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-rw-r--r--policy-core/pom.xml6
-rw-r--r--policy-core/src/main/java/org/onap/policy/drools/core/lock/Lock.java162
-rw-r--r--policy-core/src/main/java/org/onap/policy/drools/core/lock/PolicyResourceLockManager.java208
-rw-r--r--policy-core/src/main/java/org/onap/policy/drools/core/lock/SimpleLockManager.java168
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/LockRequestFutureTest.java431
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/LockTest.java131
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockFeatureAPITest.java76
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockManagerTest.java509
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/SimpleLockManagerTest.java280
-rw-r--r--policy-core/src/test/java/org/onap/policy/drools/core/lock/TestUtils.java59
-rw-r--r--policy-utils/src/main/java/org/onap/policy/drools/utils/Reference.java72
-rw-r--r--policy-utils/src/test/java/org/onap/policy/drools/utils/ReferenceTest.java84
12 files changed, 2186 insertions, 0 deletions
diff --git a/policy-core/pom.xml b/policy-core/pom.xml
index 8cecd362..ecd5b19e 100644
--- a/policy-core/pom.xml
+++ b/policy-core/pom.xml
@@ -94,5 +94,11 @@
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
+ <dependency>
+ <groupId>org.mockito</groupId>
+ <artifactId>mockito-core</artifactId>
+ <version>2.13.0</version>
+ <scope>test</scope>
+ </dependency>
</dependencies>
</project>
diff --git a/policy-core/src/main/java/org/onap/policy/drools/core/lock/Lock.java b/policy-core/src/main/java/org/onap/policy/drools/core/lock/Lock.java
new file mode 100644
index 00000000..ea5e2521
--- /dev/null
+++ b/policy-core/src/main/java/org/onap/policy/drools/core/lock/Lock.java
@@ -0,0 +1,162 @@
+/*
+ * ============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.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map.Entry;
+import org.onap.policy.drools.utils.Pair;
+
+/**
+ * Lock that is held for a resource. This not only identifies the current owner of the
+ * lock, but it also includes a queue of requesters. An item is associated with each
+ * requester that is waiting in the queue. Note: this class is <b>not</b> thread-safe.
+ *
+ * @param <T> type of item to be associated with a request
+ */
+public class Lock<T> {
+
+ /**
+ * Result returned by <i>removeRequester()</i>.
+ */
+ public enum RemoveResult {
+ /**
+ * The requester was the owner of the lock, and the lock is no longer needed,
+ * because there were no other requesters waiting to get the lock.
+ */
+ UNLOCKED,
+
+ /**
+ * The requester was the owner of the lock, and has been replaced with the next
+ * requester waiting in the queue.
+ */
+ RELOCKED,
+
+ /**
+ * The requester had been waiting in the queue, and has now been removed.
+ */
+ REMOVED,
+
+ /**
+ * The requester was not the owner, nor was it waiting in the queue.
+ */
+ NOT_FOUND
+ };
+
+ /**
+ * The last owner to grab the lock, never {@code null}.
+ */
+ private String owner;
+
+ /**
+ * Requesters waiting to get the lock. Maps the requester (i.e., owner for which the
+ * request is being made) to its associated item. Uses a Linked map so that the order
+ * of the requesters is maintained. We don't expect many requesters for any given
+ * lock, thus we'll start with a small hash size.
+ */
+ private LinkedHashMap<String, T> requester2item = new LinkedHashMap<>(5);
+
+ /**
+ *
+ * @param owner the current owner of this lock
+ */
+ public Lock(String owner) {
+ this.owner = owner;
+ }
+
+ /**
+ *
+ * @return the current owner of the lock, or the last owner of the lock, if the lock
+ * is not currently owned. (This will never be {@code null}.)
+ */
+ public String getOwner() {
+ return owner;
+ }
+
+ /**
+ * Adds a new requester to the queue of requesters.
+ *
+ * @param requester
+ * @param item to be associated with the requester, must not be {@code null}
+ * @return {@code true} if the requester was added, {@code false} if it already owns
+ * the lock or is already in the queue
+ * @throws IllegalArgumentException if the item is null
+ */
+ public boolean add(String requester, T item) {
+ if (item == null) {
+ throw LockRequestFuture.makeNullArgException("lock requester item is null");
+ }
+
+ if (requester.equals(owner)) {
+ // requester already owns the lock
+ return false;
+ }
+
+ T prev = requester2item.putIfAbsent(requester, item);
+
+ // if there's a previous value, then that means this requester is already
+ // waiting for a lock on this resource. In that case, we return false
+ return (prev == null);
+ }
+
+ /**
+ * Removes a requester from the lock. The requester may currently own the lock, or it
+ * may be in the queue waiting for the lock. Note: as this is agnostic to the type of
+ * item associated with the requester, it is unable to notify the new owner that it's
+ * the new owner; that is left up to the code that invokes this method.
+ *
+ * @param requester
+ * @param newOwner the new owner info is placed here, if the result is <i>RELOCKED</i>
+ * @return the result
+ */
+ public RemoveResult removeRequester(String requester, Pair<String, T> newOwner) {
+
+ if (!requester.equals(owner)) {
+ // requester does not currently own the lock - remove it from the
+ // queue
+ T ent = requester2item.remove(requester);
+
+ // if there was an entry in the queue, then return true to indicate
+ // that it was removed. Otherwise, return false
+ return (ent != null ? RemoveResult.REMOVED : RemoveResult.NOT_FOUND);
+ }
+
+ /*
+ * requester was the owner - find something to take over
+ */
+ Iterator<Entry<String, T>> it = requester2item.entrySet().iterator();
+ if (!it.hasNext()) {
+ // no one to take over the lock - it's now unlocked
+ return RemoveResult.UNLOCKED;
+ }
+
+ // there's another requester to take over
+ Entry<String, T> ent = it.next();
+ it.remove();
+
+ owner = ent.getKey();
+
+ newOwner.first(owner);
+ newOwner.second(ent.getValue());
+
+ return RemoveResult.RELOCKED;
+ }
+}
diff --git a/policy-core/src/main/java/org/onap/policy/drools/core/lock/PolicyResourceLockManager.java b/policy-core/src/main/java/org/onap/policy/drools/core/lock/PolicyResourceLockManager.java
new file mode 100644
index 00000000..d51f2b91
--- /dev/null
+++ b/policy-core/src/main/java/org/onap/policy/drools/core/lock/PolicyResourceLockManager.java
@@ -0,0 +1,208 @@
+/*
+ * ============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 static org.onap.policy.drools.core.lock.LockRequestFuture.MSG_NULL_OWNER;
+import static org.onap.policy.drools.core.lock.LockRequestFuture.MSG_NULL_RESOURCE_ID;
+import static org.onap.policy.drools.core.lock.LockRequestFuture.makeNullArgException;
+import java.util.List;
+import java.util.concurrent.Future;
+import java.util.function.Function;
+import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureAPI.Callback;
+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 to access various objects.
+ */
+ public static Factory factory = new Factory();
+
+ /**
+ * Used by junit tests.
+ */
+ protected PolicyResourceLockManager() {
+ super();
+ }
+
+ /**
+ *
+ * @return the manager singleton
+ */
+ public static PolicyResourceLockManager getInstance() {
+ return Singleton.instance;
+ }
+
+ protected static Factory getFactory() {
+ return factory;
+ }
+
+ /**
+ * Sets the factory to be used by junit tests.
