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/*-
* ============LICENSE_START=======================================================
* guard
* ================================================================================
* Copyright (C) 2017 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.guard;
import java.util.UUID;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import org.onap.policy.controlloop.policy.TargetType;
import org.onap.policy.drools.core.lock.PolicyResourceLockManager;
import org.onap.policy.guard.impl.PNFTargetLock;
import org.onap.policy.guard.impl.VMTargetLock;
import org.onap.policy.guard.impl.VNFTargetLock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class PolicyGuard {
private PolicyGuard() {
// Cannot instantiate this static class
}
private static final Logger logger = LoggerFactory.getLogger(PolicyGuard.class);
/**
* Factory to access various objects. Can be changed for junit tests.
*/
private static Factory factory = new Factory();
public static class LockResult<A, B> {
private A parameterA;
private B parameterB;
public static <A, B> LockResult<A, B> createLockResult(A parameterA, B parameterB) {
return new LockResult<>(parameterA, parameterB);
}
public LockResult(A parameterA, B parameterB) {
this.parameterA = parameterA;
this.parameterB = parameterB;
}
public A getA() {
return parameterA;
}
public B getB() {
return parameterB;
}
}
/**
* @return the factory used to access various objects
*/
protected static Factory getFactory() {
return factory;
}
/**
* Sets the factory to be used by junit tests.
* @param factory
*/
protected static void setFactory(Factory factory) {
PolicyGuard.factory = factory;
}
/**
* Lock a target.
*
* @param targetType the target type
* @param targetInstance the target instance
* @param requestID the request Id
* @param callback the LockCallback
* @return the LockResult
* @throws IllegalArgumentException if an argument is null
*/
public static LockResult<GuardResult, TargetLock> lockTarget(TargetType targetType, String targetInstance,
UUID requestID, LockCallback callback) {
String owner = makeOwner(targetType, requestID);
GuardResult guardResult = managerLockTarget(targetInstance, owner);
if(guardResult != GuardResult.LOCK_ACQUIRED) {
return LockResult.createLockResult(guardResult, null);
}
TargetLock lock = null;
switch (targetType) {
case PNF:
//
// Create the Lock object
//
lock = new PNFTargetLock(targetType, targetInstance, requestID, callback);
break;
case VM:
//
// Create the Lock object
//
lock = new VMTargetLock(targetType, targetInstance, requestID, callback);
break;
case VNF:
//
// Create the Lock object
//
lock = new VNFTargetLock(targetType, targetInstance, requestID, callback);
break;
default:
logger.error("invalid target type {} for lock on {}", targetType, targetInstance);
factory.getManager().unlock(targetInstance, owner);
return LockResult.createLockResult(GuardResult.LOCK_EXCEPTION, null);
}
//
// Return result
//
logger.debug("Locked {}", lock);
return LockResult.createLockResult(GuardResult.LOCK_ACQUIRED, lock);
}
/**
* Asks the manager to lock the given target.
* @param targetInstance
* @param owner
* @return the result: acquired, denied, or exception
*/
private static GuardResult managerLockTarget(String targetInstance, String owner) {
try {
Future<Boolean> result = factory.getManager().lock(targetInstance, owner, null);
return(result.get() ? GuardResult.LOCK_ACQUIRED : GuardResult.LOCK_DENIED);
} catch(IllegalStateException e) {
logger.warn("{} attempted to re-lock {}", owner, targetInstance);
return GuardResult.LOCK_DENIED;
} catch (InterruptedException e) {
logger.error("exception getting lock for {}", targetInstance, e);
Thread.currentThread().interrupt();
return GuardResult.LOCK_EXCEPTION;
} catch (ExecutionException e) {
logger.error("exception getting lock for {}", targetInstance, e);
return GuardResult.LOCK_EXCEPTION;
}
}
/**
* Unlock a target.
*
* @param lock the target lock to unlock
* @return <code>true</code> if the target is successfully unlocked, <code>false</code>
* otherwise
* @throws IllegalArgumentException if an argument is null
*/
public static boolean unlockTarget(TargetLock lock) {
String owner = makeOwner(lock.getTargetType(), lock.getRequestID());
boolean result = factory.getManager().unlock(lock.getTargetInstance(), owner);
if(result) {
logger.debug("Unlocked {}", lock);
return true;
}
return false;
}
/**
* Check if a target is locked.
*
* @param targetType the target type
* @param targetInstance the target instance
* @param requestID the request Id
* @return <code>true</code> if the target is locked, <code>false</code> otherwise
* @throws IllegalArgumentException if an argument is null
*/
public static boolean isLocked(TargetType targetType, String targetInstance, UUID requestID) {
String owner = makeOwner(targetType, requestID);
return factory.getManager().isLockedBy(targetInstance, owner);
}
/**
* Combines the target type and request ID to yield a single, "owner" string.
* @param targetType
* @param requestID
* @return the "owner" of a resource
* @throws IllegalArgumentException if either argument is null
*/
private static String makeOwner(TargetType targetType, UUID requestID) {
if(targetType == null) {
throw new IllegalArgumentException("null targetType for lock request id " + requestID);
}
if(requestID == null) {
throw new IllegalArgumentException("null requestID for lock type " + targetType);
}
return targetType.toString() + ":" + requestID.toString();
}
/**
* Factory to access various objects.
*/
public static class Factory {
/**
* @return the lock manager to be used
*/
public PolicyResourceLockManager getManager() {
return PolicyResourceLockManager.getInstance();
}
}
}
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