Merge branch 'master' of ssh://git.samba.org/data/git/samba
authorAndrew Tridgell <tridge@samba.org>
Tue, 31 Mar 2009 02:59:56 +0000 (13:59 +1100)
committerAndrew Tridgell <tridge@samba.org>
Tue, 31 Mar 2009 02:59:56 +0000 (13:59 +1100)
lib/tdb/common/transaction.c
lib/tdb/docs/README
lib/tdb/include/tdb.h
lib/tdb/tools/tdbtorture.c

index 7acda640c8d32338de6e8651971d5f848740aae6..1cb7063a38432750973b8017cdb1277894ae3d2e 100644 (file)
@@ -116,6 +116,10 @@ struct tdb_transaction {
           but don't create a new transaction */
        int nesting;
 
+       /* set when a prepare has already occurred */
+       bool prepared;
+       tdb_off_t magic_offset;
+
        /* old file size before transaction */
        tdb_len_t old_map_size;
 };
@@ -130,6 +134,14 @@ 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);
@@ -187,6 +199,14 @@ static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
 {
        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_write: transaction already prepared, write not allowed\n"));
+               tdb->transaction->transaction_error = 1;
+               return -1;
+       }
+
        /* if the write is to a hash head, then update the transaction
           hash heads */
        if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
@@ -497,12 +517,38 @@ fail:
 }
 
 
+/*
+  sync to disk
+*/
+static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
+{      
+       if (fsync(tdb->fd) != 0) {
+               tdb->ecode = TDB_ERR_IO;
+               TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
+               return -1;
+       }
+#ifdef HAVE_MMAP
+       if (tdb->map_ptr) {
+               tdb_off_t moffset = offset & ~(tdb->page_size-1);
+               if (msync(moffset + (char *)tdb->map_ptr, 
+                         length + (offset - moffset), MS_SYNC) != 0) {
+                       tdb->ecode = TDB_ERR_IO;
+                       TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
+                                strerror(errno)));
+                       return -1;
+               }
+       }
+#endif
+       return 0;
+}
+
+
 /*
   cancel the current transaction
 */
 int tdb_transaction_cancel(struct tdb_context *tdb)
 {      
-       int i;
+       int i, ret = 0;
 
        if (tdb->transaction == NULL) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
@@ -525,6 +571,18 @@ int tdb_transaction_cancel(struct tdb_context *tdb)
        }
        SAFE_FREE(tdb->transaction->blocks);
 
+       if (tdb->transaction->magic_offset) {
+               const struct tdb_methods *methods = tdb->transaction->io_methods;
+               uint32_t zero = 0;
+
+               /* remove the recovery marker */
+               if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 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);
@@ -550,32 +608,7 @@ int tdb_transaction_cancel(struct tdb_context *tdb)
        SAFE_FREE(tdb->transaction->hash_heads);
        SAFE_FREE(tdb->transaction);
        
-       return 0;
-}
-
-/*
-  sync to disk
-*/
-static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
-{      
-       if (fsync(tdb->fd) != 0) {
-               tdb->ecode = TDB_ERR_IO;
-               TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
-               return -1;
-       }
-#ifdef HAVE_MMAP
-       if (tdb->map_ptr) {
-               tdb_off_t moffset = offset & ~(tdb->page_size-1);
-               if (msync(moffset + (char *)tdb->map_ptr, 
-                         length + (offset - moffset), MS_SYNC) != 0) {
-                       tdb->ecode = TDB_ERR_IO;
-                       TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
-                                strerror(errno)));
-                       return -1;
-               }
-       }
-#endif
-       return 0;
+       return ret;
 }
 
 
@@ -826,36 +859,39 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 }
 
 /*
-  commit the current transaction
+  prepare to commit the current transaction
 */
-int tdb_transaction_commit(struct tdb_context *tdb)
+int tdb_transaction_prepare_commit(struct tdb_context *tdb)
 {      
        const struct tdb_methods *methods;
-       tdb_off_t magic_offset = 0;
-       uint32_t zero = 0;
        int i;
 
        if (tdb->transaction == NULL) {
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
+               return -1;
+       }
+
+       if (tdb->transaction->prepared) {
+               tdb->ecode = TDB_ERR_EINVAL;
+               tdb_transaction_cancel(tdb);
+               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(tdb);
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
                return -1;
        }
 
 
        if (tdb->transaction->nesting != 0) {
-               tdb->transaction->nesting--;
                return 0;
        }               
 
        /* check for a null transaction */
        if (tdb->transaction->blocks == NULL) {
-               tdb_transaction_cancel(tdb);
                return 0;
        }
 
@@ -865,14 +901,14 @@ int tdb_transaction_commit(struct tdb_context *tdb)
           nested their locks properly, so fail the transaction */
        if (tdb->num_locks || tdb->global_lock.count) {
                tdb->ecode = TDB_ERR_LOCK;
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n"));
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
                tdb_transaction_cancel(tdb);
                return -1;
        }
 
