Refactor duplicate code from lock managers

Change-Id: I8910a1a4267d824f064b52c6ad08945590bd9617
Issue-ID: POLICY-2203
Signed-off-by: Jim Hahn <jrh3@att.com>

2 files changed, 84 insertions, 227 deletions

diff --git a/feature-distributed-locking/src/main/java/org/onap/policy/distributed/locking/DistributedLockManager.java b/feature-distributed-locking/src/main/java/org/onap/policy/distributed/locking/DistributedLockManager.java
index 7ee786b9..6f83ea15 100644
--- a/feature-distributed-locking/src/main/java/org/onap/policy/distributed/locking/DistributedLockManager.java
+++ b/feature-distributed-locking/src/main/java/org/onap/policy/distributed/locking/DistributedLockManager.java
@@ -30,9 +30,9 @@ import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 import java.util.UUID;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
@@ -42,15 +42,15 @@ import lombok.Setter;
 import org.apache.commons.dbcp2.BasicDataSource;
 import org.apache.commons.dbcp2.BasicDataSourceFactory;
 import org.onap.policy.common.utils.network.NetworkUtil;
-import org.onap.policy.drools.core.lock.AlwaysFailLock;
-import org.onap.policy.drools.core.lock.Lock;
 import org.onap.policy.drools.core.lock.LockCallback;
-import org.onap.policy.drools.core.lock.LockImpl;
 import org.onap.policy.drools.core.lock.LockState;
 import org.onap.policy.drools.core.lock.PolicyResourceLockManager;
 import org.onap.policy.drools.features.PolicyEngineFeatureApi;
 import org.onap.policy.drools.persistence.SystemPersistenceConstants;
 import org.onap.policy.drools.system.PolicyEngine;
+import org.onap.policy.drools.system.PolicyEngineConstants;
+import org.onap.policy.drools.system.internal.FeatureLockImpl;
+import org.onap.policy.drools.system.internal.LockManager;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -78,13 +78,12 @@ import org.slf4j.LoggerFactory;
  * instance.</li>
  * </dl>
  */
-public class DistributedLockManager implements PolicyResourceLockManager, PolicyEngineFeatureApi {
+public class DistributedLockManager extends LockManager<DistributedLockManager.DistributedLock>
+                implements PolicyEngineFeatureApi {
 
     private static final Logger logger = LoggerFactory.getLogger(DistributedLockManager.class);
 
     private static final String CONFIGURATION_PROPERTIES_NAME = "feature-distributed-locking";
-    private static final String LOCK_LOST_MSG = "lock lost";
-    private static final String NOT_LOCKED_MSG = "not locked";
 
     @Getter(AccessLevel.PROTECTED)
     @Setter(AccessLevel.PROTECTED)
@@ -108,23 +107,23 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
      * lock is added to the map, it remains in the map until the lock is lost or until the
      * unlock request completes.
      */
-    private final Map<String, DistributedLock> resource2lock = new ConcurrentHashMap<>();
+    private final Map<String, DistributedLock> resource2lock;
 
     /**
-     * Engine with which this manager is associated.
+     * Thread pool used to check for lock expiration and to notify owners when locks are
+     * granted or lost.
      */
-    private PolicyEngine engine;
+    private ScheduledExecutorService exsvc = null;
 
     /**
-     * Feature properties.
+     * Used to cancel the expiration checker on shutdown.
      */
-    private DistributedLockProperties featProps;
+    private ScheduledFuture<?> checker = null;
 
     /**
-     * Thread pool used to check for lock expiration and to notify owners when locks are
-     * granted or lost.
+     * Feature properties.
      */
-    private ScheduledExecutorService exsvc = null;
+    private DistributedLockProperties featProps;
 
     /**
      * Data source used to connect to the DB.
@@ -137,6 +136,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
      */
     public DistributedLockManager() {
         this.hostName = NetworkUtil.getHostname();
+        this.resource2lock = getResource2lock();
     }
 
     @Override
@@ -145,49 +145,10 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
     }
 