+ *
+ * @param factory
+ */
+ protected static void setFactory(Factory factory) {
+ PolicyResourceLockManager.factory = factory;
+ }
+
+ @Override
+ public Future<Boolean> lock(String resourceId, String owner, Callback callback) {
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ if (owner == null) {
+ throw makeNullArgException(MSG_NULL_OWNER);
+ }
+
+ Future<Boolean> result = doIntercept(null, impl -> impl.beforeLock(resourceId, owner, callback));
+ if (result != null) {
+ return result;
+ }
+
+ // implementer didn't do the work - use superclass
+ result = super.lock(resourceId, owner, callback);
+
+ boolean locked = ((LockRequestFuture) result).isLocked();
+
+ doIntercept(false, impl -> impl.afterLock(resourceId, owner, locked));
+
+ return result;
+ }
+
+ @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);
+ }
+
+ Boolean result = doIntercept(null, impl -> impl.beforeUnlock(resourceId, owner));
+ if (result != null) {
+ return result;
+ }
+
+ // implementer didn't do the work - use superclass
+ boolean unlocked = super.unlock(resourceId, owner);
+
+ doIntercept(false, impl -> impl.afterUnlock(resourceId, owner, unlocked));
+
+ return unlocked;
+ }
+
+ /**
+ *
+ * @throws IllegalArgumentException if the resourceId is {@code null}
+ */
+ @Override
+ public boolean isLocked(String resourceId) {
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ Boolean result = doIntercept(null, impl -> impl.beforeIsLocked(resourceId));
+ if (result != null) {
+ return result;
+ }
+
+ return super.isLocked(resourceId);
+ }
+
+ /**
+ *
+ * @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);
+ }
+
+ Boolean result = doIntercept(null, impl -> impl.beforeIsLockedBy(resourceId, owner));
+ if (result != null) {
+ return result;
+ }
+
+ return super.isLockedBy(resourceId, owner);
+ }
+
+ /**
+ * 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/>
+ */
+ public static <T> T doIntercept(T continueValue, Function<PolicyResourceLockFeatureAPI, T> func) {
+
+ for (PolicyResourceLockFeatureAPI impl : factory.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;
+ }
+
+ /**
+ * Initialization-on-demand holder idiom.
+ */
+ private static class Singleton {
+ private static final PolicyResourceLockManager instance = new PolicyResourceLockManager();
+ }
+
+ /**
+ * Used to access various objects.
+ */
+ public static class Factory {
+
+ /**
+ *
+ * @return the list of feature implementers
+ */
+ public List<PolicyResourceLockFeatureAPI> getImplementers() {
+ return PolicyResourceLockFeatureAPI.impl.getList();
+ }
+ }
+}
diff --git a/policy-core/src/main/java/org/onap/policy/drools/core/lock/SimpleLockManager.java b/policy-core/src/main/java/org/onap/policy/drools/core/lock/SimpleLockManager.java
new file mode 100644
index 00000000..14cffaab
--- /dev/null
+++ b/policy-core/src/main/java/org/onap/policy/drools/core/lock/SimpleLockManager.java
@@ -0,0 +1,168 @@
+/*
+ * ============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 static org.onap.policy.drools.core.lock.LockRequestFuture.MSG_NULL_OWNER;
+import static org.onap.policy.drools.core.lock.LockRequestFuture.MSG_NULL_RESOURCE_ID;
+import static org.onap.policy.drools.core.lock.LockRequestFuture.makeNullArgException;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Future;
+import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureAPI.Callback;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Simple lock manager. Callbacks are ignored. Does not redirect to lock feature
+ * implementers.
+ */
+public class SimpleLockManager {
+
+ protected static Logger logger = LoggerFactory.getLogger(SimpleLockManager.class);
+
+ /**
+ * Maps a resource to the owner that holds the lock on it.
+ */
+ private ConcurrentHashMap<String, String> resource2owner = new ConcurrentHashMap<>();
+
+ /**
+ *
+ */
+ public SimpleLockManager() {
+ super();
+ }
+
+ // TODO: for ease of use by clients, should we always invoke the callback, even though
+ // this is synchronous?
+
+ /**
+ * Attempts to lock a resource. This method ignores the callback and always returns a
+ * {@link CompletedLockRequest}.
+ *
+ * @param resourceId
+ * @param owner
+ * @param callback function to invoke, if the requester wishes to wait for the lock to
+ * be acquired, {@code null} to provide immediate replies
+ * @return a future for the lock request. The future will be in one of three states:
+ * <dl>
+ * <dt>isDone()=true and get()=true</dt>
+ * <dd>the lock has been acquired; the callback may or may not have been
+ * invoked</dd>
+ * <dt>isDone()=true and get()=false</dt>
+ * <dd>the lock request has been denied; the callback may or may not have been
+ * invoked</dd>
+ * <dt>isDone()=false</dt>
+ * <dd>the lock was not immediately available and a callback was provided. The
+ * callback will be invoked once the lock is acquired (or denied). In this
+ * case, the future may be used to cancel the request</dd>
+ * </dl>
+ * @throws IllegalArgumentException if the resourceId or owner is {@code null}
+ * @throws IllegalStateException if the owner already holds the lock or is already in
+ * the queue to get the lock
+ */
+ public Future<Boolean> lock(String resourceId, String owner, Callback callback) {
+
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ if (owner == null) {
+ throw makeNullArgException(MSG_NULL_OWNER);
+ }
+
+ boolean locked = (resource2owner.putIfAbsent(resourceId, owner) == null);
+
+ if (!locked && owner.equals(resource2owner.get(resourceId))) {
+ throw new IllegalStateException("lock for resource " + resourceId + " already owned by " + owner);
+ }
+
+ logger.info("lock {} for resource {} owner {}", locked, resourceId, owner);
+
+ return new LockRequestFuture(resourceId, owner, locked);
+ }
+
+ /**
+ * Unlocks a resource.
+ *
+ * @param resourceId
+ * @param owner
+ * @return {@code true} if unlocked, {@code false} if the given owner does not
+ * currently hold a lock on the resource
+ * @throws IllegalArgumentException if the resourceId or owner is {@code null}
+ */
+ public boolean unlock(String resourceId, String owner) {
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ if (owner == null) {
+ throw makeNullArgException(MSG_NULL_OWNER);
+ }
+
+ boolean unlocked = resource2owner.remove(resourceId, owner);
+ logger.info("unlock resource {} owner {} = {}", resourceId, owner, unlocked);
+
+ return unlocked;
+ }
+
+ /**
+ * Determines if a resource is locked by anyone.
+ *
+ * @param resourceId
+ * @return {@code true} if the resource is locked, {@code false} otherwise
+ * @throws IllegalArgumentException if the resourceId is {@code null}
+ */
+ public boolean isLocked(String resourceId) {
+
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ boolean locked = resource2owner.containsKey(resourceId);
+
+ logger.debug("resource {} isLocked = {}", resourceId, locked);
+
+ return locked;
+ }
+
+ /**
+ * Determines if a resource is locked by a particular owner.
