From 00dfd0d07cbb23ad637a99ab72d528fc61767219 Mon Sep 17 00:00:00 2001
From: Austin Bales <arbales@gmail.com>
Date: Sat, 16 Jul 2011 12:00:02 -0700
Subject: [PATCH 1/2] In PeriodicalExcuter, removed unnecessary
 `currentlyExecuting` ivar and other code relating to parallel execution.

---
 src/prototype/lang/periodical_executer.js | 31 +++++++----------------
 test/unit/periodical_executer_test.js     | 20 ---------------
 2 files changed, 9 insertions(+), 42 deletions(-)

diff --git a/src/prototype/lang/periodical_executer.js b/src/prototype/lang/periodical_executer.js
index aa3b97715..49bc02671 100644
--- a/src/prototype/lang/periodical_executer.js
+++ b/src/prototype/lang/periodical_executer.js
@@ -31,13 +31,18 @@ var PeriodicalExecuter = Class.create({
   initialize: function(callback, frequency) {
     this.callback = callback;
     this.frequency = frequency;
-    this.currentlyExecuting = false;
 
-    this.registerCallback();
+    this.start();
   },
 
-  registerCallback: function() {
-    this.timer = setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
+  /**
+   *  PeriodicalExecuter#start() -> undefined
+   *
+   *  Starts the [[PeriodicalExecuter]] or restarts it if `#stop`
+   *  was previously called.
+  **/
+  start: function() {
+    this.timer = setInterval(this.execute.bind(this), this.frequency * 1000);
   },
 
   execute: function() {
@@ -71,22 +76,4 @@ var PeriodicalExecuter = Class.create({
     clearInterval(this.timer);
     this.timer = null;
   },
-
-  onTimerEvent: function() {
-    if (!this.currentlyExecuting) {
-      // IE doesn't support `finally` statements unless all errors are caught.
-      // We mimic the behaviour of `finally` statements by duplicating code
-      // that would belong in it. First at the bottom of the `try` statement
-      // (for errorless cases). Secondly, inside a `catch` statement which
-      // rethrows any caught errors.
-      try {
-        this.currentlyExecuting = true;
-        this.execute();
-        this.currentlyExecuting = false;
-      } catch(e) {
-        this.currentlyExecuting = false;
-        throw e;
-      }
-    }
-  }
 });
diff --git a/test/unit/periodical_executer_test.js b/test/unit/periodical_executer_test.js
index 4fa19099b..6ce6ba955 100644
--- a/test/unit/periodical_executer_test.js
+++ b/test/unit/periodical_executer_test.js
@@ -12,24 +12,4 @@ new Test.Unit.Runner({
       this.assertEqual(3, peEventCount);
     });
   },
-
-  testOnTimerEventMethod: function() {
-    var testcase = this,
-        pe = {
-          onTimerEvent: PeriodicalExecuter.prototype.onTimerEvent,
-          execute: function() {
-            testcase.assert(pe.currentlyExecuting);
-          }
-        };
-
-    pe.onTimerEvent();
-    this.assert(!pe.currentlyExecuting);
-
-    pe.execute = function() {
-      testcase.assert(pe.currentlyExecuting);
-      throw new Error()
-    }
-    this.assertRaise('Error', pe.onTimerEvent.bind(pe));
-    this.assert(!pe.currentlyExecuting);
-  }
 });
\ No newline at end of file

From 2b67f9e1be0658cc9eab9ac6416020a951362fed Mon Sep 17 00:00:00 2001
From: Austin Bales <arbales@gmail.com>
Date: Sat, 16 Jul 2011 12:10:22 -0700
Subject: [PATCH 2/2] Check to ensure that `this.timer` doesn't exist before
 assigning it in `#start`

---
 src/prototype/lang/periodical_executer.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/prototype/lang/periodical_executer.js b/src/prototype/lang/periodical_executer.js
index 49bc02671..5eb79220b 100644
--- a/src/prototype/lang/periodical_executer.js
+++ b/src/prototype/lang/periodical_executer.js
@@ -42,7 +42,7 @@ var PeriodicalExecuter = Class.create({
    *  was previously called.
   **/
   start: function() {
-    this.timer = setInterval(this.execute.bind(this), this.frequency * 1000);
+    if (!this.timer) this.timer = setInterval(this.execute.bind(this), this.frequency * 1000);
   },
 
   execute: function() {