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Diffstat (limited to 'jar/src/main/java/org/onap/music/lockingservice/ZkStatelessLockService.java')
| -rw-r--r-- | jar/src/main/java/org/onap/music/lockingservice/ZkStatelessLockService.java | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/jar/src/main/java/org/onap/music/lockingservice/ZkStatelessLockService.java b/jar/src/main/java/org/onap/music/lockingservice/ZkStatelessLockService.java new file mode 100644 index 00000000..e99df255 --- /dev/null +++ b/jar/src/main/java/org/onap/music/lockingservice/ZkStatelessLockService.java @@ -0,0 +1,339 @@ +/* + * ============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 java.util.List; +import java.util.SortedSet; +import java.util.TreeSet; +import org.apache.zookeeper.CreateMode; +import org.apache.zookeeper.KeeperException; +import org.apache.zookeeper.KeeperException.NoNodeException; +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; + +/** + * A <a href="package.html">protocol to implement an exclusive write lock or to elect a leader</a>. + * <p/> + * You invoke {@link #lock()} to start the process of grabbing the lock; you may get the lock then + * or it may be some time later. + * <p/> + * You can register a listener so that you are invoked when you get the lock; otherwise you can ask + * if you have the lock by calling {@link #isOwner()} + * + */ +public class ZkStatelessLockService extends ProtocolSupport { + public ZkStatelessLockService(ZooKeeper zk) { + zookeeper = zk; + } + + private static EELFLoggerDelegate logger = + EELFLoggerDelegate.getLogger(ZkStatelessLockService.class); + + protected void createLock(final String path, final byte[] data) { + final List<ACL> acl = ZooDefs.Ids.OPEN_ACL_UNSAFE; + try { + retryOperation(new ZooKeeperOperation() { + public boolean execute() throws KeeperException, InterruptedException { + zookeeper.create(path, data, acl, CreateMode.PERSISTENT); + return true; + } + }); + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + }catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + } + + public void close() { + try { + zookeeper.close(); + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + } + + public void setNodeData(final String lockName, final byte[] data) { + try { + retryOperation(new ZooKeeperOperation() { + public boolean execute() throws KeeperException, InterruptedException { + zookeeper.getSessionId(); + zookeeper.setData("/" + lockName, data, -1); + return true; + } + }); + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + }catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + + } + + public byte[] getNodeData(final String lockName) { + try { + if (zookeeper.exists("/" + lockName, null) != null) + return zookeeper.getData("/" + lockName, false, null); + else + return null; + + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + }catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + return null; + } + + public boolean checkIfLockExists(String lockName) { + boolean result = false; + try { + Stat stat = zookeeper.exists(lockName, false); + if (stat != null) { + result = true; + } + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + }catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + return result; + } + + public void createNode(String nodeName) { + ensurePathExists(nodeName); + } + + public String createLockId(String dir) { + ensurePathExists(dir); + LockZooKeeperOperation zop = new LockZooKeeperOperation(dir); + try { + retryOperation(zop); + }catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + }catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + } + return zop.getId(); + } + + /** + * Attempts to acquire the exclusive write lock returning whether or not it was acquired. Note + * that the exclusive lock may be acquired some time later after this method has been invoked + * due to the current lock owner going away. + */ + public synchronized boolean lock(String dir, String lockId) + throws KeeperException, InterruptedException { + if (isClosed()) { + return false; + } + LockZooKeeperOperation zop = new LockZooKeeperOperation(dir, lockId); + return (Boolean) retryOperation(zop); + } + + /** + * Removes the lock or associated znode if you no longer require the lock. this also removes + * your request in the queue for locking in case you do not already hold the lock. + * + * @throws RuntimeException throws a runtime exception if it cannot connect to zookeeper. + * @throws NoNodeException + */ + public synchronized void unlock(String lockId) throws RuntimeException, KeeperException.NoNodeException { + final String id = lockId; + if (!isClosed() && id != null) { + try { + ZooKeeperOperation zopdel = new ZooKeeperOperation() { + public boolean execute() throws KeeperException, InterruptedException { + zookeeper.delete(id, -1); + return Boolean.TRUE; + } + }; + zopdel.execute(); + } catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + // set that we have been interrupted. + Thread.currentThread().interrupt(); + } catch (KeeperException.NoNodeException e) { + // do nothing + throw new KeeperException.NoNodeException("Lock doesn't exists. Release lock operation failed."); + } catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + throw (RuntimeException) new RuntimeException(e.getMessage()).initCause(e); + } + } + } + + public synchronized String currentLockHolder(String mainLock) { + final String id = mainLock; + if (!isClosed() && id != null) { + List<String> names; + try { + names = zookeeper.getChildren(id, false); + if (names.isEmpty()) + return ""; + SortedSet<ZNodeName> sortedNames = new TreeSet<ZNodeName>(); + for (String name : names) { + sortedNames.add(new ZNodeName(id + "/" + name)); + } + return sortedNames.first().getName(); + } catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + // set that we have been interrupted. + Thread.currentThread().interrupt(); + } catch (KeeperException.NoNodeException e) { + // do nothing + } catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + throw (RuntimeException) new RuntimeException(e.getMessage()).initCause(e); + } + } + return "No lock holder!"; + } + + public synchronized void deleteLock(String mainLock) { + final String id = mainLock; + if (!isClosed() && id != null) { + try { + ZooKeeperOperation zopdel = new ZooKeeperOperation() { + public boolean execute() throws KeeperException, InterruptedException { + List<String> names = zookeeper.getChildren(id, false); + for (String name : names) { + zookeeper.delete(id + "/" + name, -1); + } + zookeeper.delete(id, -1); + return Boolean.TRUE; + } + }; + zopdel.execute(); + } catch (InterruptedException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.EXECUTIONINTERRUPTED, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + // set that we have been interrupted. + Thread.currentThread().interrupt(); + } catch (KeeperException.NoNodeException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + // do nothing + } catch (KeeperException e) { + logger.error(EELFLoggerDelegate.errorLogger, e.getMessage(),AppMessages.KEEPERERROR, ErrorSeverity.ERROR, ErrorTypes.LOCKINGERROR); + throw (RuntimeException) new RuntimeException(e.getMessage()).initCause(e); + } + } + + } + + /** + * a zoookeeper operation that is mainly responsible for all the magic required for locking. + */ + private class LockZooKeeperOperation implements ZooKeeperOperation { + + /** + * find if we have been created earlier if not create our node + * + * @param prefix the prefix node + * @param zookeeper the zookeeper client + * @param dir the dir parent + * @throws KeeperException + * @throws InterruptedException + */ + private String dir; + private String id = null; + + public String getId() { + return id; + } + + public LockZooKeeperOperation(String dir) { + this.dir = dir; + } + + public LockZooKeeperOperation(String dir, String id) { + this.dir = dir; + this.id = id; + } + + /** + * the command that is run and retried for actually obtaining the lock + * + * @return if the command was successful or not + */ + public boolean execute() throws KeeperException, InterruptedException { + do { + if (id == null) { + String prefix = "x-"; + byte[] data = {0x12, 0x34}; + id = zookeeper.create(dir + "/" + prefix, data, getAcl(), + CreateMode.PERSISTENT_SEQUENTIAL); + + if (logger.isDebugEnabled()) { + logger.debug(EELFLoggerDelegate.debugLogger, "Created id: " + id); + } + if (id != null) + break; + } + if (id != null) { + List<String> names = zookeeper.getChildren(dir, false); + if (names.isEmpty()) { + logger.info(EELFLoggerDelegate.applicationLogger, "No children in: " + dir + + " when we've just " + "created one! Lets recreate it..."); + // lets force the recreation of the id + id = null; + return Boolean.FALSE; + + } else { + // lets sort them explicitly (though they do seem to come back in order + // ususally :) + ZNodeName idName = new ZNodeName(id); + SortedSet<ZNodeName> sortedNames = new TreeSet<ZNodeName>(); + for (String name : names) { + sortedNames.add(new ZNodeName(dir + "/" + name)); + } + if (!sortedNames.contains(idName)) + return Boolean.FALSE; + + SortedSet<ZNodeName> lessThanMe = sortedNames.headSet(idName); + if (!lessThanMe.isEmpty()) { + ZNodeName lastChildName = lessThanMe.last(); + String lastChildId = lastChildName.getName(); + if (logger.isDebugEnabled()) { + logger.debug(EELFLoggerDelegate.debugLogger, "watching less than me node: " + lastChildId); + } + Stat stat = zookeeper.exists(lastChildId, false); + if (stat != null) { + return Boolean.FALSE; + } else { + logger.info(EELFLoggerDelegate.applicationLogger, + "Could not find the" + " stats for less than me: " + + lastChildName.getName()); + } + } else + return Boolean.TRUE; + } + } + } while (id == null); + return Boolean.FALSE; + } + } + +} + |