From 79c6bbc1891d1f61e7950f10ce6511529f068003 Mon Sep 17 00:00:00 2001
From: Steve Gravrock <sdg@panix.com>
Date: Sat, 13 Aug 2022 08:54:32 -0700
Subject: [PATCH] clearStack optimizations

* Avoid setTimeout in Node, because we don't need the overhead there.
* Still call setTimeout in browsers to prevent the tab from being killed.
* Use queueMicrotask in Safari, because it's dramatically faster than
  MessageChannel there.
* Continue to use MessageChannel in other supported browsers becuase it's
  somewhat faster than queueMicrotask there.
* Don't use setImmediate any more because there's a faster alternative in
  all supported envs.

In jasmine-core's own test suite, this yields a roughly 50-70% speedup
in Node, ~20% in Edge, and 75-90%(!) in Safari.
---
 lib/jasmine-core/jasmine.js      |  72 ++++---
 spec/core/ClearStackSpec.js      | 326 ++++++++++++++++++-------------
 spec/core/integration/EnvSpec.js |  39 +++-
 src/core/ClearStack.js           |  72 ++++---
 4 files changed, 322 insertions(+), 187 deletions(-)

diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index 6a429e53..534da5df 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -2789,8 +2789,32 @@ getJasmineRequireObj().CallTracker = function(j$) {
 getJasmineRequireObj().clearStack = function(j$) {
   const maxInlineCallCount = 10;
 
-  function messageChannelImpl(global, setTimeout) {
-    const channel = new global.MessageChannel();
+  function browserQueueMicrotaskImpl(global) {
+    const { setTimeout, queueMicrotask } = global;
+    let currentCallCount = 0;
+    return function clearStack(fn) {
+      currentCallCount++;
+
+      if (currentCallCount < maxInlineCallCount) {
+        queueMicrotask(fn);
+      } else {
+        currentCallCount = 0;
+        setTimeout(fn);
+      }
+    };
+  }
+
+  function nodeQueueMicrotaskImpl(global) {
+    const { queueMicrotask } = global;
+
+    return function(fn) {
+      queueMicrotask(fn);
+    };
+  }
+
+  function messageChannelImpl(global) {
+    const { MessageChannel, setTimeout } = global;
+    const channel = new MessageChannel();
     let head = {};
     let tail = head;
 
@@ -2801,7 +2825,7 @@ getJasmineRequireObj().clearStack = function(j$) {
       delete head.task;
 
       if (taskRunning) {
-        global.setTimeout(task, 0);
+        setTimeout(task, 0);
       } else {
         try {
           taskRunning = true;
@@ -2827,29 +2851,31 @@ getJasmineRequireObj().clearStack = function(j$) {
   }
 
   function getClearStack(global) {
-    let currentCallCount = 0;
-    const realSetTimeout = global.setTimeout;
-    const setTimeoutImpl = function clearStack(fn) {
-      Function.prototype.apply.apply(realSetTimeout, [global, [fn, 0]]);
-    };
+    const NODE_JS =
+      global.process &&
+      global.process.versions &&
+      typeof global.process.versions.node === 'string';
 
-    if (j$.isFunction_(global.setImmediate)) {
-      const realSetImmediate = global.setImmediate;
-      return function(fn) {
-        currentCallCount++;
+    const SAFARI =
+      global.navigator &&
+      /^((?!chrome|android).)*safari/i.test(global.navigator.userAgent);
 
-        if (currentCallCount < maxInlineCallCount) {
-          realSetImmediate(fn);
-        } else {
-          currentCallCount = 0;
-
-          setTimeoutImpl(fn);
-        }
-      };
-    } else if (!j$.util.isUndefined(global.MessageChannel)) {
-      return messageChannelImpl(global, setTimeoutImpl);
+    if (NODE_JS) {
+      // Unlike browsers, Node doesn't require us to do a periodic setTimeout
+      // so we avoid the overhead.
+      return nodeQueueMicrotaskImpl(global);
+    } else if (
+      SAFARI ||
+      j$.util.isUndefined(global.MessageChannel) /* tests */
+    ) {
+      // queueMicrotask is dramatically faster than MessageChannel in Safari.
+      // Some of our own integration tests provide a mock queueMicrotask in all
+      // environments because it's simpler to mock than MessageChannel.
+      return browserQueueMicrotaskImpl(global);
     } else {
-      return setTimeoutImpl;
+      // MessageChannel is faster than queueMicrotask in supported browsers
+      // other than Safari.
+      return messageChannelImpl(global);
     }
   }
 
