- OSSpinLock 自旋锁 (忙等)
@property (assign, nonatomic) OSSpinLock lock;
OSSpinLockLock(&_ lock);
//code
OSSpinLockUnlock(&_ lock);
- os_unfair_lock 互斥锁
@property (assign, nonatomic) os_unfair_lock lock;
os_unfair_lock_lock(&_ lock);
//code
os_unfair_lock_unlock(&_ lock);
- pthread_mutex_t 跨平台通用
@property (assign, nonatomic) pthread_mutex_t lock;
// 初始化属性
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
// PTHREAD_MUTEX_DEFAULT 互斥锁
// PTHREAD_MUTEX_RECURSIVE 递归锁
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_DEFAULT);
// 初始化锁
pthread_mutex_init(&_lock, &attr);
// 销毁属性
pthread_mutexattr_destroy(&attr);
pthread_mutex_lock(&_ lock);
//code
pthread_mutex_unlock(&_ lock);
- (void)dealloc{
pthread_mutex_destroy(& lock);
}
PTHREAD_MUTEX_RECURSIVE 递归锁：允许同一个线程对一把锁进行重复加锁
PTHREAD_MUTEX_DEFAULT 互斥锁：每次只能加一把锁，循环加锁会变成死锁
- pthread_cond_init
@property (assign, nonatomic) pthread_mutex_t mutex;
@property (assign, nonatomic) pthread_cond_t cond;
// 初始化属性
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
// 初始化锁
pthread_mutex_init(&_mutex, &attr);
// 销毁属性
pthread_mutexattr_destroy(&attr);
// 初始化条件
pthread_cond_init(&_cond, NULL);
[[[NSThread alloc] initWithTarget:self selector:@selector(__remove) object:nil] start];
[[[NSThread alloc] initWithTarget:self selector:@selector(__add) object:nil] start];
// 删除数组中的元素
- (void)__remove
{
pthread_mutex_lock(&_mutex);
NSLog(@"__remove - begin");
if (self.data.count == 0) {
// 等待,直到收到信号，才会继续执行
pthread_cond_wait(&_cond, &_mutex);
}
[self.data removeLastObject];
NSLog(@"删除了元素");
pthread_mutex_unlock(&_mutex);
}
// 线程2
// 往数组中添加元素
- (void)__add
{
pthread_mutex_lock(&_mutex);
sleep(1);
[self.data addObject:@"Test"];
NSLog(@"添加了元素");
// 信号
pthread_cond_signal(&_cond);
// 广播
// pthread_cond_broadcast(&_cond);
pthread_mutex_unlock(&_mutex);
}
- (void)dealloc
{
pthread_mutex_destroy(&_mutex);
pthread_cond_destroy(&_cond);
}
-
NSLock 是对
pthread_mutex_t的PTHREAD_MUTEX_DEFAULT的OC封装
@property (strong, nonatomic) NSLock *lock;
self.lock = [[NSLock alloc] init];
[self. lock lock];
//code
[self. lock unlock];
-
NSCondition 是对
pthread_cond_init的OC封装
@property (strong, nonatomic) NSCondition *condition;
self.condition = [[NSCondition alloc] init];
[[[NSThread alloc] initWithTarget:self selector:@selector(__remove) object:nil] start];
[[[NSThread alloc] initWithTarget:self selector:@selector(__add) object:nil] start];
// 线程1
// 删除数组中的元素
- (void)__remove
{
[self.condition lock];
NSLog(@"__remove - begin");
if (self.data.count == 0) {
// 等待
[self.condition wait];
}
[self.data removeLastObject];
NSLog(@"删除了元素");
[self.condition unlock];
}
// 线程2
// 往数组中添加元素
- (void)__add
{
[self.condition lock];
sleep(1);
[self.data addObject:@"Test"];
NSLog(@"添加了元素");
// 信号
[self.condition signal];
sleep(2);
[self.condition unlock];
}
-
NSRecursiveLock 是对
pthread_mutex_t的PTHREAD_MUTEX_RECURSIVE的OC封装
@property (strong, nonatomic) NSRecursiveLock *recursiveLock;
self.recursiveLock = [[NSRecursiveLock alloc] init];
- (void)otherTest
{
[self.recursiveLock lock];
NSLog(@"%s", __func__);
static int count = 0;
if (count < 10) {
count++;
[self otherTest];
}
[self.recursiveLock unlock];
}
- NSConditionLock 锁的顺序控制
@property (strong, nonatomic) NSConditionLock *conditionLock;
self.conditionLock = [[NSConditionLock alloc] initWithCondition:1];
[[[NSThread alloc] initWithTarget:self selector:@selector(__one) object:nil] start];
[[[NSThread alloc] initWithTarget:self selector:@selector(__two) object:nil] start];
[[[NSThread alloc] initWithTarget:self selector:@selector(__three) object:nil] start];
- (void)__one
{
[self.conditionLock lock];
NSLog(@"__one");
sleep(1);
[self.conditionLock unlockWithCondition:2];
}
- (void)__two
{
[self.conditionLock lockWhenCondition:2];
NSLog(@"__two");
sleep(1);
[self.conditionLock unlockWithCondition:3];
}
- (void)__three
{
[self.conditionLock lockWhenCondition:3];
NSLog(@"__three");
[self.conditionLock unlock];
}
- dispatch_queue_t GCD也可以控制串行运行，保证数据安全
@property (strong, nonatomic) dispatch_queue_t queue;
self.queue = dispatch_queue_create("ticketQueue", DISPATCH_QUEUE_SERIAL);
dispatch_sync(self.queue, ^{
//code
});
- dispatch_semaphore_t 控制信号量在1和0之间切换，也可以实现串行运行保证线程安全
@property (strong, nonatomic) dispatch_semaphore_t semaphore;
self.semaphore = dispatch_semaphore_create(1);
for (int i = 0; i < 20; i++) {
[[[NSThread alloc] initWithTarget:self selector:@selector(test) object:nil] start];
}
- (void)test
{
// 如果信号量的值 > 0，就让信号量的值减1，然后继续往下执行代码
// 如果信号量的值 <= 0，就会休眠等待，直到信号量的值变成>0，就让信号量的值减1，然后继续往下执行代码
dispatch_semaphore_wait(self.semaphore, DISPATCH_TIME_FOREVER);
NSLog(@"test - %@", [NSThread currentThread]);
// 让信号量的值+1
dispatch_semaphore_signal(self.semaphore);
}
- @synchronized 不能保证绝对的线程安全
@synchronized([self class]) { // objc_sync_enter
[super __saveMoney];
} // objc_sync_exit
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