RunLoop详解
- 2019 年 10 月 8 日
- 筆記
一、CFRunLoop部分源码
阅读源码:CFRunLoop.c
CFRunLoopRef CFRunLoopGetCurrent(void) { CHECK_FOR_FORK(); CFRunLoopRef rl = (CFRunLoopRef)_CFGetTSD(__CFTSDKeyRunLoop); if (rl) return rl; return _CFRunLoopGet0(pthread_self()); }
CF_EXPORT CFRunLoopRef _CFRunLoopGet0(pthread_t t) { ... //从字典获取runloop CFRunLoopRef loop = (CFRunLoopRef)CFDictionaryGetValue(__CFRunLoops, pthreadPointer(t)); __CFUnlock(&loopsLock); // 如果没获取到 if (!loop) { //创建新的runloop CFRunLoopRef newLoop = __CFRunLoopCreate(t); __CFLock(&loopsLock); // 从字典里再找 loop = (CFRunLoopRef)CFDictionaryGetValue(__CFRunLoops, pthreadPointer(t)); if (!loop) { //如果还没有 就把新的存进去 CFDictionarySetValue(__CFRunLoops, pthreadPointer(t), newLoop); // 新创建的赋值给loop loop = newLoop; } // don't release run loops inside the loopsLock, because CFRunLoopDeallocate may end up taking it __CFUnlock(&loopsLock); CFRelease(newLoop); } ... }
从源码中可以看出
一个线程对应一个RunLoop
RunLoop保存在一个全局的字典里 线程为key RunLoop作为Value
线程刚创建的时候没有Ru nLoop对象，RunLoop会在第一次获取它的时候创建
主线程的RunLoop已经自动获取(创建)，子线程默认没有开启RunLoop 只有调用[NSRunLoop currentRunLoop] 才创建runLoop
由于key是线程 所以在线程结束的时候RunLoop也会随之销毁
二 Runtime相关的类
1、Core Fuoundation中愿意RunLoop有5个类
CFRunLoopRef
CFRunLoopModelRef
CFRunLoopSourceRef
CFRunLoopTimerRef
CFRunLoopObserverRef
2、CFRunLoop
struct __CFRunLoop { CFRuntimeBase _base; pthread_mutex_t _lock; /* locked for accessing mode list */ __CFPort _wakeUpPort; // used for CFRunLoopWakeUp Boolean _unused; volatile _per_run_data *_perRunData; // reset for runs of the run loop pthread_t _pthread; uint32_t _winthread; CFMutableSetRef _commonModes; CFMutableSetRef _commonModeItems; CFRunLoopModeRef _currentMode; CFMutableSetRef _modes; struct _block_item *_blocks_head; struct _block_item *_blocks_tail; CFAbsoluteTime _runTime; CFAbsoluteTime _sleepTime; CFTypeRef _counterpart; };
重点看下面几个
struct __CFRunLoop { // 线程对象 pthread_t _pthread; CFMutableSetRef _commonModes; CFMutableSetRef _commonModeItems; CFRunLoopModeRef _currentMode; //当前模式CFRunLoopMode CFMutableSetRef _modes; // CFRunLoopModes }
看一下CFRunLoopModeRef
typedef struct __CFRunLoopMode *CFRunLoopModeRef; struct __CFRunLoopMode { ... char _padding[3]; CFMutableSetRef _sources0; //CFRunLoopSource CFMutableSetRef _sources1; //CFRunLoopSource CFMutableArrayRef _observers; //CFRunLoopObserver CFMutableArrayRef _timers; //CFRunLoopTimer ... };
3、RunLoop结构
Sources0
触摸事件处理
performSelector:OnThread:
Source1
基于Port的线程间通信
系统事件的捕捉(source1 捕捉 source0处理)
Timers
NSTimer
performSelector:withObject:afterDealy:
observer
用于监听RunLoop的状态
UI刷新(BeforeWaiting)
AutoRelease pool
observer 监听类型
typedef CF_OPTIONS(CFOptionFlags, CFRunLoopActivity) { kCFRunLoopEntry = (1UL << 0), // 进入runloop kCFRunLoopBeforeTimers = (1UL << 1), // 即将进入timers kCFRunLoopBeforeSources = (1UL << 2), // 即将进入source kCFRunLoopBeforeWaiting = (1UL << 5), // 即将进入休眠 kCFRunLoopAfterWaiting = (1UL << 6), //刚从个休眠中唤醒 kCFRunLoopExit = (1UL << 7), //即将推出Loop kCFRunLoopAllActivities = 0x0FFFFFFFU };
- 如果model里没有任何source0/source1/observers/timers 会退出runloop
- CFRunLoopMode