diff --git a/spec/core/ClearStackSpec.js b/spec/core/ClearStackSpec.js
index 1cfaf6ad..626969f5 100644
--- a/spec/core/ClearStackSpec.js
+++ b/spec/core/ClearStackSpec.js
@@ -9,160 +9,216 @@ describe('ClearStack', function() {
     });
   });
 
-  it('uses setImmediate when available', function() {
-    const setImmediate = jasmine
-        .createSpy('setImmediate')
-        .and.callFake(function(fn) {
-          fn();
-        }),
-      global = { setImmediate: setImmediate },
-      clearStack = jasmineUnderTest.getClearStack(global);
-    let called = false;
+  describe('in Safari', function() {
+    usesQueueMicrotaskWithSetTimeout(function() {
+      return {
+        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'
+        },
+        // queueMicrotask should be used even though MessageChannel is present
+        MessageChannel: fakeMessageChannel
+      };
+    });
+  });
 
-    clearStack(function() {
-      called = true;
+  describe('in browsers other than Safari', function() {
+    usesMessageChannel(function() {
+      return {
+        navigator: {
+          // Chrome's user agent string contains "Safari" so it's a good test case
+          userAgent:
+            'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36'
+        }
+      };
     });
 
-    expect(called).toBe(true);
-    expect(setImmediate).toHaveBeenCalled();
+    describe('when MessageChannel is unavailable', function() {
+      usesQueueMicrotaskWithSetTimeout(function() {
+        return {
+          navigator: {
+            userAgent: 'CERN-LineMode/2.15 libwww/2.17b3',
+            MessageChannel: undefined
+          }
+        };
+      });
+    });
   });
 
-  it('uses setTimeout instead of setImmediate every 10 calls to make sure we release the CPU', function() {
-    const setImmediate = jasmine.createSpy('setImmediate'),
-      setTimeout = jasmine.createSpy('setTimeout'),
-      global = { setImmediate: setImmediate, setTimeout: setTimeout },
-      clearStack = jasmineUnderTest.getClearStack(global);
-
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-
-    expect(setImmediate).toHaveBeenCalled();
-    expect(setTimeout).not.toHaveBeenCalled();
-
-    clearStack(function() {});
-    expect(setImmediate.calls.count()).toEqual(9);
-    expect(setTimeout.calls.count()).toEqual(1);
-
-    clearStack(function() {});
-    expect(setImmediate.calls.count()).toEqual(10);
-    expect(setTimeout.calls.count()).toEqual(1);
-  });
-
-  it('uses MessageChannels when available', function() {
-    const fakeChannel = {
-        port1: {},
-        port2: {
-          postMessage: function() {
-            fakeChannel.port1.onmessage();
+  describe('in Node', function() {
+    usesQueueMicrotaskWithoutSetTimeout(function() {
+      return {
+        process: {
+          versions: {
+            node: '3.1415927'
           }
         }
-      },
-      global = {
-        MessageChannel: function() {
-          return fakeChannel;
-        }
-      },
-      clearStack = jasmineUnderTest.getClearStack(global);
-    let called = false;
+      };
+    });
+  });
 
-    clearStack(function() {
-      called = true;
+  function usesMessageChannel(makeGlobal) {
+    it('uses MessageChannel', function() {
+      const global = {
+        ...makeGlobal(),
+        MessageChannel: fakeMessageChannel
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+      let called = false;
+
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
     });
 
