如掉 async 模块引用

lib/async.js

@@ -0,0 +1,56 @@
+var eachLimit = function (arr, limit, iterator, callback) {
+    callback = callback || function () {};
+    if (!arr.length || limit <= 0) {
+        return callback();
+    }
+
+    var completed = 0;
+    var started = 0;
+    var running = 0;
+
+    (function replenish () {
+        if (completed >= arr.length) {
+            return callback();
+        }
+
+        while (running < limit && started < arr.length) {
+            started += 1;
+            running += 1;
+            iterator(arr[started - 1], function (err) {
+
+                if (err) {
+                    callback(err);
+                    callback = function () {};
+                } else {
+                    completed += 1;
+                    running -= 1;
+                    if (completed >= arr.length) {
+                        callback();
+                    } else {
+                        replenish();
+                    }
+                }
+            });
+        }
+    })();
+};
+
+var retry = function (times, iterator, callback) {
+    var next = function (index) {
+        iterator(function (err, data) {
+            if (err && index < times) {
+                next(index + 1);
+            } else {
+                callback(err, data);
+            }
+        });
+    };
+    next(1);
+};
+
+var async = {
+    eachLimit: eachLimit,
+    retry: retry
+};
+
+module.exports = async;