     @Override
-    public boolean isAlive() {
-        return (exsvc != null);
-    }
-
-    @Override
-    public boolean start() {
-        // handled via engine API
-        return true;
-    }
-
-    @Override
-    public boolean stop() {
-        // handled via engine API
-        return true;
-    }
-
-    @Override
-    public void shutdown() {
-        // handled via engine API
-    }
-
-    @Override
-    public boolean isLocked() {
-        return false;
-    }
-
-    @Override
-    public boolean lock() {
-        return true;
-    }
-
-    @Override
-    public boolean unlock() {
-        return true;
-    }
-
-    @Override
     public PolicyResourceLockManager beforeCreateLockManager(PolicyEngine engine, Properties properties) {
 
         try {
-            this.engine = engine;
             this.featProps = new DistributedLockProperties(getProperties(CONFIGURATION_PROPERTIES_NAME));
-            this.exsvc = getThreadPool();
             this.dataSource = makeDataSource();
 
             return this;
@@ -201,8 +162,9 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
     public boolean afterStart(PolicyEngine engine) {
 
         try {
+            exsvc = PolicyEngineConstants.getManager().getExecutorService();
             exsvc.execute(this::deleteExpiredDbLocks);
-            exsvc.schedule(this::checkExpired, featProps.getExpireCheckSec(), TimeUnit.SECONDS);
+            checker = exsvc.schedule(this::checkExpired, featProps.getExpireCheckSec(), TimeUnit.SECONDS);
 
             setLatestInstance(this);
 
@@ -257,6 +219,11 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
     @Override
     public boolean afterStop(PolicyEngine engine) {
         exsvc = null;
+
+        if (checker != null) {
+            checker.cancel(true);
+        }
+
         closeDataSource();
         return false;
     }
@@ -278,49 +245,36 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
     }
 
     @Override
-    public Lock createLock(String resourceId, String ownerKey, int holdSec, LockCallback callback,
-                    boolean waitForLock) {
-
-        if (latestInstance != this) {
-            AlwaysFailLock lock = new AlwaysFailLock(resourceId, ownerKey, holdSec, callback);
-            lock.notifyUnavailable();
-            return lock;
-        }
-
-        DistributedLock lock = makeLock(LockState.WAITING, resourceId, ownerKey, holdSec, callback);
-
-        DistributedLock existingLock = resource2lock.putIfAbsent(resourceId, lock);
-
-        // do these outside of compute() to avoid blocking other map operations
-        if (existingLock == null) {
-            logger.debug("added lock to map {}", lock);
-            lock.scheduleRequest(lock::doLock);
-        } else {
-            lock.deny("resource is busy", true);
-        }
+    protected boolean hasInstanceChanged() {
+        return (getLatestInstance() != this);
+    }
 
-        return lock;
+    @Override
+    protected void finishLock(DistributedLock lock) {
+        lock.scheduleRequest(lock::doLock);
     }
 
     /**
      * Checks for expired locks.
      */
     private void checkExpired() {
-
         try {
             logger.info("checking for expired locks");
             Set<String> expiredIds = new HashSet<>(resource2lock.keySet());
             identifyDbLocks(expiredIds);
             expireLocks(expiredIds);
 
-            exsvc.schedule(this::checkExpired, featProps.getExpireCheckSec(), TimeUnit.SECONDS);
+            checker = exsvc.schedule(this::checkExpired, featProps.getExpireCheckSec(), TimeUnit.SECONDS);
 
         } catch (RejectedExecutionException e) {
             logger.warn("thread pool is no longer accepting requests", e);
 
         } catch (SQLException | RuntimeException e) {
             logger.error("error checking expired locks", e);
-            exsvc.schedule(this::checkExpired, featProps.getRetrySec(), TimeUnit.SECONDS);
+
+            if (isAlive()) {
+                checker = exsvc.schedule(this::checkExpired, featProps.getRetrySec(), TimeUnit.SECONDS);
+            }
         }
 
         logger.info("done checking for expired locks");
@@ -387,7 +341,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
             DistributedLock lock = lockref.get();
             if (lock != null) {
                 logger.debug("removed lock from map {}", lock);
-                lock.deny(LOCK_LOST_MSG, false);
+                lock.deny(DistributedLock.LOCK_LOST_MSG, false);
             }
         }
     }
@@ -395,7 +349,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
     /**
      * Distributed Lock implementation.
      */
-    public static class DistributedLock extends LockImpl {
+    public static class DistributedLock extends FeatureLockImpl {
         private static final String SQL_FAILED_MSG = "request failed for lock: {}";
 
         private static final long serialVersionUID = 1L;
@@ -439,6 +393,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
          * Constructs the object.
          */
         public DistributedLock() {
+            this.feature = null;
             this.hostName = "";
             this.uuidString = "";
         }
@@ -464,58 +419,9 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
             this.uuidString = feature.uuidString;
         }
 
