- 0， RunLoop 的入口函数
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
// 这里断点， bt
// 函数调用栈
NSLog(@"%s", __func__);
} 可看到 RunLoop 的入口函数是
CFRunLoopRunSpecific
从
bt
中
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
* frame #0: 0x000000010ed9fd2d RunLooper`-[ViewController touchesBegan:withEvent:](self=0x00007fb2ccd073d0, _cmd="touchesBegan:withEvent:", touches=1 element, event=0x00006000022d98c0) at ViewController.m:180:5
frame #1: 0x00007fff4935345e UIKitCore`forwardTouchMethod + 323
frame #2: 0x00007fff4935330a UIKitCore`-[UIResponder touchesBegan:withEvent:] + 49
frame #3: 0x00007fff49362227 UIKitCore`-[UIWindow _sendTouchesForEvent:] + 622
frame #4: 0x00007fff4936428d UIKitCore`-[UIWindow sendEvent:] + 4501
frame #5: 0x00007fff4933e6d1 UIKitCore`-[UIApplication sendEvent:] + 356
frame #6: 0x00007fff493c94ce UIKitCore`__dispatchPreprocessedEventFromEventQueue + 7628
frame #7: 0x00007fff493cc692 UIKitCore`__handleEventQueueInternal + 6584
frame #8: 0x00007fff493c2f35 UIKitCore`__handleHIDEventFetcherDrain + 88
frame #9: 0x00007fff23da1c91 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
frame #10: 0x00007fff23da1bbc CoreFoundation`__CFRunLoopDoSource0 + 76
frame #11: 0x00007fff23da1394 CoreFoundation`__CFRunLoopDoSources0 + 180
frame #12: 0x00007fff23d9bf8e CoreFoundation`__CFRunLoopRun + 974
frame #13: 0x00007fff23d9b8a4 CoreFoundation`CFRunLoopRunSpecific + 404
frame #14: 0x00007fff38c39bbe GraphicsServices`GSEventRunModal + 139
frame #15: 0x00007fff49325968 UIKitCore`UIApplicationMain + 1605
frame #16: 0x000000010eda0082 RunLooper`main(argc=1, argv=0x00007ffee0e5fd30) at main.m:18:12
frame #17: 0x00007fff520ce1fd libdyld.dylib`start + 1- 第一个函数 CFRunLoopRunSpecific
SInt32 CFRunLoopRunSpecific(CFRunLoopRef rl, CFStringRef modeName, CFTimeInterval seconds, Boolean returnAfterSourceHandled) { /* DOES CALLOUT */
CHECK_FOR_FORK();
if (__CFRunLoopIsDeallocating(rl)) return kCFRunLoopRunFinished;
__CFRunLoopLock(rl);
CFRunLoopModeRef currentMode = __CFRunLoopFindMode(rl, modeName, false);
if (NULL == currentMode || __CFRunLoopModeIsEmpty(rl, currentMode, rl->_currentMode)) {
Boolean did = false;
if (currentMode) __CFRunLoopModeUnlock(currentMode);
__CFRunLoopUnlock(rl);
return did ? kCFRunLoopRunHandledSource : kCFRunLoopRunFinished;
}
volatile _per_run_data *previousPerRun = __CFRunLoopPushPerRunData(rl);
CFRunLoopModeRef previousMode = rl->_currentMode;
rl->_currentMode = currentMode;
int32_t result = kCFRunLoopRunFinished;
// 通知 Observers， 进入 Loops
if (currentMode->_observerMask & kCFRunLoopEntry ) __CFRunLoopDoObservers(rl, currentMode, kCFRunLoopEntry);
// 这个是主逻辑， Run Loop 具体要做的事情
result = __CFRunLoopRun(rl, currentMode, seconds, returnAfterSourceHandled, previousMode);
// 通知 Observers， 退出 Loops
if (currentMode->_observerMask & kCFRunLoopExit ) __CFRunLoopDoObservers(rl, currentMode, kCFRunLoopExit);
__CFRunLoopModeUnlock(currentMode);
__CFRunLoopPopPerRunData(rl, previousPerRun);
rl->_currentMode = previousMode;
__CFRunLoopUnlock(rl);
return result;
}- 第 2 个函数 __CFRunLoopRun
