Fix iOS JS timers when the system clock changes

packages/react-native/React/CoreModules/RCTTiming.mm

@@ -7,22 +7,32 @@
 
 #import "RCTTiming.h"
 
+#include <math.h>
+#include <chrono>
+
 #import <React/RCTAssert.h>
 #import <React/RCTConvert.h>
 #import <React/RCTLog.h>
 #import <React/RCTUtils.h>
 
 static const NSTimeInterval kMinimumSleepInterval = 1;
+static const NSTimeInterval kNoTimerTarget = INFINITY;
 
 // These timing contants should be kept in sync with the ones in `JSTimers.js`.
 // The duration of a frame. This assumes that we want to run at 60 fps.
 static const NSTimeInterval kFrameDuration = 1.0 / 60.0;
 // The minimum time left in a frame to trigger the idle callback.
 static const NSTimeInterval kIdleCallbackFrameDeadline = 0.001;
 
+static NSTimeInterval RCTMonotonicTime()
+{
+  // Apple libc++ uses CLOCK_MONOTONIC_RAW, which includes time spent asleep.
+  return std::chrono::duration<NSTimeInterval>(std::chrono::steady_clock::now().time_since_epoch()).count();
+}
+
 @interface _RCTTimer : NSObject
 
-@property (nonatomic, strong, readonly) NSDate *target;
+@property (nonatomic, assign, readonly) NSTimeInterval target;
 @property (nonatomic, assign, readonly) BOOL repeats;
 @property (nonatomic, copy, readonly) NSNumber *callbackID;
 @property (nonatomic, assign, readonly) NSTimeInterval interval;
@@ -40,26 +50,23 @@ - (instancetype)initWithCallbackID:(NSNumber *)callbackID
     _interval = interval;
     _repeats = repeats;
     _callbackID = callbackID;
-    _target = [NSDate dateWithTimeIntervalSinceNow:targetTime];
+    _target = RCTMonotonicTime() + targetTime;
   }
   return self;
 }
 
 /**
  * Returns `YES` if we should invoke the JS callback.
  */
-- (BOOL)shouldFire:(NSDate *)now
+- (BOOL)shouldFire:(NSTimeInterval)now
 {
-  if (_target && [_target timeIntervalSinceDate:now] <= 0) {
-    return YES;
-  }
-  return NO;
+  return _target <= now;
 }
 
 - (void)reschedule
 {
   // The JS Timers will do fine grained calculating of expired timeouts.
-  _target = [NSDate dateWithTimeIntervalSinceNow:_interval];
+  _target = RCTMonotonicTime() + _interval;
 }
 
 @end
@@ -92,6 +99,7 @@ - (void)timerDidFire
 @implementation RCTTiming {
   NSMutableDictionary<NSNumber *, _RCTTimer *> *_timers;
   NSTimer *_sleepTimer;
+  NSTimeInterval _sleepTimerTarget;
   BOOL _sendIdleEvents;
   BOOL _inBackground;
   id<RCTTimingDelegate> _timingDelegate;
@@ -226,31 +234,39 @@ - (BOOL)hasPendingTimers
 
 - (void)didUpdateFrame:(RCTFrameUpdate *)update
 {
-  NSDate *nextScheduledTarget = [NSDate distantFuture];
+  NSTimeInterval nextScheduledTarget = kNoTimerTarget;
   NSMutableArray<_RCTTimer *> *timersToCall = [NSMutableArray new];
-  NSDate *now = [NSDate date]; // compare all the timers to the same base time
+  NSTimeInterval now = RCTMonotonicTime();
   @synchronized(_timers) {
     for (_RCTTimer *timer in _timers.allValues) {
       if ([timer shouldFire:now]) {
         [timersToCall addObject:timer];
-      } else {
-        nextScheduledTarget = [nextScheduledTarget earlierDate:timer.target];
+      } else if (timer.target < nextScheduledTarget) {
+        nextScheduledTarget = timer.target;
       }
     }
   }
 
