expose payload again, and allow it to be changed. Closes #744

3 files changed, 33 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 65b27dd..c665896 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ New Features:
 - Various internal updates (#786, #801, #802, #803)
 - Various doc fixes (#790, #794)
 
+Bug Fixes:
+- `cargo` now exposes the `payload` size, and `cargo.payload` can be changed on the fly after the `cargo` is created. (#740, #744, #783)
 
 # v1.2.1
 
diff --git a/lib/async.js b/lib/async.js
index 4c638ef..1547592 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -903,6 +903,7 @@
         var q = {
             tasks: [],
             concurrency: concurrency,
+            payload: payload,
             saturated: noop,
             empty: noop,
             drain: noop,
@@ -921,8 +922,8 @@
             process: function () {
                 if (!q.paused && workers < q.concurrency && q.tasks.length) {
                     while(workers < q.concurrency && q.tasks.length){
-                        var tasks = payload ?
-                            q.tasks.splice(0, payload) :
+                        var tasks = q.payload ?
+                            q.tasks.splice(0, q.payload) :
                             q.tasks.splice(0, q.tasks.length);
 
                         var data = _map(tasks, function (task) {
diff --git a/test/test-async.js b/test/test-async.js
index 52e6a17..821d5fa 100755
--- a/test/test-async.js
+++ b/test/test-async.js
@@ -3797,6 +3797,34 @@ exports['cargo'] = {
     q.push('moo', function () {calls.push('moo cb');});
 },
 
+'expose payload': function (test) {
+    test.expect(5);
+    var called_once = false;
+    var cargo= async.cargo(function(tasks, cb) {
+        if (!called_once) {
+            test.equal(cargo.payload, 1);
+            test.ok(tasks.length === 1, 'should start with payload = 1');
+        } else {
+            test.equal(cargo.payload, 2);
+            test.ok(tasks.length === 2, 'next call shold have payload = 2');
+        }
+        called_once = true;
+        setTimeout(cb, 25);
+    }, 1);
+
+    cargo.drain = function () {
+        test.done();
+    };
+
+    test.equals(cargo.payload, 1);
+
+    cargo.push([1, 2, 3]);
+
+    setTimeout(function () {
+        cargo.payload = 2;
+    }, 15);
+}
+
 };