-    expect(called).toBe(true);
-  });
-
-  it('uses setTimeout instead of MessageChannel every 10 calls to make sure we release the CPU', function() {
-    const fakeChannel = {
-        port1: {},
-        port2: {
-          postMessage: jasmine
-            .createSpy('postMessage')
-            .and.callFake(function() {
-              fakeChannel.port1.onmessage();
-            })
-        }
-      },
-      setTimeout = jasmine.createSpy('setTimeout'),
-      global = {
+    it('uses setTimeout instead of MessageChannel every 10 calls to make sure we release the CPU', function() {
+      const fakeChannel = fakeMessageChannel();
+      spyOn(fakeChannel.port2, 'postMessage');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        setTimeout,
         MessageChannel: function() {
           return fakeChannel;
-        },
-        setTimeout: setTimeout
-      },
-      clearStack = jasmineUnderTest.getClearStack(global);
-
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-    clearStack(function() {});
-
-    expect(fakeChannel.port2.postMessage).toHaveBeenCalled();
-    expect(setTimeout).not.toHaveBeenCalled();
-
-    clearStack(function() {});
-    expect(fakeChannel.port2.postMessage.calls.count()).toEqual(9);
-    expect(setTimeout.calls.count()).toEqual(1);
-
-    clearStack(function() {});
-    expect(fakeChannel.port2.postMessage.calls.count()).toEqual(10);
-    expect(setTimeout.calls.count()).toEqual(1);
-  });
-
-  it('calls setTimeout when onmessage is called recursively', function() {
-    const fakeChannel = {
-        port1: {},
-        port2: {
-          postMessage: function() {
-            fakeChannel.port1.onmessage();
-          }
         }
-      },
-      setTimeout = jasmine.createSpy('setTimeout'),
-      global = {
-        MessageChannel: function() {
-          return fakeChannel;
-        },
-        setTimeout: setTimeout
-      },
-      clearStack = jasmineUnderTest.getClearStack(global),
-      fn = jasmine.createSpy('second clearStack function');
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
 
-    clearStack(function() {
-      clearStack(fn);
+      for (let i = 0; i < 9; i++) {
+        clearStack(function() {});
+      }
+
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalled();
+      expect(setTimeout).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(9);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+
+      clearStack(function() {});
+      expect(fakeChannel.port2.postMessage).toHaveBeenCalledTimes(10);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
     });
 
-    expect(fn).not.toHaveBeenCalled();
-    expect(setTimeout).toHaveBeenCalledWith(fn, 0);
-  });
+    it('calls setTimeout when onmessage is called recursively', function() {
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        setTimeout,
+        MessageChannel: fakeMessageChannel
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+      const fn = jasmine.createSpy('second clearStack function');
 
-  it('falls back to setTimeout', function() {
-    const setTimeout = jasmine
-        .createSpy('setTimeout')
-        .and.callFake(function(fn) {
+      clearStack(function() {
+        clearStack(fn);
+      });
+
+      expect(fn).not.toHaveBeenCalled();
+      expect(setTimeout).toHaveBeenCalledWith(fn, 0);
+    });
+  }
+
+  function usesQueueMicrotaskWithSetTimeout(makeGlobal) {
+    it('uses queueMicrotask', function() {
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask: function(fn) {
           fn();
-        }),
-      global = { setTimeout: setTimeout },
-      clearStack = jasmineUnderTest.getClearStack(global);
-    let called = false;
+        }
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+      let called = false;
 
-    clearStack(function() {
-      called = true;
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
     });
 
