Synchronization
Synchronization
协调多个执行线程，同步访问资源。
To synchronize access to a resource, use one of the synchronization objects in one of the wait functions.
The state of a synchronization object is either signaled or nonsignaled.
The wait functions allow a thread to block its own execution until a specified nonsignaled object is set to the signaled state.
Wait Functions
Wait functions allow a thread to block its own execution. until the conditions of the wait criteria have been met or the specified time-out interval elapses.
1.Alertable Wait Functions
线程要是希望分到CPU执行时间，必须是可以调度状态。
2.Registered Wait Functions
3.Waiting on an Address
Synchronization Objects
A synchronization object is an object whose handle can be specified in one of the wait functions to coordinate the execution of multiple threads.
More than one process can have a handle to the same synchronization object, making interprocess synchronization possible.
In some circumstances, you can also use a file, named pipe, or communications device as a synchronization object;
however, their use for this purpose is discouraged. Instead, use asynchronous I/O and wait on the event object set in the OVERLAPPED structure.
It is safer to use the event object because of the confusion that can occur when multiple simultaneous overlapped operations are performed on the same file, named pipe, or communications device.
In this situation, there is no way to know which operation caused the object’s state to be signaled.
1.Event Objects
2.Mutex Objects
3.Semaphore Objects
4.Waitable Timer Objects
可以同时和APC共同使用，TimerAPCProc callback function
5.Synchronization Object Security and Access Rights
Interprocess Synchronization
Multiple processes can have handles to the same event, mutex, semaphore, or timer object, so these objects can be used to accomplish interprocess synchronization.
1.Object Names
2.Object Namespaces
3.Object Inheritance
4.Object Duplication
About Synchronization
以下章节需要作为扩展至少再次学习,学习就是一个记忆到理解的过程，理解不来就先记住，记不住就过段时间再来理解。
1.Synchronization and Multiprocessor Issues
多处理器可以同时运行优先级不同的线程。
2.Synchronization and Overlapped Input and Output
If an event is not used, each completed I/O operation will signal the file, named pipe, or communications device.
使用举例Pipes
只能用于同步的两个函数，The ReadFileEx and WriteFileEx functions provide another form of overlapped I/O. 做异步。
Synchronous and Overlapped Pipe I/O
相关章节，这里牵扯的还是复杂啊I/O Completion Ports
3.Asynchronous Procedure Calls
应用程序借用操作系统实现异步调用。electron借用渲染线程实现异步调用
4.Critical Section Objects
就是对同时访问共享资源的代码进行锁定不能同时执行，这块代码可以是同一块由不同线程执行的代码，也可以不是同一块代码但是访问同样的资源。
5.Condition Variables
6.Slim Reader/Writer (SRW) Locks
轻量级的锁，Chromium在win上实现的锁就是使用这个作为mutex.
7.One-Time Initialization
8.Interlocked Variable Access
9.Interlocked Singly Linked Lists
10.Timer Queues
11.Synchronization Barriers