   // Call timers that need to be called
   if (timersToCall.count > 0) {
     NSArray<NSNumber *> *sortedTimers = [[timersToCall sortedArrayUsingComparator:^(_RCTTimer *a, _RCTTimer *b) {
-      return [a.target compare:b.target];
+      if (a.target < b.target) {
+        return NSOrderedAscending;
+      }
+      if (a.target > b.target) {
+        return NSOrderedDescending;
+      }
+      return NSOrderedSame;
     }] valueForKey:@"callbackID"];
     [_timingDelegate callTimers:sortedTimers];
   }
 
   for (_RCTTimer *timer in timersToCall) {
     if (timer.repeats) {
       [timer reschedule];
-      nextScheduledTarget = [nextScheduledTarget earlierDate:timer.target];
+      if (timer.target < nextScheduledTarget) {
+        nextScheduledTarget = timer.target;
+      }
     } else {
       @synchronized(_timers) {
         [_timers removeObjectForKey:timer.callbackID];
@@ -275,7 +291,7 @@ - (void)didUpdateFrame:(RCTFrameUpdate *)update
     timerCount = _timers.count;
   }
   if (_inBackground) {
-    if (timerCount != 0u) {
+    if (nextScheduledTarget != kNoTimerTarget) {
       [self scheduleSleepTimer:nextScheduledTarget];
     }
   } else if (!_sendIdleEvents && timersToCall.count == 0) {
@@ -285,26 +301,30 @@ - (void)didUpdateFrame:(RCTFrameUpdate *)update
       _paused = YES;
     }
     // If the next timer is more than 1 second out, pause and schedule an NSTimer;
-    else if ([nextScheduledTarget timeIntervalSinceNow] > kMinimumSleepInterval) {
+    else if (
+        nextScheduledTarget != kNoTimerTarget && nextScheduledTarget - RCTMonotonicTime() > kMinimumSleepInterval) {
       [self scheduleSleepTimer:nextScheduledTarget];
       _paused = YES;
     }
   }
 }
 
-- (void)scheduleSleepTimer:(NSDate *)sleepTarget
+- (void)scheduleSleepTimer:(NSTimeInterval)sleepTarget
 {
   @synchronized(self) {
+    NSTimeInterval delay = MAX(sleepTarget - RCTMonotonicTime(), 0);
     if ((_sleepTimer == nil) || !_sleepTimer.valid) {
-      _sleepTimer = [[NSTimer alloc] initWithFireDate:sleepTarget
-                                             interval:0
-                                               target:[_RCTTimingProxy proxyWithTarget:self]
-                                             selector:@selector(timerDidFire)
-                                             userInfo:nil
-                                              repeats:NO];
+      _sleepTimer = [NSTimer timerWithTimeInterval:delay
+                                            target:[_RCTTimingProxy proxyWithTarget:self]
+                                          selector:@selector(timerDidFire)
+                                          userInfo:nil
+                                           repeats:NO];
+      _sleepTimerTarget = sleepTarget;
       [[NSRunLoop currentRunLoop] addTimer:_sleepTimer forMode:NSDefaultRunLoopMode];
-    } else {
-      _sleepTimer.fireDate = [_sleepTimer.fireDate earlierDate:sleepTarget];
+    } else if (sleepTarget <= _sleepTimerTarget) {
+      // Convert to a date only when setting the run loop's wakeup.
+      _sleepTimer.fireDate = [NSDate dateWithTimeIntervalSinceNow:delay];
+      _sleepTimerTarget = sleepTarget;
     }
   }
 }
@@ -347,7 +367,7 @@ - (void)createTimerForNextFrame:(nonnull NSNumber *)callbackID
   if (_inBackground) {
     [self scheduleSleepTimer:timer.target];
   } else if (_paused) {
-    if ([timer.target timeIntervalSinceNow] > kMinimumSleepInterval) {
+    if (timer.target - RCTMonotonicTime() > kMinimumSleepInterval) {
       [self scheduleSleepTimer:timer.target];
     } else {
       [self startTimers];

