Avoid deadlocks when calling autoFocus from onAutoFocus callback. (f05c1d63) · Commits · e / os / android_frameworks_base

core/java/android/hardware/Camera.java

+31 −30

Original line number	Diff line number	Diff line
		@@ -155,7 +155,7 @@ public class Camera {
		private boolean mOneShot;
		private boolean mWithBuffer;
		private boolean mFaceDetectionRunning = false;
		private ReentrantLock mFocusLock = new ReentrantLock();
		private Object mAutoFocusCallbackLock = new Object();

		/**
		* Broadcast Action: A new picture is taken by the camera, and the entry of
		@@ -508,7 +508,9 @@ public class Camera {
		mRawImageCallback = null;
		mPostviewCallback = null;
		mJpegCallback = null;
		synchronized (mAutoFocusCallbackLock) {
		mAutoFocusCallback = null;
		}
		mAutoFocusMoveCallback = null;
		}

		@@ -748,14 +750,13 @@ public class Camera {
		return;

		case CAMERA_MSG_FOCUS:
		mFocusLock.lock();
		try {
		if (mAutoFocusCallback != null) {
		boolean success = msg.arg1 == 0 ? false : true;
		mAutoFocusCallback.onAutoFocus(success, mCamera);
		AutoFocusCallback cb = null;
		synchronized (mAutoFocusCallbackLock) {
		cb = mAutoFocusCallback;
		}
		} finally {
		mFocusLock.unlock();
		if (cb != null) {
		boolean success = msg.arg1 == 0 ? false : true;
		cb.onAutoFocus(success, mCamera);
		}
		return;

		@@ -880,13 +881,10 @@ public class Camera {
		*/
		public final void autoFocus(AutoFocusCallback cb)
		{
		mFocusLock.lock();
		try {
		synchronized (mAutoFocusCallbackLock) {
		mAutoFocusCallback = cb;
		native_autoFocus();
		} finally {
		mFocusLock.unlock();
		}
		native_autoFocus();
		}
		private native final void native_autoFocus();

		@@ -900,14 +898,26 @@ public class Camera {
		*/
		public final void cancelAutoFocus()
		{
		mFocusLock.lock();
		try {
		synchronized (mAutoFocusCallbackLock) {
		mAutoFocusCallback = null;
		native_cancelAutoFocus();
		removePendingAFCompletionMessages();
		} finally {
		mFocusLock.unlock();
		}
		native_cancelAutoFocus();
		// CAMERA_MSG_FOCUS should be removed here because the following
		// scenario can happen:
		// - An application uses the same thread for autoFocus, cancelAutoFocus
		// and looper thread.
		// - The application calls autoFocus.
		// - HAL sends CAMERA_MSG_FOCUS, which enters the looper message queue.
		// Before event handler's handleMessage() is invoked, the application
		// calls cancelAutoFocus and autoFocus.
		// - The application gets the old CAMERA_MSG_FOCUS and thinks autofocus
		// has been completed. But in fact it is not.
		//
		// As documented in the beginning of the file, apps should not use
		// multiple threads to call autoFocus and cancelAutoFocus at the same
		// time. It is HAL's responsibility not to send a CAMERA_MSG_FOCUS
		// message after native_cancelAutoFocus is called.
		mEventHandler.removeMessages(CAMERA_MSG_FOCUS);
		}
		private native final void native_cancelAutoFocus();

		@@ -3596,13 +3606,4 @@ public class Camera {
		return false;
		}
		};

		/*
		* At any time, there should be at most one pending auto focus completion
		* message, but we simply remove all pending AF completion messages in
		* the looper's queue.
		*/
		private void removePendingAFCompletionMessages() {
		mEventHandler.removeMessages(CAMERA_MSG_FOCUS);
		}
		}