Execute queries in Fibers to support yielding APIs. (#92)

* Execute queries in Fibers to support yielding APIs.

See also: https://github.com/meteor/promise/blob/master/promise.d.ts

* Improve comment about Promise.await.

* Don't make Promises aware of Fibers except in tests.

The Promise used by Meteor will already be Fiber-enabled, so calling
makeCompatible in the tests is just simulating running in a Meteor
environment.

package.json

@@ -49,12 +49,14 @@
     "chai": "^3.5.0",
     "connect": "^3.4.1",
     "express": "^4.14.0",
+    "fibers": "^1.0.13",
     "graphql": "^0.6.1",
     "hapi": "^14.0.0",
     "istanbul": "1.0.0-alpha.2",
     "koa": "^2.0.0-alpha.4",
     "koa-bodyparser": "^3.0.0",
     "koa-router": "^7.0.1",
+    "meteor-promise": "^0.7.3",
     "mocha": "^3.0.0",
     "multer": "^1.1.0",
     "remap-istanbul": "^0.6.4",

src/core/runQuery.test.ts

@@ -13,6 +13,12 @@ import {
 
 import { runQuery } from './runQuery';
 
+// Make the global Promise constructor Fiber-aware to simulate a Meteor
+// environment.
+import { makeCompatible } from 'meteor-promise';
+import Fiber = require('fibers');
+makeCompatible(Promise, Fiber);
+
 const QueryType = new GraphQLObjectType({
     name: 'QueryType',
     fields: {
@@ -43,6 +49,15 @@ const QueryType = new GraphQLObjectType({
                 base: { type: new GraphQLNonNull(GraphQLInt) },
             },
         },
+        testAwaitedValue: {
+            type: GraphQLString,
+            resolve(root) {
+                // Calling Promise.await is legal here even though this is
+                // not an async function, because we are guaranteed to be
+                // running in a Fiber.
+                return 'it ' + (<any>Promise).await('works');
+            },
+        },
     },
 });
 
@@ -170,6 +185,16 @@ describe('runQuery', () => {
       });
   });
 
+    it('supports yielding resolver functions', () => {
+        return runQuery({
+            schema: Schema,
+            query: `{ testAwaitedValue }`,
+        }).then((res) => {
+            expect(res.data).to.deep.equal({
+                testAwaitedValue: 'it works',
+            });
+        });
+    });
 
     it('runs the correct operation when operationName is specified', () => {
         const query = `

src/core/runQuery.ts

@@ -32,7 +32,14 @@ export interface QueryOptions {
  formatResponse?: Function;
 }
 
+const resolvedPromise = Promise.resolve();
+
 function runQuery(options: QueryOptions): Promise<GraphQLResult> {
+    // Fiber-aware Promises run their .then callbacks in Fibers.
+    return resolvedPromise.then(() => doRunQuery(options));
+}
+
+function doRunQuery(options: QueryOptions): Promise<GraphQLResult> {
     let documentAST: Document;
 
     const logFunction = options.logFunction || function(){ return null; };

tslint.json

@@ -63,7 +63,6 @@
     "no-unused-variable": true,
     "no-use-before-declare": true,
     "no-var-keyword": true,
-    "no-var-requires": true,
     "object-literal-sort-keys": false,
     "one-line": [
       true,

typings.json

@@ -9,8 +9,9 @@
     "connect": "registry:dt/connect#3.4.0+20160317120654",
     "cookies": "registry:dt/cookies#0.5.1+20160316171810",
     "express": "registry:dt/express#4.0.0+20160708185218",
-    "express-serve-static-core": "registry:dt/express-serve-static-core#4.0.0+20160715232503",
-    "hapi": "registry:dt/hapi#13.0.0+20160709092105",
+    "express-serve-static-core": "registry:dt/express-serve-static-core#4.0.0+20160805091045",
+    "fibers": "registry:dt/fibers#0.0.0+20160317120654",
+    "hapi": "registry:dt/hapi#13.0.0+20160803202811",
     "koa": "registry:dt/koa#2.0.0+20160724024233",
     "koa-bodyparser": "registry:dt/koa-bodyparser#3.0.0+20160414124440",
     "koa-router": "registry:dt/koa-router#7.0.0+20160314083221",