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/**
* Copyright (C) 2006-2009 Dustin Sallings
* Copyright (C) 2009-2012 Couchbase, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALING
* IN THE SOFTWARE.
*/
package net.spy.memcached.internal;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicReference;
import net.spy.memcached.MemcachedConnection;
import net.spy.memcached.compat.SpyObject;
import net.spy.memcached.ops.Operation;
import net.spy.memcached.ops.OperationState;
import net.spy.memcached.ops.OperationStatus;
/**
* Managed future for operations.
*
* From an OperationFuture, application code can determine if the status of a
* given Operation in an asynchronous manner.
*
*
If for example we needed to update the keys "user::name",
* "user::friendlist" because later in the method we were going to
* verify the change occurred as expected interacting with the user, we can
* fire multiple IO operations simultaneously with this concept.
*
* @param Type of object returned from this future.
*/
public class OperationFuture extends SpyObject implements Future {
private final CountDownLatch latch;
private final AtomicReference objRef;
protected OperationStatus status;
private final long timeout;
private Operation op;
private final String key;
private Long cas;
/**
* Create an OperationFuture for a given async operation.
*
* This is intended for internal use only.
*
* @param k the key for the operation
* @param l the latch to be used counting down the OperationFuture
* @param opTimeout the timeout within which the operation needs to be done
*/
public OperationFuture(String k, CountDownLatch l, long opTimeout) {
this(k, l, new AtomicReference(null), opTimeout);
}
/**
* Create an OperationFuture for a given async operation.
*
* This is intended for internal use only.
*
* @param k the key for the operation
* @param l the latch to be used counting down the OperationFuture
* @param oref an AtomicReference associated with the operation
* @param opTimeout the timeout within which the operation needs to be done
*/
public OperationFuture(String k, CountDownLatch l, AtomicReference oref,
long opTimeout) {
super();
latch = l;
objRef = oref;
status = null;
timeout = opTimeout;
key = k;
cas = null;
}
/**
* Cancel this operation, if possible.
*
* @param ign not used
* @deprecated
* @return true if the operation has not yet been written to the network
*/
public boolean cancel(boolean ign) {
assert op != null : "No operation";
op.cancel();
return op.getState() == OperationState.WRITE_QUEUED;
}
/**
* Cancel this operation, if possible.
*
* @return true if the operation has not yet been written to the network
*/
public boolean cancel() {
assert op != null : "No operation";
op.cancel();
return op.getState() == OperationState.WRITE_QUEUED;
}
/**
* Get the results of the given operation.
*
* As with the Future interface, this call will block until the results of
* the future operation has been received.
*
* @return the operation results of this OperationFuture
* @throws InterruptedException
* @throws ExecutionException
*/
public T get() throws InterruptedException, ExecutionException {
try {
return get(timeout, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
throw new RuntimeException("Timed out waiting for operation", e);
}
}
/**
* Get the results of the given operation.
*
* As with the Future interface, this call will block until the results of
* the future operation has been received.
*
* @param duration amount of time to wait
* @param units unit of time to wait
* @return the operation results of this OperationFuture
* @throws InterruptedException
* @throws TimeoutException
* @throws ExecutionException
*/
public T get(long duration, TimeUnit units) throws InterruptedException,
TimeoutException, ExecutionException {
if (!latch.await(duration, units)) {
// whenever timeout occurs, continuous timeout counter will increase by 1.
MemcachedConnection.opTimedOut(op);
if (op != null) { // op can be null on a flush
op.timeOut();
}
throw new CheckedOperationTimeoutException(
"Timed out waiting for operation", op);
} else {
// continuous timeout counter will be reset
MemcachedConnection.opSucceeded(op);
}
if (op != null && op.hasErrored()) {
throw new ExecutionException(op.getException());
}
if (isCancelled()) {
throw new ExecutionException(new CancellationException("Cancelled"));
}
if (op != null && op.isTimedOut()) {
throw new ExecutionException(new CheckedOperationTimeoutException(
"Operation timed out.", op));
}
/* TODO: re-add assertion that op.getState() == OperationState.COMPLETE */
return objRef.get();
}
/**
* Get the key for this operation.
*
* @return the key for this operation
*/
public String getKey() {
return key;
}
/**
* Set the key for this operation.
*
* @param inCas the CAS value
*/
public void setCas(long inCas) {
this.cas = inCas;
}
/**
* Get the CAS for this operation.
*
* @throws UnsupportedOperationException If this is for an ASCII protocol
* configured client.
* @return the CAS for this operation or null if unsuccessful.
*
*/
public Long getCas() {
if (cas == null) {
try {
get();
} catch (InterruptedException e) {
status = new OperationStatus(false, "Interrupted");
Thread.currentThread().isInterrupted();
} catch (ExecutionException e) {
getLogger().warn("Error getting cas of operation", e);
}
}
if (cas == null && status.isSuccess()) {
throw new UnsupportedOperationException("This operation doesn't return"
+ "a cas value.");
}
return cas;
}
/**
* Get the current status of this operation.
*
* Note that the operation status may change as the operation is tried and
* potentially retried against the servers specified by the NodeLocator.
*
* @return OperationStatus
*/
public OperationStatus getStatus() {
if (status == null) {
try {
get();
} catch (InterruptedException e) {
status = new OperationStatus(false, "Interrupted");
Thread.currentThread().isInterrupted();
} catch (ExecutionException e) {
getLogger().warn("Error getting status of operation", e);
}
}
return status;
}
/**
* Set the Operation associated with this OperationFuture.
*
* This is intended for internal use only.
*
* @param o the Operation object itself
* @param s the OperationStatus associated with this operation
*/
public void set(T o, OperationStatus s) {
objRef.set(o);
status = s;
}
/**
* Set the Operation associated with this OperationFuture.
*
* This is intended for internal use only.
*
* @param to the Operation to set this OperationFuture to be tracking
*/
public void setOperation(Operation to) {
op = to;
}
/**
* Whether or not the Operation associated with this OperationFuture has been
* canceled.
*
* One scenario in which this can occur is if the connection is lost and the
* Operation has been sent over the network. In this case, the operation may
* or may not have reached the server before the connection was dropped.
*
* @return true if the Operation has been canceled
*/
public boolean isCancelled() {
assert op != null : "No operation";
return op.isCancelled();
}
/**
* Whether or not the Operation is done and result can be retrieved with
* get().
*
* The most common way to wait for this OperationFuture is to use the get()
* method which will block. This method allows one to check if it's complete
* without blocking.
*
* @return true if the Operation is done
*/
public boolean isDone() {
assert op != null : "No operation";
return latch.getCount() == 0 || op.isCancelled()
|| op.getState() == OperationState.COMPLETE;
}
}