Marcus Hagerott | a89f523 | 2016-12-07 10:04:00 -0800 | [diff] [blame] | 1 | // Copyright 2016 Google Inc. All Rights Reserved. |
| 2 | package com.android.contacts.util.concurrent; |
| 3 | |
| 4 | import android.os.AsyncTask; |
| 5 | import android.os.Handler; |
| 6 | import android.os.Looper; |
| 7 | import android.support.annotation.NonNull; |
| 8 | |
| 9 | import com.google.common.util.concurrent.ForwardingFuture; |
| 10 | import com.google.common.util.concurrent.Futures; |
| 11 | import com.google.common.util.concurrent.ListeningExecutorService; |
| 12 | import com.google.common.util.concurrent.MoreExecutors; |
| 13 | import com.google.common.util.concurrent.SettableFuture; |
| 14 | |
| 15 | import java.util.List; |
| 16 | import java.util.concurrent.AbstractExecutorService; |
| 17 | import java.util.concurrent.Callable; |
| 18 | import java.util.concurrent.Delayed; |
| 19 | import java.util.concurrent.ExecutorService; |
| 20 | import java.util.concurrent.Executors; |
| 21 | import java.util.concurrent.Future; |
| 22 | import java.util.concurrent.LinkedBlockingQueue; |
| 23 | import java.util.concurrent.RunnableScheduledFuture; |
| 24 | import java.util.concurrent.ScheduledExecutorService; |
| 25 | import java.util.concurrent.ScheduledFuture; |
| 26 | import java.util.concurrent.ThreadPoolExecutor; |
| 27 | import java.util.concurrent.TimeUnit; |
| 28 | |
| 29 | /** |
| 30 | * Provides some common executors for use with {@link Futures} |
| 31 | */ |
| 32 | public class ContactsExecutors { |
| 33 | |
| 34 | private ContactsExecutors() {} |
| 35 | |
| 36 | private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors(); |
| 37 | private static final int CORE_POOL_SIZE = CPU_COUNT + 1; |
| 38 | |
| 39 | // AsyncTask.THREAD_POOL_EXECUTOR is a ThreadPoolExecutor so we should end up always using that |
| 40 | // but we have a fallback in case the platform implementation changes in some future release. |
| 41 | private static final ListeningExecutorService DEFAULT_THREAD_POOL_EXECUTOR = |
| 42 | (AsyncTask.THREAD_POOL_EXECUTOR instanceof ExecutorService) ? |
| 43 | MoreExecutors.listeningDecorator( |
| 44 | (ExecutorService) AsyncTask.THREAD_POOL_EXECUTOR) : |
| 45 | MoreExecutors.listeningDecorator( |
| 46 | Executors.newFixedThreadPool(CORE_POOL_SIZE)); |
| 47 | |
| 48 | // We initialize this lazily since in some cases we may never even read from the SIM card |
| 49 | private static ListeningExecutorService sSimExecutor; |
| 50 | |
| 51 | /** |
| 52 | * Returns the default thread pool that can be used for background work. |
| 53 | */ |
| 54 | public static ListeningExecutorService getDefaultThreadPoolExecutor() { |
| 55 | return DEFAULT_THREAD_POOL_EXECUTOR; |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Creates an executor that runs commands on the application UI thread |
| 60 | */ |
| 61 | public static ScheduledExecutorService newUiThreadExecutor() { |
| 62 | return newHandlerExecutor(new Handler(Looper.getMainLooper())); |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * Create an executor that posts commands to the provided handler |
| 67 | */ |
| 68 | public static ScheduledExecutorService newHandlerExecutor(final Handler handler) { |
| 69 | return new HandlerExecutorService(handler); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Returns an ExecutorService that can be used to read from the SIM card. |
| 74 | * |
| 75 | * <p>See b/32831092</p> |
| 76 | * <p>A different executor than {@link ContactsExecutors#getDefaultThreadPoolExecutor()} is |
| 77 | * provided for this case because reads of the SIM card can block for long periods of time |
| 78 | * and if they do we might exhaust our thread pool. Additionally it appears that reading from |
| 79 | * the SIM provider from multiple threads concurrently can cause problems. |
| 80 | * </p> |
| 81 | */ |
| 82 | public synchronized static ListeningExecutorService getSimReadExecutor() { |
| 83 | if (sSimExecutor == null) { |
| 84 | final ThreadPoolExecutor executor = new ThreadPoolExecutor( |
| 85 | 1, 1, 30, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); |
| 86 | executor.allowCoreThreadTimeOut(true); |
| 87 | sSimExecutor = MoreExecutors.listeningDecorator(executor); |
| 88 | } |
| 89 | return sSimExecutor; |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Wrapper around a handler that implements a subset of the ScheduledExecutorService |