/* rl, rlm are locked on entrance and exit */
static int32_t __CFRunLoopRun(CFRunLoopRef rl, CFRunLoopModeRef rlm, CFTimeInterval seconds, Boolean stopAfterHandle, CFRunLoopModeRef previousMode) {
uint64_t startTSR = mach_absolute_time();
if (__CFRunLoopIsStopped(rl)) {
__CFRunLoopUnsetStopped(rl);
return kCFRunLoopRunStopped;
} else if (rlm->_stopped) {
rlm->_stopped = false;
return kCFRunLoopRunStopped;
}
mach_port_name_t dispatchPort = MACH_PORT_NULL;
Boolean libdispatchQSafe = pthread_main_np() && ((HANDLE_DISPATCH_ON_BASE_INVOCATION_ONLY && NULL == previousMode) || (!HANDLE_DISPATCH_ON_BASE_INVOCATION_ONLY && 0 == _CFGetTSD(__CFTSDKeyIsInGCDMainQ)));
if (libdispatchQSafe && (CFRunLoopGetMain() == rl) && CFSetContainsValue(rl->_commonModes, rlm->_name)) dispatchPort = _dispatch_get_main_queue_port_4CF();
#if USE_DISPATCH_SOURCE_FOR_TIMERS
mach_port_name_t modeQueuePort = MACH_PORT_NULL;
if (rlm->_queue) {
modeQueuePort = _dispatch_runloop_root_queue_get_port_4CF(rlm->_queue);
if (!modeQueuePort) {
CRASH("Unable to get port for run loop mode queue (%d)", -1);
}
}
#endif
dispatch_source_t timeout_timer = NULL;
struct __timeout_context *timeout_context = (struct __timeout_context *)malloc(sizeof(*timeout_context));
if (seconds <= 0.0) { // instant timeout
seconds = 0.0;
timeout_context->termTSR = 0ULL;
} else if (seconds <= TIMER_INTERVAL_LIMIT) {
dispatch_queue_t queue = pthread_main_np() ? __CFDispatchQueueGetGenericMatchingMain() : __CFDispatchQueueGetGenericBackground();
timeout_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
dispatch_retain(timeout_timer);
timeout_context->ds = timeout_timer;
timeout_context->rl = (CFRunLoopRef)CFRetain(rl);
timeout_context->termTSR = startTSR + __CFTimeIntervalToTSR(seconds);
dispatch_set_context(timeout_timer, timeout_context); // source gets ownership of context
dispatch_source_set_event_handler_f(timeout_timer, __CFRunLoopTimeout);
dispatch_source_set_cancel_handler_f(timeout_timer, __CFRunLoopTimeoutCancel);
uint64_t ns_at = (uint64_t)((__CFTSRToTimeInterval(startTSR) + seconds) * 1000000000ULL);
dispatch_source_set_timer(timeout_timer, dispatch_time(1, ns_at), DISPATCH_TIME_FOREVER, 1000ULL);
dispatch_resume(timeout_timer);
} else { // infinite timeout
seconds = 9999999999.0;
timeout_context->termTSR = UINT64_MAX;
}
Boolean didDispatchPortLastTime = true;
int32_t retVal = 0;
do {
// 条件编译
// 部署平台，如果是 MACOSX
// 或者是 EMBEDDED，嵌入式， 例如手机和平板
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
voucher_mach_msg_state_t voucherState = VOUCHER_MACH_MSG_STATE_UNCHANGED;
voucher_t voucherCopy = NULL;
#endif
uint8_t msg_buffer[3 * 1024];
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
mach_msg_header_t *msg = NULL;
mach_port_t livePort = MACH_PORT_NULL;
// 条件编译
// 部署平台，如果是 WINDOWS
#elif DEPLOYMENT_TARGET_WINDOWS
HANDLE livePort = NULL;
Boolean windowsMessageReceived = false;
#endif
__CFPortSet waitSet = rlm->_portSet;
__CFRunLoopUnsetIgnoreWakeUps(rl);
// 通知 Observers: 即将处理 Timers
if (rlm->_observerMask & kCFRunLoopBeforeTimers) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeTimers);
