Better API demo, open activity from service, discover crypto provider with packagemanager instead of register intent

OpenPGP-Keychain/src/org/sufficientlysecure/keychain/util/PausableThreadPoolExecutor.java

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+/*
+ * Copyright (C) 2013 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * 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 org.sufficientlysecure.keychain.util;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * Example from
+ * http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ThreadPoolExecutor.html
+ */
+public class PausableThreadPoolExecutor extends ThreadPoolExecutor {
+
+    public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
+            TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
+        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
+    }
+
+    public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
+            TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory,
+            RejectedExecutionHandler handler) {
+        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
+    }
+
+    public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
+            TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {
+        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
+    }
+
+    public PausableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,
+            TimeUnit unit, BlockingQueue<Runnable> workQueue) {
+        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
+    }
+
+    private boolean isPaused;
+    private ReentrantLock pauseLock = new ReentrantLock();
+    private Condition unpaused = pauseLock.newCondition();
+
+    protected void beforeExecute(Thread t, Runnable r) {
+        super.beforeExecute(t, r);
+        pauseLock.lock();
+        try {
+            while (isPaused)
+                unpaused.await();
+        } catch (InterruptedException ie) {
+            t.interrupt();
+        } finally {
+            pauseLock.unlock();
+        }
+    }
+
+    public void pause() {
+        pauseLock.lock();
+        try {
+            isPaused = true;
+        } finally {
+            pauseLock.unlock();
+        }
+    }
+
+    public void resume() {
+        pauseLock.lock();
+        try {
+            isPaused = false;
+            unpaused.signalAll();
+        } finally {
+            pauseLock.unlock();
+        }
+    }
+}