+ *
+ * @param resourceId
+ * @param owner
+ * @return {@code true} if the resource is locked, {@code false} otherwise
+ * @throws IllegalArgumentException if the resourceId or owner is {@code null}
+ */
+ public boolean isLockedBy(String resourceId, String owner) {
+
+ if (resourceId == null) {
+ throw makeNullArgException(MSG_NULL_RESOURCE_ID);
+ }
+
+ if (owner == null) {
+ throw makeNullArgException(MSG_NULL_OWNER);
+ }
+
+ boolean locked = owner.equals(resource2owner.get(resourceId));
+ logger.debug("resource {} isLockedBy {} = {}", resourceId, owner, locked);
+
+ return locked;
+ }
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockRequestFutureTest.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockRequestFutureTest.java
new file mode 100644
index 00000000..883778eb
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockRequestFutureTest.java
@@ -0,0 +1,431 @@
+/*
+ * ============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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.onap.policy.drools.core.lock.TestUtils.expectException;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureAPI.Callback;
+
+public class LockRequestFutureTest {
+
+ private static final int WAIT_SEC = 1;
+ private static final String RESOURCE = "my.resource";
+ private static final String OWNER = "my.owner";
+ private static final String EXPECTED_EXCEPTION = "expected exception";
+
+ private Callback callback;
+ private LockRequestFuture fut;
+
+ @Before
+ public void setUp() {
+ callback = mock(Callback.class);
+ fut = new LockRequestFuture(RESOURCE, OWNER, callback);
+ }
+
+ @Test
+ public void testLockRequestFutureStringStringBoolean_False() throws Exception {
+ fut = new LockRequestFuture(RESOURCE, OWNER, false);
+
+ assertTrue(fut.isDone());
+ assertEquals(RESOURCE, fut.getResourceId());
+ assertEquals(OWNER, fut.getOwner());
+
+ assertFalse(fut.isLocked());
+ assertFalse(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testLockRequestFutureStringStringBoolean_True() throws Exception {
+ fut = new LockRequestFuture(RESOURCE, OWNER, true);
+
+ assertTrue(fut.isDone());
+ assertEquals(RESOURCE, fut.getResourceId());
+ assertEquals(OWNER, fut.getOwner());
+
+ assertTrue(fut.isLocked());
+ assertTrue(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testLockRequestFutureStringStringBoolean_ArgEx() throws Exception {
+
+ // null resource id
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class,
+ xxx -> new LockRequestFuture(null, OWNER, true));
+ assertEquals("null resourceId", ex.getMessage());
+
+
+ // null owner
+ ex = expectException(IllegalArgumentException.class, xxx -> new LockRequestFuture(RESOURCE, null, true));
+ assertEquals("null owner", ex.getMessage());
+ }
+
+ @Test
+ public void testLockRequestFutureStringStringCallback() throws Exception {
+ assertFalse(fut.isDone());
+ assertEquals(RESOURCE, fut.getResourceId());
+ assertEquals(OWNER, fut.getOwner());
+
+ fut.setLocked(true);
+ fut.invokeCallback();
+
+ // ensure it invoked the callback
+ verify(callback).set(true);
+ }
+
+ @Test
+ public void testLockRequestFutureStringStringCallback_ArgEx() throws Exception {
+
+ // null resource id
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class,
+ xxx -> new LockRequestFuture(null, OWNER, callback));
+ assertEquals("null resourceId", ex.getMessage());
+
+
+ // null owner
+ ex = expectException(IllegalArgumentException.class, xxx -> new LockRequestFuture(RESOURCE, null, callback));
+ assertEquals("null owner", ex.getMessage());
+
+
+ // null callback is OK
+ new LockRequestFuture(RESOURCE, OWNER, null);
+ }
+
+ @Test
+ public void testGetResourceId() {
+ assertEquals(RESOURCE, fut.getResourceId());
+ }
+
+ @Test
+ public void testGetOwner() {
+ assertEquals(OWNER, fut.getOwner());
+ }
+
+ @Test
+ public void testCancel() throws Exception {
+ // not cancelled yet
+ assertFalse(fut.isDone());
+
+ // cancel it
+ assertTrue(fut.cancel(false));
+ assertTrue(fut.isDone());
+
+ // should not block now
+ expectException(CancellationException.class, xxx -> fut.get(0, TimeUnit.SECONDS));
+
+ }
+
+ @Test
+ public void testCancel_AlreadyCancelled() throws Exception {
+
+ fut.cancel(true);
+
+ assertFalse(fut.cancel(true));
+ assertTrue(fut.isDone());
+
+ expectException(CancellationException.class, xxx -> fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testCancel_AlreadyAcquired() throws Exception {
+
+ fut.setLocked(true);
+
+ assertFalse(fut.cancel(true));
+ assertTrue(fut.isDone());
+ assertTrue(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testCancel_AlreadyDenied() throws Exception {
+
+ fut.setLocked(false);
+
+ assertFalse(fut.cancel(true));
+ assertTrue(fut.isDone());
+ assertFalse(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testSetLocked_True() throws Exception {
+ assertTrue(fut.setLocked(true));
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testSetLocked_False() throws Exception {
+ assertTrue(fut.setLocked(false));
+
+ assertTrue(fut.isDone());
+ assertFalse(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testSetLocked_AlreadyCancelled() {
+
+ fut.cancel(true);
+
+ assertFalse(fut.setLocked(true));
+ assertFalse(fut.setLocked(false));
+
+ assertTrue(fut.isDone());
+ expectException(CancellationException.class, xxx -> fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testSetLocked_AlreadyAcquired() throws Exception {
+ fut.setLocked(true);
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get(0, TimeUnit.SECONDS));
+
+ assertFalse(fut.cancel(true));
+ assertFalse(fut.setLocked(true));
+ assertFalse(fut.setLocked(false));
+ }
+
+ @Test
+ public void testSetLocked_AlreadyDenied() throws Exception {
+ fut.setLocked(false);
+
+ assertTrue(fut.isDone());
+ assertFalse(fut.get(0, TimeUnit.SECONDS));
+
+ assertFalse(fut.cancel(true));
+ assertFalse(fut.setLocked(true));
+ assertFalse(fut.setLocked(false));
+ }
+
+ @Test
+ public void testIsCancelled() {
+ assertFalse(fut.isCancelled());
+
+ fut.cancel(false);
+ assertTrue(fut.isCancelled());
+ }
+
+ @Test
+ public void testIsCancelled_Acquired() {
+ fut.setLocked(true);
+ assertFalse(fut.isCancelled());
+ }
+
+ @Test
+ public void testIsCancelled_Denied() {
+ fut.setLocked(false);
+ assertFalse(fut.isCancelled());
+ }
+
+ @Test
+ public void testIsDone_Cancelled() {
+ fut.cancel(false);
+ assertTrue(fut.isDone());
+ }
+
+ @Test
+ public void testIsDone_Acquired() {
+ fut.setLocked(true);
+ assertTrue(fut.isDone());
+ }
+
+ @Test
+ public void testIsDone_Denied() {
+ fut.setLocked(false);
