add Ox.queue

source/Ox/js/Async.js

@@ -284,4 +284,44 @@
     };
     // FIXME: The above test with 10000 iterations blows the stack
 
+
+    /*@
+    Ox.queue <f>
+        cached process queue, passed function is exectued in parallel and
+        results are cached based on all but last argument,
+        last argument is a callback that gets called with results
+        fn <f> function
+        options <o>
+            maxThreads <n> number of concurrent threads
+        callback <f> gets called with object containing duration, width, height
+    @*/
+    Ox.queue = function(fn, options) {
+        var queue = [],
+            threads = 0;
+
+        function process() {
+            var next = Math.min(queue.length, options.maxThreads-threads);
+            if (next) {
+                threads += next;
+                Ox.parallelForEach(queue.splice(0, next), function(args, index, array, done) {
+                    fn.apply(this, args.slice(0, -1).concat(function(result) {
+                        threads--;
+                        args.slice(-1)[0](result);
+                        done();
+                    }));
+                }, process);
+            }
+        }
+
+        return Ox.cache(function() {
+            queue.push(Ox.toArray(arguments));
+            process();
+        }, {
+            async: true,
+            key: function(args) {
+                return JSON.stringify(args.slice(0, -1));
+            }
+        });
+    };
+
 }());