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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.core.lock;
import java.io.Serializable;
import lombok.Getter;
import lombok.NonNull;
import lombok.Setter;
import lombok.ToString;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Lock implementation.
*/
@Getter
@Setter
@ToString(exclude = {"callback"})
public class LockImpl implements Lock, Serializable {
private static final long serialVersionUID = 1L;
private static final Logger logger = LoggerFactory.getLogger(LockImpl.class);
private LockState state;
private final String resourceId;
private final String ownerKey;
private transient LockCallback callback;
private int holdSec;
/**
* Constructs the object.
*/
public LockImpl() {
this.state = LockState.UNAVAILABLE;
this.resourceId = null;
this.ownerKey = null;
this.callback = null;
this.holdSec = 0;
}
/**
* Constructs the object.
*
* @param state the initial lock state
* @param resourceId identifier of the resource to be locked
* @param ownerKey information identifying the owner requesting the lock
* @param holdSec amount of time, in seconds, for which the lock should be held once
* it has been granted, after which it will automatically be released
* @param callback callback to be invoked once the lock is granted, or subsequently
* lost; must not be {@code null}
*/
public LockImpl(@NonNull LockState state, @NonNull String resourceId, @NonNull String ownerKey, int holdSec,
@NonNull LockCallback callback) {
if (holdSec < 0) {
throw new IllegalArgumentException("holdSec is negative");
}
this.state = state;
this.resourceId = resourceId;
this.ownerKey = ownerKey;
this.callback = callback;
this.holdSec = holdSec;
}
@Override
public boolean isActive() {
return (getState() == LockState.ACTIVE);
}
@Override
public boolean isUnavailable() {
return (getState() == LockState.UNAVAILABLE);
}
@Override
public boolean isWaiting() {
return (getState() == LockState.WAITING);
}
/**
* This method always succeeds, unless the lock is already unavailable.
*/
@Override
public synchronized boolean free() {
if (isUnavailable()) {
return false;
}
logger.info("releasing lock: {}", this);
setState(LockState.UNAVAILABLE);
return true;
}
/**
* This method always succeeds, unless the lock is already unavailable.
*/
@Override
public void extend(int holdSec, LockCallback callback) {
synchronized (this) {
if (isUnavailable()) {
return;
}
logger.info("lock granted: {}", this);
setState(LockState.ACTIVE);
setHoldSec(holdSec);
setCallback(callback);
}
notifyAvailable();
}
/**
* Invokes the {@link LockCallback#lockAvailable(Lock)}, <i>from the current
* thread</i>. Note: subclasses may choose to invoke the callback from other threads.
*/
public void notifyAvailable() {
try {
callback.lockAvailable(this);
} catch (RuntimeException e) {
logger.warn("lock callback threw an exception", e);
}
}
/**
* Invokes the {@link LockCallback#lockUnavailable(Lock)}, <i>from the current
* thread</i>. Note: subclasses may choose to invoke the callback from other threads.
*/
public void notifyUnavailable() {
try {
callback.lockUnavailable(this);
} catch (RuntimeException e) {
logger.warn("lock callback threw an exception", e);
}
}
}
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