+ assertTrue(fut.isDone());
+ }
+
+ @Test
+ public void testIsDone_Waiting() {
+ assertFalse(fut.isDone());
+ }
+
+ @Test
+ public void testIsLocked_Cancelled() {
+ fut.cancel(false);
+ assertFalse(fut.isLocked());
+ }
+
+ @Test
+ public void testIsLocked_Acquired() {
+ fut.setLocked(true);
+ assertTrue(fut.isLocked());
+ }
+
+ @Test
+ public void testIsLocked_Denied() {
+ fut.setLocked(false);
+ assertFalse(fut.isLocked());
+ }
+
+ @Test
+ public void testIsLocked_Waiting() {
+ assertFalse(fut.isLocked());
+ }
+
+ @Test
+ public void testGet_Cancelled() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.cancel(false);
+ }
+ }.start();
+
+ expectException(CancellationException.class, xxx -> fut.get());
+ }
+
+ @Test
+ public void testGet_Acquired() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.setLocked(true);
+ }
+ }.start();
+
+ assertTrue(fut.get());
+ }
+
+ @Test
+ public void testGet_Denied() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.setLocked(false);
+ }
+ }.start();
+
+ assertFalse(fut.get());
+ }
+
+ @Test
+ public void testGetLongTimeUnit() throws Exception {
+ expectException(TimeoutException.class, xxx -> fut.get(0, TimeUnit.SECONDS));
+
+ fut.setLocked(true);
+ assertTrue(fut.get(0, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testGetLongTimeUnit_Timeout() throws Exception {
+ expectException(TimeoutException.class, xxx -> fut.get(0, TimeUnit.SECONDS));
+ expectException(TimeoutException.class, xxx -> fut.get(2, TimeUnit.MILLISECONDS));
+ }
+
+ @Test
+ public void testGetLongTimeUnit_Cancelled() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.cancel(false);
+ }
+ }.start();
+
+ expectException(CancellationException.class, xxx -> fut.get(WAIT_SEC, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testGetLongTimeUnit_Acquired() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.setLocked(true);
+ }
+ }.start();
+
+ assertTrue(fut.get(WAIT_SEC, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testGetLongTimeUnit_Denied() throws Exception {
+ new Thread() {
+ @Override
+ public void run() {
+ fut.setLocked(false);
+ }
+ }.start();
+
+ assertFalse(fut.get(WAIT_SEC, TimeUnit.SECONDS));
+ }
+
+ @Test(expected = IllegalStateException.class)
+ public void testInvokeCallback() {
+ fut.setLocked(true);
+ fut.invokeCallback();
+
+ // re-invoke - should throw an exception
+ fut.invokeCallback();
+ }
+
+ @Test(expected = IllegalStateException.class)
+ public void testInvokeCallback_Cancelled() {
+ fut.cancel(false);
+
+ // invoke after cancel - should throw an exception
+ fut.invokeCallback();
+ }
+
+ @Test
+ public void testInvokeCallback_Acquired() {
+ fut.setLocked(true);
+ fut.invokeCallback();
+
+ verify(callback).set(true);
+ verify(callback, never()).set(false);
+ }
+
+ @Test
+ public void testInvokeCallback_Denied() {
+ fut.setLocked(false);
+ fut.invokeCallback();
+
+ verify(callback).set(false);
+ verify(callback, never()).set(true);
+ }
+
+ @Test
+ public void testInvokeCallback_Ex() {
+ doThrow(new RuntimeException(EXPECTED_EXCEPTION)).when(callback).set(anyBoolean());
+
+ fut.setLocked(false);
+ fut.invokeCallback();
+ }
+
+ @Test
+ public void testMakeNullArgException() {
+ IllegalArgumentException ex = LockRequestFuture.makeNullArgException(EXPECTED_EXCEPTION);
+ assertEquals(EXPECTED_EXCEPTION, ex.getMessage());
+ }
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockTest.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockTest.java
new file mode 100644
index 00000000..bd11dcf9
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/LockTest.java
@@ -0,0 +1,131 @@
+/*
+ * ============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 static org.junit.Assert.*;
+import org.junit.Before;
+import org.junit.Test;
+import org.onap.policy.drools.core.lock.Lock.RemoveResult;
+import org.onap.policy.drools.utils.Pair;
+
+public class LockTest {
+
+ private static final String OWNER = "my.owner";
+ private static final String OWNER2 = "another.owner";
+ private static final String OWNER3 = "third.owner";
+
+ private static final Integer ITEM2 = 10;
+ private static final Integer ITEM3 = 20;
+
+ private Lock<Integer> lock;
+ private Pair<String, Integer> newOwner;
+
+ @Before
+ public void setUp() {
+ lock = new Lock<>(OWNER);
+ newOwner = new Pair<>(null, null);
+ }
+
+
+ @Test
+ public void testLock() {
+ assertEquals(OWNER, lock.getOwner());
+ }
+
+ @Test
+ public void testGetOwner() {
+ assertEquals(OWNER, lock.getOwner());
+ }
+
+ @Test
+ public void testAdd() {
+ assertTrue(lock.add(OWNER2, ITEM2));
+ assertTrue(lock.add(OWNER3, ITEM3));
+
+ // attempt to re-add owner2 with the same item - should fail
+ assertFalse(lock.add(OWNER2, ITEM2));
+
+ // attempt to re-add owner2 with a different item - should fail
+ assertFalse(lock.add(OWNER2, ITEM3));
+ }
+
+ @Test(expected = IllegalArgumentException.class)
+ public void testAdd_ArgEx() {
+ lock.add(OWNER2, null);
+ }
+
+ @Test
+ public void testAdd_AlreadyOwner() {
+ assertFalse(lock.add(OWNER, ITEM2));
+ }
+
+ @Test
+ public void testAdd_AlreadyInQueue() {
+ lock.add(OWNER2, ITEM2);
+
+ assertFalse(lock.add(OWNER2, ITEM2));
+ }
+
+ @Test
+ public void testRemoveRequester_Owner_QueueEmpty() {
+ assertEquals(RemoveResult.UNLOCKED, lock.removeRequester(OWNER, newOwner));
+ }
+
+ @Test
+ public void testRemoveRequester_Owner_QueueHasOneItem() {
+ lock.add(OWNER2, ITEM2);
+
+ assertEquals(RemoveResult.RELOCKED, lock.removeRequester(OWNER, newOwner));
+ assertEquals(OWNER2, newOwner.first());
+ assertEquals(ITEM2, newOwner.second());
+
+ assertEquals(RemoveResult.UNLOCKED, lock.removeRequester(OWNER2, newOwner));
+ }
+
+ @Test
+ public void testRemoveRequester_Owner_QueueHasMultipleItems() {
+ lock.add(OWNER2, ITEM2);
+ lock.add(OWNER3, ITEM3);
+
+ assertEquals(RemoveResult.RELOCKED, lock.removeRequester(OWNER, newOwner));
+ assertEquals(OWNER2, newOwner.first());
+ assertEquals(ITEM2, newOwner.second());
+
+ assertEquals(RemoveResult.RELOCKED, lock.removeRequester(OWNER2, newOwner));
+ assertEquals(OWNER3, newOwner.first());
+ assertEquals(ITEM3, newOwner.second());
+
+ assertEquals(RemoveResult.UNLOCKED, lock.removeRequester(OWNER3, newOwner));
+ }
+
+ @Test
+ public void testRemoveRequester_InQueue() {
+ lock.add(OWNER2, ITEM2);
+
+ assertEquals(RemoveResult.REMOVED, lock.removeRequester(OWNER2, newOwner));
+ }
+
+ @Test
+ public void testRemoveRequester_NeitherOwnerNorInQueue() {
+ assertEquals(RemoveResult.NOT_FOUND, lock.removeRequester(OWNER2, newOwner));
+ }
+