// 通知 Observers: 即将处理 Sources
if (rlm->_observerMask & kCFRunLoopBeforeSources) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeSources);
// 处理 Blocks
__CFRunLoopDoBlocks(rl, rlm);
// 处理 Sources0
Boolean sourceHandledThisLoop = __CFRunLoopDoSources0(rl, rlm, stopAfterHandle);
if (sourceHandledThisLoop) {
// 处理完 Sources0， 接着处理 Blocks
__CFRunLoopDoBlocks(rl, rlm);
}
Boolean poll = sourceHandledThisLoop || (0ULL == timeout_context->termTSR);
if (MACH_PORT_NULL != dispatchPort && !didDispatchPortLastTime) {
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
msg = (mach_msg_header_t *)msg_buffer;
// 处理端口 port 相关
// 判断有无 source 1
// source 1, 通过端口，通知线程干事情
if (__CFRunLoopServiceMachPort(dispatchPort, &msg, sizeof(msg_buffer), &livePort, 0, &voucherState, NULL)) {
// 如果有 source 1, 跳转到 handle_msg 标签
goto handle_msg;
}
#elif DEPLOYMENT_TARGET_WINDOWS
if (__CFRunLoopWaitForMultipleObjects(NULL, &dispatchPort, 0, 0, &livePort, NULL)) {
goto handle_msg;
}
#endif
}
didDispatchPortLastTime = false;
// 通知 Observers: 即将休眠
if (!poll && (rlm->_observerMask & kCFRunLoopBeforeWaiting)) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeWaiting);
__CFRunLoopSetSleeping(rl);
// do not do any user callouts after this point (after notifying of sleeping)
// Must push the local-to-this-activation ports in on every loop
// iteration, as this mode could be run re-entrantly and we don't
// want these ports to get serviced.
__CFPortSetInsert(dispatchPort, waitSet);
__CFRunLoopModeUnlock(rlm);
__CFRunLoopUnlock(rl);
CFAbsoluteTime sleepStart = poll ? 0.0 : CFAbsoluteTimeGetCurrent();
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
#if USE_DISPATCH_SOURCE_FOR_TIMERS
// do ... while (1)
// 循环跑圈
do {
if (kCFUseCollectableAllocator) {
// objc_clear_stack(0);
//
memset(msg_buffer, 0, sizeof(msg_buffer));
}
msg = (mach_msg_header_t *)msg_buffer;
// 这一句是，核心函数
// 等待别的消息，来唤醒，当前的线程
__CFRunLoopServiceMachPort(waitSet, &msg, sizeof(msg_buffer), &livePort, poll ? 0 : TIMEOUT_INFINITY, &voucherState, &voucherCopy);
// 一旦唤醒，就继续处理
// 如果没有唤醒，就相当于阻塞在这里，
// 进程停滞在这里
if (modeQueuePort != MACH_PORT_NULL && livePort == modeQueuePort) {
// Drain the internal queue. If one of the callout blocks sets the timerFired flag, break out and service the timer.
while (_dispatch_runloop_root_queue_perform_4CF(rlm->_queue));
if (rlm->_timerFired) {
// Leave livePort as the queue port, and service timers below
rlm->_timerFired = false;
break;
} else {
if (msg && msg != (mach_msg_header_t *)msg_buffer) free(msg);
}
} else {
// Go ahead and leave the inner loop.
break;
}
} while (1);
#else
if (kCFUseCollectableAllocator) {
// objc_clear_stack(0);
//
memset(msg_buffer, 0, sizeof(msg_buffer));
}
msg = (mach_msg_header_t *)msg_buffer;
__CFRunLoopServiceMachPort(waitSet, &msg, sizeof(msg_buffer), &livePort, poll ? 0 : TIMEOUT_INFINITY, &voucherState, &voucherCopy);
#endif
#elif DEPLOYMENT_TARGET_WINDOWS
// Here, use the app-supplied message queue mask. They will set this if they are interested in having this run loop receive windows messages.
