Bug 1530715 - P11: Remove OwnedCriticalSection in cubeb context. r=padenot

The OwnedCriticalSection is a custom mutex directly translated from the
C code of the Cubeb library. Replacing the custom mutex by standard Rust
mutex make the code fit in the Rust design better and make debugging the
code easier. The variables protected by the custom mutex in the cubeb
context is moved to the Rust standard mutex in previous patches. The
custom mutex in the cubeb context is able to be removed since we no
longer rely on it.

Differential Revision: https://phabricator.services.mozilla.com/D29983

--HG--
extra : moz-landing-system : lando

media/libcubeb/cubeb-coreaudio-rs/README_MOZILLA

@@ -3,4 +3,4 @@ git repository using the update.sh script.
 
 The cubeb-coreaudio-rs git repository is: https://github.com/ChunMinChang/cubeb-coreaudio-rs
 
-The git commit ID used was 5ba439078762852b921fbad803ef76a5353e7742 (2019-06-21 14:25:39 -0700)
+The git commit ID used was 98f1c507e678a76aa19fe1cfeb532cd68455a712 (2019-06-21 14:26:53 -0700)

media/libcubeb/cubeb-coreaudio-rs/src/backend/mod.rs

@@ -2309,7 +2309,6 @@ pub const OPS: Ops = capi_new!(AudioUnitContext, AudioUnitStream);
 #[derive(Debug)]
 pub struct AudioUnitContext {
     _ops: *const Ops,
-    mutex: OwnedCriticalSection,
     // serial_queue will be created by dispatch_queue_create(create_dispatch_queue)
     // without ARC(Automatic Reference Counting) support, so it should be released
     // by dispatch_release(release_dispatch_queue).
@@ -2324,7 +2323,6 @@ impl AudioUnitContext {
     fn new() -> Self {
         Self {
             _ops: &OPS as *const _,
-            mutex: OwnedCriticalSection::new(),
             serial_queue: create_dispatch_queue(DISPATCH_QUEUE_LABEL, DISPATCH_QUEUE_SERIAL),
             layout: atomic::Atomic::new(ChannelLayout::UNDEFINED),
             channels: 0,
@@ -2333,10 +2331,6 @@ impl AudioUnitContext {
         }
     }
 
-    fn init(&mut self) {
-        self.mutex.init();
-    }
-
     fn active_streams(&self) -> u32 {
         let controller = self.latency_controller.lock().unwrap();
         controller.streams
@@ -2455,8 +2449,7 @@ impl AudioUnitContext {
 impl ContextOps for AudioUnitContext {
     fn init(_context_name: Option<&CStr>) -> Result<Context> {
         set_notification_runloop();
-        let mut ctx = Box::new(AudioUnitContext::new());
-        ctx.init();
+        let ctx = Box::new(AudioUnitContext::new());
         Ok(unsafe { Context::from_ptr(Box::into_raw(ctx) as *mut _) })
     }
 
@@ -2661,9 +2654,6 @@ impl ContextOps for AudioUnitContext {
             );
         }
 
-        let mutex_ptr = &mut self.mutex as *mut OwnedCriticalSection;
-        let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
-
         let mut boxed_stream = Box::new(AudioUnitStream::new(
             self,
             user_ptr,
@@ -2740,8 +2730,6 @@ impl ContextOps for AudioUnitContext {
         if devtype == DeviceType::UNKNOWN {
             return Err(Error::invalid_parameter());
         }
-        let mutex_ptr = &mut self.mutex as *mut OwnedCriticalSection;
-        let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
         if collection_changed_callback.is_some() {
             self.add_devices_changed_listener(devtype, collection_changed_callback, user_ptr)
         } else {
@@ -2752,9 +2740,6 @@ impl ContextOps for AudioUnitContext {
 
 impl Drop for AudioUnitContext {
     fn drop(&mut self) {
-        let mutex_ptr = &mut self.mutex as *mut OwnedCriticalSection;
-        let _lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
-
         {
             let controller = self.latency_controller.lock().unwrap();
             // Disabling this assert for bug 1083664 -- we seem to leak a stream
@@ -3101,8 +3086,6 @@ impl<'ctx> AudioUnitStream<'ctx> {
     }
 
     fn reinit(&mut self, flags: device_flags) -> Result<()> {
-        let mutex_ptr = &mut self.context.mutex as *mut OwnedCriticalSection;
-        let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
         assert!(!self.input_unit.is_null() || !self.output_unit.is_null());
         assert!(
             (self.input_unit.is_null() || flags.contains(device_flags::DEV_INPUT))
@@ -4262,8 +4245,6 @@ impl<'ctx> AudioUnitStream<'ctx> {
     }
 
     fn destroy_internal(&mut self) {
-        self.context.mutex.assert_current_thread_owns();
-
         if self.uninstall_system_changed_callback().is_err() {
             cubeb_log!(
                 "({:p}) Could not uninstall the device changed callback",
@@ -4331,8 +4312,6 @@ impl<'ctx> AudioUnitStream<'ctx> {
 
     fn destroy(&mut self) {
         if !self.shutdown.load(Ordering::SeqCst) {
-            let mutex_ptr = &mut self.context.mutex as *mut OwnedCriticalSection;
-            let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
             self.stop_internal();
             *self.shutdown.get_mut() = true;
         }
@@ -4346,8 +4325,6 @@ impl<'ctx> AudioUnitStream<'ctx> {
         // with reinit when un/plug devices
         sync_dispatch(queue, move || {
             let mut stm_guard = also_mutexed_stm.lock().unwrap();
-            let mutex_ptr = &mut stm_guard.context.mutex as *mut OwnedCriticalSection;
-            let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
             stm_guard.destroy_internal();
         });
 
@@ -4365,9 +4342,6 @@ impl<'ctx> Drop for AudioUnitStream<'ctx> {
 
 impl<'ctx> StreamOps for AudioUnitStream<'ctx> {
     fn start(&mut self) -> Result<()> {
-        let mutex_ptr = &mut self.context.mutex as *mut OwnedCriticalSection;
-        let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
-
         *self.shutdown.get_mut() = false;
         *self.draining.get_mut() = false;
 
@@ -4390,9 +4364,6 @@ impl<'ctx> StreamOps for AudioUnitStream<'ctx> {
         Ok(())
     }
     fn stop(&mut self) -> Result<()> {
-        let mutex_ptr = &mut self.context.mutex as *mut OwnedCriticalSection;
-        let _context_lock = AutoLock::new(unsafe { &mut (*mutex_ptr) });
-
         *self.shutdown.get_mut() = true;
 
         self.stop_internal();