Move VM-specific logic out of schedule_microtask.dart.

Adds trivial hooks that other platforms can inline
for no extra overhead, and the VM can specialize
to do whatever extra checking they need.

Avoids adding unnecessary code to other platforms.

Tested: Refactoringm covered by existing test.
Change-Id: I3816f27548fd883fd98eba0428be8d58e27da12e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/437481
Reviewed-by: Martin Kustermann <[email protected]>
Commit-Queue: Lasse Nielsen <[email protected]>
Reviewed-by: Stephen Adams <[email protected]>
Reviewed-by: Slava Egorov <[email protected]>

Author: lrhn

sdk/lib/_internal/vm/lib/schedule_microtask_patch.dart

@@ -4,24 +4,65 @@
 
 part of "async_patch.dart";
 
-@patch
+@pragma("vm:entry-point", !const bool.fromEnvironment("dart.vm.product"))
 abstract final class _MicrotaskMirrorQueue {
-  @patch
+  // This will be set to true by the native runtime's
+  // `DartUtils::PrepareAsyncLibrary` when the CLI flag `--profile-microtasks`
+  // is set.
+  @pragma("vm:entry-point", !const bool.fromEnvironment("dart.vm.product"))
+  static bool _shouldProfileMicrotasks = false;
+
   @pragma("vm:external-name", "MicrotaskMirrorQueue_onScheduleAsyncCallback")
   external static void _onScheduleAsyncCallback();
 
-  @patch
   @pragma(
     "vm:external-name",
     "MicrotaskMirrorQueue_onSchedulePriorityAsyncCallback",
   )
   external static void _onSchedulePriorityAsyncCallback();
 
-  @patch
   @pragma("vm:external-name", "MicrotaskMirrorQueue_onAsyncCallbackComplete")
   external static void _onAsyncCallbackComplete(int startTime, int endTime);
 }
 
+@patch
+void _beforeScheduleMicrotaskCallback() {
+  if (!const bool.fromEnvironment("dart.vm.product") &&
+      _MicrotaskMirrorQueue._shouldProfileMicrotasks) {
+    _MicrotaskMirrorQueue._onScheduleAsyncCallback();
+  }
+}
+
+@patch
+void _beforeSchedulePriorityCallback() {
+  if (!const bool.fromEnvironment("dart.vm.product") &&
+      _MicrotaskMirrorQueue._shouldProfileMicrotasks) {
+    _MicrotaskMirrorQueue._onSchedulePriorityAsyncCallback();
+  }
+}
+
+@patch
+void Function() _microtaskEntryCallback(_AsyncCallbackEntry entry) {
+  if (const bool.fromEnvironment("dart.vm.product") ||
+      !_MicrotaskMirrorQueue._shouldProfileMicrotasks) {
+    return entry.callback;
+  } else {
+    @pragma("vm:invisible")
+    void timedCallback() {
+      final callbackStartTime = Timeline.now;
+      (entry.callback)();
+      final callbackEndTime = Timeline.now;
+      _MicrotaskMirrorQueue._onAsyncCallbackComplete(
+        callbackStartTime,
+        callbackEndTime,
+      );
+    }
+
+    ;
+    return timedCallback;
+  }
+}
+
 @patch
 class _AsyncRun {
   @patch

sdk/lib/async/schedule_microtask.dart

@@ -37,18 +37,7 @@ void _microtaskLoop() {
     var next = entry.next;
     _nextCallback = next;
     if (next == null) _lastCallback = null;
-    if (const bool.fromEnvironment("dart.vm.product") ||
-        !_MicrotaskMirrorQueue._shouldProfileMicrotasks) {
-      (entry.callback)();
-    } else {
-      final callbackStartTime = Timeline.now;
-      (entry.callback)();
-      final callbackEndTime = Timeline.now;
-      _MicrotaskMirrorQueue._onAsyncCallbackComplete(
-        callbackStartTime,
-        callbackEndTime,
-      );
-    }
+    _microtaskEntryCallback(entry)();
   }
 }
 
@@ -73,10 +62,7 @@ void _startMicrotaskLoop() {
 /// microtasks, but as part of the current system event.
 void _scheduleAsyncCallback(_AsyncCallback callback) {
   _AsyncCallbackEntry newEntry = _AsyncCallbackEntry(callback);
-  if (!const bool.fromEnvironment("dart.vm.product") &&
-      _MicrotaskMirrorQueue._shouldProfileMicrotasks) {
-    _MicrotaskMirrorQueue._onScheduleAsyncCallback();
-  }
+  _beforeScheduleMicrotaskCallback();
   _AsyncCallbackEntry? lastCallback = _lastCallback;
   if (lastCallback == null) {
     _nextCallback = _lastCallback = newEntry;
@@ -102,10 +88,7 @@ void _schedulePriorityAsyncCallback(_AsyncCallback callback) {
     return;
   }
   _AsyncCallbackEntry entry = _AsyncCallbackEntry(callback);
-  if (!const bool.fromEnvironment("dart.vm.product") &&
-      _MicrotaskMirrorQueue._shouldProfileMicrotasks) {
-    _MicrotaskMirrorQueue._onSchedulePriorityAsyncCallback();
-  }
+  _beforeSchedulePriorityCallback();
   _AsyncCallbackEntry? lastPriorityCallback = _lastPriorityCallback;
   if (lastPriorityCallback == null) {
     entry.next = _nextCallback;
@@ -121,6 +104,20 @@ void _schedulePriorityAsyncCallback(_AsyncCallback callback) {
   }
 }
 
+// Overridden by VM.
+@pragma("dart2js:prefer-inline")
+@pragma("dart2wasm:prefer-inline")
+void _beforeSchedulePriorityCallback() {}
+
+@pragma("dart2js:prefer-inline")
+@pragma("dart2wasm:prefer-inline")
+void _beforeScheduleMicrotaskCallback() {}
+
+@pragma("dart2js:prefer-inline")
+@pragma("dart2wasm:prefer-inline")
+void Function() _microtaskEntryCallback(_AsyncCallbackEntry entry) =>
+    entry.callback;
+
 /// Runs a function asynchronously.
 ///
 /// Callbacks registered through this function are always executed in order and
@@ -167,22 +164,6 @@ void scheduleMicrotask(void Function() callback) {
   Zone.current.scheduleMicrotask(Zone.current.bindCallbackGuarded(callback));
 }
 
-@pragma("vm:entry-point", !const bool.fromEnvironment("dart.vm.product"))
-abstract final class _MicrotaskMirrorQueue {
-  // This will be set to true by the native runtime's
-  // `DartUtils::PrepareAsyncLibrary` when the CLI flag `--profile-microtasks`
-  // is set.
-  @pragma("vm:entry-point", !const bool.fromEnvironment("dart.vm.product"))
-  static bool _shouldProfileMicrotasks = false;
-
-  // The following methods are only implemented for the native runtime. Those
-  // implementations are in
-  // `sdk/lib/_internal/vm/lib/schedule_microtask_patch.dart`.
-  static void _onScheduleAsyncCallback() {}
-  static void _onSchedulePriorityAsyncCallback() {}
-  static void _onAsyncCallbackComplete(int startTime, int endTime) {}
-}
-
 class _AsyncRun {
   /// Schedule the given callback before any other event in the event-loop.
   external static void _scheduleImmediate(void Function() callback);