Can client class provide DelEvent method?

[Crazyokd]

i found the eventHandlers of client only have OnEvent method.

If I add event handlers dynamically, will there be any concurrency issues (I don't really see locks being used).
If there is no concurrency issue, is it possible to provide DelEvent method? like below:

    void DelEvent(const std::string& type) {
        eventHandlers.erase(type);
    }

(But multimap in our scenario seems to be able to delete only all handlers corresponding to the same type, is it possible to provide more granular control?)

[daniele77]

Hi @Crazyokd,

This library is designed for single-threaded use with asynchronous programming. Essentially, you have boost::io_context, which is a task queue where tasks are run in the thread that calls io_context::run()—usually the main thread.

With this in mind, the method Client::OnEvent should run in the same thread where the handlers are executed, i.e., the thread running io_context::run().

This shouldn't be a problem. Since the application is event-based, if you want to dynamically add or remove an event handler (even though only removal is currently possible), you'll likely do so inside an event handler that runs in the io_context thread.

However, if you need to call the Client::OnEvent method from a different thread, you can use boost::io_context::post to schedule its execution in the io_context thread:

io_context.post(
     [client]()
     {
         // this will run in the library thread (i.e., the thread that called io_context::run()
         client->OnEvent(...);
     } 
); 

The feature you propose—removing a single handler for an event—can indeed be useful, but it requires the library to return a handle for the callback, allowing you to remove the callback using the handle. I'm going to create a GitHub issue for this.

[daniele77]

Opened issue #71

[Crazyokd]

Hi @daniele77

Thank you for your reply.

I want to use this library in Lua&C&C++, So I want it to be as flexible as possible.

io_context.post(
     [client]()
     {
         // this will run in the library thread (i.e., the thread that called io_context::run()
         client->OnEvent(...);
     } 
); 

This answer is very helpful!

Then I also can use io_context.post to easily delete all eventHandler without any concurrent problem.

Thank you again.