Don't allocate an additional array in Promise.each

Closes #1057
petkaantonov · Aug 29, 2016 · b26b205 · b26b205
1 parent 5a381ab
commit b26b205
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Showing 3 changed files with 19 additions and 9 deletions.
diff --git a/src/each.js b/src/each.js
@@ -12,18 +12,19 @@ function PromiseMapSeries(promises, fn) {
 }
 
 Promise.prototype.each = function (fn) {
-    return this.mapSeries(fn)
-            ._then(promiseAllThis, undefined, undefined, this, undefined);
+    return PromiseReduce(this, fn, INTERNAL, 0)
+              ._then(promiseAllThis, undefined, undefined, this, undefined);
 };
 
 Promise.prototype.mapSeries = function (fn) {
     return PromiseReduce(this, fn, INTERNAL, INTERNAL);
 };
 
 Promise.each = function (promises, fn) {
-    return PromiseMapSeries(promises, fn)
-            ._then(promiseAllThis, undefined, undefined, promises, undefined);
+    return PromiseReduce(promises, fn, INTERNAL, 0)
+              ._then(promiseAllThis, undefined, undefined, promises, undefined);
 };
 
 Promise.mapSeries = PromiseMapSeries;
 };
+
diff --git a/src/map.js b/src/map.js
@@ -10,7 +10,6 @@ var getDomain = Promise._getDomain;
 var util = require("./util");
 var tryCatch = util.tryCatch;
 var errorObj = util.errorObj;
-var EMPTY_ARRAY = [];
 
 function MappingPromiseArray(promises, fn, limit, _filter) {
     this.constructor$(promises);
@@ -22,7 +21,7 @@ function MappingPromiseArray(promises, fn, limit, _filter) {
         : null;
     this._limit = limit;
     this._inFlight = 0;
-    this._queue = limit >= 1 ? [] : EMPTY_ARRAY;
+    this._queue = [];
     this._init$(undefined, RESOLVE_ARRAY);
 }
 util.inherits(MappingPromiseArray, PromiseArray);

diff --git a/src/reduce.js b/src/reduce.js
@@ -19,20 +19,30 @@ function ReductionPromiseArray(promises, fn, initialValue, _each) {
     }
     this._initialValue = initialValue;
     this._currentCancellable = null;
-    this._eachValues = _each === INTERNAL ? [] : undefined;
+    if(_each === INTERNAL) {
+        this._eachValues = Array(this._length);
+    } else if (_each === 0) {
+        this._eachValues = null;
+    } else {
+        this._eachValues = undefined;
+    }
     this._promise._captureStackTrace();
     this._init$(undefined, RESOLVE_CALL_METHOD);
 }
 util.inherits(ReductionPromiseArray, PromiseArray);
 
 ReductionPromiseArray.prototype._gotAccum = function(accum) {
-    if (this._eachValues !== undefined && accum !== INTERNAL) {
+    if (this._eachValues !== undefined && 
+        this._eachValues !== undefined && 
+        accum !== INTERNAL) {
         this._eachValues.push(accum);
     }
 };
 
 ReductionPromiseArray.prototype._eachComplete = function(value) {
-    this._eachValues.push(value);
+    if (this._eachValues !== null) {
+        this._eachValues.push(value);
+    }
     return this._eachValues;
 };