data;
 	memset(rec, 0, sizeof(*rec));
 
-	rec->magic    = 0;
+	rec->magic    = TDB_RECOVERY_INVALID_MAGIC;
 	rec->data_len = recovery_size;
 	rec->rec_len  = recovery_max_size;
 	rec->key_len  = old_map_size;
@@ -857,7 +865,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	magic = TDB_RECOVERY_MAGIC;
 	CONVERT(magic);
 
-	*magic_offset = recovery_offset + offsetof(struct list_struct, magic);
+	*magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
 
 	if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
@@ -878,7 +886,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	return 0;
 }
 
-static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
+static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 {	
 	const struct tdb_methods *methods;
 
@@ -889,14 +897,14 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 
 	if (tdb->transaction->prepared) {
 		tdb->ecode = TDB_ERR_EINVAL;
-		tdb_transaction_cancel(tdb);
+		_tdb_transaction_cancel(tdb, F_WRLCK);
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
 		return -1;
 	}
 
 	if (tdb->transaction->transaction_error) {
 		tdb->ecode = TDB_ERR_IO;
-		tdb_transaction_cancel_internal(tdb);
+		_tdb_transaction_cancel(tdb, F_RDLCK);
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
 		return -1;
 	}
@@ -907,11 +915,6 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 		return 0;
 	}		
 
-#ifdef TDB_TRACE
-	/* store seqnum now, before reading becomes illegal. */
-	tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &tdb->transaction_prepare_seqnum);
-#endif
-
 	/* check for a null transaction */
 	if (tdb->transaction->blocks == NULL) {
 		return 0;
@@ -921,10 +924,10 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 	
 	/* if there are any locks pending then the caller has not
 	   nested their locks properly, so fail the transaction */
-	if (tdb->num_locks || tdb->global_lock.count) {
+	if (tdb_have_extra_locks(tdb)) {
 		tdb->ecode = TDB_ERR_LOCK;
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
-		tdb_transaction_cancel_internal(tdb);
+		_tdb_transaction_cancel(tdb, F_RDLCK);
 		return -1;
 	}
 
@@ -932,16 +935,15 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 	if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
 		tdb->ecode = TDB_ERR_LOCK;
-		tdb_transaction_cancel_internal(tdb);
+		_tdb_transaction_cancel(tdb, F_RDLCK);
 		return -1;
 	}
 
-	/* get the global lock - this prevents new users attaching to the database
+	/* get the open lock - this prevents new users attaching to the database
 	   during the commit */
-	if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
-		tdb->ecode = TDB_ERR_LOCK;
-		tdb_transaction_cancel_internal(tdb);
+	if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
+		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
+		_tdb_transaction_cancel(tdb, F_WRLCK);
 		return -1;
 	}
 
@@ -949,8 +951,7 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 		/* write the recovery data to the end of the file */
 		if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
-			tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-			tdb_transaction_cancel_internal(tdb);
+			_tdb_transaction_cancel(tdb, F_WRLCK);
 			return -1;
 		}
 	}
@@ -964,15 +965,14 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 					     tdb->transaction->old_map_size) == -1) {
 			tdb->ecode = TDB_ERR_IO;
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
-			tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-			tdb_transaction_cancel_internal(tdb);
+			_tdb_transaction_cancel(tdb, F_WRLCK);
 			return -1;
 		}
 		tdb->map_size = tdb->transaction->old_map_size;
 		methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 	}
 
-	/* Keep the global lock until the actual commit */
+	/* Keep the open lock until the actual commit */
 
 	return 0;
 }
@@ -983,7 +983,7 @@ static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
 {	
 	tdb_trace(tdb, "tdb_transaction_prepare_commit");
-	return tdb_transaction_prepare_commit_internal(tdb);
+	return _tdb_transaction_prepare_commit(tdb);
 }
 
 /*
@@ -993,19 +993,14 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 {	
 	const struct tdb_methods *methods;
 	int i;
+	bool need_repack;
 
 	if (tdb->transaction == NULL) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
 		return -1;
 	}
 
-	/* If we've prepared, can't read seqnum. */
-	if (tdb->transaction->prepared) {
-		tdb_trace_seqnum(tdb, tdb->transaction_prepare_seqnum,
-				 "tdb_transaction_commit");
-	} else {
-		tdb_trace(tdb, "tdb_transaction_commit");
-	}
+	tdb_trace(tdb, "tdb_transaction_commit");
 
 	if (tdb->transaction->transaction_error) {
 		tdb->ecode = TDB_ERR_IO;
@@ -1022,12 +1017,12 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
 	/* check for a null transaction */
 	if (tdb->transaction->blocks == NULL) {
-		tdb_transaction_cancel_internal(tdb);
+		_tdb_transaction_cancel(tdb, F_RDLCK);
 		return 0;
 	}
 
 	if (!tdb->transaction->prepared) {
-		int ret = tdb_transaction_prepare_commit_internal(tdb);
+		int ret = _tdb_transaction_prepare_commit(tdb);
 		if (ret)
 			return ret;
 	}
@@ -1058,8 +1053,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 			tdb->methods = methods;
 			tdb_transaction_recover(tdb); 
 
-			tdb_transaction_cancel_internal(tdb);
-			tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
+			_tdb_transaction_cancel(tdb, F_WRLCK);
 
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
 			return -1;
@@ -1075,8 +1069,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 		return -1;
 	}
 
-	tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
-
 	/*
 	  TODO: maybe write to some dummy hdr field, or write to magic
 	  offset without mmap, before the last sync, instead of the
@@ -1092,9 +1084,15 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 	utime(tdb->name, NULL);
 #endif
 
+	need_repack = tdb->transaction->need_repack;
+
 	/* use a transaction cancel to free memory and remove the
 	   transaction locks */
-	tdb_transaction_cancel_internal(tdb);
+	_tdb_transaction_cancel(tdb, F_WRLCK);
+
+	if (need_repack) {
+		return tdb_repack(tdb);
+	}
 
 	return 0;
 }
@@ -1102,7 +1100,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
 /*
   recover from an aborted transaction. Must be called with exclusive
-  database write access already established (including the global
+  database write access already established (including the open
   lock to prevent new processes attaching)
 */
 int tdb_transaction_recover(struct tdb_context *tdb)
@@ -1110,7 +1108,7 @@ int tdb_transaction_recover(struct tdb_context *tdb)
 	tdb_off_t recovery_head, recovery_eof;
 	unsigned char *data, *p;
 	uint32_t zero = 0;
-	struct list_struct rec;
+	struct tdb_record rec;
 
 	/* find the recovery area */
 	if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
@@ -1197,7 +1195,7 @@ int tdb_transaction_recover(struct tdb_context *tdb)
 	}
 
 	/* remove the recovery magic */
-	if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic), 
+	if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
 			  &zero) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
 		tdb->ecode = TDB_ERR_IO;