Merge branch 'master' into ls-android-readme-tweaksupstream/ls-android-readme-tweaks

1 files changed, 24 insertions, 3 deletions

diff --git a/platform/node/index.js b/platform/node/index.js
index 54ba5c0dc6..5944a0a27d 100644
--- a/platform/node/index.js
+++ b/platform/node/index.js
@@ -4,6 +4,7 @@
 
 var mbgl = require('../../lib/mapbox_gl_native.node');
 var constructor = mbgl.Map.prototype.constructor;
+var process = require('process');
 
 var Map = function(options) {
     if (!(options instanceof Object)) {
@@ -18,9 +19,29 @@ var Map = function(options) {
 
     return new constructor(Object.assign(options, {
         request: function(req) {
-            request(req, function() {
-                req.respond.apply(req, arguments);
-            });
+            // Protect against `request` implementations that call the callback synchronously,
+            // call it multiple times, or throw exceptions.
+            // http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony
+
+            var responded = false;
+            var callback = function() {
+                var args = arguments;
+                if (!responded) {
+                    responded = true;
+                    process.nextTick(function() {
+                        req.respond.apply(req, args);
+                    });
+                } else {
+                    console.warn('request function responded multiple times; it should call the callback only once');
+                }
+            };
+
+            try {
+                request(req, callback);
+            } catch (e) {
+                console.warn('request function threw an exception; it should call the callback with an error instead');
+                callback(e);
+            }
         }
     }));
 };