315442 - Need a scriptable way to post an event to an event target

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement, P2)

Description

[Benjamin Smedberg]

From bug 315087: We need a scriptable way to post an event to an event target. Since I don't really understand PLEvent all that well, here's my understand of our options:

1) add a method postScriptableEvent(in nsIRunnable); on the current nsIEventTarget

2) add a helper service something like this:

interface nsIScriptableEventHelper : nsISupports
{
  void postScriptableEvent(in nsIEventTarget, in nsIRunnable);
};

Either way would end up wrapping the nsIRunnable with a PLEvent and calling it on the other end.

Comment 1

[Darin Fisher]

I believe that we also want an interface that would be a good candidate for being frozen for use not only by JS but also by C++.  My current thinking is to go with something more like suggestion 2 -- to build a service that provides functions for operating on a nsIEventTarget.

  [scriptable, uuid(...)]
  interface nsIEventTargetManager : nsISupports {
    void post(in nsIEventTarget target, in nsIRunnable runnable,
              in boolean synchronous);
    nsIEventTarget getEventTarget(in ACString name);
    nsIEventTarget setEventTarget(in ACString name, in nsIEventTarget target);
  };

This interface gives consumers a way to not only post an event (in the form of a nsIRunnable), but it also gives them a way to access "special" nsIEventTargets such as the following:

  "main"
  "current"
  "socket"
  "io-thread-pool"

The last two are examples of nsIEventTarget instances that are added dynamically by Necko.  We might want to treat the empty string as equivalent to "current".

Anyways, this is still a thought in progress, but I wanted to jot it down.

Comment 2

[Darin Fisher]

My proposed interface is wiki'd here:
http://wiki.mozilla.org/XPCOM:nsIEventTargetManager

Please read that instead of comment #1.

Comment 3

[Darin Fisher]

FYI, I'm planning something quite different from what is proposed here and on the wiki page.  More in a while...

Comment 4

[Darin Fisher]

The revised plan goes something like this:
http://wiki.mozilla.org/XPCOM:nsIThreadManager

Comment 5

[Darin Fisher]

This bug is fixed by the threadmanager patch in bug 326273.