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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.zookeeper.server;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.KeeperException.SessionExpiredException;
/**
* This is a full featured SessionTracker. It tracks session in grouped by tick
* interval. It always rounds up the tick interval to provide a sort of grace
* period. Sessions are thus expired in batches made up of sessions that expire
* in a given interval.
*/
public class SessionTrackerImpl extends Thread implements SessionTracker {
private static final Logger LOG = LoggerFactory.getLogger(SessionTrackerImpl.class);
HashMap sessionsById = new HashMap();
HashMap sessionSets = new HashMap();
ConcurrentHashMap sessionsWithTimeout;
long nextSessionId = 0;
long nextExpirationTime;
int expirationInterval;
public static class SessionImpl implements Session {
SessionImpl(long sessionId, int timeout, long expireTime) {
this.sessionId = sessionId;
this.timeout = timeout;
this.tickTime = expireTime;
isClosing = false;
}
final long sessionId;
final int timeout;
long tickTime;
boolean isClosing;
Object owner;
public long getSessionId() { return sessionId; }
public int getTimeout() { return timeout; }
public boolean isClosing() { return isClosing; }
}
public static long initializeNextSession(long id) {
long nextSid = 0;
nextSid = (System.currentTimeMillis() << 24) >>> 8;
nextSid = nextSid | (id <<56);
return nextSid;
}
static class SessionSet {
HashSet sessions = new HashSet();
}
SessionExpirer expirer;
private long roundToInterval(long time) {
// We give a one interval grace period
return (time / expirationInterval + 1) * expirationInterval;
}
public SessionTrackerImpl(SessionExpirer expirer,
ConcurrentHashMap sessionsWithTimeout, int tickTime,
long sid)
{
super("SessionTracker");
this.expirer = expirer;
this.expirationInterval = tickTime;
this.sessionsWithTimeout = sessionsWithTimeout;
nextExpirationTime = roundToInterval(System.currentTimeMillis());
this.nextSessionId = initializeNextSession(sid);
for (Entry e : sessionsWithTimeout.entrySet()) {
addSession(e.getKey(), e.getValue());
}
}
volatile boolean running = true;
volatile long currentTime;
synchronized public void dumpSessions(PrintWriter pwriter) {
pwriter.print("Session Sets (");
pwriter.print(sessionSets.size());
pwriter.println("):");
ArrayList keys = new ArrayList(sessionSets.keySet());
Collections.sort(keys);
for (long time : keys) {
pwriter.print(sessionSets.get(time).sessions.size());
pwriter.print(" expire at ");
pwriter.print(new Date(time));
pwriter.println(":");
for (SessionImpl s : sessionSets.get(time).sessions) {
pwriter.print("\t0x");
pwriter.println(Long.toHexString(s.sessionId));
}
}
}
@Override
synchronized public String toString() {
StringWriter sw = new StringWriter();
PrintWriter pwriter = new PrintWriter(sw);
dumpSessions(pwriter);
pwriter.flush();
pwriter.close();
return sw.toString();
}
@Override
synchronized public void run() {
try {
while (running) {
currentTime = System.currentTimeMillis();
if (nextExpirationTime > currentTime) {
this.wait(nextExpirationTime - currentTime);
continue;
}
SessionSet set;
set = sessionSets.remove(nextExpirationTime);
if (set != null) {
for (SessionImpl s : set.sessions) {
setSessionClosing(s.sessionId);
expirer.expire(s);
}
}
nextExpirationTime += expirationInterval;
}
} catch (InterruptedException e) {
LOG.error("Unexpected interruption", e);
}
LOG.info("SessionTrackerImpl exited loop!");
}
synchronized public boolean touchSession(long sessionId, int timeout) {
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,
ZooTrace.CLIENT_PING_TRACE_MASK,
"SessionTrackerImpl --- Touch session: 0x"
+ Long.toHexString(sessionId) + " with timeout " + timeout);
}
SessionImpl s = sessionsById.get(sessionId);
// Return false, if the session doesn't exists or marked as closing
if (s == null || s.isClosing()) {
return false;
}
long expireTime = roundToInterval(System.currentTimeMillis() + timeout);
if (s.tickTime >= expireTime) {
// Nothing needs to be done
return true;
}
SessionSet set = sessionSets.get(s.tickTime);
if (set != null) {
set.sessions.remove(s);
}
s.tickTime = expireTime;
set = sessionSets.get(s.tickTime);
if (set == null) {
set = new SessionSet();
sessionSets.put(expireTime, set);
}
set.sessions.add(s);
return true;
}
synchronized public void setSessionClosing(long sessionId) {
if (LOG.isTraceEnabled()) {
LOG.info("Session closing: 0x" + Long.toHexString(sessionId));
}
SessionImpl s = sessionsById.get(sessionId);
if (s == null) {
return;
}
s.isClosing = true;
}
synchronized public void removeSession(long sessionId) {
SessionImpl s = sessionsById.remove(sessionId);
sessionsWithTimeout.remove(sessionId);
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG, ZooTrace.SESSION_TRACE_MASK,
"SessionTrackerImpl --- Removing session 0x"
+ Long.toHexString(sessionId));
}
if (s != null) {
SessionSet set = sessionSets.get(s.tickTime);
// Session expiration has been removing the sessions
if(set != null){
set.sessions.remove(s);
}
}
}
public void shutdown() {
LOG.info("Shutting down");
running = false;
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG, ZooTrace.getTextTraceLevel(),
"Shutdown SessionTrackerImpl!");
}
}
synchronized public long createSession(int sessionTimeout) {
addSession(nextSessionId, sessionTimeout);
return nextSessionId++;
}
synchronized public void addSession(long id, int sessionTimeout) {
sessionsWithTimeout.put(id, sessionTimeout);
if (sessionsById.get(id) == null) {
SessionImpl s = new SessionImpl(id, sessionTimeout, 0);
sessionsById.put(id, s);
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG, ZooTrace.SESSION_TRACE_MASK,
"SessionTrackerImpl --- Adding session 0x"
+ Long.toHexString(id) + " " + sessionTimeout);
}
} else {
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG, ZooTrace.SESSION_TRACE_MASK,
"SessionTrackerImpl --- Existing session 0x"
+ Long.toHexString(id) + " " + sessionTimeout);
}
}
touchSession(id, sessionTimeout);
}
synchronized public void checkSession(long sessionId, Object owner) throws KeeperException.SessionExpiredException, KeeperException.SessionMovedException {
SessionImpl session = sessionsById.get(sessionId);
if (session == null || session.isClosing()) {
throw new KeeperException.SessionExpiredException();
}
if (session.owner == null) {
session.owner = owner;
} else if (session.owner != owner) {
throw new KeeperException.SessionMovedException();
}
}
synchronized public void setOwner(long id, Object owner) throws SessionExpiredException {
SessionImpl session = sessionsById.get(id);
if (session == null || session.isClosing()) {
throw new KeeperException.SessionExpiredException();
}
session.owner = owner;
}
}