org.apache.zookeeper.test.system.InstanceManager Maven / Gradle / Ivy
/**
* 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.zookeeper.test.system;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.zookeeper.AsyncCallback;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.KeeperException.ConnectionLossException;
import org.apache.zookeeper.KeeperException.NoNodeException;
import org.apache.zookeeper.KeeperException.NodeExistsException;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.data.Stat;
import org.apache.zookeeper.common.Time;
/**
* This class doles out assignments to InstanceContainers that are registered to
* a ZooKeeper znode. The znode will have four child nodes:
* * ready: this znode indicates that the InstanceManager is running
* * available: the children of this znode are ephemeral nodes representing
* running InstanceContainers
* * assignments: there will be a child under this znode for each available
* InstanceContainer. those znodes will have a child for each
* assigned instance
* * reports: there will be a child under this znode for each instance that is
* running. it will have the report string from the instance.
*/
public class InstanceManager implements AsyncCallback.ChildrenCallback, Watcher {
final private static Logger LOG = LoggerFactory.getLogger(InstanceManager.class);
private ZooKeeper zk;
private String prefixNode;
private String reportsNode = "reports";
private String readyNode = "ready";
private String assignmentsNode = "assignments";
private String statusNode = "available";
private static final int maxTries = 3;
private static final class Assigned {
String container;
int weight;
Assigned(String container, int weight) {
this.container = container;
this.weight = weight;
}
}
private static List preferredList = new ArrayList();
static {
String list = System.getProperty("ic.preferredList");
if (list != null) {
preferredList = Arrays.asList(list.split(","));
System.err.println("Preferred List: " + preferredList);
} else {
System.err.println("Preferred List is empty");
}
}
private Map> assignments = new HashMap>();
private Map instanceToAssignment = new HashMap();
public InstanceManager(ZooKeeper zk, String prefix) throws KeeperException, InterruptedException {
this.zk = zk;
this.prefixNode = prefix;
this.readyNode = prefix + '/' + this.readyNode;
this.assignmentsNode = prefix + '/' + this.assignmentsNode;
this.reportsNode = prefix + '/' + this.reportsNode;
this.statusNode = prefix + '/' + this.statusNode;
for(int i = 0; i < maxTries; i++) {
try {
setupNodes(zk);
break;
} catch(ConnectionLossException e) {}
}
ConnectionLossException lastException = null;
for(int i = 0; i < maxTries; i++) {
try {
List children = zk.getChildren(statusNode, this);
processResult(0, statusNode, null, children);
lastException = null;
break;
} catch(ConnectionLossException e) {
lastException = e;
}
}
if (lastException != null) {
throw lastException;
}
}
private void setupNodes(ZooKeeper zk) throws KeeperException,
InterruptedException {
try {
zk.create(prefixNode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} catch(NodeExistsException e) { /* this is ok */ }
try {
zk.create(assignmentsNode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} catch(NodeExistsException e) { /* this is ok */ }
try {
zk.create(statusNode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} catch(NodeExistsException e) { /* this is ok */ }
try {
zk.create(reportsNode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} catch(NodeExistsException e) { /* this is ok */ }
try {
zk.create(readyNode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} catch(NodeExistsException e) { /* this is ok */ }
}
synchronized public void processResult(int rc, String path, Object ctx,
List children) {
if (rc != KeeperException.Code.OK.intValue()) {
zk.getChildren(statusNode, this, this, null);
return;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Got " + children + " children from " + path);
}
Map> newAssignments = new HashMap>();
for(String c: children) {
HashSet a = assignments.remove(c);
if (a != null) {
newAssignments.put(c, a);
} else {
newAssignments.put(c, new HashSet());
}
}
// Clean up the dead machines
for(String dead: assignments.keySet()) {
try {
removeInstance(dead);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
assignments = newAssignments;
}
public void process(WatchedEvent event) {
if (event.getPath().equals(statusNode)) {
zk.getChildren(statusNode, this, this, null);
}
}
synchronized public String assignInstance(String name, Class clazz, String params, int weight) throws NoAvailableContainers, DuplicateNameException, InterruptedException, KeeperException {
