From 365f19c1916a461c430e58a51ffe91ae6e964f59 Mon Sep 17 00:00:00 2001
From: Alexander Early <alexander.early@gmail.com>
Date: Sun, 3 Jun 2018 17:55:26 -0700
Subject: cancellable auto

---
 lib/auto.js  |  9 +++++++--
 test/auto.js | 25 +++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/lib/auto.js b/lib/auto.js
index a6150aa..0175fda 100644
--- a/lib/auto.js
+++ b/lib/auto.js
@@ -102,6 +102,7 @@ export default function (tasks, concurrency, callback) {
 
     var results = {};
     var runningTasks = 0;
+    var canceled = false;
     var hasError = false;
 
     var listeners = Object.create(null);
@@ -156,7 +157,7 @@ export default function (tasks, concurrency, callback) {
     }
 
     function processQueue() {
-        if (readyTasks.length === 0 && runningTasks === 0) {
+        if (readyTasks.length === 0 && runningTasks === 0 && !canceled) {
             return callback(null, results);
         }
         while(readyTasks.length && runningTasks < concurrency) {
@@ -189,6 +190,10 @@ export default function (tasks, concurrency, callback) {
 
         var taskCallback = onlyOnce(function(err, result) {
             runningTasks--;
+            if (err === false) {
+                canceled = true
+                return
+            }
             if (arguments.length > 2) {
                 result = slice(arguments, 1);
             }
@@ -200,7 +205,7 @@ export default function (tasks, concurrency, callback) {
                 safeResults[key] = result;
                 hasError = true;
                 listeners = Object.create(null);
-
+                if (canceled) return
                 callback(err, safeResults);
             } else {
                 results[key] = result;
diff --git a/test/auto.js b/test/auto.js
index 489dbea..1c90135 100644
--- a/test/auto.js
+++ b/test/auto.js
@@ -168,6 +168,31 @@ describe('auto', function () {
         setTimeout(done, 100);
     });
 
+    it('auto canceled', function(done){
+        const call_order = []
+        async.auto({
+            task1: function(callback){
+                call_order.push(1)
+                callback(false);
+            },
+            task2: ['task1', function(/*results, callback*/){
+                call_order.push(2)
+                throw new Error('task2 should not be called');
+            }],
+            task3: function(callback){
+                call_order.push(3)
+                callback('testerror2');
+            }
+        },
+        function(err){
+            throw new Error('should not get here')
+        });
+        setTimeout(() => {
+            expect(call_order).to.eql([1, 3])
+            done()
+        }, 10);
+    });
+
     it('auto no callback', function(done){
         async.auto({
             task1: function(callback){callback();},
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