-        /**
-         * Grants this lock. The notification is <i>always</i> invoked via the
-         * <i>foreground</i> thread.
-         */
-        protected void grant() {
-            synchronized (this) {
-                if (isUnavailable()) {
-                    return;
-                }
-
-                setState(LockState.ACTIVE);
-            }
-
-            logger.info("lock granted: {}", this);
-
-            notifyAvailable();
-        }
-
-        /**
-         * Permanently denies this lock.
-         *
-         * @param reason the reason the lock was denied
-         * @param foreground {@code true} if the callback can be invoked in the current
-         *        (i.e., foreground) thread, {@code false} if it should be invoked via the
-         *        executor
-         */
-        protected void deny(String reason, boolean foreground) {
-            synchronized (this) {
-                setState(LockState.UNAVAILABLE);
-            }
-
-            logger.info("{}: {}", reason, this);
-
-            if (feature == null || foreground) {
-                notifyUnavailable();
-
-            } else {
-                feature.exsvc.execute(this::notifyUnavailable);
-            }
-        }
-
         @Override
         public boolean free() {
-            // do a quick check of the state
-            if (isUnavailable()) {
-                return false;
-            }
-
-            logger.info("releasing lock: {}", this);
-
-            if (!attachFeature()) {
-                setState(LockState.UNAVAILABLE);
+            if (!freeAllowed()) {
                 return false;
             }
 
@@ -546,16 +452,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
 
         @Override
         public void extend(int holdSec, LockCallback callback) {
-            if (holdSec < 0) {
-                throw new IllegalArgumentException("holdSec is negative");
-            }
-
-            setHoldSec(holdSec);
-            setCallback(callback);
-
-            // do a quick check of the state
-            if (isUnavailable() || !attachFeature()) {
-                deny(LOCK_LOST_MSG, true);
+            if (!extendAllowed(holdSec, callback)) {
                 return;
             }
 
@@ -580,19 +477,9 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
             }
         }
 
-        /**
-         * Attaches to the feature instance, if not already attached.
-         *
-         * @return {@code true} if the lock is now attached to a feature, {@code false}
-         *         otherwise
-         */
-        private synchronized boolean attachFeature() {
-            if (feature != null) {
-                // already attached
-                return true;
-            }
-
-            feature = latestInstance;
+        @Override
+        protected boolean addToFeature() {
+            feature = getLatestInstance();
             if (feature == null) {
                 logger.warn("no feature yet for {}", this);
                 return false;
@@ -613,7 +500,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
             logger.debug("schedule lock action {}", this);
             nretries = 0;
             request = schedreq;
-            feature.exsvc.execute(this::doRequest);
+            getThreadPool().execute(this::doRequest);
         }
 
         /**
@@ -633,7 +520,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
                 if (nretries++ < feature.featProps.getMaxRetries()) {
                     logger.debug("reschedule for {}s {}", feature.featProps.getRetrySec(), this);
                     request = req;
-                    feature.exsvc.schedule(this::doRequest, feature.featProps.getRetrySec(), TimeUnit.SECONDS);
+                    getThreadPool().schedule(this::doRequest, feature.featProps.getRetrySec(), TimeUnit.SECONDS);
                     return;
                 }
             }
@@ -752,7 +639,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
                 }
 
                 if (success) {
-                    grant();
+                    grant(true);
                     return;
                 }
             }
@@ -803,7 +690,7 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
                  * the record, thus we have to try to insert, if the update fails
                  */
                 if (doDbUpdate(conn) || doDbInsert(conn)) {
-                    grant();
+                    grant(true);
                     return;
                 }
             }
@@ -927,10 +814,6 @@ public class DistributedLockManager implements PolicyResourceLockManager, Policy
         return SystemPersistenceConstants.getManager().getProperties(fileName);
     }
 
