core: make operations promise friendly

packages/bigquery/src/job.js

@@ -343,6 +343,27 @@ Job.prototype.listenForEvents_ = function() {
   });
 };
 
+/**
+ * Convenience method that wraps the `complete` and `error` events in a
+ * Promise.
+ *
+ * @return {promise}
+ *
+ * @example
+ * job.promise().then(function(metadata) {
+ *   // The job is complete.
+ * }, function(err) {
+ *   // An error occurred during the job.
+ * });
+ */
+Job.prototype.promise = function() {
+  var self = this;
+
+  return new common.util.Promise(function(resolve, reject) {
+    self.on('error', reject).on('complete', resolve);
+  });
+};
+
 /**
  * Poll `getMetadata` to check the operation's status. This runs a loop to ping
  * the API on an interval.

packages/common/src/grpc-operation.js

@@ -164,6 +164,19 @@ GrpcOperation.prototype.listenForEvents_ = function() {
   });
 };
 
+/**
+ * Wraps the `complete` and `error` events in a Promise.
+ *
+ * @return {promise}
+ */
+GrpcOperation.prototype.promise = function() {
+  var self = this;
+
+  return new util.Promise(function(resolve, reject) {
+    self.on('error', reject).on('complete', resolve);
+  });
+};
+
 /**
  * Poll `getMetadata` to check the operation's status. This runs a loop to ping
  * the API on an interval.

packages/common/src/service.js

@@ -62,7 +62,7 @@ function Service(config, options) {
   this.projectIdRequired = config.projectIdRequired !== false;
 
   if (options.promise) {
-    util.setPromiseOverride(options.promise);
+    util.Promise = options.promise;
   }
 }
 

packages/common/src/util.js

@@ -51,8 +51,6 @@ var errorMessage = format([
   path: '/docs/guides/authentication'
 });
 
-var PromiseOverride;
-
 var missingProjectIdError = new Error(errorMessage);
 
 util.missingProjectIdError = missingProjectIdError;
@@ -634,6 +632,13 @@ function getUserAgentFromPackageJson(packageJson) {
 
 util.getUserAgentFromPackageJson = getUserAgentFromPackageJson;
 
+/**
+ * Rather than making getters and setters for getting the Promise override
+ * let's just store it on the util object and reference that.
+ * By default we'll use the native Promise object.
+ */
+util.Promise = Promise;
+
 /**
  * Wraps a callback style function to conditionally return a promise.
  *
@@ -656,9 +661,7 @@ function promisify(originalMethod) {
       return originalMethod.apply(context, args);
     }
 
-    var PromiseCtor = PromiseOverride || Promise;
-
-    return new PromiseCtor(function(resolve, reject) {
+    return new util.Promise(function(resolve, reject) {
       args.push(function() {
         var callbackArgs = slice.call(arguments);
         var err = callbackArgs.shift();
@@ -708,15 +711,3 @@ function promisifyAll(Class, options) {
 }
 
 util.promisifyAll = promisifyAll;
-
-/**
- * Allows user to override the Promise constructor without the need to touch
- * globals. Override should be ES6 Promise compliant.
- *
- * @param {promise} override
- */
-function setPromiseOverride(override) {
-  PromiseOverride = override;
-}
-
-module.exports.setPromiseOverride = setPromiseOverride;

packages/compute/src/operation.js

@@ -261,6 +261,27 @@ Operation.prototype.listenForEvents_ = function() {
   });
 };
 
+/**
+ * Convenience method that wraps the `complete` and `error` events in a
+ * Promise.
+ *
+ * @return {promise}
+ *
+ * @example
+ * operation.promise().then(function(metadata) {
+ *   // The operation is complete.
+ * }, function(err) {
+ *   // An error occurred during the operation.
+ * });
+ */
+Operation.prototype.promise = function() {
+  var self = this;
+
+  return new common.util.Promise(function(resolve, reject) {
+    self.on('error', reject).on('complete', resolve);
+  });
+};
+
 /**
  * Poll `getMetadata` to check the operation's status. This runs a loop to ping
  * the API on an interval.