-    expect(called).toBe(true);
-    expect(setTimeout).toHaveBeenCalledWith(jasmine.any(Function), 0);
-  });
+    it('uses setTimeout instead of queueMicrotask every 10 calls to make sure we release the CPU', function() {
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask,
+        setTimeout
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+
+      for (let i = 0; i < 9; i++) {
+        clearStack(function() {});
+      }
+
+      expect(queueMicrotask).toHaveBeenCalled();
+      expect(setTimeout).not.toHaveBeenCalled();
+
+      clearStack(function() {});
+      expect(queueMicrotask).toHaveBeenCalledTimes(9);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+
+      clearStack(function() {});
+      expect(queueMicrotask).toHaveBeenCalledTimes(10);
+      expect(setTimeout).toHaveBeenCalledTimes(1);
+    });
+  }
+
+  function usesQueueMicrotaskWithoutSetTimeout(makeGlobal) {
+    it('uses queueMicrotask', function() {
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask: function(fn) {
+          fn();
+        }
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+      let called = false;
+
+      clearStack(function() {
+        called = true;
+      });
+
+      expect(called).toBe(true);
+    });
+
+    it('does not use setTimeout', function() {
+      const queueMicrotask = jasmine.createSpy('queueMicrotask');
+      const setTimeout = jasmine.createSpy('setTimeout');
+      const global = {
+        ...makeGlobal(),
+        queueMicrotask,
+        setTimeout
+      };
+      const clearStack = jasmineUnderTest.getClearStack(global);
+
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+      clearStack(function() {});
+
+      expect(queueMicrotask).toHaveBeenCalledTimes(10);
+      expect(setTimeout).not.toHaveBeenCalled();
+    });
+  }
+
+  function fakeMessageChannel() {
+    const channel = {
+      port1: {},
+      port2: {
+        postMessage: function() {
+          channel.port1.onmessage();
+        }
+      }
+    };
+    return channel;
+  }
 });
diff --git a/spec/core/integration/EnvSpec.js b/spec/core/integration/EnvSpec.js
index 01533038..92f27ad4 100644
--- a/spec/core/integration/EnvSpec.js
+++ b/spec/core/integration/EnvSpec.js
@@ -436,6 +436,9 @@ describe('Env integration', function() {
         },
         clearTimeout: function(fn, delay) {
           clearTimeout(fn, delay);
+        },
+        queueMicrotask: function(fn) {
+          queueMicrotask(fn);
         }
       };
       spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -473,6 +476,9 @@ describe('Env integration', function() {
           },
           clearTimeout: function(fn) {
             clearTimeout(fn);
+          },
+          queueMicrotask: function(fn) {
+            queueMicrotask(fn);
           }
         };
         spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -529,6 +535,9 @@ describe('Env integration', function() {
         },
         clearTimeout: function(fn, delay) {
           clearTimeout(fn, delay);
+        },
+        queueMicrotask: function(fn) {
+          queueMicrotask(fn);
         }
       };
       spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -545,8 +554,8 @@ describe('Env integration', function() {
         env.it('fails', function(specDone) {
           setTimeout(function() {
             specDone();
-            setTimeout(function() {
-              setTimeout(function() {
+            queueMicrotask(function() {
+              queueMicrotask(function() {
                 global.onerror('fail');
               });
             });
@@ -578,6 +587,9 @@ describe('Env integration', function() {
           },
           clearTimeout: function(fn, delay) {
             clearTimeout(fn, delay);
+          },
+          queueMicrotask: function(fn) {
+            queueMicrotask(fn);
           }
         };
         spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -638,6 +650,9 @@ describe('Env integration', function() {
           },
           clearTimeout: function(fn, delay) {
             clearTimeout(fn, delay);
+          },
+          queueMicrotask: function(fn) {
+            queueMicrotask(fn);
           }
         };
         spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -677,6 +692,9 @@ describe('Env integration', function() {
         },
         clearTimeout: function(fn) {
           clearTimeout(fn);
+        },
+        queueMicrotask: function(fn) {
+          queueMicrotask(fn);
         }
       };
       spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -1427,8 +1445,8 @@ describe('Env integration', function() {
       global: {
         setTimeout: globalSetTimeout,
         clearTimeout: clearTimeout,
-        setImmediate: function(cb) {
-          return setTimeout(cb, 0);
+        queueMicrotask: function(fn) {
+          queueMicrotask(fn);
         }
       }
     });
@@ -1501,8 +1519,8 @@ describe('Env integration', function() {
           clearTimeout: clearTimeout,
           setInterval: setInterval,
           clearInterval: clearInterval,
-          setImmediate: function(cb) {
-            return realSetTimeout(cb, 0);
+          queueMicrotask: function(fn) {
+            queueMicrotask(fn);
           }
         }
       });
@@ -2625,6 +2643,9 @@ describe('Env integration', function() {
       clearTimeout: function(fn, delay) {
         clearTimeout(fn, delay);
       },
+      queueMicrotask: function(fn) {
+        queueMicrotask(fn);
+      },
       onerror: function() {}
     };
     spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -2680,6 +2701,9 @@ describe('Env integration', function() {
         clearTimeout: function(fn, delay) {
           clearTimeout(fn, delay);
         },
+        queueMicrotask: function(fn) {
+          queueMicrotask(fn);
+        },
         onerror: originalOnerror
       };
       spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
@@ -2869,6 +2893,9 @@ describe('Env integration', function() {
           },
           clearTimeout: function(fn, delay) {
             return clearTimeout(fn, delay);
+          },
+          queueMicrotask: function(fn) {
+            queueMicrotask(fn);
           }
         };
         spyOn(jasmineUnderTest, 'getGlobal').and.returnValue(global);
diff --git a/src/core/ClearStack.js b/src/core/ClearStack.js
index 3d864244..ced9605a 100644
--- a/src/core/ClearStack.js
+++ b/src/core/ClearStack.js
@@ -1,8 +1,32 @@
 getJasmineRequireObj().clearStack = function(j$) {
   const maxInlineCallCount = 10;
 