- CFRunLoopDefaultMode 默认
- UITrackingRunLoopMode 用于界面跟踪Mode用于scrollview追踪触摸滑动，保证界面滑动不受其他的mode影响
- CFRunLoopCommonModes
4、RunLoop运行逻辑
通过在打印调用栈 找到CFRunLoopRunSpecific
我们查看源码 看一下RunLoop的运行逻辑
/* rl, rlm are locked on entrance and exit */ static int32_t __CFRunLoopRun(CFRunLoopRef rl, CFRunLoopModeRef rlm, CFTimeInterval seconds, Boolean stopAfterHandle, CFRunLoopModeRef previousMode) { //如果有timer 处理timer ->kCFRunLoopBeforeTimers if (rlm->_observerMask & kCFRunLoopBeforeTimers) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeTimers); //如果有Source 处理Source - >kCFRunLoopBeforeSources if (rlm->_observerMask & kCFRunLoopBeforeSources) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeSources); // 处理Block __CFRunLoopDoBlocks(rl, rlm); //处理Source0 如果Source有block 处理Source0的block ->__CFRunLoopDoSources0 Boolean sourceHandledThisLoop = __CFRunLoopDoSources0(rl, rlm, stopAfterHandle); if (sourceHandledThisLoop) { __CFRunLoopDoBlocks(rl, rlm); } if (MACH_PORT_NULL != dispatchPort && !didDispatchPortLastTime) { msg = (mach_msg_header_t *)msg_buffer; // 处理Source1中的事件 port __CFRunLoopServiceMachPort 如果有事件 goto-> handle_msg if (__CFRunLoopServiceMachPort(dispatchPort, &msg, sizeof(msg_buffer), &livePort, 0, &voucherState, NULL)) { goto handle_msg; } } //即将休眠 __CFRunLoopSetSleeping if (!poll && (rlm->_observerMask & kCFRunLoopBeforeWaiting)) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopBeforeWaiting); __CFRunLoopSetSleeping(rl); do { //等待唤醒 __CFRunLoopServiceMachPort(waitSet, &msg, sizeof(msg_buffer), &livePort, poll ? 0 : TIMEOUT_INFINITY, &voucherState, &voucherCopy); 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); // 被唤醒后 调用 即将唤醒 __CFRunLoopUnsetSleeping(rl); //继续监听 if (!poll && (rlm->_observerMask & kCFRunLoopAfterWaiting)) __CFRunLoopDoObservers(rl, rlm, kCFRunLoopAfterWaiting); handle_msg:; if (modeQueuePort != MACH_PORT_NULL && livePort == modeQueuePort) { CFRUNLOOP_WAKEUP_FOR_TIMER(); // 如果有timer 处理timer; ->__CFRunLoopDoTimers if (!__CFRunLoopDoTimers(rl, rlm, mach_absolute_time())) { // Re-arm the next timer, because we apparently fired early __CFArmNextTimerInMode(rlm, rl); } } else if (rlm->_timerPort != MACH_PORT_NULL && livePort == rlm->_timerPort) { CFRUNLOOP_WAKEUP_FOR_TIMER(); // 如果有timer 处理timer; ->__CFRunLoopDoTimers if (!__CFRunLoopDoTimers(rl, rlm, mach_absolute_time())) { __CFArmNextTimerInMode(rlm, rl); } } // GCD唤醒 else if (livePort == dispatchPort) { // ansy to MainQueue 同步到主线程 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__(msg); } else { //处理Source1 sourceHandledThisLoop = __CFRunLoopDoSource1(rl, rlm, rls, msg, msg->msgh_size, &reply) || sourceHandledThisLoop; // Restore the previous voucher _CFSetTSD(__CFTSDKeyMachMessageHasVoucher, previousVoucher, os_release); } //处理block __CFRunLoopDoBlocks(rl, rlm); //设置返回值 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; } return retVal; }
mach_msg()直接睡眠 内核层面
- [ NSRunLoop currentRunLoop]run ] 是无法停止的 是一个永不销毁的线程。//可以看方法注释
- CFRunloopRunInMode 第三个参数是 执行完source后是否退出
- 结构体初始化最好赋值为{0} 避免内存垃圾
