# asio run vs poll

asio run vs poll

discussions

Using io_service::poll instead of io_service::run is perfectly acceptable. The difference is explained in the documentation

The poll() function may also be used to dispatch ready handlers, but without blocking.

Note that io_service::run will block if there's any work left in the queue

The work class is used to inform the io_service when work starts and finishes. This ensures that the io_service object's run() function will not exit while work is underway, and that it does exit when there is no unfinished work remaining.

whereas io_service::poll does not exhibit this behavior, it just invokes ready handlers. Also note that you will need to invoke io_service::reset on any subsequent invocation to io_service:run or io_service::poll.

summary

1. run: will block if there's any work left in the queue

2. poll: dispatch ready handlers, but without blocking

3. blocking vs non-blocking

   1. 所谓的blocking：除了invoke ready handlers,还会等待这些handler结束，以及继续执行ready queue里面的task
   2. 所谓的nonblocking：只是执行ready queue里面的task，但不会继续等待这些handler结束

如何集成到GraphApi中去

idea1： 一个graph配一个io_service. 用io_service的run()驱动graph执行

Pros:简单，容易debug。应用层是同步处理，用法简单

Cons:io_service创建的effort大不大？

idead2：所有graph使用同一个io_service。io_service在一个单独的线程执行。graph方面不提供同步的run函数。

Pros:

Cons:复杂，可能不好debug。由于应用层会是全异步，Mat生命周期管理会复杂一些

Ref

https://stackoverflow.com/questions/4705411/boostasio-io-service-run-vs-poll-or-how-do-i-integrate-boostasio-in-ma