__CFRunLoopWaitForMultipleObjects(waitSet, NULL, poll ? 0 : TIMEOUT_INFINITY, rlm->_msgQMask, &livePort, &windowsMessageReceived);
#endif
__CFRunLoopLock(rl);
__CFRunLoopModeLock(rlm);
rl->_sleepTime += (poll ? 0.0 : (CFAbsoluteTimeGetCurrent() - sleepStart));
// Must remove the local-to-this-activation ports in on every loop
// iteration, as this mode could be run re-entrantly and we don't
// want these ports to get serviced. Also, we don't want them left
// in there if this function returns.
__CFPortSetRemove(dispatchPort, waitSet);
__CFRunLoopSetIgnoreWakeUps(rl);
// 通知 Observers: 结束休眠
// user callouts now OK again
__CFRunLoopUnsetSleeping(rl);
if (!poll && (rlm->_observerMask & kCFRunLoopAfterWaiting)) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopAfterWaiting);
// 跳转标签
handle_msg:;
__CFRunLoopSetIgnoreWakeUps(rl);
#if DEPLOYMENT_TARGET_WINDOWS
if (windowsMessageReceived) {
// These Win32 APIs cause a callout, so make sure we're unlocked first and relocked after
__CFRunLoopModeUnlock(rlm);
__CFRunLoopUnlock(rl);
if (rlm->_msgPump) {
rlm->_msgPump();
} else {
MSG msg;
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE | PM_NOYIELD)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
__CFRunLoopLock(rl);
__CFRunLoopModeLock(rlm);
sourceHandledThisLoop = true;
// To prevent starvation of sources other than the message queue, we check again to see if any other sources need to be serviced
// Use 0 for the mask so windows messages are ignored this time. Also use 0 for the timeout, because we're just checking to see if the things are signalled right now -- we will wait on them again later.
// NOTE: Ignore the dispatch source (it's not in the wait set anymore) and also don't run the observers here since we are polling.
__CFRunLoopSetSleeping(rl);
__CFRunLoopModeUnlock(rlm);
__CFRunLoopUnlock(rl);
__CFRunLoopWaitForMultipleObjects(waitSet, NULL, 0, 0, &livePort, NULL);
__CFRunLoopLock(rl);
__CFRunLoopModeLock(rlm);
__CFRunLoopUnsetSleeping(rl);
// If we have a new live port then it will be handled below as normal
}
#endif
if (MACH_PORT_NULL == livePort) {
CFRUNLOOP_WAKEUP_FOR_NOTHING();
// handle nothing
} else if (livePort == rl->_wakeUpPort) {
CFRUNLOOP_WAKEUP_FOR_WAKEUP();
// do nothing on Mac OS
#if DEPLOYMENT_TARGET_WINDOWS
// Always reset the wake up port, or risk spinning forever
ResetEvent(rl->_wakeUpPort);
#endif
}
#if USE_DISPATCH_SOURCE_FOR_TIMERS
// 被 timer 唤醒的，第一种情况
else if (modeQueuePort != MACH_PORT_NULL && livePort == modeQueuePort) {
CFRUNLOOP_WAKEUP_FOR_TIMER();
// 处理 Timers
if (!__CFRunLoopDoTimers(rl, rlm, mach_absolute_time())) {
// Re-arm the next timer, because we apparently fired early
__CFArmNextTimerInMode(rlm, rl);
}
}
#endif
#if USE_MK_TIMER_TOO
// 被 timer 唤醒的，第 2 种情况
else if (rlm->_timerPort != MACH_PORT_NULL && livePort == rlm->_timerPort) {
CFRUNLOOP_WAKEUP_FOR_TIMER();
// On Windows, we have observed an issue where the timer port is set before the time which we requested it to be set. For example, we set the fire time to be TSR 167646765860, but it is actually observed firing at TSR 167646764145, which is 1715 ticks early. The result is that, when __CFRunLoopDoTimers checks to see if any of the run loop timers should be firing, it appears to be 'too early' for the next timer, and no timers are handled.
