[lldb-dev] Process::SetPrivateState / SetPublicState

Greg Clayton gclayton at apple.com
Thu Nov 6 14:05:14 PST 2014

> What is the difference between these two, and when would I use one over the other?  SetPrivateState() doesn't appear to modify the public state, and SetPublicState doesn't appear to modify the private state, so it seems a little confusing that these can get out of sync with each other.  What's the use case here?

When you detect the truth (when your process starts or stops), you set the private state. The public state could be set to running, but you are implementing a source line single step which may involve starting and stopping the process 100s of times before the step is actually done. So the thread plans use the private state and determine when the public state should be updated. Another example is running an expression. The public state may say "stopped", but privately the process can be resumed and stopped many times when evaluating the expression, but you wouldn't want the public (people listening to the process events) to know about such changes.

So the thread plans and process use the private state to make things happen and this tracks the "truth" of what the current process is doing. The public facing state is what causes the events to be broadcast to whomever is listening to the process events and should only notify the GUI or command line when it would like to update the views or display the stop reason, etc.

In the classes that are controlling your actual process, you should always be setting the private state. Never touch the public state yourself.


More information about the lldb-dev mailing list