| 1 | package net.spy.memcached.transcoders; |
| 2 | |
| 3 | import java.util.concurrent.ArrayBlockingQueue; |
| 4 | import java.util.concurrent.Callable; |
| 5 | import java.util.concurrent.ExecutionException; |
| 6 | import java.util.concurrent.Future; |
| 7 | import java.util.concurrent.FutureTask; |
| 8 | import java.util.concurrent.ThreadPoolExecutor; |
| 9 | import java.util.concurrent.TimeUnit; |
| 10 | import java.util.concurrent.TimeoutException; |
| 11 | import java.util.concurrent.atomic.AtomicBoolean; |
| 12 | |
| 13 | import net.spy.memcached.CachedData; |
| 14 | import net.spy.memcached.compat.SpyObject; |
| 15 | |
| 16 | /** |
| 17 | * Asynchronous transcoder. |
| 18 | */ |
| 19 | public class TranscodeService extends SpyObject { |
| 20 | |
| 21 | private final ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 10, 60L, |
| 22 | TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(100), |
| 23 | new ThreadPoolExecutor.DiscardPolicy()); |
| 24 | |
| 25 | /** |
| 26 | * Perform a decode. |
| 27 | */ |
| 28 | public <T> Future<T> decode(final Transcoder<T> tc, |
| 29 | final CachedData cachedData) { |
| 30 | |
| 31 | assert !pool.isShutdown() : "Pool has already shut down."; |
| 32 | |
| 33 | TranscodeService.Task<T> task = new TranscodeService.Task<T>( |
| 34 | new Callable<T>() { |
| 35 | public T call() { |
| 36 | return tc.decode(cachedData); |
| 37 | } |
| 38 | }); |
| 39 | |
| 40 | if (tc.asyncDecode(cachedData)) { |
| 41 | this.pool.execute(task); |
| 42 | } |
| 43 | return task; |
| 44 | } |
| 45 | |
| 46 | /** |
| 47 | * Shut down the pool. |
| 48 | */ |
| 49 | public void shutdown() { |
| 50 | pool.shutdown(); |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * Ask whether this service has been shut down. |
| 55 | */ |
| 56 | public boolean isShutdown() { |
| 57 | return pool.isShutdown(); |
| 58 | } |
| 59 | |
| 60 | private static class Task<T> extends FutureTask<T> { |
| 61 | private final AtomicBoolean isRunning = new AtomicBoolean(false); |
| 62 | |
| 63 | public Task(Callable<T> callable) { |
| 64 | super(callable); |
| 65 | } |
| 66 | |
| 67 | @Override |
| 68 | public T get() throws InterruptedException, ExecutionException { |
| 69 | this.run(); |
| 70 | return super.get(); |
| 71 | } |
| 72 | |
| 73 | @Override |
| 74 | public T get(long timeout, TimeUnit unit) throws InterruptedException, |
| 75 | ExecutionException, TimeoutException { |
| 76 | this.run(); |
| 77 | return super.get(timeout, unit); |
| 78 | } |
| 79 | |
| 80 | @Override |
| 81 | public void run() { |
| 82 | if (this.isRunning.compareAndSet(false, true)) { |
| 83 | super.run(); |
| 84 | } |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | } |