| 1 | package net.spy.memcached.internal; |
| 2 | |
| 3 | import java.util.concurrent.CountDownLatch; |
| 4 | import java.util.concurrent.ExecutionException; |
| 5 | import java.util.concurrent.Future; |
| 6 | import java.util.concurrent.TimeUnit; |
| 7 | import java.util.concurrent.TimeoutException; |
| 8 | import java.util.concurrent.atomic.AtomicReference; |
| 9 | |
| 10 | import net.spy.memcached.ops.Operation; |
| 11 | import net.spy.memcached.ops.OperationState; |
| 12 | |
| 13 | /** |
| 14 | * Managed future for operations. |
| 15 | * |
| 16 | * Not intended for general use. |
| 17 | * |
| 18 | * @param <T> Type of object returned from this future. |
| 19 | */ |
| 20 | public class OperationFuture<T> implements Future<T> { |
| 21 | |
| 22 | private final CountDownLatch latch; |
| 23 | private final AtomicReference<T> objRef; |
| 24 | private final long timeout; |
| 25 | private Operation op; |
| 26 | |
| 27 | public OperationFuture(CountDownLatch l, long opTimeout) { |
| 28 | this(l, new AtomicReference<T>(null), opTimeout); |
| 29 | } |
| 30 | |
| 31 | public OperationFuture(CountDownLatch l, AtomicReference<T> oref, |
| 32 | long opTimeout) { |
| 33 | super(); |
| 34 | latch=l; |
| 35 | objRef=oref; |
| 36 | timeout = opTimeout; |
| 37 | } |
| 38 | |
| 39 | public boolean cancel(boolean ign) { |
| 40 | assert op != null : "No operation"; |
| 41 | op.cancel(); |
| 42 | // This isn't exactly correct, but it's close enough. If we're in |
| 43 | // a writing state, we *probably* haven't started. |
| 44 | return op.getState() == OperationState.WRITING; |
| 45 | } |
| 46 | |
| 47 | public T get() throws InterruptedException, ExecutionException { |
| 48 | try { |
| 49 | return get(timeout, TimeUnit.MILLISECONDS); |
| 50 | } catch (TimeoutException e) { |
| 51 | throw new RuntimeException( |
| 52 | "Timed out waiting for operation", e); |
| 53 | } |
| 54 | } |
| 55 | |
| 56 | public T get(long duration, TimeUnit units) |
| 57 | throws InterruptedException, TimeoutException, ExecutionException { |
| 58 | if(!latch.await(duration, units)) { |
| 59 | throw new CheckedOperationTimeoutException( |
| 60 | "Timed out waiting for operation", op); |
| 61 | } |
| 62 | if(op != null && op.hasErrored()) { |
| 63 | throw new ExecutionException(op.getException()); |
| 64 | } |
| 65 | if(isCancelled()) { |
| 66 | throw new ExecutionException(new RuntimeException("Cancelled")); |
| 67 | } |
| 68 | |
| 69 | return objRef.get(); |
| 70 | } |
| 71 | |
| 72 | public void set(T o) { |
| 73 | objRef.set(o); |
| 74 | } |
| 75 | |
| 76 | public void setOperation(Operation to) { |
| 77 | op=to; |
| 78 | } |
| 79 | |
| 80 | public boolean isCancelled() { |
| 81 | assert op != null : "No operation"; |
| 82 | return op.isCancelled(); |
| 83 | } |
| 84 | |
| 85 | public boolean isDone() { |
| 86 | assert op != null : "No operation"; |
| 87 | return latch.getCount() == 0 || |
| 88 | op.isCancelled() || op.getState() == OperationState.COMPLETE; |
| 89 | } |
| 90 | |
| 91 | } |