478304 - Let nsRunnableMethod be used with non-void-returning functions

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Attachment: Patch, v1

nsRunnableMethod's restriction on void callback functions is unnecessary and there are lots of functions that return nsresults. Patch attached lets us use nsRunnableMethod with functions that return just about anything (besides already_AddRefed). Also lets us remove a runnable class added in bug 340345.

Comment 1

[Benjamin Smedberg]

Comment on attachment 362148 [details] [diff] [review]
Patch, v1

>diff --git a/xpcom/glue/nsThreadUtils.h b/xpcom/glue/nsThreadUtils.h

>   NS_IMETHOD Run() {
>+    // Make sure this return type is safe.
>+    ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafeForRunnableMethod();

There's no need for this to be an actual method call. Just make it a static typename, at class scope:

typedef typename ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafe returntypecheck;

>+  // These ReturnTypeEnforcer classes set up a blacklist for return types that
>+  // we know are not safe. The default ReturnTypeEnforcer compiles just fine but
>+  // already_AddRefed will not.
>+  template <typename OtherReturnType>
>+  class ReturnTypeEnforcer
>+  {
>+  public:
>+    static void ReturnTypeIsSafeForRunnableMethod() { }

and then
  typedef int ReturnTypeIsSafe;

Comment 2

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Attachment: Patch, v1.1

With those changes, ready for checkin.

Comment 3

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Pushed changeset c877b7e214a1 to mozilla-central.

Comment 4

[Ben Newman (:bnewman) (:benjamn)]

Awesome, I've been wanting this for a while. Christmas in February!