if (weight < 1) {
// if the weights are not above zero, things will get messed up
weight = 1;
}
String instanceSpec = clazz.getName() + ' ' + params;
if (instanceToAssignment.get(name) != null) {
throw new DuplicateNameException(name + " already exists");
}
// find most idle node
String mostIdle = null;
int mostIdleWeight = Integer.MAX_VALUE;
for(String preferred: preferredList) {
HashSet assignmentList = assignments.get(preferred);
int w = 0;
if (assignmentList != null) {
for(Assigned a: assignmentList) {
w += a.weight;
}
if (w < mostIdleWeight) {
mostIdleWeight = w;
mostIdle = preferred;
}
}
}
for(Entry> e: assignments.entrySet()) {
int w = 0;
for(Assigned a: e.getValue()) {
w += a.weight;
}
if (w < mostIdleWeight) {
mostIdleWeight = w;
mostIdle = e.getKey();
}
}
if (mostIdle == null) {
throw new NoAvailableContainers("No available containers");
}
Assigned a = new Assigned(mostIdle, weight);
instanceToAssignment.put(name, a);
HashSet as = assignments.get(mostIdle);
if (as == null) {
as = new HashSet();
assignments.put(mostIdle, as);
}
as.add(a);
KeeperException lastException = null;
for(int i = 0; i < maxTries; i++) {
try {
zk.create(assignmentsNode + '/' + mostIdle + '/' + name, instanceSpec.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
return mostIdle;
} catch(NodeExistsException e) {
return mostIdle;
} catch (KeeperException e) {
lastException = e;
}
}
throw lastException;
}
public void reconfigureInstance(String name, String params) throws NoAssignmentException, InterruptedException, KeeperException {
if (LOG.isDebugEnabled()) {
LOG.debug("Reconfiguring " + name + " with " + params);
}
Assigned assigned = instanceToAssignment.get(name);
if (assigned == null) {
throw new NoAssignmentException();
}
KeeperException lastException = null;
for(int i = 0; i < maxTries; i++) {
try {
zk.setData(assignmentsNode + '/' + assigned.container + '/' + name, ("update " + params).getBytes(), -1);
break;
} catch (ConnectionLossException e) {
lastException = e;
}
}
if (lastException != null) {
throw lastException;
}
}
private void doDelete(String path) throws InterruptedException, KeeperException {
KeeperException lastException = null;
for(int i = 0; i < maxTries; i++) {
try {
zk.delete(path, -1);
return;
} catch(NoNodeException e) {
return;
} catch (KeeperException e) {
lastException = e;
}
}
throw lastException;
}
synchronized public void removeInstance(String name) throws InterruptedException, KeeperException {
Assigned assigned = instanceToAssignment.remove(name);
if (assigned == null) {
return;
}
assignments.get(assigned.container).remove(name);
doDelete(assignmentsNode + '/' + assigned.container + '/' + name);
doDelete(reportsNode + '/' + name);
}
synchronized boolean isAlive(String name) {
return instanceToAssignment.get(name) != null;
}
public void resetStatus(String name) throws InterruptedException, KeeperException {
KeeperException lastException = null;
for(int i = 0; i < maxTries; i++) {
try {
zk.delete(reportsNode + '/' + name, -1);
lastException = null;
break;
} catch(ConnectionLossException e) {
lastException = e;
} catch(NoNodeException e) {
// great this is what we want!
}
}
if (lastException != null) {
throw lastException;
}
}
public String getStatus(String name, long timeout) throws KeeperException, InterruptedException {
Stat stat = new Stat();
byte[] data = null;
long endTime = Time.currentElapsedTime() + timeout;
KeeperException lastException = null;
for(int i = 0; i < maxTries && endTime > Time.currentElapsedTime(); i++) {
try {
data = zk.getData(reportsNode + '/' + name, false, stat);
if (LOG.isDebugEnabled()) {
LOG.debug("Got Data: " + ((data == null) ? "null" : new String(data)));
}
lastException = null;
break;
} catch(ConnectionLossException e) {
lastException = e;
} catch(NoNodeException e) {
final Object eventObj = new Object();
synchronized(eventObj) {
// wait for the node to appear
Stat eStat = zk.exists(reportsNode + '/' + name, new Watcher() {
public void process(WatchedEvent event) {
synchronized(eventObj) {
eventObj.notifyAll();
}
}});
if (eStat == null) {
eventObj.wait(endTime - Time.currentElapsedTime());
}
}
lastException = e;
}
}
if (lastException != null) {
throw lastException;
}
return new String(data);
}
synchronized public void close() throws InterruptedException {
for(String name: instanceToAssignment.keySet().toArray(new String[0])) {
try {
removeInstance(name);
} catch(KeeperException e) {
e.printStackTrace();
}
}
try {
doDelete(readyNode);
} catch (KeeperException e) {
e.printStackTrace();
}
}
}
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