mongodb deadlock tweaks

lib/db/memory.js

@@ -48,7 +48,8 @@ MemoryDB.prototype.commit = function(collection, id, op, snapshot, options, call
 
     var transaction;
     if (options.transaction) {
-      transaction = db._getTransaction(options.transaction);
+      transaction = db._transactions[options.transaction];
+      if (!transaction) return callback(null, false);
       version = version + transaction.commits.length;
     }
 
@@ -149,14 +150,23 @@ MemoryDB.prototype.query = function(collection, query, fields, options, callback
   });
 };
 
+MemoryDB.prototype.startTransaction = function(id, callback) {
+  if (this._transactions[id]) callback(new Error('Transaction already started'));
+  this._transactions[id] = this._transactions[id] || {};
+  this._transactions[id].commits = [];
+  callback();
+};
+
+MemoryDB.prototype.restartTransaction = function(id, callback) {
+  delete this._transactions[id];
+  this.startTransaction(id, callback);
+};
+
 MemoryDB.prototype.commitTransaction = function(id, callback) {
   var transaction = this._transactions[id];
-  if (!transaction) {
-    throw new Error('No transaction found');
-  }
+  if (!transaction) return callback();
 
   delete this._transactions[id];
-  // transaction.callbacks.push(callback);
 
   // Heavy-handed but effective approach to synchronous transaction writing:
   // let's just save the DB state before and restore if the transaction fails
@@ -235,9 +245,3 @@ MemoryDB.prototype._getVersionSync = function(collection, id) {
   var collectionOps = this.ops[collection];
   return (collectionOps && collectionOps[id] && collectionOps[id].length) || 0;
 };
-
-MemoryDB.prototype._getTransaction = function(id) {
-  var transaction = this._transactions[id] = this._transactions[id] || {};
-  transaction.commits = transaction.commits || [];
-  return transaction;
-}

lib/transaction/pending-transaction.js

@@ -18,6 +18,11 @@ PendingTransaction.prototype.abort = function() {
 };
 
 PendingTransaction.prototype.registerSubmitRequest = function(request) {
+  if (!this._transaction._requests.length) {
+    this._transaction.backend.db.startTransaction(this._transaction.id, function(error) {
+      // TODO: Handle errors / wait for callback
+    });
+  }
   this._transaction._requests.push(request);
   this.update();
 };
@@ -34,16 +39,20 @@ PendingTransaction.prototype.retry = function(callback) {
   }
 
   var transaction = this._transaction;
-  transaction.backend.db.abortTransaction(this._transaction.id, function(error) {
+  var db = transaction.backend.db;
+  db.abortTransaction(this._transaction.id, function(error) {
     if (error) return cb(error);
-    var requests = transaction._requests.slice();
-    var retryNext = function(error) {
+    db.restartTransaction(transaction.id, function(error) {
       if (error) return cb(error);
-      var request = requests.shift();
-      if (!request) return cb();
-      request.retry(retryNext);
-    }
-    retryNext();
+      var requests = transaction._requests.slice();
+      var retryNext = function(error) {
+        if (error) return cb(error);
+        var request = requests.shift();
+        if (!request) return cb();
+        request.retry(retryNext);
+      }
+      retryNext();
+    });
   });
 };