// In this case, the timer port has been automatically reset (since it was returned from MsgWaitForMultipleObjectsEx), and if we do not re-arm it, then no timers will ever be serviced again unless something adjusts the timer list (e.g. adding or removing timers). The fix for the issue is to reset the timer here if CFRunLoopDoTimers did not handle a timer itself. 9308754
if (!__CFRunLoopDoTimers(rl, rlm, mach_absolute_time())) {
// Re-arm the next timer
__CFArmNextTimerInMode(rlm, rl);
}
}
#endif
else if (livePort == dispatchPort) {
// 被 gcd 唤醒
CFRUNLOOP_WAKEUP_FOR_DISPATCH();
__CFRunLoopModeUnlock(rlm);
__CFRunLoopUnlock(rl);
_CFSetTSD(__CFTSDKeyIsInGCDMainQ, (void *)6, NULL);
#if DEPLOYMENT_TARGET_WINDOWS
void *msg = 0;
#endif
// 处理 gcd 相关
__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__(msg);
_CFSetTSD(__CFTSDKeyIsInGCDMainQ, (void *)0, NULL);
__CFRunLoopLock(rl);
__CFRunLoopModeLock(rlm);
sourceHandledThisLoop = true;
didDispatchPortLastTime = true;
} else {
// 剩下的情况，被认为是 source 1
// 被 source 1 唤醒
CFRUNLOOP_WAKEUP_FOR_SOURCE();
// If we received a voucher from this mach_msg, then put a copy of the new voucher into TSD. CFMachPortBoost will look in the TSD for the voucher. By using the value in the TSD we tie the CFMachPortBoost to this received mach_msg explicitly without a chance for anything in between the two pieces of code to set the voucher again.
voucher_t previousVoucher = _CFSetTSD(__CFTSDKeyMachMessageHasVoucher, (void *)voucherCopy, os_release);
// Despite the name, this works for windows handles as well
CFRunLoopSourceRef rls = __CFRunLoopModeFindSourceForMachPort(rl, rlm, livePort);
if (rls) {
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
mach_msg_header_t *reply = NULL;
// 处理 source 1
sourceHandledThisLoop = __CFRunLoopDoSource1(rl, rlm, rls, msg, msg->msgh_size, &reply) || sourceHandledThisLoop;
if (NULL != reply) {
(void)mach_msg(reply, MACH_SEND_MSG, reply->msgh_size, 0, MACH_PORT_NULL, 0, MACH_PORT_NULL);
CFAllocatorDeallocate(kCFAllocatorSystemDefault, reply);
}
#elif DEPLOYMENT_TARGET_WINDOWS
sourceHandledThisLoop = __CFRunLoopDoSource1(rl, rlm, rls) || sourceHandledThisLoop;
#endif
}
// Restore the previous voucher
_CFSetTSD(__CFTSDKeyMachMessageHasVoucher, previousVoucher, os_release);
}
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
if (msg && msg != (mach_msg_header_t *)msg_buffer) free(msg);
#endif
// 再处理一遍 blocks
__CFRunLoopDoBlocks(rl, rlm);
// 设置返回值
// 处理情况，有返回值 retVal
if (sourceHandledThisLoop && stopAfterHandle) {
retVal = kCFRunLoopRunHandledSource;
} else if (timeout_context->termTSR < mach_absolute_time()) {
retVal = kCFRunLoopRunTimedOut;
} else if (__CFRunLoopIsStopped(rl)) {
__CFRunLoopUnsetStopped(rl);
retVal = kCFRunLoopRunStopped;
} else if (rlm->_stopped) {
rlm->_stopped = false;
retVal = kCFRunLoopRunStopped;
} else if (__CFRunLoopModeIsEmpty(rl, rlm, previousMode)) {
retVal = kCFRunLoopRunFinished;
}
#if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI
voucher_mach_msg_revert(voucherState);
os_release(voucherCopy);
#endif
} while (0 == retVal);
if (timeout_timer) {
dispatch_source_cancel(timeout_timer);
dispatch_release(timeout_timer);
} else {
free(timeout_context);
}
return retVal;
} 3， 有两层循环，
外面的
int32_t retVal = 0;
do {
} while (0 == retVal);
里面的
do {
} while (1);
4， 跳转有一个优先级
RunLoop 的运行逻辑
第 6 步跳转，
可看出，
处理 Source 1, 比处理 Timer 和处理 GCD Async To Main Queue 重要一些
Source 1, 基于系统的线程间通信和系统事件捕捉，比较重要
系统事件比常规事件 （ Timer 和处理 GCD Async To Main Queue ） 重要一些