| 94 | * |
| 95 | * <p>This class is useful for testability because Handler can't be mocked since it's |
| 96 | * methods are final. It might be better to just use Executors.newSingleThreadScheduledExecutor |
| 97 | * in the cases where we need to run some time based tasks. |
| 98 | * </p> |
| 99 | */ |
| 100 | private static class HandlerExecutorService extends AbstractExecutorService |
| 101 | implements ScheduledExecutorService { |
| 102 | private final Handler mHandler; |
| 103 | |
| 104 | private HandlerExecutorService(Handler handler) { |
| 105 | mHandler = handler; |
| 106 | } |
| 107 | |
| 108 | @NonNull |
| 109 | @Override |
| 110 | public ScheduledFuture<?> schedule(final Runnable command, long delay, TimeUnit unit) { |
| 111 | final HandlerFuture<Void> future = HandlerFuture |
| 112 | .fromRunnable(mHandler, delay, unit, command); |
| 113 | mHandler.postDelayed(future, unit.toMillis(delay)); |
| 114 | return future; |
| 115 | } |
| 116 | |
| 117 | @NonNull |
| 118 | @Override |
| 119 | public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) { |
| 120 | final HandlerFuture<V> future = new HandlerFuture<>(mHandler, delay, unit, callable); |
| 121 | mHandler.postDelayed(future, unit.toMillis(delay)); |
| 122 | return future; |
| 123 | } |
| 124 | |
| 125 | @NonNull |
| 126 | @Override |
| 127 | public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, |
| 128 | long period, TimeUnit unit) { |
| 129 | throw new UnsupportedOperationException(); |
| 130 | } |
| 131 | |
| 132 | @NonNull |
| 133 | @Override |
| 134 | public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, |
| 135 | long delay, TimeUnit unit) { |
| 136 | throw new UnsupportedOperationException(); |
| 137 | } |
| 138 | |
| 139 | @Override |
| 140 | public void shutdown() { |
| 141 | } |
| 142 | |
| 143 | @Override |
| 144 | public List<Runnable> shutdownNow() { |
| 145 | return null; |
| 146 | } |
| 147 | |
| 148 | @Override |
| 149 | public boolean isShutdown() { |
| 150 | return false; |
| 151 | } |
| 152 | |
| 153 | @Override |
| 154 | public boolean isTerminated() { |
| 155 | return false; |
| 156 | } |
| 157 | |
| 158 | @Override |
| 159 | public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException { |
| 160 | throw new UnsupportedOperationException(); |
| 161 | } |
| 162 | |
| 163 | @Override |
| 164 | public void execute(Runnable command) { |
| 165 | mHandler.post(command); |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | private static class HandlerFuture<T> extends ForwardingFuture<T> implements |
| 170 | RunnableScheduledFuture<T> { |
| 171 | |
| 172 | private final Handler mHandler; |
| 173 | private final TimeUnit mUnit; |
| 174 | private final long mDelay; |
| 175 | private final Callable<T> mTask; |
| 176 | private final SettableFuture<T> mDelegate = SettableFuture.create(); |
| 177 | |
| 178 | private HandlerFuture(Handler handler, long delay, TimeUnit timeUnit, Callable<T> task) { |
| 179 | mHandler = handler; |
| 180 | mUnit = timeUnit; |
| 181 | mDelay = delay; |
| 182 | mTask = task; |
| 183 | } |
| 184 | |
| 185 | @Override |
| 186 | public boolean isPeriodic() { |
| 187 | return false; |
| 188 | } |
| 189 | |
| 190 | @Override |
| 191 | public long getDelay(TimeUnit unit) { |
| 192 | return unit.convert(mDelay, mUnit); |
| 193 | } |
| 194 | |
| 195 | @Override |
| 196 | public int compareTo(Delayed o) { |
| 197 | return Long.compare(mDelay, o.getDelay(mUnit)); |
| 198 | } |
| 199 | |
| 200 | @Override |
| 201 | protected Future<T> delegate() { |
| 202 | return mDelegate; |
| 203 | } |
| 204 | |
| 205 | @Override |
| 206 | public boolean cancel(boolean b) { |
| 207 | mHandler.removeCallbacks(this); |
| 208 | return super.cancel(b); |
| 209 | } |
| 210 | |
| 211 | @Override |
| 212 | public void run() { |
| 213 | try { |
| 214 | mDelegate.set(mTask.call()); |
| 215 | } catch (Exception e) { |
| 216 | mDelegate.setException(e); |
| 217 | } |
| 218 | } |
| 219 | |
| 220 | public static HandlerFuture<Void> fromRunnable(Handler handler, long delay, TimeUnit unit, |
| 221 | final Runnable command) { |
| 222 | return new HandlerFuture<>(handler, delay, unit, new Callable<Void>() { |
| 223 | @Override |
| 224 | public Void call() throws Exception { |
| 225 | command.run(); |
| 226 | return null; |
| 227 | } |
| 228 | }); |
| 229 | } |
| 230 | } |
| 231 | } |