packages/rn-tester/RNTesterPods.xcodeproj/project.pbxproj

@@ -17,6 +17,7 @@
 		602160B9478DAFF2BAB56595 /* RCTUtilsTests.m in Sources */ = {isa = PBXBuildFile; fileRef = D5D13FB1445C5C19639921CC /* RCTUtilsTests.m */; };
 		79B29C2E2E607A99007612A5 /* SceneDelegate.mm in Sources */ = {isa = PBXBuildFile; fileRef = 79B29C2D2E607A99007612A5 /* SceneDelegate.mm */; };
 		7F806D4D4D97AD6403558B35 /* RCTStatusBarAppearanceTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 67B0814814F7C07E196BC295 /* RCTStatusBarAppearanceTests.mm */; };
+		A8717727467541429C262C63 /* RCTTimingClockChangeTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = A8717727467541429C262C64 /* RCTTimingClockChangeTests.mm */; };
 		8145AE06241172D900A3F8DA /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 8145AE05241172D900A3F8DA /* LaunchScreen.storyboard */; };
 		832F45BB2A8A6E1F0097B4E6 /* SwiftTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 832F45BA2A8A6E1F0097B4E6 /* SwiftTest.swift */; };
 		A975CA6C2C05EADF0043F72A /* RCTNetworkTaskTests.m in Sources */ = {isa = PBXBuildFile; fileRef = A975CA6B2C05EADE0043F72A /* RCTNetworkTaskTests.m */; };
@@ -89,6 +90,7 @@
 		51BC9297B6C3163C14532020 /* Pods-RNTester.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-RNTester.release.xcconfig"; path = "Target Support Files/Pods-RNTester/Pods-RNTester.release.xcconfig"; sourceTree = "<group>"; };
 		5C60EB1B226440DB0018C04F /* AppDelegate.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = AppDelegate.mm; path = RNTester/AppDelegate.mm; sourceTree = "<group>"; };
 		67B0814814F7C07E196BC295 /* RCTStatusBarAppearanceTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = RCTStatusBarAppearanceTests.mm; sourceTree = "<group>"; };
+		A8717727467541429C262C64 /* RCTTimingClockChangeTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = RCTTimingClockChangeTests.mm; sourceTree = "<group>"; };
 		79B29C2C2E607A99007612A5 /* SceneDelegate.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = SceneDelegate.h; path = RNTester/SceneDelegate.h; sourceTree = "<group>"; };
 		79B29C2D2E607A99007612A5 /* SceneDelegate.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = SceneDelegate.mm; path = RNTester/SceneDelegate.mm; sourceTree = "<group>"; };
 		8145AE05241172D900A3F8DA /* LaunchScreen.storyboard */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.storyboard; name = LaunchScreen.storyboard; path = RNTester/LaunchScreen.storyboard; sourceTree = "<group>"; };
@@ -318,6 +320,7 @@
 				D5D13FB1445C5C19639921CC /* RCTUtilsTests.m */,
 				E7DB20B322B2BAA4005AC45F /* RNTesterUnitTestsBundle.js */,
 				67B0814814F7C07E196BC295 /* RCTStatusBarAppearanceTests.mm */,
+				A8717727467541429C262C64 /* RCTTimingClockChangeTests.mm */,
 			);
 			path = RNTesterUnitTests;
 			sourceTree = "<group>";
@@ -637,6 +640,7 @@
 				E7DB20D822B2BAA6005AC45F /* RCTJSONTests.m in Sources */,
 				602160B9478DAFF2BAB56595 /* RCTUtilsTests.m in Sources */,
 				7F806D4D4D97AD6403558B35 /* RCTStatusBarAppearanceTests.mm in Sources */,
+				A8717727467541429C262C63 /* RCTTimingClockChangeTests.mm in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

