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RunLoop详解
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
本文分享自微信公众号 - 老沙课堂（gh_f73a6b772d4f），作者：rui4u
原文出处及转载信息见文内详细说明，如有侵权，请联系 yunjia_community@tencent.com 删除。
原始发表时间：2019-08-30
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