From f1263b393f8a24d8a86636e1445921287908d92a Mon Sep 17 00:00:00 2001
From: Alexander Early <aearly@fluid.com>
Date: Mon, 1 Jun 2015 19:19:34 -0700
Subject: [PATCH] add timesLimit.  Closes #743

---
 lib/async.js       | 26 +++++++++++++-------------
 test/test-async.js | 42 +++++++++++++++++++++++++++++++-----------
 2 files changed, 44 insertions(+), 24 deletions(-)

diff --git a/lib/async.js b/lib/async.js
index abc1f7b29..add42193a 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -93,6 +93,10 @@
       return result;
     }
 
+    function _range(count) {
+        return _map(Array(count), function (v, i) { return i; });
+    }
+
     function _reduce(arr, iterator, memo) {
         _arrayEach(arr, function (x, i, a) {
             memo = iterator(memo, x, i, a);
@@ -1056,20 +1060,16 @@
       };
     };
 
-    async.times = function (count, iterator, callback) {
-        var counter = [];
-        for (var i = 0; i < count; i++) {
-            counter.push(i);
-        }
-        return async.map(counter, iterator, callback);
-    };
+    function _times(mapper) {
+        return function (count, iterator, callback) {
+            mapper(_range(count), iterator, callback);
+        };
+    }
 
-    async.timesSeries = function (count, iterator, callback) {
-        var counter = [];
-        for (var i = 0; i < count; i++) {
-            counter.push(i);
-        }
-        return async.mapSeries(counter, iterator, callback);
+    async.times = _times(async.map);
+    async.timesSeries = _times(async.mapSeries);
+    async.timesLimit = function (count, limit, iterator, callback) {
+        return async.mapLimit(_range(count), limit, iterator, callback);
     };
 
     async.seq = function (/* functions... */) {
diff --git a/test/test-async.js b/test/test-async.js
index 113ac0719..14ea48426 100755
--- a/test/test-async.js
+++ b/test/test-async.js
@@ -2347,8 +2347,9 @@ var console_fn_tests = function(name){
 };
 
 
+exports['times'] = {
 
-exports['times'] = function(test) {
+'times': function(test) {
   async.times(5, function(n, next) {
     next(null, n);
   }, function(err, results) {
@@ -2356,9 +2357,9 @@ exports['times'] = function(test) {
     test.same(results, [0,1,2,3,4]);
     test.done();
   });
-};
+},
 
-exports['times'] = function(test){
+'times 3': function(test){
     var args = [];
     async.times(3, function(n, callback){
         setTimeout(function(){
@@ -2370,9 +2371,9 @@ exports['times'] = function(test){
         test.same(args, [0,1,2]);
         test.done();
     });
-};
+},
 
-exports['times 0'] = function(test){
+'times 0': function(test){
     test.expect(1);
     async.times(0, function(n, callback){
         test.ok(false, 'iterator should not be called');
@@ -2382,9 +2383,9 @@ exports['times 0'] = function(test){
         test.ok(true, 'should call callback');
     });
     setTimeout(test.done, 25);
-};
+},
 
-exports['times error'] = function(test){
+'times error': function(test){
     test.expect(1);
     async.times(3, function(n, callback){
         callback('error');
@@ -2392,9 +2393,9 @@ exports['times error'] = function(test){
         test.equals(err, 'error');
     });
     setTimeout(test.done, 50);
-};
+},
 
-exports['timesSeries'] = function(test){
+'timesSeries': function(test){
     var call_order = [];
     async.timesSeries(5, function(n, callback){
         setTimeout(function(){
@@ -2406,9 +2407,9 @@ exports['timesSeries'] = function(test){
         test.same(results, [0,1,2,3,4]);
         test.done();
     });
-};
+},
 
-exports['timesSeries error'] = function(test){
+'timesSeries error': function(test){
     test.expect(1);
     async.timesSeries(5, function(n, callback){
         callback('error');
@@ -2416,6 +2417,25 @@ exports['timesSeries error'] = function(test){
         test.equals(err, 'error');
     });
     setTimeout(test.done, 50);
+},
+
+'timesLimit': function(test){
+    var limit = 2;
+    var running = 0;
+    async.timesLimit(5, limit, function (i, next) {
+        running++;
+        test.ok(running <= limit && running > 0, running);
+        setTimeout(function () {
+            running--;
+            next(null, i * 2);
+        }, (3 - i) * 10);
+    }, function(err, results){
+        test.ok(err === null, err + " passed instead of 'null'");
+        test.same(results, [0, 2, 4, 6, 8]);
+        test.done();
+    });
+}
+
 };
 
 console_fn_tests('log');