1 files changed, 208 insertions, 0 deletions
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();
+        }
+    }
+}