        /* upgrade the main transaction lock region to a write lock */
        if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n"));
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
                tdb->ecode = TDB_ERR_LOCK;
                tdb_transaction_cancel(tdb);
                return -1;
@@ -881,7 +917,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
        /* get the global 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_commit: failed to get global lock\n"));
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
                tdb->ecode = TDB_ERR_LOCK;
                tdb_transaction_cancel(tdb);
                return -1;
@@ -889,21 +925,23 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 
        if (!(tdb->flags & TDB_NOSYNC)) {
                /* write the recovery data to the end of the file */
-               if (transaction_setup_recovery(tdb, &magic_offset) == -1) {
-                       TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n"));
+               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(tdb);
                        return -1;
                }
        }
 
+       tdb->transaction->prepared = true;
+
        /* expand the file to the new size if needed */
        if (tdb->map_size != tdb->transaction->old_map_size) {
                if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, 
                                             tdb->map_size - 
                                             tdb->transaction->old_map_size) == -1) {
                        tdb->ecode = TDB_ERR_IO;
-                       TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: expansion failed\n"));
+                       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(tdb);
                        return -1;
@@ -912,6 +950,51 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                methods->tdb_oob(tdb, tdb->map_size + 1, 1);
        }
 
+       /* Keep the global lock until the actual commit */
+
+       return 0;
+}
+
+/*
+  commit the current transaction
+*/
+int tdb_transaction_commit(struct tdb_context *tdb)
+{      
+       const struct tdb_methods *methods;
+       int i;
+
+       if (tdb->transaction == NULL) {
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
+               return -1;
+       }
+
+       if (tdb->transaction->transaction_error) {
+               tdb->ecode = TDB_ERR_IO;
+               tdb_transaction_cancel(tdb);
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
+               return -1;
+       }
+
+
+       if (tdb->transaction->nesting != 0) {
+               tdb->transaction->nesting--;
+               return 0;
+       }
+
+       /* check for a null transaction */
+       if (tdb->transaction->blocks == NULL) {
+               tdb_transaction_cancel(tdb);
+               return 0;
+       }
+
+       if (!tdb->transaction->prepared) {
+               int ret = tdb_transaction_prepare_commit(tdb);
+               if (ret)
+                       return ret;
+       }
+
+       methods = tdb->transaction->io_methods;
+
        /* perform all the writes */
        for (i=0;i<tdb->transaction->num_blocks;i++) {
                tdb_off_t offset;
@@ -953,17 +1036,6 @@ int tdb_transaction_commit(struct tdb_context *tdb)
                if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
                        return -1;
                }
-
-               /* remove the recovery marker */
-               if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) {
-                       TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n"));
-                       return -1;
-               }
-
-               /* ensure the recovery marker has been removed on disk */
-               if (transaction_sync(tdb, magic_offset, 4) == -1) {
-                       return -1;
-               }
        }
 
        tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
index 63fcf5e049b13ef01fc3cae78c7326be332287a8..454e4ba032b81275219bca255e20405f23ad1cea 100644 (file)
@@ -236,3 +236,11 @@ int tdb_transaction_commit(TDB_CONTEXT *tdb)
    commit a current transaction, updating the database and releasing
    the transaction locks.
 
+----------------------------------------------------------------------
+int tdb_transaction_prepare_commit(TDB_CONTEXT *tdb)
+
+   prepare to commit a current transaction, for two-phase commits.
+   Once prepared for commit, the only allowed calls are
+   tdb_transaction_commit() or tdb_transaction_cancel(). Preparing
+   allocates disk space for the pending updates, so a subsequent
+   commit should succeed (barring any hardware failures).
index 94b5e366b90cd28002ca4c21e405a0f2197b5ffb..22496f56f01d69fc981282221382bb15c46b825f 100644 (file)
@@ -129,6 +129,7 @@ int tdb_fd(struct tdb_context *tdb);
 tdb_log_func tdb_log_fn(struct tdb_context *tdb);
 void *tdb_get_logging_private(struct tdb_context *tdb);
 int tdb_transaction_start(struct tdb_context *tdb);
+int tdb_transaction_prepare_commit(struct tdb_context *tdb);
 int tdb_transaction_commit(struct tdb_context *tdb);
 int tdb_transaction_cancel(struct tdb_context *tdb);
 int tdb_transaction_recover(struct tdb_context *tdb);
index 9265cf07aa27976f36c54801758e2f6862e2b613..0c9bbd613d8b35a470cbf987540a8737eec0c977 100644 (file)
@@ -18,6 +18,7 @@
 #define STORE_PROB 4
 #define APPEND_PROB 6
 #define TRANSACTION_PROB 10
+#define TRANSACTION_PREPARE_PROB 2
 #define LOCKSTORE_PROB 5
 #define TRAVERSE_PROB 20
 #define TRAVERSE_READ_PROB 20
@@ -109,6 +110,11 @@ static void addrec_db(void)
                goto next;
        }
        if (in_transaction && random() % TRANSACTION_PROB == 0) {
+               if (random() % TRANSACTION_PREPARE_PROB == 0) {
+                       if (tdb_transaction_prepare_commit(db) != 0) {
+                               fatal("tdb_transaction_prepare_commit failed");
+                       }
+               }
                if (tdb_transaction_commit(db) != 0) {
                        fatal("tdb_transaction_commit failed");
                }