| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.camera.async; |
| |
| import java.util.concurrent.Executor; |
| |
| import com.android.camera.util.Callback; |
| |
| /** |
| * Wraps {@link ConcurrentState} with {@link #setCallback} semantics which |
| * overwrite any existing callback. |
| */ |
| public class ListenableConcurrentState<T> implements Listenable<T> { |
| private final ConcurrentState<T> mState; |
| private final Executor mExecutor; |
| private final Object mLock; |
| private boolean mClosed; |
| private SafeCloseable mExistingCallbackHandle; |
| |
| public ListenableConcurrentState(ConcurrentState<T> state, Executor executor) { |
| mState = state; |
| mExecutor = executor; |
| mLock = new Object(); |
| mClosed = false; |
| mExistingCallbackHandle = null; |
| } |
| |
| /** |
| * Sets the callback, removing any existing callback first. |
| */ |
| @Override |
| public void setCallback(Callback<T> callback) { |
| synchronized (mLock) { |
| if (mClosed) { |
| return; |
| } |
| if (mExistingCallbackHandle != null) { |
| // Unregister any existing callback |
| mExistingCallbackHandle.close(); |
| } |
| mExistingCallbackHandle = mState.addCallback(callback, mExecutor); |
| } |
| } |
| |
| @Override |
| public void close() { |
| synchronized (mLock) { |
| mClosed = true; |
| if (mExistingCallbackHandle != null) { |
| // Unregister any existing callback |
| mExistingCallbackHandle.close(); |
| } |
| } |
| } |
| } |