| 1 | // Copyright (c) 2006 Dustin Sallings <dustin@spy.net> |
| 2 | |
| 3 | package net.spy.memcached.compat; |
| 4 | |
| 5 | import java.util.ArrayList; |
| 6 | import java.util.Collection; |
| 7 | import java.util.IdentityHashMap; |
| 8 | import java.util.concurrent.Callable; |
| 9 | import java.util.concurrent.CountDownLatch; |
| 10 | import java.util.concurrent.CyclicBarrier; |
| 11 | |
| 12 | /** |
| 13 | * Thread that invokes a callable multiple times concurrently. |
| 14 | */ |
| 15 | public class SyncThread<T> extends SpyThread { |
| 16 | |
| 17 | private final Callable<T> callable; |
| 18 | private final CyclicBarrier barrier; |
| 19 | private final CountDownLatch latch; |
| 20 | private Throwable throwable=null; |
| 21 | private T rv=null; |
| 22 | |
| 23 | /** |
| 24 | * Get a SyncThread that will call the given callable when the given |
| 25 | * barrier allows it past. |
| 26 | * |
| 27 | * @param b the barrier |
| 28 | * @param c the callable |
| 29 | */ |
| 30 | public SyncThread(CyclicBarrier b, Callable<T> c) { |
| 31 | super("SyncThread"); |
| 32 | setDaemon(true); |
| 33 | callable=c; |
| 34 | barrier=b; |
| 35 | latch=new CountDownLatch(1); |
| 36 | start(); |
| 37 | } |
| 38 | |
| 39 | /** |
| 40 | * Wait for the barrier, invoke the callable and capture the result or an |
| 41 | * exception. |
| 42 | */ |
| 43 | @Override |
| 44 | public void run() { |
| 45 | try { |
| 46 | barrier.await(); |
| 47 | rv=callable.call(); |
| 48 | } catch(Throwable t) { |
| 49 | throwable=t; |
| 50 | } |
| 51 | latch.countDown(); |
| 52 | } |
| 53 | |
| 54 | /** |
| 55 | * Get the result from the invocation. |
| 56 | * |
| 57 | * @return the result |
| 58 | * @throws Throwable if an error occurred when evaluating the callable |
| 59 | */ |
| 60 | public T getResult() throws Throwable { |
| 61 | latch.await(); |
| 62 | if(throwable != null) { |
| 63 | throw throwable; |
| 64 | } |
| 65 | return rv; |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * Get a collection of SyncThreads that all began as close to the |
| 70 | * same time as possible and have all completed. |
| 71 | * @param <T> the result type of the SyncThread |
| 72 | * @param num the number of concurrent threads to execute |
| 73 | * @param callable the thing to call |
| 74 | * @return the completed SyncThreads |
| 75 | * @throws InterruptedException if we're interrupted during join |
| 76 | */ |
| 77 | public static <T> Collection<SyncThread<T>> getCompletedThreads( |
| 78 | int num, Callable<T> callable) throws InterruptedException { |
| 79 | Collection<SyncThread<T>> rv=new ArrayList<SyncThread<T>>(num); |
| 80 | |
| 81 | CyclicBarrier barrier=new CyclicBarrier(num); |
| 82 | for(int i=0; i<num; i++) { |
| 83 | rv.add(new SyncThread<T>(barrier, callable)); |
| 84 | } |
| 85 | |
| 86 | for(SyncThread<T> t : rv) { |
| 87 | t.join(); |
| 88 | } |
| 89 | |
| 90 | return rv; |
| 91 | } |
| 92 | |
| 93 | /** |
| 94 | * Get the distinct result count for the given callable at the given |
| 95 | * concurrency. |
| 96 | * |
| 97 | * @param <T> the type of the callable |
| 98 | * @param num the concurrency |
| 99 | * @param callable the callable to invoke |
| 100 | * @return the number of distinct (by identity) results found |
| 101 | * @throws Throwable if an exception occurred in one of the invocations |
| 102 | */ |
| 103 | public static <T> int getDistinctResultCount(int num, Callable<T> callable) |
| 104 | throws Throwable { |
| 105 | IdentityHashMap<T, Object> found=new IdentityHashMap<T, Object>(); |
| 106 | Collection<SyncThread<T>> threads=getCompletedThreads(num, callable); |
| 107 | for(SyncThread<T> s : threads) { |
| 108 | found.put(s.getResult(), new Object()); |
| 109 | } |
| 110 | return found.size(); |
| 111 | } |
| 112 | } |