/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.accumulo.fate.zookeeper;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.accumulo.fate.zookeeper.ZooUtil.ZooKeeperConnectionInfo;
import org.apache.zookeeper.AsyncCallback.VoidCallback;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.KeeperException.Code;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Stat;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ZooReader implements IZooReader {
private static final Logger log = LoggerFactory.getLogger(ZooReader.class);
protected String keepers;
protected int timeout;
private final RetryFactory retryFactory;
private final ZooKeeperConnectionInfo info;
protected ZooKeeper getSession(String keepers, int timeout, String scheme, byte[] auth) {
return ZooSession.getSession(keepers, timeout, scheme, auth);
}
protected ZooKeeper getZooKeeper() {
return getSession(keepers, timeout, null, null);
}
protected RetryFactory getRetryFactory() {
return retryFactory;
}
protected void retryOrThrow(Retry retry, KeeperException e) throws KeeperException {
log.warn("Saw (possibly) transient exception communicating with ZooKeeper", e);
if (retry.canRetry()) {
retry.useRetry();
return;
}
log.error("Retry attempts (" + retry.retriesCompleted() + ") exceeded trying to communicate with ZooKeeper");
throw e;
}
@Override
public byte[] getData(String zPath, Stat stat) throws KeeperException, InterruptedException {
return getData(zPath, false, stat);
}
@Override
public byte[] getData(String zPath, boolean watch, Stat stat) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().getData(zPath, watch, stat);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public byte[] getData(String zPath, Watcher watcher, Stat stat) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().getData(zPath, watcher, stat);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public Stat getStatus(String zPath) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().exists(zPath, false);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public Stat getStatus(String zPath, Watcher watcher) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().exists(zPath, watcher);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public List<String> getChildren(String zPath) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().getChildren(zPath, false);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public List<String> getChildren(String zPath, Watcher watcher) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().getChildren(zPath, watcher);
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public boolean exists(String zPath) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().exists(zPath, false) != null;
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public boolean exists(String zPath, Watcher watcher) throws KeeperException, InterruptedException {
final Retry retry = getRetryFactory().create();
while (true) {
try {
return getZooKeeper().exists(zPath, watcher) != null;
} catch (KeeperException e) {
final Code code = e.code();
if (code == Code.CONNECTIONLOSS || code == Code.OPERATIONTIMEOUT || code == Code.SESSIONEXPIRED) {
retryOrThrow(retry, e);
} else {
throw e;
}
}
retry.waitForNextAttempt();
}
}
@Override
public void sync(final String path) throws KeeperException, InterruptedException {
final AtomicInteger rc = new AtomicInteger();
final CountDownLatch waiter = new CountDownLatch(1);
getZooKeeper().sync(path, new VoidCallback() {
@Override
public void processResult(int code, String arg1, Object arg2) {
rc.set(code);
waiter.countDown();
}
}, null);
waiter.await();
Code code = Code.get(rc.get());
if (code != KeeperException.Code.OK) {
throw KeeperException.create(code);
}
}
@Override
public List<ACL> getACL(String zPath, Stat stat) throws KeeperException, InterruptedException {
return ZooUtil.getACL(info, zPath, stat);
}
public ZooReader(String keepers, int timeout) {
this.keepers = keepers;
this.timeout = timeout;
this.retryFactory = RetryFactory.DEFAULT_INSTANCE;
this.info = new ZooKeeperConnectionInfo(keepers, timeout, null, null);
}
}