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockFeatureAPITest.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockFeatureAPITest.java
new file mode 100644
index 00000000..5a826bb7
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockFeatureAPITest.java
@@ -0,0 +1,76 @@
+/*
+ * ============LICENSE_START=======================================================
+ * api-resource-locks
+ * ================================================================================
+ * 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 static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import org.junit.Before;
+import org.junit.Test;
+
+public class PolicyResourceLockFeatureAPITest {
+
+ private static final String RESOURCE_ID = "the resource";
+ private static final String OWNER = "the owner";
+
+ private PolicyResourceLockFeatureAPI api;
+
+ @Before
+ public void setUp() {
+ api = new PolicyResourceLockFeatureAPI() {
+ @Override
+ public int getSequenceNumber() {
+ return 0;
+ }
+ };
+ }
+
+ @Test
+ public void testBeforeLock() {
+ assertNull(api.beforeLock(RESOURCE_ID, OWNER, null));
+ }
+
+ @Test
+ public void testAfterLock() {
+ assertFalse(api.afterLock(RESOURCE_ID, OWNER, true));
+ assertFalse(api.afterLock(RESOURCE_ID, OWNER, false));
+ }
+
+ @Test
+ public void testBeforeUnlock() {
+ assertNull(api.beforeUnlock(RESOURCE_ID, OWNER));
+ }
+
+ @Test
+ public void testAfterUnlock() {
+ assertFalse(api.afterUnlock(RESOURCE_ID, OWNER, true));
+ assertFalse(api.afterUnlock(RESOURCE_ID, OWNER, false));
+ }
+
+ @Test
+ public void testBeforeIsLocked() {
+ assertNull(api.beforeIsLocked(RESOURCE_ID));
+ }
+
+ @Test
+ public void testBeforeIsLockedBy() {
+ assertNull(api.beforeIsLockedBy(RESOURCE_ID, OWNER));
+ }
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockManagerTest.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockManagerTest.java
new file mode 100644
index 00000000..2f8b5f83
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/PolicyResourceLockManagerTest.java
@@ -0,0 +1,509 @@
+/*
+ * ============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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.onap.policy.drools.core.lock.TestUtils.expectException;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.concurrent.Future;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.onap.policy.drools.core.lock.PolicyResourceLockFeatureAPI.Callback;
+import org.onap.policy.drools.core.lock.PolicyResourceLockManager.Factory;
+
+public class PolicyResourceLockManagerTest {
+
+ private static final String NULL_RESOURCE_ID = "null resourceId";
+ private static final String NULL_OWNER = "null owner";
+
+ private static final String RESOURCE_A = "resource.a";
+ private static final String RESOURCE_B = "resource.b";
+ private static final String RESOURCE_C = "resource.c";
+
+ private static final String OWNER1 = "owner.one";
+ private static final String OWNER2 = "owner.two";
+ private static final String OWNER3 = "owner.three";
+
+ /**
+ * Saved at the start of the tests and restored once all tests complete.
+ */
+ private static Factory saveFactory;
+
+ private Callback callback1;
+ private PolicyResourceLockFeatureAPI impl1;
+ private PolicyResourceLockFeatureAPI impl2;
+ private List<PolicyResourceLockFeatureAPI> implList;
+
+ private Future<Boolean> fut;
+
+ private PolicyResourceLockManager mgr;
+
+ @BeforeClass
+ public static void setUpBeforeClass() {
+ saveFactory = PolicyResourceLockManager.getFactory();
+ }
+
+ @AfterClass
+ public static void tearDownAfterClass() {
+ PolicyResourceLockManager.setFactory(saveFactory);
+ }
+
+ @Before
+ public void setUp() {
+ callback1 = mock(Callback.class);
+ impl1 = mock(PolicyResourceLockFeatureAPI.class);
+ impl2 = mock(PolicyResourceLockFeatureAPI.class);
+
+ initImplementer(impl1);
+ initImplementer(impl2);
+
+ // list of feature API implementers
+ implList = new LinkedList<>(Arrays.asList(impl1, impl2));
+
+ PolicyResourceLockManager.setFactory(new Factory() {
+
+ @Override
+ public List<PolicyResourceLockFeatureAPI> getImplementers() {
+ return implList;
+ }
+ });
+
+ mgr = new PolicyResourceLockManager();
+ }
+
+ /**
+ * Initializes an implementer so it always returns {@code null}.
+ *
+ * @param impl
+ */
+ private void initImplementer(PolicyResourceLockFeatureAPI impl) {
+ when(impl.beforeLock(anyString(), anyString(), any(Callback.class))).thenReturn(null);
+ when(impl.beforeUnlock(anyString(), anyString())).thenReturn(null);
+ when(impl.beforeIsLocked(anyString())).thenReturn(null);
+ when(impl.beforeIsLockedBy(anyString(), anyString())).thenReturn(null);
+ }
+
+ @Test
+ public void testLock() throws Exception {
+ fut = mgr.lock(RESOURCE_A, OWNER1, callback1);
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ verify(impl1).beforeLock(RESOURCE_A, OWNER1, callback1);
+ verify(impl2).beforeLock(RESOURCE_A, OWNER1, callback1);
+ verify(impl1).afterLock(RESOURCE_A, OWNER1, true);
+ verify(impl2).afterLock(RESOURCE_A, OWNER1, true);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+ assertTrue(mgr.isLockedBy(RESOURCE_A, OWNER1));
+ assertFalse(mgr.isLocked(RESOURCE_B));
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER2));
+
+ // null callback - not locked yet
+ fut = mgr.lock(RESOURCE_C, OWNER3, null);
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ // null callback - already locked
+ fut = mgr.lock(RESOURCE_A, OWNER3, null);
+ assertTrue(fut.isDone());
+ assertFalse(fut.get());
+ }
+
+ @Test
+ public void testLock_ArgEx() {
+ IllegalArgumentException ex =
+ expectException(IllegalArgumentException.class, xxx -> mgr.lock(null, OWNER1, callback1));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.lock(RESOURCE_A, null, callback1));
+ assertEquals(NULL_OWNER, ex.getMessage());
+
+ // this should not throw an exception
+ mgr.lock(RESOURCE_A, OWNER1, null);
+ }
+
+ @Test
+ public void testLock_BeforeIntercepted() {
+ fut = mock(LockRequestFuture.class);
+
+ // NOT async
+ when(fut.isDone()).thenReturn(true);
+
+ // have impl1 intercept
+ when(impl1.beforeLock(RESOURCE_A, OWNER1, callback1)).thenReturn(fut);
+
+ assertEquals(fut, mgr.lock(RESOURCE_A, OWNER1, callback1));
+
+ verify(impl1).beforeLock(RESOURCE_A, OWNER1, callback1);
+ verify(impl2, never()).beforeLock(anyString(), anyString(), any(Callback.class));
+
+ verify(impl1, never()).afterLock(anyString(), anyString(), anyBoolean());
+ verify(impl2, never()).afterLock(anyString(), anyString(), anyBoolean());
+ }
+
+ @Test
