1 files changed, 164 insertions, 0 deletions
diff --git a/controlloop/m2/lock/src/main/java/org/onap/policy/drools/m2/lock/LockAdjunct.java b/controlloop/m2/lock/src/main/java/org/onap/policy/drools/m2/lock/LockAdjunct.java
new file mode 100644
index 000000000..e81ab6288
--- /dev/null
+++ b/controlloop/m2/lock/src/main/java/org/onap/policy/drools/m2/lock/LockAdjunct.java
@@ -0,0 +1,164 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * m2/lock
+ * ================================================================================
+ * Copyright (C) 2020 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.m2.lock;
+
+import java.io.Serializable;
+import java.util.HashMap;
+
+import org.onap.policy.drools.core.lock.Lock;
+import org.onap.policy.drools.core.lock.LockCallback;
+import org.onap.policy.drools.system.PolicyEngineConstants;
+import org.onap.policy.m2.base.Transaction;
+
+/*
+ * Adjunct data placed within the transaction, to contain locks
+ * on control loop use case basis. This same instance is shared
+ * among all actor operation instances within the transaction
+ * regardless of what actor is in the policy chain. As a result,
+ * the lock gets passed from one to the next, and is only freed
+ * when the transaction completes.
+ */
+public class LockAdjunct implements Transaction.Adjunct, LockCallback,
+    Serializable {
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * This is the callback interface, which is only used if the lock is
+     * initially not available, and we end up waiting for it.
+     */
+    public interface Requestor {
+        /**
+         * This method is called once the lock has been acquired.
+         */
+        void lockAvailable();
+
+        /**
+         * This method is called to notify the requestor that the lock could not
+         * be obtained.
+         */
+        void lockUnavailable();
+    }
+
+    // lock associated with all of the AOTS and SDNR operations
+    // within the transaction
+    private Lock lock = null;
+
+    // the initial requestor of the lock
+    // (only set if we don't immediately acquire the lock)
+    private Requestor requestor = null;
+
+    /**
+     * allocate a lock on behalf of the requestor.
+     *
+     * @param requestor
+     *            the AOTS or SDNR operation requesting the lock
+     * @param key
+     *            string key identifying the lock
+     * @param ownerKey
+     *            string key identifying the owner
+     * @param waitForLock
+     *            used to determine if an operation should wait for a lock to
+     *            become available or fail immediately
+     * @return 'true' if we immediately acquired the lock, 'false' if the lock
+     *         is currently in use by another transaction, and we need to wait
+     */
+    public boolean getLock(Requestor requestor, String key, String ownerKey,
+                           boolean waitForLock) {
+        if (lock != null) {
+            if (lock.isActive()) {
+                // we already have an active lock
+                return true;
+            }
+
+            // We may have timed out earlier waiting for the lock, or
+            // we may have lost the lock after persistent restore. In
+            // any case, free the lock we have now, and allocate a new one.
+            lock.free();
+        }
+
+        // register the requestor in case the lockUnavailable() callback runs
+        // immediately. Previously the requestor would be set after the
+        // lock constructor ran but now the lockUnavailable() callback
+        // could be executed while the constructor is still on the stack which
+        // would result in a null requestor, thus the callback never
+        // notifying the requestor that the lock was unavailable.
+        this.requestor = requestor;
+
+        // try to allocate a new lock
+        if ((lock = PolicyEngineConstants.getManager().createLock(
+            key, ownerKey, 600, this, waitForLock)).isActive()) {
+            // the lock is good
+            return true;
+        }
+
+        // we need to wait for the lock -- return false,
+        return false;
+    }
+
+    /*=================================*/
+    /* 'Transaction.Adjunct' interface */
+    /*=================================*/
+
+    /**
+     * Notification that the transaction has completed.
+     *
+     * {@inheritDoc}
+     */
+    @Override
+    public void cleanup(Transaction transaction) {
+        if (lock != null) {
+            // free the lock or cancel the reservation
+            lock.free();
+        }
+    }
+
+    /*==========================*/
+    /* 'LockCallback' interface */
+    /*==========================*/
+
+    /**
+     * Notification that the lock is available.
+     *
+     * {@inheritDoc}
+     */
+    @Override
+    public void lockAvailable(Lock lock) {
+        this.lock = lock;
+        if (requestor != null) {
+            // notify requestor
+            requestor.lockAvailable();
+        }
+    }
+
+    /**
+     * Notification that the lock is not available.
+     *
+     * {@inheritDoc}
+     */
+    @Override
+    public void lockUnavailable(Lock lock) {
+        this.lock = lock;
+        if (requestor != null) {
+            // notify requestor
+            requestor.lockUnavailable();
+        }
+    }
+}