/** * Copyright (c) 2014-present, Facebook, Inc. All rights reserved. * * You are hereby granted a non-exclusive, worldwide, royalty-free license to use, * copy, modify, and distribute this software in source code or binary form for use * in connection with the web services and APIs provided by Facebook. * * As with any software that integrates with the Facebook platform, your use of * this software is subject to the Facebook Developer Principles and Policies * [http://developers.facebook.com/policy/]. This copyright notice shall be * included in all copies or substantial portions of the software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ package com.facebook.internal; import com.facebook.FacebookSdk; import java.util.concurrent.Callable; import java.util.concurrent.CountDownLatch; import java.util.concurrent.FutureTask; public class LockOnGetVariable<T> { private T value; private CountDownLatch initLatch; public LockOnGetVariable(T value) { this.value = value; } public LockOnGetVariable(final Callable<T> callable) { initLatch = new CountDownLatch(1); FacebookSdk.getExecutor().execute( new FutureTask<>(new Callable<Void>() { @Override public Void call() throws Exception { try { LockOnGetVariable.this.value = callable.call(); } finally { initLatch.countDown(); } return null; } })); } public T getValue() { this.waitOnInit(); return this.value; } private void waitOnInit() { if (initLatch == null) { return; } try { initLatch.await(); } catch (InterruptedException ex) { // ignore } } }