Modifying lock to improve code performance #667
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This was referenced Mar 22, 2019
Closed
kinarobin
commented
Mar 22, 2019
| MJProperty *propertyObj = objc_getAssociatedObject(self, property); | ||
| if (propertyObj == nil) { | ||
| propertyObj = [[self alloc] init]; | ||
| propertyObj.property = property; | ||
| objc_setAssociatedObject(self, property, propertyObj, OBJC_ASSOCIATION_RETAIN_NONATOMIC); | ||
| } | ||
| MJExtensionSemaphoreSignal |
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MJPropertySemaphoreCreate
MJ_LOCK(_propertySemaphore);
NSArray *cachedProperties = [self properties];
MJ_UNLOCK(_propertySemaphore);在[self properties];方法已加锁，此处并没有其他线程同时进入，所以并不需要加锁
kinarobin
commented
Mar 22, 2019
| MJPropertyType *type = types[code]; | ||
| if (type == nil) { | ||
| type = [[self alloc] init]; | ||
| type.code = code; | ||
| types[code] = type; | ||
| } | ||
| MJExtensionSemaphoreSignal |
This was referenced Mar 22, 2019
wolfcon
requested changes
Mar 26, 2019
MJExtension/NSObject+MJClass.m
Outdated
| MJExtensionSemaphoreCreate | ||
| MJExtensionSemaphoreWait | ||
| MJClassSemaphoreCreate | ||
| MJ_LOCK(_classSemaphore); |
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MJClassSemaphoreCreate 这里的宏, 并没有指出真正的变量内容
MJ_LOCK(_classSemaphore); 这里使用的 _classSemaphore 太隐含了.
| dispatch_semaphore_wait(signalSemaphore, DISPATCH_TIME_FOREVER); | ||
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| #define MJExtensionSemaphoreSignal \ | ||
| dispatch_semaphore_signal(signalSemaphore); |
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上面删掉的代码在其他类里的改动和放在这里应该是一样的. define 宏定义只是在编译阶段替换而已.
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使用 MJ_LOCK () 主要原因是不使用全局的一把锁，在每个对应的功能点加锁，后期如果还有线程安全相关问题，使用自己定义的锁，提高锁的效率：
MJ_LOCK(self.propertyKeysLock);
self.propertyKeysDict[key] = propertyKeys;
MJ_UNLOCK(self.propertyKeysLock);
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修复
MJProperty类中可变容器getter方法没有加锁引发线程安全问题的bug 多线程环境下崩溃 #660 (comment) .当前MJExtension使用全局的一把锁，影响效率：
a-> 针对全局静态容器，为每一个容器新建一把静态全局锁(总共两把静态锁，之前是一把静态锁)。
b-> 对于
MJProperty中可变容器的锁跟随MJProperty类的生命周期一起，不需要使用全局的锁。下面方法本来在
[self properties]就加锁了，属于单一线程执行，没有必要再加锁：