+ public void testLock_Acquired_AfterIntercepted() throws Exception {
+
+ // impl1 intercepts during afterLock()
+ when(impl1.afterLock(RESOURCE_A, OWNER1, true)).thenReturn(true);
+
+ fut = mgr.lock(RESOURCE_A, OWNER1, callback1);
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ // impl1 sees it, but impl2 does not
+ verify(impl1).afterLock(RESOURCE_A, OWNER1, true);
+ verify(impl2, never()).afterLock(anyString(), anyString(), anyBoolean());
+ }
+
+ @Test
+ public void testLock_Acquired() throws Exception {
+ fut = mgr.lock(RESOURCE_A, OWNER1, callback1);
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ verify(impl1).afterLock(RESOURCE_A, OWNER1, true);
+ verify(impl2).afterLock(RESOURCE_A, OWNER1, true);
+ }
+
+ @Test
+ public void testLock_Denied_AfterIntercepted() throws Exception {
+
+ mgr.lock(RESOURCE_A, OWNER1, callback1);
+
+ // impl1 intercepts during afterLock()
+ when(impl1.afterLock(RESOURCE_A, OWNER2, false)).thenReturn(true);
+
+ // owner2 tries to lock
+ fut = mgr.lock(RESOURCE_A, OWNER2, null);
+
+ assertTrue(fut.isDone());
+ assertFalse(fut.get());
+
+ // impl1 sees it, but impl2 does not
+ verify(impl1).afterLock(RESOURCE_A, OWNER2, false);
+ verify(impl2, never()).afterLock(RESOURCE_A, OWNER2, false);
+ }
+
+ @Test
+ public void testLock_Denied() {
+
+ mgr.lock(RESOURCE_A, OWNER1, callback1);
+
+ // owner2 tries to lock
+ fut = mgr.lock(RESOURCE_A, OWNER2, null);
+
+ verify(impl1).afterLock(RESOURCE_A, OWNER2, false);
+ verify(impl2).afterLock(RESOURCE_A, OWNER2, false);
+ }
+
+ @Test
+ public void testUnlock() throws Exception {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+ mgr.lock(RESOURCE_B, OWNER1, null);
+
+ assertTrue(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2).beforeUnlock(RESOURCE_A, OWNER1);
+
+ verify(impl1).afterUnlock(RESOURCE_A, OWNER1, true);
+ verify(impl2).afterUnlock(RESOURCE_A, OWNER1, true);
+ }
+
+ @Test
+ public void testUnlock_ArgEx() {
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class, xxx -> mgr.unlock(null, OWNER1));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.unlock(RESOURCE_A, null));
+ assertEquals(NULL_OWNER, ex.getMessage());
+ }
+
+ @Test
+ public void testUnlock_BeforeInterceptedTrue() {
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // have impl1 intercept
+ when(impl1.beforeUnlock(RESOURCE_A, OWNER1)).thenReturn(true);
+
+ assertTrue(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2, never()).beforeUnlock(anyString(), anyString());
+
+ verify(impl1, never()).afterUnlock(anyString(), anyString(), anyBoolean());
+ verify(impl2, never()).afterUnlock(anyString(), anyString(), anyBoolean());
+ }
+
+ @Test
+ public void testUnlock_BeforeInterceptedFalse() {
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // have impl1 intercept
+ when(impl1.beforeUnlock(RESOURCE_A, OWNER1)).thenReturn(false);
+
+ assertFalse(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2, never()).beforeUnlock(anyString(), anyString());
+
+ verify(impl1, never()).afterUnlock(anyString(), anyString(), anyBoolean());
+ verify(impl2, never()).afterUnlock(anyString(), anyString(), anyBoolean());
+ }
+
+ @Test
+ public void testUnlock_Unlocked() {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2).beforeUnlock(RESOURCE_A, OWNER1);
+
+ verify(impl1).afterUnlock(RESOURCE_A, OWNER1, true);
+ verify(impl2).afterUnlock(RESOURCE_A, OWNER1, true);
+ }
+
+ @Test
+ public void testUnlock_Unlocked_AfterIntercepted() {
+ // have impl1 intercept
+ when(impl1.afterUnlock(RESOURCE_A, OWNER1, true)).thenReturn(true);
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2).beforeUnlock(RESOURCE_A, OWNER1);
+
+ verify(impl1).afterUnlock(RESOURCE_A, OWNER1, true);
+ verify(impl2, never()).afterUnlock(RESOURCE_A, OWNER1, true);
+ }
+
+ @Test
+ public void testUnlock_NotUnlocked() {
+ assertFalse(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2).beforeUnlock(RESOURCE_A, OWNER1);
+
+ verify(impl1).afterUnlock(RESOURCE_A, OWNER1, false);
+ verify(impl2).afterUnlock(RESOURCE_A, OWNER1, false);
+ }
+
+ @Test
+ public void testUnlock_NotUnlocked_AfterIntercepted() {
+ // have impl1 intercept
+ when(impl1.afterUnlock(RESOURCE_A, OWNER1, false)).thenReturn(true);
+
+ assertFalse(mgr.unlock(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeUnlock(RESOURCE_A, OWNER1);
+ verify(impl2).beforeUnlock(RESOURCE_A, OWNER1);
+
+ verify(impl1).afterUnlock(RESOURCE_A, OWNER1, false);
+ verify(impl2, never()).afterUnlock(RESOURCE_A, OWNER1, false);
+ }
+
+ @Test
+ public void testIsLocked_True() {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2).beforeIsLocked(RESOURCE_A);
+ }
+
+ @Test
+ public void testIsLocked_False() {
+ assertFalse(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2).beforeIsLocked(RESOURCE_A);
+ }
+
+ @Test
+ public void testIsLocked_ArgEx() {
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class, xxx -> mgr.isLocked(null));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+ }
+
+ @Test
+ public void testIsLocked_BeforeIntercepted_True() {
+
+ // have impl1 intercept
+ when(impl1.beforeIsLocked(RESOURCE_A)).thenReturn(true);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2, never()).beforeIsLocked(RESOURCE_A);
+ }
+
+ @Test
+ public void testIsLocked_BeforeIntercepted_False() {
+
+ // lock it so we can verify that impl1 overrides the superclass isLocker()
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // have impl1 intercept
+ when(impl1.beforeIsLocked(RESOURCE_A)).thenReturn(false);
+
+ assertFalse(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2, never()).beforeIsLocked(RESOURCE_A);
+ }
+
+ @Test
+ public void testIsLockedBy_True() {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(mgr.isLockedBy(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ verify(impl2).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ }
+
+ @Test
+ public void testIsLockedBy_False() {
+ // different owner
+ mgr.lock(RESOURCE_A, OWNER2, null);
+
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ verify(impl2).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ }
+
+ @Test
+ public void testIsLockedBy_ArgEx() {
+ IllegalArgumentException ex =
+ expectException(IllegalArgumentException.class, xxx -> mgr.isLockedBy(null, OWNER1));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.isLockedBy(RESOURCE_A, null));
+ assertEquals(NULL_OWNER, ex.getMessage());
+ }
+
+ @Test
+ public void testIsLockedBy_BeforeIntercepted_True() {
+
+ // have impl1 intercept
+ when(impl1.beforeIsLockedBy(RESOURCE_A, OWNER1)).thenReturn(true);
