/*
* ====================================================================
* 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http.impl.nio.reactor;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.ClosedSelectorException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Collections;
import java.util.HashSet;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import org.apache.http.annotation.ThreadSafe;
import org.apache.http.nio.reactor.IOReactor;
import org.apache.http.nio.reactor.IOReactorException;
import org.apache.http.nio.reactor.IOReactorStatus;
import org.apache.http.nio.reactor.IOSession;
import org.apache.http.util.Args;
import org.apache.http.util.Asserts;
/**
* Generic implementation of {@link IOReactor} that can used as a subclass
* for more specialized I/O reactors. It is based on a single {@link Selector}
* instance.
*
* @since 4.0
*/
@ThreadSafe // public methods only
public abstract class AbstractIOReactor implements IOReactor {
private volatile IOReactorStatus status;
private final Object statusMutex;
private final long selectTimeout;
private final boolean interestOpsQueueing;
private final Selector selector;
private final Set<IOSession> sessions;
private final Queue<InterestOpEntry> interestOpsQueue;
private final Queue<IOSession> closedSessions;
private final Queue<ChannelEntry> newChannels;
/**
* Creates new AbstractIOReactor instance.
*
* @param selectTimeout the select timeout.
* @throws IOReactorException in case if a non-recoverable I/O error.
*/
public AbstractIOReactor(final long selectTimeout) throws IOReactorException {
this(selectTimeout, false);
}
/**
* Creates new AbstractIOReactor instance.
*
* @param selectTimeout the select timeout.
* @param interestOpsQueueing Ops queueing flag.
*
* @throws IOReactorException in case if a non-recoverable I/O error.
*
* @since 4.1
*/
public AbstractIOReactor(final long selectTimeout, final boolean interestOpsQueueing) throws IOReactorException {
super();
Args.positive(selectTimeout, "Select timeout");
this.selectTimeout = selectTimeout;
this.interestOpsQueueing = interestOpsQueueing;
this.sessions = Collections.synchronizedSet(new HashSet<IOSession>());
this.interestOpsQueue = new ConcurrentLinkedQueue<InterestOpEntry>();
this.closedSessions = new ConcurrentLinkedQueue<IOSession>();
this.newChannels = new ConcurrentLinkedQueue<ChannelEntry>();
try {
this.selector = Selector.open();
} catch (final IOException ex) {
throw new IOReactorException("Failure opening selector", ex);
}
this.statusMutex = new Object();
this.status = IOReactorStatus.INACTIVE;
}
/**
* Triggered when the key signals {@link SelectionKey#OP_ACCEPT} readiness.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
*/
protected abstract void acceptable(SelectionKey key);
/**
* Triggered when the key signals {@link SelectionKey#OP_CONNECT} readiness.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
*/
protected abstract void connectable(SelectionKey key);
/**
* Triggered when the key signals {@link SelectionKey#OP_READ} readiness.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
*/
protected abstract void readable(SelectionKey key);
/**
* Triggered when the key signals {@link SelectionKey#OP_WRITE} readiness.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
*/
protected abstract void writable(SelectionKey key);
/**
* Triggered to validate keys currently registered with the selector. This
* method is called after each I/O select loop.
* <p>
* Super-classes can implement this method to run validity checks on
* active sessions and include additional processing that needs to be
* executed after each I/O select loop.
*
* @param keys all selection keys registered with the selector.
*/
protected abstract void validate(Set<SelectionKey> keys);
/**
* Triggered when new session has been created.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
* @param session new I/O session.
*/
protected void sessionCreated(final SelectionKey key, final IOSession session) {
}
/**
* Triggered when a session has been closed.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param session closed I/O session.
*/
protected void sessionClosed(final IOSession session) {
}
/**
* Triggered when a session has timed out.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param session timed out I/O session.
*/
protected void sessionTimedOut(final IOSession session) {
}
/**
* Obtains {@link IOSession} instance associated with the given selection
* key.
*
* @param key the selection key.
* @return I/O session.
*/
protected IOSession getSession(final SelectionKey key) {
return (IOSession) key.attachment();
}
@Override
public IOReactorStatus getStatus() {
return this.status;
}
/**
* Returns {@code true} if interest Ops queueing is enabled, {@code false} otherwise.
*
* @since 4.1
*/
public boolean getInterestOpsQueueing() {
return this.interestOpsQueueing;
}
/**
* Adds new channel entry. The channel will be asynchronously registered
* with the selector.
*
* @param channelEntry the channel entry.
*/
public void addChannel(final ChannelEntry channelEntry) {
Args.notNull(channelEntry, "Channel entry");
this.newChannels.add(channelEntry);
this.selector.wakeup();
}
/**
* Activates the I/O reactor. The I/O reactor will start reacting to
* I/O events and triggering notification methods.
