ea93f1f5ad501d01e80f6e4a62853cf3eeed35d5
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / datastore / OperationLimiter.java
1 /*
2  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
3  *
4  * This program and the accompanying materials are made available under the
5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6  * and is available at http://www.eclipse.org/legal/epl-v10.html
7  */
8 package org.opendaylight.controller.cluster.datastore;
9
10 import com.google.common.annotations.VisibleForTesting;
11 import com.google.common.base.Preconditions;
12 import java.util.concurrent.Semaphore;
13 import java.util.concurrent.TimeUnit;
14 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
15 import org.slf4j.Logger;
16 import org.slf4j.LoggerFactory;
17
18 /**
19  * Class for limiting operations.
20  */
21 public class OperationLimiter  {
22     private static final Logger LOG = LoggerFactory.getLogger(OperationLimiter.class);
23     private final TransactionIdentifier identifier;
24     private final long acquireTimeout;
25     private final Semaphore semaphore;
26     private final int maxPermits;
27
28     OperationLimiter(final TransactionIdentifier identifier, final int maxPermits, final long acquireTimeoutSeconds) {
29         this.identifier = Preconditions.checkNotNull(identifier);
30
31         Preconditions.checkArgument(acquireTimeoutSeconds >= 0);
32         this.acquireTimeout = TimeUnit.SECONDS.toNanos(acquireTimeoutSeconds);
33
34         Preconditions.checkArgument(maxPermits >= 0);
35         this.maxPermits = maxPermits;
36         this.semaphore = new Semaphore(maxPermits);
37     }
38
39     boolean acquire() {
40         return acquire(1);
41     }
42
43     boolean acquire(final int acquirePermits) {
44         try {
45             if (semaphore.tryAcquire(acquirePermits, acquireTimeout, TimeUnit.NANOSECONDS)) {
46                 return true;
47             }
48
49             LOG.warn("Failed to acquire operation permit for transaction {}", identifier);
50         } catch (InterruptedException e) {
51             if (LOG.isDebugEnabled()) {
52                 LOG.debug("Interrupted when trying to acquire operation permit for transaction {}", identifier, e);
53             } else {
54                 LOG.warn("Interrupted when trying to acquire operation permit for transaction {}", identifier);
55             }
56         }
57
58         return false;
59     }
60
61     void release() {
62         release(1);
63     }
64
65     void release(int permits) {
66         this.semaphore.release(permits);
67     }
68
69     public TransactionIdentifier getIdentifier() {
70         return identifier;
71     }
72
73     @VisibleForTesting
74     int availablePermits() {
75         return semaphore.availablePermits();
76     }
77
78     /**
79      * Release all the permits.
80      */
81     public void releaseAll() {
82         this.semaphore.release(maxPermits - availablePermits());
83     }
84 }

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