+
+ assertTrue(mgr.isLockedBy(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ verify(impl2, never()).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ }
+
+ @Test
+ public void testIsLockedBy_BeforeIntercepted_False() {
+
+ // lock it so we can verify that impl1 overrides the superclass isLocker()
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // have impl1 intercept
+ when(impl1.beforeIsLockedBy(RESOURCE_A, OWNER1)).thenReturn(false);
+
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER1));
+
+ verify(impl1).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ verify(impl2, never()).beforeIsLockedBy(RESOURCE_A, OWNER1);
+ }
+
+ @Test
+ public void testGetInstance() {
+ PolicyResourceLockManager inst = PolicyResourceLockManager.getInstance();
+ assertNotNull(inst);
+
+ // should return the same instance each time
+ assertEquals(inst, PolicyResourceLockManager.getInstance());
+ assertEquals(inst, PolicyResourceLockManager.getInstance());
+ }
+
+ @Test
+ public void testDoIntercept_Empty() {
+ // clear the implementer list
+ implList.clear();
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+ assertFalse(mgr.isLocked(RESOURCE_B));
+
+ verify(impl1, never()).beforeIsLocked(anyString());
+ }
+
+ @Test
+ public void testDoIntercept_Impl1() {
+ when(impl1.beforeIsLocked(RESOURCE_A)).thenReturn(true);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2, never()).beforeIsLocked(anyString());
+ }
+
+ @Test
+ public void testDoIntercept_Impl2() {
+ when(impl2.beforeIsLocked(RESOURCE_A)).thenReturn(true);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2).beforeIsLocked(RESOURCE_A);
+ }
+
+ @Test
+ public void testDoIntercept_Ex() {
+ doThrow(new RuntimeException("expected exception")).when(impl1).beforeIsLocked(RESOURCE_A);
+
+ assertFalse(mgr.isLocked(RESOURCE_A));
+
+ verify(impl1).beforeIsLocked(RESOURCE_A);
+ verify(impl2).beforeIsLocked(RESOURCE_A);
+ }
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/SimpleLockManagerTest.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/SimpleLockManagerTest.java
new file mode 100644
index 00000000..6abc5bf9
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/SimpleLockManagerTest.java
@@ -0,0 +1,280 @@
+/*
+ * ============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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.onap.policy.drools.core.lock.TestUtils.expectException;
+import java.util.LinkedList;
+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.atomic.AtomicInteger;
+import org.junit.Before;
+import org.junit.Test;
+
+public class SimpleLockManagerTest {
+
+ private static final String NULL_RESOURCE_ID = "null resourceId";
+ private static final String NULL_OWNER = "null owner";
+
+ private static final String RESOURCE_A = "resource.a";
+ private static final String RESOURCE_B = "resource.b";
+ private static final String RESOURCE_C = "resource.c";
+
+ private static final String OWNER1 = "owner.one";
+ private static final String OWNER2 = "owner.two";
+ private static final String OWNER3 = "owner.three";
+
+ private Future<Boolean> fut;
+ private SimpleLockManager mgr;
+
+ @Before
+ public void setUp() {
+ mgr = new SimpleLockManager();
+ }
+
+ @Test
+ public void testLock() throws Exception {
+ fut = mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+ assertTrue(mgr.isLockedBy(RESOURCE_A, OWNER1));
+ assertFalse(mgr.isLocked(RESOURCE_B));
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER2));
+
+ // null callback - not locked yet
+ fut = mgr.lock(RESOURCE_C, OWNER3, null);
+ assertTrue(fut.isDone());
+ assertTrue(fut.get());
+
+ // null callback - already locked
+ fut = mgr.lock(RESOURCE_A, OWNER3, null);
+ assertTrue(fut.isDone());
+ assertFalse(fut.get());
+ }
+
+ @Test
+ public void testLock_AlreadyLocked() throws Exception {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ fut = mgr.lock(RESOURCE_A, OWNER2, null);
+ assertTrue(fut.isDone());
+ assertFalse(fut.get());
+ }
+
+ @Test(expected = IllegalStateException.class)
+ public void testLock_SameOwner() throws Exception {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // should throw an exception
+ mgr.lock(RESOURCE_A, OWNER1, null);
+ }
+
+ @Test
+ public void testLock_ArgEx() {
+ IllegalArgumentException ex =
+ expectException(IllegalArgumentException.class, xxx -> mgr.lock(null, OWNER1, null));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.lock(RESOURCE_A, null, null));
+ assertEquals(NULL_OWNER, ex.getMessage());
+
+ // this should not throw an exception
+ mgr.lock(RESOURCE_A, OWNER1, null);
+ }
+
+ @Test
+ public void testUnlock() throws Exception {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // unlock it
+ assertTrue(mgr.unlock(RESOURCE_A, OWNER1));
+ }
+
+ @Test
+ public void testUnlock_ArgEx() {
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class, xxx -> mgr.unlock(null, OWNER1));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.unlock(RESOURCE_A, null));
+ assertEquals(NULL_OWNER, ex.getMessage());
+ }
+
+ @Test
+ public void testUnlock_NotLocked() {
+ assertFalse(mgr.unlock(RESOURCE_A, OWNER1));
+ }
+
+ @Test
+ public void testIsLocked() {
+ assertFalse(mgr.isLocked(RESOURCE_A));
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+ mgr.lock(RESOURCE_B, OWNER1, null);
+
+ assertTrue(mgr.isLocked(RESOURCE_A));
+ assertTrue(mgr.isLocked(RESOURCE_B));
+ assertFalse(mgr.isLocked(RESOURCE_C));
+
+ // unlock from first resource
+ mgr.unlock(RESOURCE_A, OWNER1);
+ assertFalse(mgr.isLocked(RESOURCE_A));
+ assertTrue(mgr.isLocked(RESOURCE_B));
+ assertFalse(mgr.isLocked(RESOURCE_C));
+
+ // unlock from second resource
+ mgr.unlock(RESOURCE_B, OWNER1);
+ assertFalse(mgr.isLocked(RESOURCE_A));
+ assertFalse(mgr.isLocked(RESOURCE_B));
+ assertFalse(mgr.isLocked(RESOURCE_C));
+ }
+
+ @Test
+ public void testIsLocked_ArgEx() {
+ IllegalArgumentException ex = expectException(IllegalArgumentException.class, xxx -> mgr.isLocked(null));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+ }
+
+ @Test
+ public void testIsLockedBy() {
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER1));
+
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ assertFalse(mgr.isLockedBy(RESOURCE_B, OWNER1));
+
+ assertTrue(mgr.isLockedBy(RESOURCE_A, OWNER1));
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER2));
+
+ // unlock from the resource
+ mgr.unlock(RESOURCE_A, OWNER1);
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER1));
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER2));