packages/rn-tester/RNTesterUnitTests/RCTTimingClockChangeTests.mm

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <XCTest/XCTest.h>
+#import <objc/runtime.h>
+
+#import <React/RCTTiming.h>
+
+static constexpr NSTimeInterval kClockJump = 60 * 60;
+static constexpr NSTimeInterval kTimerDelay = 0.05;
+static thread_local NSTimeInterval wallClockOffset;
+
+static Method dateMethod()
+{
+  return class_getClassMethod(NSDate.class, @selector(date));
+}
+
+static auto originalDateImplementation()
+{
+  static const auto implementation = method_getImplementation(dateMethod());
+  return implementation;
+}
+
+static NSDate *dateWithClockOffset(id receiver, SEL selector)
+{
+  auto originalDate = reinterpret_cast<NSDate *(*)(id, SEL)>(originalDateImplementation());
+  NSDate *now = originalDate(receiver, selector);
+  return wallClockOffset == 0 ? now : [now dateByAddingTimeInterval:wallClockOffset];
+}
+
+@interface RCTTimingClockChangeTests : XCTestCase <RCTTimingDelegate>
+@end
+
+@implementation RCTTimingClockChangeTests {
+  RCTTiming *_timing;
+  NSMutableArray<NSNumber *> *_callbacks;
+}
+
+- (void)setUp
+{
+  [super setUp];
+  _callbacks = [NSMutableArray new];
+  _timing = [[RCTTiming alloc] initWithDelegate:self];
+}
+
+- (void)tearDown
+{
+  [_timing invalidate];
+  _timing = nil;
+  [super tearDown];
+}
+
+- (void)callTimers:(NSArray<NSNumber *> *)timers
+{
+  [_callbacks addObjectsFromArray:timers];
+}
+
+- (void)immediatelyCallTimer:(NSNumber *)callbackID
+{
+  [_callbacks addObject:callbackID];
+}
+
+- (void)callIdleCallbacks:(NSNumber *)absoluteFrameStartMS
+{
+}
+
+- (void)updateFrameWithClockOffset:(NSTimeInterval)offset
+{
+  // Simulate a clock change after scheduling. Only this thread sees the
+  // shifted time, and only while checking which timers are due.
+  IMP original = originalDateImplementation();
+  wallClockOffset = offset;
+  method_setImplementation(dateMethod(), reinterpret_cast<IMP>(dateWithClockOffset));
+  @try {
+    [_timing didUpdateFrame:nil];
+  } @finally {
+    method_setImplementation(dateMethod(), original);
+    wallClockOffset = 0;
+  }
+}
+
+- (void)testClockMovingForwardDoesNotFirePendingTimeoutEarly
+{
+  [_timing createTimerForNextFrame:@1 duration:60 jsSchedulingTime:nil repeats:NO];
+
+  [self updateFrameWithClockOffset:kClockJump];
+
+  XCTAssertEqual(_callbacks.count, 0u);
+}
+
+- (void)testClockMovingBackwardDoesNotDelayDueTimeout
+{
+  [_timing createTimerForNextFrame:@1 duration:kTimerDelay jsSchedulingTime:nil repeats:NO];
+  [NSThread sleepForTimeInterval:2 * kTimerDelay];
+
+  [self updateFrameWithClockOffset:-kClockJump];
+
+  XCTAssertEqualObjects(_callbacks, (@[ @1 ]));
+}
+
+- (void)testClockMovingBackwardDoesNotDelayRescheduledInterval
+{
+  [_timing createTimerForNextFrame:@1 duration:kTimerDelay jsSchedulingTime:nil repeats:YES];
+  [NSThread sleepForTimeInterval:2 * kTimerDelay];
+  [_timing didUpdateFrame:nil];
+  XCTAssertEqualObjects(_callbacks, (@[ @1 ]));
+
+  [NSThread sleepForTimeInterval:2 * kTimerDelay];
+  [self updateFrameWithClockOffset:-kClockJump];
+
+  XCTAssertEqualObjects(_callbacks, (@[ @1, @1 ]));
+}
+
+@end