From bbebea0fa57217a59d958715f315c890ed2b0c03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Cs=C3=A1sz=C3=A1r?=
 <dcsaszar@users.noreply.github.com>
Date: Sun, 1 Sep 2024 09:31:52 +0200
Subject: [PATCH 1/4] Refactor: extract postMessage

---
 src/core/ClearStack.js | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/core/ClearStack.js b/src/core/ClearStack.js
index c8b2ed21..a9f645ed 100644
--- a/src/core/ClearStack.js
+++ b/src/core/ClearStack.js
@@ -25,6 +25,23 @@ getJasmineRequireObj().clearStack = function(j$) {
   }
 
   function messageChannelImpl(global) {
+    const { setTimeout } = global;
+    const postMessage = getPostMessage(global);
+
+    let currentCallCount = 0;
+    return function clearStack(fn) {
+      currentCallCount++;
+
+      if (currentCallCount < maxInlineCallCount) {
+        postMessage(fn);
+      } else {
+        currentCallCount = 0;
+        setTimeout(fn);
+      }
+    };
+  }
+
+  function getPostMessage(global) {
     const { MessageChannel, setTimeout } = global;
     const channel = new MessageChannel();
     let head = {};
@@ -48,17 +65,9 @@ getJasmineRequireObj().clearStack = function(j$) {
       }
     };
 
-    let currentCallCount = 0;
-    return function clearStack(fn) {
-      currentCallCount++;
-
-      if (currentCallCount < maxInlineCallCount) {
-        tail = tail.next = { task: fn };
-        channel.port2.postMessage(0);
-      } else {
-        currentCallCount = 0;
-        setTimeout(fn);
-      }
+    return function postMessage(fn) {
+      tail = tail.next = { task: fn };
+      channel.port2.postMessage(0);
     };
   }
 

From 1c743566913f9b2451153de488775fccbf73b821 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Cs=C3=A1sz=C3=A1r?=
 <dcsaszar@users.noreply.github.com>
Date: Sun, 1 Sep 2024 09:37:47 +0200
Subject: [PATCH 2/4] Add unclampedSetTimeout helper

---
 src/core/ClearStack.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/core/ClearStack.js b/src/core/ClearStack.js
index a9f645ed..29ec3688 100644
--- a/src/core/ClearStack.js
+++ b/src/core/ClearStack.js
@@ -41,6 +41,18 @@ getJasmineRequireObj().clearStack = function(j$) {
     };
   }
 
+  function getUnclampedSetTimeout(global) {
+    const { setTimeout } = global;
+    if (j$.util.isUndefined(global.MessageChannel)) return setTimeout;
+
+    const postMessage = getPostMessage(global);
+    return function unclampedSetTimeout(fn) {
+      postMessage(function() {
+        setTimeout(fn);
+      });
+    };
+  }
+
   function getPostMessage(global) {
     const { MessageChannel, setTimeout } = global;
     const channel = new MessageChannel();

From acc777c2678746681de37c06df617bd9f5f29f96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Cs=C3=A1sz=C3=A1r?=
 <dcsaszar@users.noreply.github.com>
Date: Sun, 1 Sep 2024 09:41:41 +0200
Subject: [PATCH 3/4] Unclamp setTimeout in Safari

Fixes #2008

wrapping setTimeout in postMessage is a trade-off between
* slowdown due to postMessage (slow on Safari)
* speedup due to no setTimeout clamping (can be severe on Safari)
---
 src/core/ClearStack.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/core/ClearStack.js b/src/core/ClearStack.js
index 29ec3688..3ae237f0 100644
--- a/src/core/ClearStack.js
+++ b/src/core/ClearStack.js
@@ -2,7 +2,8 @@ getJasmineRequireObj().clearStack = function(j$) {
   const maxInlineCallCount = 10;
 
   function browserQueueMicrotaskImpl(global) {
-    const { setTimeout, queueMicrotask } = global;
+    const unclampedSetTimeout = getUnclampedSetTimeout(global);
+    const { queueMicrotask } = global;
     let currentCallCount = 0;
     return function clearStack(fn) {
       currentCallCount++;
@@ -11,7 +12,7 @@ getJasmineRequireObj().clearStack = function(j$) {
         queueMicrotask(fn);
       } else {
         currentCallCount = 0;
-        setTimeout(fn);
+        unclampedSetTimeout(fn);
       }
     };
   }

From 35f16e812509826a2b94b282a6b1532073662bb6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Cs=C3=A1sz=C3=A1r?=
 <dcsaszar@users.noreply.github.com>
Date: Sun, 1 Sep 2024 10:22:16 +0200
Subject: [PATCH 4/4] Add test for unclamping setTimeout in Safari

---
 spec/core/ClearStackSpec.js | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/spec/core/ClearStackSpec.js b/spec/core/ClearStackSpec.js
index b60aee7e..2e846ffc 100644
--- a/spec/core/ClearStackSpec.js
+++ b/spec/core/ClearStackSpec.js
@@ -20,6 +20,32 @@ describe('ClearStack', function() {
         MessageChannel: fakeMessageChannel
       };
     });
+
+    it('uses MessageChannel to reduce setTimeout clamping', function() {
+      const fakeChannel = fakeMessageChannel();
+      spyOn(fakeChannel.port2, 'postMessage');
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const global = {
+        navigator: {
+          userAgent:
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.0.8 (KHTML, like Gecko) Version/15.1 Safari/605.0.8'
+        },
+        MessageChannel: function() {
+          return fakeChannel;
+        },
+        queueMicrotask
+      };
+
+      const clearStack = jasmineUnderTest.getClearStack(global);
+
+      for (let i = 0; i < 9; i++) clearStack(function() {});
+
+      expect(fakeChannel.port2.postMessage).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(1);
+    });
   });
 
   describe("in WebKit (Playwright's build for Windows)", function() {