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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2018 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.util.List;
import java.util.function.Function;
import java.util.function.Supplier;
import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureApi.OperResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Manager of resource locks. Checks for API implementers.
*/
public class PolicyResourceLockManager extends SimpleLockManager {
private static Logger logger = LoggerFactory.getLogger(PolicyResourceLockManager.class);
/**
* Used by junit tests.
*/
protected PolicyResourceLockManager() {
super();
}
/**
* Get instance.
*
* @return the manager singleton
*/
public static PolicyResourceLockManager getInstance() {
return Singleton.instance;
}
@Override
public boolean lock(String resourceId, String owner, int holdSec) {
if (resourceId == null) {
throw makeNullArgException(MSG_NULL_RESOURCE_ID);
}
if (owner == null) {
throw makeNullArgException(MSG_NULL_OWNER);
}
return doBoolIntercept(impl -> impl.beforeLock(resourceId, owner, holdSec), () -> {
// implementer didn't do the work - defer to the superclass
boolean locked = super.lock(resourceId, owner, holdSec);
doIntercept(false, impl -> impl.afterLock(resourceId, owner, locked));
return locked;
});
}
@Override
public boolean refresh(String resourceId, String owner, int holdSec) {
if (resourceId == null) {
throw makeNullArgException(MSG_NULL_RESOURCE_ID);
}
if (owner == null) {
throw makeNullArgException(MSG_NULL_OWNER);
}
return doBoolIntercept(impl -> impl.beforeRefresh(resourceId, owner, holdSec), () -> {
// implementer didn't do the work - defer to the superclass
boolean refreshed = super.refresh(resourceId, owner, holdSec);
doIntercept(false, impl -> impl.afterRefresh(resourceId, owner, refreshed));
return refreshed;
});
}
@Override
public boolean unlock(String resourceId, String owner) {
if (resourceId == null) {
throw makeNullArgException(MSG_NULL_RESOURCE_ID);
}
if (owner == null) {
throw makeNullArgException(MSG_NULL_OWNER);
}
return doBoolIntercept(impl -> impl.beforeUnlock(resourceId, owner), () -> {
// implementer didn't do the work - defer to the superclass
boolean unlocked = super.unlock(resourceId, owner);
doIntercept(false, impl -> impl.afterUnlock(resourceId, owner, unlocked));
return unlocked;
});
}
/**
* Is locked.
*
* @throws IllegalArgumentException if the resourceId is {@code null}
*/
@Override
public boolean isLocked(String resourceId) {
if (resourceId == null) {
throw makeNullArgException(MSG_NULL_RESOURCE_ID);
}
return doBoolIntercept(impl -> impl.beforeIsLocked(resourceId), () ->
// implementer didn't do the work - defer to the superclass
super.isLocked(resourceId)
);
}
/**
* Is locked by.
*
* @throws IllegalArgumentException if the resourceId or owner is {@code null}
*/
@Override
public boolean isLockedBy(String resourceId, String owner) {
if (resourceId == null) {
throw makeNullArgException(MSG_NULL_RESOURCE_ID);
}
if (owner == null) {
throw makeNullArgException(MSG_NULL_OWNER);
}
return doBoolIntercept(impl -> impl.beforeIsLockedBy(resourceId, owner), () ->
// implementer didn't do the work - defer to the superclass
super.isLockedBy(resourceId, owner)
);
}
/**
* Applies a function to each implementer of the lock feature. Returns as soon as one
* of them returns a result other than <b>OPER_UNHANDLED</b>. If they all return
* <b>OPER_UNHANDLED</b>, then it returns the result of applying the default function.
*
* @param interceptFunc intercept function
* @param defaultFunc default function
* @return {@code true} if success, {@code false} otherwise
*/
private boolean doBoolIntercept(Function<PolicyResourceLockFeatureApi, OperResult> interceptFunc,
Supplier<Boolean> defaultFunc) {
OperResult result = doIntercept(OperResult.OPER_UNHANDLED, interceptFunc);
if (result != OperResult.OPER_UNHANDLED) {
return (result == OperResult.OPER_ACCEPTED);
}
return defaultFunc.get();
}
/**
* Applies a function to each implementer of the lock feature. Returns as soon as one
* of them returns a non-null value.
*
* @param continueValue if the implementer returns this value, then it continues to
* check addition implementers
* @param func function to be applied to the implementers
* @return first non-null value returned by an implementer, <i>continueValue</i> if
* they all returned <i>continueValue</i>
*/
private <T> T doIntercept(T continueValue, Function<PolicyResourceLockFeatureApi, T> func) {
for (PolicyResourceLockFeatureApi impl : getImplementers()) {
try {
T result = func.apply(impl);
if (result != continueValue) {
return result;
}
} catch (RuntimeException e) {
logger.warn("lock feature {} threw an exception", impl, e);
}
}
return continueValue;
}
// these may be overridden by junit tests
/**
* Get implementers.
*
* @return the list of feature implementers
*/
protected List<PolicyResourceLockFeatureApi> getImplementers() {
return PolicyResourceLockFeatureApi.impl.getList();
}
/**
* Initialization-on-demand holder idiom.
*/
private static class Singleton {
private static final PolicyResourceLockManager instance = new PolicyResourceLockManager();
/**
* Not invoked.
*/
private Singleton() {
super();
}
}
}
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