+ assertFalse(mgr.isLockedBy(RESOURCE_B, OWNER1));
+ }
+
+ @Test
+ public void testIsLockedBy_ArgEx() {
+ IllegalArgumentException ex =
+ expectException(IllegalArgumentException.class, xxx -> mgr.isLockedBy(null, OWNER1));
+ assertEquals(NULL_RESOURCE_ID, ex.getMessage());
+
+ ex = expectException(IllegalArgumentException.class, xxx -> mgr.isLockedBy(RESOURCE_A, null));
+ assertEquals(NULL_OWNER, ex.getMessage());
+ }
+
+ @Test
+ public void testIsLockedBy_NotLocked() {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // different resource, thus no lock
+ assertFalse(mgr.isLockedBy(RESOURCE_B, OWNER1));
+ }
+
+ @Test
+ public void testIsLockedBy_LockedButNotOwner() {
+ mgr.lock(RESOURCE_A, OWNER1, null);
+
+ // different owner
+ assertFalse(mgr.isLockedBy(RESOURCE_A, OWNER2));
+ }
+
+ @Test
+ public void testMultiThreaded() throws InterruptedException {
+ int nthreads = 10;
+ int nlocks = 100;
+
+ LinkedList<Thread> threads = new LinkedList<>();
+
+ String[] resources = {RESOURCE_A, RESOURCE_B};
+
+ AtomicInteger nfail = new AtomicInteger(0);
+
+ CountDownLatch stopper = new CountDownLatch(1);
+ CountDownLatch completed = new CountDownLatch(nthreads);
+
+ for (int x = 0; x < nthreads; ++x) {
+ String owner = "owner." + x;
+
+ Thread t = new Thread() {
+ @Override
+ public void run() {
+
+ for (int y = 0; y < nlocks; ++y) {
+ String res = resources[y % resources.length];
+
+ try {
+ // some locks will be acquired, some denied
+ mgr.lock(res, owner, null).get();
+
+ // do some "work"
+ stopper.await(1L, TimeUnit.MILLISECONDS);
+
+ mgr.unlock(res, owner);
+
+ } catch (CancellationException | ExecutionException e) {
+ nfail.incrementAndGet();
+
+ } catch (InterruptedException expected) {
+ Thread.currentThread().interrupt();
+ break;
+ }
+ }
+
+ completed.countDown();
+ }
+ };
+
+ t.setDaemon(true);
+ threads.add(t);
+ }
+
+ // start the threads
+ for (Thread t : threads) {
+ t.start();
+ }
+
+ // wait for them to complete
+ completed.await(5000L, TimeUnit.SECONDS);
+
+ // stop the threads from sleeping
+ stopper.countDown();
+
+ completed.await(1L, TimeUnit.SECONDS);
+
+ // interrupt those that are still alive
+ for (Thread t : threads) {
+ if (t.isAlive()) {
+ t.interrupt();
+ }
+ }
+
+ assertEquals(0, nfail.get());
+ }
+
+}
diff --git a/policy-core/src/test/java/org/onap/policy/drools/core/lock/TestUtils.java b/policy-core/src/test/java/org/onap/policy/drools/core/lock/TestUtils.java
new file mode 100644
index 00000000..2e353936
--- /dev/null
+++ b/policy-core/src/test/java/org/onap/policy/drools/core/lock/TestUtils.java
@@ -0,0 +1,59 @@
+/*
+ * ============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;
+
+public class TestUtils {
+
+ /**
+ * Invokes a function that is expected to throw an exception.
+ *
+ * @param clazz class of exception that is expected
+ * @param func
+ * @return
+ */
+ public static <T> T expectException(Class<T> clazz, VoidFunction func) {
+ try {
+ func.apply(null);
+ throw new AssertionError("missing exception");
+
+ } catch (Exception e) {
+ try {
+ return clazz.cast(e);
+
+ } catch (ClassCastException e2) {
+ throw new AssertionError("incorrect exception type", e2);
+ }
+ }
+ }
+
+ /**
+ * Void function that may throw an exception.
+ */
+ @FunctionalInterface
+ public static interface VoidFunction {
+
+ /**
+ *
+ * @param arg always {@code null}
+ */
+ public void apply(Void arg) throws Exception;
+ }
+}
diff --git a/policy-utils/src/main/java/org/onap/policy/drools/utils/Reference.java b/policy-utils/src/main/java/org/onap/policy/drools/utils/Reference.java
new file mode 100644
index 00000000..0c4155fe
--- /dev/null
+++ b/policy-utils/src/main/java/org/onap/policy/drools/utils/Reference.java
@@ -0,0 +1,72 @@
+/*
+ * ============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.utils;
+
+/**
+ * Reference to an object. Used within functional methods, where thread-safety is not
+ * required.
+ *
+ * @param <T> type of object contained within the reference
+ */
+public class Reference<T> {
+ private T value;
+
+ /**
+ *
+ * @param value
+ */
+ public Reference(T value) {
+ this.value = value;
+ }
+
+ /**
+ * @return the current value
+ */
+ public final T get() {
+ return value;
+ }
+
+ /**
+ * Sets the reference to point to a new value.
+ *
+ * @param newValue
+ */
+ public final void set(T newValue) {
+ this.value = newValue;
+ }
+
+ /**
+ * Sets the value to a new value, if the value is currently the same as the old value.
+ *
+ * @param oldValue
+ * @param newValue
+ * @return {@code true} if the value was updated, {@code false} otherwise
+ */
+ public boolean compareAndSet(T oldValue, T newValue) {
+ if (value == oldValue) {
+ value = newValue;
+ return true;
+
+ } else {
+ return false;
+ }
+ }
+}
diff --git a/policy-utils/src/test/java/org/onap/policy/drools/utils/ReferenceTest.java b/policy-utils/src/test/java/org/onap/policy/drools/utils/ReferenceTest.java
new file mode 100644
index 00000000..1d6b111a
--- /dev/null
+++ b/policy-utils/src/test/java/org/onap/policy/drools/utils/ReferenceTest.java
@@ -0,0 +1,84 @@
+/*
+ * ============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.utils;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+import org.onap.policy.drools.utils.Reference;
+
+public class ReferenceTest {
+
+ @Test
+ public void testReference() {
+ Reference<Integer> val = new Reference<>(null);
+ assertNull(val.get());
+
+ val = new Reference<>(10);
+ assertEquals(10, val.get().intValue());
+ }
+
+ @Test
+ public void testGet_testSet() {
+ Reference<Integer> val = new Reference<>(null);
+ assertNull(val.get());
+
+ val.set(20);
+ assertEquals(20, val.get().intValue());
+
+ val.set(30);
+ assertEquals(30, val.get().intValue());
+ }
+
+ @Test
+ public void testCompareAndSet() {
+ Reference<Integer> val = new Reference<>(null);
+
+ Integer v = 100;
+
+ // try an incorrect value - should fail and leave value unchanged
+ assertFalse(val.compareAndSet(500, v));
+ assertNull(val.get());
+
+ assertTrue(val.compareAndSet(null, v));
+ assertEquals(v, val.get());
+
+ // try an incorrect value - should fail and leave value unchanged
+ Integer v2 = 200;
+ assertFalse(val.compareAndSet(600, v2));
+ assertEquals(v, val.get());
+
+ // now try again, this time with the correct value
+ assertTrue(val.compareAndSet(v, v2));
+ assertEquals(v2, val.get());
+
+ Integer v3 = 300;
+ assertTrue(val.compareAndSet(v2, v3));
+ assertEquals(v3, val.get());
+
+ // try setting it back to null
+ assertTrue(val.compareAndSet(v3, null));
+ assertNull(val.get());
+ }
+
+}