--- /dev/null
+/*
+ * ============LICENSE_START==========================================
+ * org.onap.music
+ * ===================================================================
+ * Copyright (c) 2017 AT&T Intellectual Property
+ * ===================================================================
+ * 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.music.lockingservice;
+
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.ZooDefs;
+import org.apache.zookeeper.ZooKeeper;
+import org.apache.zookeeper.data.ACL;
+import org.apache.zookeeper.data.Stat;
+import org.onap.music.eelf.logging.EELFLoggerDelegate;
+import org.onap.music.eelf.logging.format.AppMessages;
+import org.onap.music.eelf.logging.format.ErrorSeverity;
+import org.onap.music.eelf.logging.format.ErrorTypes;
+import org.onap.music.lockingservice.ZooKeeperOperation;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * A base class for protocol implementations which provides a number of higher level helper methods
+ * for working with ZooKeeper along with retrying synchronous operations if the connection to
+ * ZooKeeper closes such as {@link #retryOperation(ZooKeeperOperation)}
+ *
+ */
+class ProtocolSupport {
+ private EELFLoggerDelegate logger = EELFLoggerDelegate.getLogger(ProtocolSupport.class);
+
+ protected ZooKeeper zookeeper;
+ private AtomicBoolean closed = new AtomicBoolean(false);
+ private long retryDelay = 500L;
+ private int retryCount = 10;
+ private List<ACL> acl = ZooDefs.Ids.OPEN_ACL_UNSAFE;
+
+ /**
+ * Closes this strategy and releases any ZooKeeper resources; but keeps the ZooKeeper instance
+ * open
+ */
+ public void close() {
+ if (closed.compareAndSet(false, true)) {
+ doClose();
+ }
+ }
+
+ /**
+ * return zookeeper client instance
+ *
+ * @return zookeeper client instance
+ */
+ public ZooKeeper getZookeeper() {
+ return zookeeper;
+ }
+
+ /**
+ * return the acl its using
+ *
+ * @return the acl.
+ */
+ public List<ACL> getAcl() {
+ return acl;
+ }
+
+ /**
+ * set the acl
+ *
+ * @param acl the acl to set to
+ */
+ public void setAcl(List<ACL> acl) {
+ this.acl = acl;
+ }
+
+ /**
+ * get the retry delay in milliseconds
+ *
+ * @return the retry delay
+ */
+ public long getRetryDelay() {
+ return retryDelay;
+ }
+
+ /**
+ * Sets the time waited between retry delays
+ *
+ * @param retryDelay the retry delay
+ */
+ public void setRetryDelay(long retryDelay) {
+ this.retryDelay = retryDelay;
+ }
+
+ /**
+ * Allow derived classes to perform some custom closing operations to release resources
+ */
+ protected void doClose() {
+ throw new UnsupportedOperationException();
+ }
+
+
+ /**
+ * Perform the given operation, retrying if the connection fails
+ *
+ * @return object. it needs to be cast to the callee's expected return type.
+ * @param operation FILL IN
+ * @throws KeeperException FILL IN
+ * @throws InterruptedException FILL IN
+ */
+ protected Object retryOperation(ZooKeeperOperation operation)
+ throws KeeperException, InterruptedException {
+ KeeperException exception = null;
+ for (int i = 0; i < retryCount; i++) {
+ try {
+ return operation.execute();
+ } catch (KeeperException.SessionExpiredException e) {
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.SESSIONEXPIRED+" for: " + zookeeper + " so reconnecting due to: " + e, ErrorSeverity.ERROR, ErrorTypes.SESSIONEXPIRED);
+ throw e;
+ } catch (KeeperException.ConnectionLossException e) {
+ if (exception == null) {
+ exception = e;
+ }
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.CONNCECTIVITYERROR, ErrorSeverity.ERROR, ErrorTypes.SESSIONEXPIRED);
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),"Attempt " + i + " failed with connection loss so attempting to reconnect: " + e);
+
+ retryDelay(i);
+ }
+ }
+ throw exception;
+ }
+
+ /**
+ * Ensures that the given path exists with no data, the current ACL and no flags
+ *
+ * @param path the lock path
+ */
+ protected void ensurePathExists(String path) {
+ ensureExists(path, null, acl, CreateMode.PERSISTENT);
+ }
+
+ /**
+ * Ensures that the given path exists with the given data, ACL and flags
+ *
+ * @param path the lock path
+ * @param data the data
+ * @param acl list of ACLs applying to the path
+ * @param flags create mode flags
+ */
+ protected void ensureExists(final String path, final byte[] data, final List<ACL> acl,
+ final CreateMode flags) {
+ try {
+ retryOperation(new ZooKeeperOperation() {
+ public boolean execute() throws KeeperException, InterruptedException {
+ Stat stat = zookeeper.exists(path, false);
+ if (stat != null) {
+ return true;
+ }
+ zookeeper.create(path, data, acl, flags);
+ return true;
+ }
+ });
+ } catch (KeeperException e) {
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR);
+ } catch (InterruptedException e) {
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR);
+ }
+ }
+
+ /**
+ * Returns true if this protocol has been closed
+ *
+ * @return true if this protocol is closed
+ */
+ protected boolean isClosed() {
+ return closed.get();
+ }
+
+ /**
+ * Performs a retry delay if this is not the first attempt
+ *
+ * @param attemptCount the number of the attempts performed so far
+ */
+ protected void retryDelay(int attemptCount) {
+ if (attemptCount > 0) {
+ try {
+ Thread.sleep(attemptCount * retryDelay);
+ } catch (InterruptedException e) {
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.GENERALSERVICEERROR);
+ logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),"Thread failed to sleep: " + e);
+ Thread.currentThread().interrupt();
+ }
+ }
+ }
+}
Code Review / music.git / blobdiff