forceParallel to finish on first valid output #5

Author: sagiegurari

README.md

@@ -137,7 +137,7 @@ See [contributing guide](.github/CONTRIBUTING.md)
 
 | Date        | Version | Description |
 | ----------- | ------- | ----------- |
-| 2019-06-21  | v1.2.0  | Added 'forceParallel' option to issue GET in parallel #5 |
+| 2019-06-24  | v1.2.1  | Added 'forceParallel' option to issue GET in parallel #5 |
 | 2017-07-26  | v1.0.61 | Added all-ready event and allConnected attribute |
 | 2017-01-18  | v1.0.29 | setnx type commands now run in sequence and not in parallel |
 | 2015-10-22  | v0.0.16 | Timeout child commands (see childCommandTimeout option) |

docs/CHANGELOG.md

@@ -1,6 +1,6 @@
 | Date        | Version | Description |
 | ----------- | ------- | ----------- |
-| 2019-06-21  | v1.2.0  | Added 'forceParallel' option to issue GET in parallel #5 |
+| 2019-06-24  | v1.2.1  | Added 'forceParallel' option to issue GET in parallel #5 |
 | 2017-07-26  | v1.0.61 | Added all-ready event and allConnected attribute |
 | 2017-01-18  | v1.0.29 | setnx type commands now run in sequence and not in parallel |
 | 2015-10-22  | v0.0.16 | Timeout child commands (see childCommandTimeout option) |

lib/multiple-redis.js

@@ -392,6 +392,36 @@ MultiRedisClient.prototype.invokeCommandOnClient = function (input) {
     }
 };
 
+/**
+ * Similar to race but stops on the first valid output.
+ *
+ * @function
+ * @memberof! MultiRedisClient
+ * @alias MultiRedisClient.parallelOnFirstValid
+ * @private
+ * @param {Array} actions - Functions array to invoke
+ * @param {function} callback - Invoked on first valid output.
+ */
+function parallelOnFirstValid(actions, callback) {
+    asyncLib.parallel(actions.map(function modifyAction(action) {
+        return function onAction(cb) {
+            action(function onActionDone(error, value) {
+                if (value) {
+                    cb(value);
+                } else {
+                    cb(null, error);
+                }
+            });
+        };
+    }), function onParallelDone(value, errors) {
+        if (value) {
+            callback(null, value);
+        } else {
+            callback(errors);
+        }
+    });
+}
+
 /**
  * Creates and returns a handler function for the given command.
  *
@@ -462,7 +492,11 @@ function createCommandFunction(command) {
         });
 
         if (runInParallel || self.forceParallel) {
-            asyncLib.parallel(actions, onRedisFlowEnd);
+            if (getCommand) {
+                parallelOnFirstValid(actions, onRedisFlowEnd);
+            } else {
+                asyncLib.parallel(actions, onRedisFlowEnd);
+            }
         } else {
             asyncLib.series(actions, onRedisFlowEnd);
         }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "multiple-redis",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "description": "Run redis commands against multiple redis instances.",
   "author": {
     "name": "Sagie Gur-Ari",

test/spec/multiple-redis-spec.js

@@ -847,7 +847,7 @@ describe('MultipleRedis', function () {
                 });
             });
 
-            it('second only has data force parallel', function (done) {
+            it('last only has data force parallel', function (done) {
                 var count = 0;
                 var createClient = function () {
                     return {
@@ -859,17 +859,23 @@ describe('MultipleRedis', function () {
                             assert.deepEqual(args, ['my key']);
                             assert.isFunction(callback);
 
-                            if (count === 2) {
-                                callback(null, 'my value');
-                            } else {
+                            switch (count) {
+                            case 1:
+                                setTimeout(callback, 30000);
+                                break;
+                            case 2:
                                 callback(null, null);
+                                break;
+                            default:
+                                callback(null, 'my value');
                             }
                         }
                     };
                 };
                 var client1 = createClient();
                 var client2 = createClient();
-                var client = MultipleRedis.createClient([client1, client2], {
+                var client3 = createClient();
+                var client = MultipleRedis.createClient([client1, client2, client3], {
                     forceParallel: true
                 });
 
@@ -878,7 +884,47 @@ describe('MultipleRedis', function () {
                 client.get('my key', function (error, response) {
                     assert.isNull(error);
                     assert.equal(response, 'my value');
-                    assert.equal(count, 2);
+                    assert.equal(count, 3);
+
+                    done();
+                });
+            });
+
+            it('all no data force parallel', function (done) {
+                var count = 0;
+                var createClient = function () {
+                    return {
+                        on: noop,
+                        send_command: function (name, args, callback) {
+                            count++;
+
+                            assert.equal(name, 'get');
+                            assert.deepEqual(args, ['my key']);
+                            assert.isFunction(callback);
+
+                            switch (count) {
+                            case 1:
+                                setTimeout(callback, 0);
+                                break;
+                            default:
+                                callback(null, null);
+                            }
+                        }
+                    };
+                };
+                var client1 = createClient();
+                var client2 = createClient();
+                var client3 = createClient();
+                var client = MultipleRedis.createClient([client1, client2, client3], {
+                    forceParallel: true
+                });
+
+                assert.isTrue(client.forceParallel);
+
+                client.get('my key', function (error, response) {
+                    assert.isDefined(error);
+                    assert.isNull(response);
+                    assert.equal(count, 3);
 
                     done();
                 });