-    protected ScheduledExecutorService getThreadPool() {
-        return engine.getExecutorService();
-    }
-
     protected DistributedLock makeLock(LockState state, String resourceId, String ownerKey, int holdSec,
                     LockCallback callback) {
         return new DistributedLock(state, resourceId, ownerKey, holdSec, callback, this);
diff --git a/feature-distributed-locking/src/test/java/org/onap/policy/distributed/locking/DistributedLockManagerTest.java b/feature-distributed-locking/src/test/java/org/onap/policy/distributed/locking/DistributedLockManagerTest.java
index 0ba92c51..c996d8d9 100644
--- a/feature-distributed-locking/src/test/java/org/onap/policy/distributed/locking/DistributedLockManagerTest.java
+++ b/feature-distributed-locking/src/test/java/org/onap/policy/distributed/locking/DistributedLockManagerTest.java
@@ -30,6 +30,7 @@ import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyBoolean;
 import static org.mockito.Matchers.anyLong;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doThrow;
@@ -55,6 +56,7 @@ import java.util.Properties;
 import java.util.concurrent.Executors;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -115,16 +117,19 @@ public class DistributedLockManagerTest {
     private static ScheduledExecutorService realExec;
 
     @Mock
+    private PolicyEngine engine;
+
+    @Mock
     private ScheduledExecutorService exsvc;
 
     @Mock
-    private LockCallback callback;
+    private ScheduledFuture<?> checker;
 
     @Mock
-    private BasicDataSource datasrc;
+    private LockCallback callback;
 
     @Mock
-    private PolicyEngine engine;
+    private BasicDataSource datasrc;
 
     private DistributedLock lock;
 
@@ -153,7 +158,6 @@ public class DistributedLockManagerTest {
         saveExec = Whitebox.getInternalState(PolicyEngineConstants.getManager(), POLICY_ENGINE_EXECUTOR_FIELD);
 
         realExec = Executors.newScheduledThreadPool(3);
-        Whitebox.setInternalState(PolicyEngineConstants.getManager(), POLICY_ENGINE_EXECUTOR_FIELD, realExec);
     }
 
     /**
@@ -181,8 +185,6 @@ public class DistributedLockManagerTest {
 
         cleanDb();
 
-        when(engine.getExecutorService()).thenReturn(exsvc);
-
         feature = new MyLockingFeature(true);
     }
 
@@ -214,52 +216,12 @@ public class DistributedLockManagerTest {
                         .anyMatch(obj -> obj instanceof DistributedLockManager));
     }
 
-    /**
-     * Tests constructor() when properties are invalid.
-     */
-    @Test
-    public void testDistributedLockManagerInvalidProperties() {
-        // use properties containing an invalid value
-        Properties props = new Properties();
-        props.setProperty(DistributedLockProperties.EXPIRE_CHECK_SEC, "abc");
-
-        feature = new MyLockingFeature(false) {
-            @Override
-            protected Properties getProperties(String fileName) {
-                return props;
-            }
-        };
-
-        assertThatThrownBy(() -> feature.afterStart(engine)).isInstanceOf(DistributedLockManagerException.class);
-    }
-
     @Test
     public void testGetSequenceNumber() {
         assertEquals(1000, feature.getSequenceNumber());
     }
 
     @Test
-    public void testStartableApi() {
-        assertTrue(feature.isAlive());
-        assertTrue(feature.start());
-        assertTrue(feature.stop());
-        feature.shutdown();
-
-        // above should have had no effect
-        assertTrue(feature.isAlive());
-
-        feature.afterStop(engine);
-        assertFalse(feature.isAlive());
-    }
-
-    @Test
-    public void testLockApi() {
-        assertFalse(feature.isLocked());
-        assertTrue(feature.lock());
-        assertTrue(feature.unlock());
-    }
-
-    @Test
     public void testBeforeCreateLockManager() {
         assertSame(feature, feature.beforeCreateLockManager(engine, new Properties()));
     }
@@ -298,8 +260,7 @@ public class DistributedLockManagerTest {
 
         feature = new MyLockingFeature(false);
 
