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/*
* 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.bookkeeper.meta;
import java.io.IOException;
import java.util.List;
import org.apache.bookkeeper.client.BKException;
import org.apache.bookkeeper.proto.BookkeeperInternalCallbacks.GenericCallback;
import org.apache.bookkeeper.util.ZkUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.zookeeper.AsyncCallback;
import org.apache.zookeeper.AsyncCallback.StringCallback;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.ACL;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ZooKeeper based ledger id generator class, which using EPHEMERAL_SEQUENTIAL
* with (ledgerIdGenPath)/ID- prefix to generate ledger id. Note
* zookeeper sequential counter has a format of %10d -- that is 10 digits with 0
* (zero) padding, i.e. "<path>0000000001", so ledger id space is
* fundamentally limited to 9 billion.
*/
public class ZkLedgerIdGenerator implements LedgerIdGenerator {
static final Logger LOG = LoggerFactory.getLogger(ZkLedgerIdGenerator.class);
static final String LEDGER_ID_GEN_PREFIX = "ID-";
final ZooKeeper zk;
final String ledgerPrefix;
final List zkAcls;
public ZkLedgerIdGenerator(ZooKeeper zk,
String ledgersPath,
String idGenZnodeName,
List zkAcls) {
this.zk = zk;
ledgerPrefix = createLedgerPrefix(ledgersPath, idGenZnodeName);
this.zkAcls = zkAcls;
}
public static String createLedgerPrefix(String ledgersPath, String idGenZnodeName) {
String ledgerIdGenPath = null;
if (StringUtils.isBlank(idGenZnodeName)) {
ledgerIdGenPath = ledgersPath;
} else {
ledgerIdGenPath = ledgersPath + "/" + idGenZnodeName;
}
return ledgerIdGenPath + "/" + LEDGER_ID_GEN_PREFIX;
}
@Override
public void generateLedgerId(final GenericCallback cb) {
generateLedgerIdImpl(cb, zk, ledgerPrefix, zkAcls);
}
public static void generateLedgerIdImpl(final GenericCallback cb, ZooKeeper zk, String ledgerPrefix,
List zkAcls) {
ZkUtils.asyncCreateFullPathOptimistic(zk, ledgerPrefix, new byte[0], zkAcls,
CreateMode.EPHEMERAL_SEQUENTIAL,
new StringCallback() {
@Override
public void processResult(int rc, String path, Object ctx, final String idPathName) {
if (rc != KeeperException.Code.OK.intValue()) {
LOG.error("Could not generate new ledger id",
KeeperException.create(KeeperException.Code.get(rc), path));
cb.operationComplete(BKException.Code.ZKException, null);
return;
}
/*
* Extract ledger id from generated path
*/
long ledgerId;
try {
ledgerId = getLedgerIdFromGenPath(idPathName, ledgerPrefix);
if (ledgerId < 0 || ledgerId >= Integer.MAX_VALUE) {
cb.operationComplete(BKException.Code.LedgerIdOverflowException, null);
} else {
cb.operationComplete(BKException.Code.OK, ledgerId);
}
} catch (IOException e) {
LOG.error("Could not extract ledger-id from id gen path:" + path, e);
cb.operationComplete(BKException.Code.ZKException, null);
return;
}
// delete the znode for id generation
zk.delete(idPathName, -1, new AsyncCallback.VoidCallback() {
@Override
public void processResult(int rc, String path, Object ctx) {
if (rc != KeeperException.Code.OK.intValue()) {
LOG.warn("Exception during deleting znode for id generation : ",
KeeperException.create(KeeperException.Code.get(rc), path));
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Deleting znode for id generation : {}", idPathName);
}
}
}
}, null);
}
}, null);
}
// get ledger id from generation path
private static long getLedgerIdFromGenPath(String nodeName, String ledgerPrefix) throws IOException {
long ledgerId;
try {
String[] parts = nodeName.split(ledgerPrefix);
ledgerId = Long.parseLong(parts[parts.length - 1]);
} catch (NumberFormatException e) {
throw new IOException(e);
}
return ledgerId;
}
@Override
public void close() throws IOException {
}
}
