背景
我们平时使用的NSMutableArray，在进行增删改查的时候，会出现数据异常的场景（关键是异常并不是必现的，不太好复现）
尝试复现场景
先执行以下代码
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 | self.muArray = [NSMutableArray new];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
[self.muArray addObject:@(i)];
NSLog(@"====[%d]", (int)self.muArray.count);
}
});
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
[self.muArray addObject:@(10000+i)];
NSLog(@"====[%d]", (int)self.muArray.count);
}
});
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运行代码，发现最后array的个数并不等于6000，多运行几次，发现每次的结果都不一样
创建线程安全的数组
1、通过NSLock锁实现
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | NSLock *lock = [NSLock new];
self.muArray = [NSMutableArray new];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
[lock lock];
[self.muArray addObject:@(i)];
NSLog(@"====[%d]", (int)self.muArray.count);
[lock unlock];
}
});
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
[lock lock];
[self.muArray addObject:@(i)];
NSLog(@"====[%d]", (int)self.muArray.count);
[lock unlock];
}
});
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2、通过串行队列实现
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | dispatch_queue_t serialQueue = dispatch_queue_create("com.name.apple", DISPATCH_QUEUE_SERIAL);
self.muArray = [NSMutableArray new];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
dispatch_async(serialQueue, ^{
[self.muArray addObject:@(i)];
NSLog(@"====[%d]", (int)self.muArray.count);
});
}
});
dispatch_async(dispatch_get_global_queue(0, 0), ^{
for (int i = 0; i < 3000; i++) {
dispatch_async(serialQueue, ^{
[self.muArray addObject:@(i)];
NSLog(@"====[%d]", (int)self.muArray.count);
});
}
});
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