/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
*
* Free Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.bam.query;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.LockSupport;
import com.caucho.bam.BamError;
import com.caucho.bam.BamException;
import com.caucho.bam.TimeoutException;
import com.caucho.util.Alarm;
import com.caucho.util.AlarmListener;
import com.caucho.util.WeakAlarm;
/**
* QueryCallbackManager is used to generate query ids and to wait
* for query callbacks.
*/
public class QueryManager {
private final AtomicLong _qId = new AtomicLong();
private final QueryMap _queryMap = new QueryMap();
private AlarmListener _listener = new TimeoutAlarmListener();
private Alarm _alarm = new WeakAlarm(_listener);
private long _timeout = 15 * 60 * 1000L;
public QueryManager()
{
}
public QueryManager(long seed)
{
_qId.set(seed);
}
public boolean isEmpty()
{
return _queryMap.isEmpty();
}
public long getTimeout()
{
return _timeout;
}
public void setTimeout(long timeout)
{
_timeout = timeout;
}
/**
* Generates a new unique query identifier.
*/
public final long nextQueryId()
{
return _qId.incrementAndGet();
}
/**
* Adds a query callback to handle a later message.
*
* @param id the unique query identifier
* @param callback the application's callback for the result
*/
public void addQueryCallback(long id,
QueryCallback callback,
long timeout)
{
_queryMap.add(id, callback, timeout);
Alarm alarm = _alarm;
long expireTime = timeout + Alarm.getCurrentTime();
if (alarm != null
&& (! alarm.isQueued()
|| expireTime < alarm.getWakeTime())) {
alarm.queueAt(expireTime);
}
}
/**
* Registers a callback future.
*/
public QueryFuture addQueryFuture(long id,
String to,
String from,
Serializable payload,
long timeout)
{
QueryFutureImpl future
= new QueryFutureImpl(id, to, from, payload, timeout);
_queryMap.add(id, future, timeout);
return future;
}
//
// callbacks and low-level routines
//
/**
* Callback from the ActorStream to handle a queryResult. Returns true
* if the client has a pending query, false otherwise.
*/
public final boolean onQueryResult(long id,
String to,
String from,
Serializable payload)
{
QueryItem item = _queryMap.remove(id);
if (item != null) {
item.onQueryResult(to, from, payload);
return true;
}
else
return false;
}
/**
* Callback from the ActorStream to handle a queryResult. Returns true
* if the client has a pending query, false otherwise.
*/
public final boolean onQueryError(long id,
String to,
String from,
Serializable payload,
BamError error)
{
QueryItem item = _queryMap.remove(id);
if (item != null) {
item.onQueryError(to, from, payload, error);
return true;
}
else
return false;
}
/**
*
*/
void checkTimeout(long now)
{
_queryMap.checkTimeout(now);
}
public void close()
{
Alarm alarm = _alarm;
_alarm = null;
if (alarm != null)
alarm.dequeue();
}
@Override
public String toString()
{
return getClass().getSimpleName() + "[]";
}
static final class QueryMap {
private final QueryItem []_entries = new QueryItem[128];
private final int _mask = _entries.length - 1;
boolean isEmpty()
{
for (QueryItem item : _entries) {
if (item != null)
return false;
}
return true;
}
void checkTimeout(long now)
{
for (QueryItem item : _entries) {
QueryItem next;
while (item != null) {
next = item.getNext();
if (item._expires < now) {
item = remove(item.getId());
if (item != null) {
QueryCallback cb = item._callback;
Exception exn = new TimeoutException();
BamError error = BamError.create(exn);
cb.onQueryError(null, null, null, error);
}
}
item = next;
}
}
}
void add(long id, QueryCallback callback, long timeout)
{
long expires = timeout + Alarm.getCurrentTime();
int hash = (int) (id & _mask);
synchronized (_entries) {
_entries[hash] = new QueryItem(id, callback, expires, _entries[hash]);
}
}
QueryItem remove(long id)
{
int hash = (int) (id & _mask);
synchronized (_entries) {
QueryItem prev = null;
QueryItem next = null;
for (QueryItem ptr = _entries[hash];
ptr != null;
ptr = next) {
next = ptr.getNext();
if (id == ptr.getId()) {
if (prev != null)
prev.setNext(next);
else
_entries[hash] = next;
return ptr;
}
prev = ptr;
ptr = next;
}
return null;
}
}
}
static final class QueryItem {
private final long _id;
private final QueryCallback _callback;
private final long _expires;
private QueryItem _next;
QueryItem(long id, QueryCallback callback, long expires, QueryItem next)
{
_id = id;
_callback = callback;
_expires = expires;
_next = next;
}
final long getId()
{
return _id;
}
final QueryItem getNext()
{
return _next;
}
final void setNext(QueryItem next)
{
_next = next;
}
final long getExpires()
{
return _expires;
}
void onQueryResult(String to, String from, Serializable value)
{
if (_callback != null)
_callback.onQueryResult(to, from, value);
}
void onQueryError(String to,
String from,
Serializable value,
BamError error)
{
if (_callback != null)
_callback.onQueryError(to, from, value, error);
}
@Override
public String toString()
{
return getClass().getSimpleName() + "[" + _id + "," + _callback + "]";
}
}
static final class QueryFutureImpl implements QueryCallback, QueryFuture {
private final long _id;
private final String _to;
private final String _from;
private final Serializable _payload;
private final long _timeout;
private volatile Serializable _result;
private volatile BamError _error;
private final AtomicBoolean _isResult = new AtomicBoolean();
private volatile Thread _thread;
QueryFutureImpl(long id,
String to,
String from,
Serializable payload,
long timeout)
{
_id = id;
_to = to;
_from = from;
_payload = payload;
_timeout = timeout;
}
public Serializable getResult()
{
return _result;
}
@Override
public Serializable get()
throws TimeoutException, BamException
{
if (! waitFor(_timeout)) {
throw new TimeoutException(this + " query timeout " + _payload
+ " {to:" + _to + "}");
}
else if (getError() != null)
throw getError().createException();
else
return getResult();
}
public BamError getError()
{
return _error;
}
boolean waitFor(long timeout)
{
_thread = Thread.currentThread();
long now = Alarm.getCurrentTimeActual();
long expires = now + timeout;
while (! _isResult.get() && Alarm.getCurrentTimeActual() < expires) {
try {
Thread.interrupted();
LockSupport.parkUntil(expires);
} catch (Exception e) {
}
}
_thread = null;
return _isResult.get();
}
@Override
public void onQueryResult(String fromAddress, String toAddress,
Serializable payload)
{
_result = payload;
_isResult.set(true);
Thread thread = _thread;
if (thread != null)
LockSupport.unpark(thread);
}
@Override
public void onQueryError(String fromAddress, String toAddress,
Serializable payload, BamError error)
{
_error = error;
_isResult.set(true);
Thread thread = _thread;
if (thread != null)
LockSupport.unpark(thread);
}
@Override
public String toString()
{
return (getClass().getSimpleName()
+ "[to=" + _to
+ ",from=" + _from
+ ",payload=" + _payload + "]");
}
}
class TimeoutAlarmListener implements AlarmListener {
@Override
public void handleAlarm(Alarm alarm)
{
try {
long now = Alarm.getCurrentTime();
checkTimeout(now);
} finally {
if (_alarm == alarm && ! isEmpty()) {
alarm.queue(getTimeout());
}
}
}
}
}