X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Ftransaction.c;h=ded3fa836fc721a07932c54a6f741b89c8329066;hp=c2e4748a8e7c668acb9c568660a59ab9c2f4cff6;hb=e9989ef0758b3b660abf444d014c5b51a3a7c1b4;hpb=b2c0ebc6f53b05b222937991f100f8a89701f9b1

diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c
index c2e4748a..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.
@@ -86,12 +86,20 @@
     fsync/msync calls are made.
 
   - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
-    tdb_add_flags() transaction is enabled.
-    The default is that transaction nesting is not allowed and an attempt
-    to create a nested transaction will fail with TDB_ERR_NESTING.
+    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.
 */
 
 
@@ -144,14 +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);
@@ -415,6 +415,9 @@ 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;
 }
 
@@ -491,33 +494,18 @@ int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
 
 	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_brunlock(tdb, tdb->global_lock.ltype,
-			     FREELIST_TOP, 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_brunlock(tdb, tdb->lockrecs[i].ltype,
-				     FREELIST_TOP+4*tdb->lockrecs[i].list, 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;
@@ -556,7 +544,7 @@ int tdb_transaction_start(struct tdb_context *tdb)
 		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 */
@@ -688,7 +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;
 
@@ -774,7 +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;
@@ -794,10 +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;
@@ -877,7 +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"));
@@ -927,11 +915,6 @@ static int _tdb_transaction_prepare_commit(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;
@@ -941,7 +924,7 @@ static int _tdb_transaction_prepare_commit(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(tdb, F_RDLCK);
@@ -956,11 +939,10 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 		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, F_WRLCK, GLOBAL_LOCK, 1, TDB_LOCK_WAIT) == -1) {
-		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
-		tdb->ecode = TDB_ERR_LOCK;
+	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;
 	}
@@ -969,7 +951,6 @@ static int _tdb_transaction_prepare_commit(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_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 0);
 			_tdb_transaction_cancel(tdb, F_WRLCK);
 			return -1;
 		}
@@ -984,7 +965,6 @@ static int _tdb_transaction_prepare_commit(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_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 0);
 			_tdb_transaction_cancel(tdb, F_WRLCK);
 			return -1;
 		}
@@ -992,7 +972,7 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 		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;
 }
@@ -1020,13 +1000,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 		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;
@@ -1080,7 +1054,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 			tdb_transaction_recover(tdb); 
 
 			_tdb_transaction_cancel(tdb, F_WRLCK);
-			tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 0);
 
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
 			return -1;
@@ -1096,8 +1069,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 		return -1;
 	}
 
-	tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
-
 	/*
 	  TODO: maybe write to some dummy hdr field, or write to magic
 	  offset without mmap, before the last sync, instead of the
@@ -1129,7 +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)
@@ -1137,7 +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) {
@@ -1224,7 +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;