[Lldb-commits] [lldb] [lldb][lldb-dap] Basic implementation of a deferred request. (PR #140260)

[Ebuka Ezike via lldb-commits]

da-viper wrote:

> Would it be possible to have the RequestHandlers advertise whether or not they should be deferred until the configuration is done (e.g. DeferredUntilConfigurationDone), and keep the latter an implementation detail of the DAP class? And strictly handle deferring at the queue level?

Yes it can, 

> What I don't like is how this introduces more statefulness, especially in the request handlers. The queueing/deferring logic isn't trivial and I would strongly prefer if we could keep it centralized as much as possible. With this PR we end up with both a separate queue and a method that makes the Run operation behaves differently depending on the global DAP state (i.e. if we've send the configuration request).

The plan is to partially resolve the request and then completing the request later on. for example. 

with the launch argument, the new method will be 
`optional<Response> DeferUntilConfig(
    const Arguments &arguments, bool &defer_request)`

```cpp
std::optional<LaunchResponse> LaunchRequestHandler::DeferUntilConfig(
    const LaunchRequestArguments &arguments, bool &defer_request) const {
  // setups the target and initcommands.
  if (LaunchResponse err = PreLaunch(arguments)) { 
    return err;
  }

  defer_request = !dap.configuration_done;
  return std::nullopt; 
}
```
since this it is then deferred it will then complete the remaining request after the configuration is done. like so 

```cpp
Error LaunchRequestHandler::Run(const LaunchRequestArguments &arguments) const {
  if (Error err = dap.RunPreRunCommands())
    return err;

  if (Error err = LaunchProcess(arguments))
    return err;

  dap.RunPostRunCommands();

  return Error::success();
}
```

The could potentially fix the breakpoints problem and also launch after configuration. Not 100% sure this is the best way hence why I have not included the commit. 



https://github.com/llvm/llvm-project/pull/140260