* <p>
* This method will enter the infinite I/O select loop on
* the {@link Selector} instance associated with this I/O reactor.
* <p>
* The method will remain blocked unto the I/O reactor is shut down or the
* execution thread is interrupted.
*
* @see #acceptable(SelectionKey)
* @see #connectable(SelectionKey)
* @see #readable(SelectionKey)
* @see #writable(SelectionKey)
* @see #timeoutCheck(SelectionKey, long)
* @see #validate(Set)
* @see #sessionCreated(SelectionKey, IOSession)
* @see #sessionClosed(IOSession)
*
* @throws InterruptedIOException if the dispatch thread is interrupted.
* @throws IOReactorException in case if a non-recoverable I/O error.
*/
protected void execute() throws InterruptedIOException, IOReactorException {
this.status = IOReactorStatus.ACTIVE;
try {
for (;;) {
final int readyCount;
try {
readyCount = this.selector.select(this.selectTimeout);
} catch (final InterruptedIOException ex) {
throw ex;
} catch (final IOException ex) {
throw new IOReactorException("Unexpected selector failure", ex);
}
if (this.status == IOReactorStatus.SHUT_DOWN) {
// Hard shut down. Exit select loop immediately
break;
}
if (this.status == IOReactorStatus.SHUTTING_DOWN) {
// Graceful shutdown in process
// Try to close things out nicely
closeSessions();
closeNewChannels();
}
// Process selected I/O events
if (readyCount > 0) {
processEvents(this.selector.selectedKeys());
}
// Validate active channels
validate(this.selector.keys());
// Process closed sessions
processClosedSessions();
// If active process new channels
if (this.status == IOReactorStatus.ACTIVE) {
processNewChannels();
}
// Exit select loop if graceful shutdown has been completed
if (this.status.compareTo(IOReactorStatus.ACTIVE) > 0
&& this.sessions.isEmpty()) {
break;
}
if (this.interestOpsQueueing) {
// process all pending interestOps() operations
processPendingInterestOps();
}
}
} catch (final ClosedSelectorException ignore) {
} finally {
hardShutdown();
synchronized (this.statusMutex) {
this.statusMutex.notifyAll();
}
}
}
private void processEvents(final Set<SelectionKey> selectedKeys) {
for (final SelectionKey key : selectedKeys) {
processEvent(key);
}
selectedKeys.clear();
}
/**
* Processes new event on the given selection key.
*
* @param key the selection key that triggered an event.
*/
protected void processEvent(final SelectionKey key) {
final IOSessionImpl session = (IOSessionImpl) key.attachment();
try {
if (key.isAcceptable()) {
acceptable(key);
}
if (key.isConnectable()) {
connectable(key);
}
if (key.isReadable()) {
session.resetLastRead();
readable(key);
}
if (key.isWritable()) {
session.resetLastWrite();
writable(key);
}
} catch (final CancelledKeyException ex) {
queueClosedSession(session);
key.attach(null);
}
}
/**
* Queues the given I/O session to be processed asynchronously as closed.
*
* @param session the closed I/O session.
*/
protected void queueClosedSession(final IOSession session) {
if (session != null) {
this.closedSessions.add(session);
}
}
private void processNewChannels() throws IOReactorException {
ChannelEntry entry;
while ((entry = this.newChannels.poll()) != null) {
final SocketChannel channel;
final SelectionKey key;
try {
channel = entry.getChannel();
channel.configureBlocking(false);
key = channel.register(this.selector, SelectionKey.OP_READ);
} catch (final ClosedChannelException ex) {
final SessionRequestImpl sessionRequest = entry.getSessionRequest();
if (sessionRequest != null) {
sessionRequest.failed(ex);
}
return;
} catch (final IOException ex) {
throw new IOReactorException("Failure registering channel " +
"with the selector", ex);
}
final SessionClosedCallback sessionClosedCallback = new SessionClosedCallback() {
@Override
public void sessionClosed(final IOSession session) {
queueClosedSession(session);
}
};
InterestOpsCallback interestOpsCallback = null;
if (this.interestOpsQueueing) {
interestOpsCallback = new InterestOpsCallback() {
@Override
public void addInterestOps(final InterestOpEntry entry) {
queueInterestOps(entry);
}
};
}
final IOSession session;
try {
session = new IOSessionImpl(key, interestOpsCallback, sessionClosedCallback);
int timeout = 0;
try {
timeout = channel.socket().getSoTimeout();
} catch (final IOException ex) {
// Very unlikely to happen and is not fatal
// as the protocol layer is expected to overwrite
// this value anyways
}
session.setAttribute(IOSession.ATTACHMENT_KEY, entry.getAttachment());
session.setSocketTimeout(timeout);
} catch (final CancelledKeyException ex) {
continue;
}
try {
this.sessions.add(session);
final SessionRequestImpl sessionRequest = entry.getSessionRequest();
if (sessionRequest != null) {
sessionRequest.completed(session);
}
key.attach(session);
sessionCreated(key, session);
} catch (final CancelledKeyException ex) {
queueClosedSession(session);
key.attach(null);
}
}
}
private void processClosedSessions() {
IOSession session;
while ((session = this.closedSessions.poll()) != null) {
if (this.sessions.remove(session)) {
try {
sessionClosed(session);
} catch (final CancelledKeyException ex) {
// ignore and move on
}
}
}
}
private void processPendingInterestOps() {
// validity check
if (!this.interestOpsQueueing) {
return;
}
InterestOpEntry entry;
while ((entry = this.interestOpsQueue.poll()) != null) {
// obtain the operation's details
final SelectionKey key = entry.getSelectionKey();
final int eventMask = entry.getEventMask();
if (key.isValid()) {
key.interestOps(eventMask);
}
}
}
private boolean queueInterestOps(final InterestOpEntry entry) {
// validity checks
Asserts.check(this.interestOpsQueueing, "Interest ops queueing not enabled");
if (entry == null) {
return false;
}
// add this operation to the interestOps() queue
this.interestOpsQueue.add(entry);
return true;
}
/**
* Triggered to verify whether the I/O session associated with the
* given selection key has not timed out.
