Skip to content

Thread detach hook for Java JNI on Android #250

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 11 commits into from
13 changes: 13 additions & 0 deletions src/queue.c
Original file line number Diff line number Diff line change
Expand Up @@ -861,6 +861,14 @@ gettid(void)
if ((f) && tsd->k) ((void(*)(void*))(f))(tsd->k); \
} while (0)

#ifdef __ANDROID__
static void (*_dispatch_thread_detach_callback)(void);
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

if it's static then the overlay which is a dynamic library can't pick it up.

@das suggested to me the right place is to export the symbol is from private/queue_private.h or private/private.h and also to use silgen like you did.

Copy link
Contributor Author

@johnno1962 johnno1962 May 27, 2017

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Global symbol is now a function _dispatch_set_detach_callback_ptr as it doesn’t seem possible to express a global var in a silgen. I’ve moved it's declaration into queue_private.h.


void _dispatch_set_detach_callback( void (*callback)(void) ) {
_dispatch_thread_detach_callback = callback;
}
#endif

void
_libdispatch_tsd_cleanup(void *ctx)
{
Expand All @@ -885,6 +893,11 @@ _libdispatch_tsd_cleanup(void *ctx)
_tsd_call_cleanup(dispatch_voucher_key, _voucher_thread_cleanup);
_tsd_call_cleanup(dispatch_deferred_items_key,
_dispatch_deferred_items_cleanup);
#ifdef __ANDROID__
if (_dispatch_thread_detach_callback) {
_dispatch_thread_detach_callback();
}
#endif
tsd->tid = 0;
}

Expand Down
11 changes: 11 additions & 0 deletions src/queue_internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -1039,4 +1039,15 @@ _dispatch_queue_is_exclusively_owned_by_current_thread_4IOHID(

#endif // __APPLE__

#ifdef __ANDROID__
/*!
* @handler dispatch_thread_detach_callback
*
* Hook to be able to detach threads from the Java JVM before they exit.
* If JNI has been used on a thread on Android it needs to have been
* "detached" before the thread exits or the application will crash.
*/
DISPATCH_EXPORT
void _dispatch_set_detach_callback( void (*callback)(void) );
#endif
#endif
14 changes: 14 additions & 0 deletions src/swift/Queue.swift
Original file line number Diff line number Diff line change
Expand Up @@ -330,6 +330,20 @@ public extension DispatchQueue {
let p = Unmanaged.passRetained(v).toOpaque()
dispatch_queue_set_specific(self.__wrapped, k, p, _destructDispatchSpecificValue)
}

#if os(Android)
@_silgen_name("_dispatch_set_detach_callback")
private static func _dispatch_set_detach_callback( _ callback: (@convention(c) () -> Void)? )

public static var threadDetachCallback: (@convention(c) () -> Void)? {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think only a one-way setter should be exposed. having a getter makes the interface un-necessarily ugly.

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks for the potiners. It helps me zero in on something you’re happy with. Changed pushed.

get {
return nil
}
set(newValue) {
_dispatch_set_detach_callback( newValue )
}
}
#endif
}

private func _destructDispatchSpecificValue(ptr: UnsafeMutableRawPointer?) {
Expand Down