-  function messageChannelImpl(global, setTimeout) {
-    const channel = new global.MessageChannel();
+  function browserQueueMicrotaskImpl(global) {
+    const { setTimeout, queueMicrotask } = global;
+    let currentCallCount = 0;
+    return function clearStack(fn) {
+      currentCallCount++;
+
+      if (currentCallCount < maxInlineCallCount) {
+        queueMicrotask(fn);
+      } else {
+        currentCallCount = 0;
+        setTimeout(fn);
+      }
+    };
+  }
+
+  function nodeQueueMicrotaskImpl(global) {
+    const { queueMicrotask } = global;
+
+    return function(fn) {
+      queueMicrotask(fn);
+    };
+  }
+
+  function messageChannelImpl(global) {
+    const { MessageChannel, setTimeout } = global;
+    const channel = new MessageChannel();
     let head = {};
     let tail = head;
 
@@ -13,7 +37,7 @@ getJasmineRequireObj().clearStack = function(j$) {
       delete head.task;
 
       if (taskRunning) {
-        global.setTimeout(task, 0);
+        setTimeout(task, 0);
       } else {
         try {
           taskRunning = true;
@@ -39,29 +63,31 @@ getJasmineRequireObj().clearStack = function(j$) {
   }
 
   function getClearStack(global) {
-    let currentCallCount = 0;
-    const realSetTimeout = global.setTimeout;
-    const setTimeoutImpl = function clearStack(fn) {
-      Function.prototype.apply.apply(realSetTimeout, [global, [fn, 0]]);
-    };
+    const NODE_JS =
+      global.process &&
+      global.process.versions &&
+      typeof global.process.versions.node === 'string';
 
-    if (j$.isFunction_(global.setImmediate)) {
-      const realSetImmediate = global.setImmediate;
-      return function(fn) {
-        currentCallCount++;
+    const SAFARI =
+      global.navigator &&
+      /^((?!chrome|android).)*safari/i.test(global.navigator.userAgent);
 
-        if (currentCallCount < maxInlineCallCount) {
-          realSetImmediate(fn);
-        } else {
-          currentCallCount = 0;
-
-          setTimeoutImpl(fn);
-        }
-      };
-    } else if (!j$.util.isUndefined(global.MessageChannel)) {
-      return messageChannelImpl(global, setTimeoutImpl);
+    if (NODE_JS) {
+      // Unlike browsers, Node doesn't require us to do a periodic setTimeout
+      // so we avoid the overhead.
+      return nodeQueueMicrotaskImpl(global);
+    } else if (
+      SAFARI ||
+      j$.util.isUndefined(global.MessageChannel) /* tests */
+    ) {
+      // queueMicrotask is dramatically faster than MessageChannel in Safari.
+      // Some of our own integration tests provide a mock queueMicrotask in all
+      // environments because it's simpler to mock than MessageChannel.
+      return browserQueueMicrotaskImpl(global);
     } else {
-      return setTimeoutImpl;
+      // MessageChannel is faster than queueMicrotask in supported browsers
+      // other than Safari.
+      return messageChannelImpl(global);
     }
   }