* <p>
* Super-classes can implement this method to react to the event.
*
* @param key the selection key.
* @param now current time as long value.
*/
protected void timeoutCheck(final SelectionKey key, final long now) {
final IOSessionImpl session = (IOSessionImpl) key.attachment();
if (session != null) {
final int timeout = session.getSocketTimeout();
if (timeout > 0) {
if (session.getLastAccessTime() + timeout < now) {
sessionTimedOut(session);
}
}
}
}
/**
* Closes out all I/O sessions maintained by this I/O reactor.
*/
protected void closeSessions() {
synchronized (this.sessions) {
for (final IOSession session : this.sessions) {
session.close();
}
}
}
/**
* Closes out all new channels pending registration with the selector of
* this I/O reactor.
* @throws IOReactorException - not thrown currently
*/
protected void closeNewChannels() throws IOReactorException {
ChannelEntry entry;
while ((entry = this.newChannels.poll()) != null) {
final SessionRequestImpl sessionRequest = entry.getSessionRequest();
if (sessionRequest != null) {
sessionRequest.cancel();
}
final SocketChannel channel = entry.getChannel();
try {
channel.close();
} catch (final IOException ignore) {
}
}
}
/**
* Closes out all active channels registered with the selector of
* this I/O reactor.
* @throws IOReactorException - not thrown currently
*/
protected void closeActiveChannels() throws IOReactorException {
try {
final Set<SelectionKey> keys = this.selector.keys();
for (final SelectionKey key : keys) {
final IOSession session = getSession(key);
if (session != null) {
session.close();
}
}
this.selector.close();
} catch (final IOException ignore) {
}
}
/**
* Attempts graceful shutdown of this I/O reactor.
*/
public void gracefulShutdown() {
synchronized (this.statusMutex) {
if (this.status != IOReactorStatus.ACTIVE) {
// Already shutting down
return;
}
this.status = IOReactorStatus.SHUTTING_DOWN;
}
this.selector.wakeup();
}
/**
* Attempts force-shutdown of this I/O reactor.
*/
public void hardShutdown() throws IOReactorException {
synchronized (this.statusMutex) {
if (this.status == IOReactorStatus.SHUT_DOWN) {
// Already shut down
return;
}
this.status = IOReactorStatus.SHUT_DOWN;
}
closeNewChannels();
closeActiveChannels();
processClosedSessions();
}
/**
* Blocks for the given period of time in milliseconds awaiting
* the completion of the reactor shutdown.
*
* @param timeout the maximum wait time.
* @throws InterruptedException if interrupted.
*/
public void awaitShutdown(final long timeout) throws InterruptedException {
synchronized (this.statusMutex) {
final long deadline = System.currentTimeMillis() + timeout;
long remaining = timeout;
while (this.status != IOReactorStatus.SHUT_DOWN) {
this.statusMutex.wait(remaining);
if (timeout > 0) {
remaining = deadline - System.currentTimeMillis();
if (remaining <= 0) {
break;
}
}
}
}
}
@Override
public void shutdown(final long gracePeriod) throws IOReactorException {
if (this.status != IOReactorStatus.INACTIVE) {
gracefulShutdown();
try {
awaitShutdown(gracePeriod);
} catch (final InterruptedException ignore) {
}
}
if (this.status != IOReactorStatus.SHUT_DOWN) {
hardShutdown();
}
}
@Override
public void shutdown() throws IOReactorException {
shutdown(1000);
}
}