Port nested transaction allow from newer ctdb.
[ccan] / ccan / tdb / transaction.c
index 1086c5f037793d9df00269ff78b14ae2ad126e72..e55285f94cc6609a2afa720d39fe66d2261a36fe 100644 (file)
     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 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.
 
+    Beware. when transactions are nested a transaction successfully
+    completed with tdb_transaction_commit() can be silently unrolled later.
 */
 
 
@@ -127,6 +129,9 @@ struct tdb_transaction {
 
        /* old file size before transaction */
        tdb_len_t old_map_size;
+
+       /* we should re-pack on commit */
+       bool need_repack;
 };
 
 
@@ -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;
 }
 
 /*
@@ -397,6 +403,8 @@ static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
                return -1;
        }
 
+       tdb->transaction->need_repack = true;
+
        return 0;
 }
 
@@ -527,16 +535,15 @@ 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) {
@@ -993,6 +1000,7 @@ 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"));
@@ -1092,10 +1100,16 @@ 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);
 
+       if (need_repack) {
+               return tdb_repack(tdb);
+       }
+
        return 0;
 }