-        when(exsvc.schedule(any(Runnable.class), anyLong(), any()))
-                        .thenThrow(new IllegalArgumentException(EXPECTED_EXCEPTION));
+        doThrow(new IllegalArgumentException(EXPECTED_EXCEPTION)).when(exsvc).execute(any());
 
         assertThatThrownBy(() -> feature.afterStart(engine)).isInstanceOf(DistributedLockManagerException.class);
     }
@@ -350,6 +311,7 @@ public class DistributedLockManagerTest {
     @Test
     public void testAfterStop() {
         shutdownFeature();
+        verify(checker).cancel(anyBoolean());
 
         feature = new DistributedLockManager();
 
@@ -424,7 +386,7 @@ public class DistributedLockManagerTest {
     }
 
     /**
-     * Tests lock() when the feature is not the latest instance.
+     * Tests createLock() when the feature is not the latest instance.
      */
     @Test
     public void testCreateLockNotLatestInstance() {
@@ -522,6 +484,27 @@ public class DistributedLockManagerTest {
         runChecker(0, 0, RETRY_SEC);
     }
 
+    /**
+     * Tests checkExpired(), when getConnection() throws an exception and the feature is
+     * no longer alive.
+     */
+    @Test
+    public void testCheckExpiredSqlExFeatureStopped() {
+        // use a data source that throws an exception when getConnection() is called
+        feature = new InvalidDbLockingFeature(TRANSIENT) {
+            @Override
+            protected SQLException makeEx() {
+                this.stop();
+                return super.makeEx();
+            }
+        };
+
+        runChecker(0, 0, EXPIRE_SEC);
+
+        // it should NOT have scheduled another check
+        verify(exsvc, times(1)).schedule(any(Runnable.class), anyLong(), any());
+    }
+
     @Test
     public void testExpireLocks() throws SQLException {
         AtomicReference<DistributedLock> freeLock = new AtomicReference<>(null);
@@ -637,20 +620,6 @@ public class DistributedLockManagerTest {
         verify(callback).lockAvailable(lock);
     }
 
-    /**
-     * Tests grant() when the lock is already unavailable.
-     */
-    @Test
-    public void testDistributedLockGrantUnavailable() {
-        DistributedLock lock = getLock(RESOURCE, OWNER_KEY, HOLD_SEC, callback, false);
-        lock.setState(LockState.UNAVAILABLE);
-        lock.grant();
-
-        assertTrue(lock.isUnavailable());
-        verify(callback, never()).lockAvailable(any());
-        verify(callback, never()).lockUnavailable(any());
-    }
-
     @Test
     public void testDistributedLockDeny() {
         // get a lock
@@ -1464,6 +1433,8 @@ public class DistributedLockManagerTest {
      */
     @Test
     public void testMultiThreaded() throws InterruptedException {
+        Whitebox.setInternalState(PolicyEngineConstants.getManager(), POLICY_ENGINE_EXECUTOR_FIELD, realExec);
+
         feature = new DistributedLockManager();
         feature.beforeCreateLockManager(PolicyEngineConstants.getManager(), new Properties());
         feature.afterStart(PolicyEngineConstants.getManager());
@@ -1661,10 +1632,12 @@ public class DistributedLockManagerTest {
             shutdownFeature();
 
             exsvc = mock(ScheduledExecutorService.class);
-            when(engine.getExecutorService()).thenReturn(exsvc);
+            when(exsvc.schedule(any(Runnable.class), anyLong(), any())).thenAnswer(ans -> checker);
+            Whitebox.setInternalState(PolicyEngineConstants.getManager(), POLICY_ENGINE_EXECUTOR_FIELD, exsvc);
 
             if (init) {
                 beforeCreateLockManager(engine, new Properties());
+                start();
                 afterStart(engine);
             }
         }
@@ -1685,6 +1658,7 @@ public class DistributedLockManagerTest {
             this.isTransient = isTransient;
 
             this.beforeCreateLockManager(engine, new Properties());
+            this.start();
             this.afterStart(engine);
         }
 
@@ -1704,7 +1678,7 @@ public class DistributedLockManagerTest {
             return datasrc;
         }
 
-        private SQLException makeEx() {
+        protected SQLException makeEx() {
             if (isTransient) {
                 return new SQLException(new SQLTransientException(EXPECTED_EXCEPTION));