src/java.base/linux/classes/sun/nio/ch/EPollSelectorImpl.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code 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.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package sun.nio.ch;

 import java.io.IOException;
 import java.nio.channels.ClosedSelectorException;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.Selector;
 import java.nio.channels.spi.SelectorProvider;
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;

 import static sun.nio.ch.EPoll.EPOLLIN;
 import static sun.nio.ch.EPoll.EPOLL_CTL_ADD;
 import static sun.nio.ch.EPoll.EPOLL_CTL_DEL;
 import static sun.nio.ch.EPoll.EPOLL_CTL_MOD;


 /**
  * Linux epoll based Selector implementation
  */

 class EPollSelectorImpl extends SelectorImpl {

     // maximum number of events to poll in one call to epoll_wait
     private static final int NUM_EPOLLEVENTS = Math.min(IOUtil.fdLimit(), 1024);

     // epoll file descriptor
     private final int epfd;

     // address of poll array when polling with epoll_wait
     private final long pollArrayAddress;

     // file descriptors used for interrupt
     private final int fd0;
     private final int fd1;

     // maps file descriptor to selection key, synchronize on selector
     private final Map<Integer, SelectionKeyImpl> fdToKey = new HashMap<>();

     // pending new registrations/updates, queued by setEventOps
     private final Object updateLock = new Object();
     private final Deque<SelectionKeyImpl> updateKeys = new ArrayDeque<>();

     // interrupt triggering and clearing
     private final Object interruptLock = new Object();
     private boolean interruptTriggered;

     EPollSelectorImpl(SelectorProvider sp) throws IOException {
         super(sp);

         this.epfd = EPoll.create();
         this.pollArrayAddress = EPoll.allocatePollArray(NUM_EPOLLEVENTS);

         try {
             long fds = IOUtil.makePipe(false);
             this.fd0 = (int) (fds >>> 32);
             this.fd1 = (int) fds;
         } catch (IOException ioe) {
             EPoll.freePollArray(pollArrayAddress);
             FileDispatcherImpl.closeIntFD(epfd);
             throw ioe;
         }

         // register one end of the socket pair for wakeups
         EPoll.ctl(epfd, EPOLL_CTL_ADD, fd0, EPOLLIN);
     }

     private void ensureOpen() {
         if (!isOpen())
             throw new ClosedSelectorException();
     }

     @Override
     protected int doSelect(Consumer<SelectionKey> action, long timeout)
         throws IOException
     {
         assert Thread.holdsLock(this);

         // epoll_wait timeout is int
         int to = (int) Math.min(timeout, Integer.MAX_VALUE);
         boolean blocking = (to != 0);
         boolean timedPoll = (to > 0);

         int numEntries;
         processUpdateQueue();
         processDeregisterQueue();
         try {
             begin(blocking);

             do {
                 long startTime = timedPoll ? System.nanoTime() : 0;
                 numEntries = EPoll.wait(epfd, pollArrayAddress, NUM_EPOLLEVENTS, to);
                 if (numEntries == IOStatus.INTERRUPTED && timedPoll) {
                     // timed poll interrupted so need to adjust timeout
                     long adjust = System.nanoTime() - startTime;
                     to -= TimeUnit.MILLISECONDS.convert(adjust, TimeUnit.NANOSECONDS);
                     if (to <= 0) {
                         // timeout expired so no retry
                         numEntries = 0;
                     }
                 }
             } while (numEntries == IOStatus.INTERRUPTED);
             assert IOStatus.check(numEntries);

         } finally {
             end(blocking);
         }
         processDeregisterQueue();
         return processEvents(numEntries, action);
     }

     /**
      * Process changes to the interest ops.
      */
     private void processUpdateQueue() {
         assert Thread.holdsLock(this);

         synchronized (updateLock) {
             SelectionKeyImpl ski;
             while ((ski = updateKeys.pollFirst()) != null) {
                 if (ski.isValid()) {
                     int fd = ski.getFDVal();
                     // add to fdToKey if needed
                     SelectionKeyImpl previous = fdToKey.putIfAbsent(fd, ski);
                     assert (previous == null) || (previous == ski);

                     int newEvents = ski.translateInterestOps();
                     int registeredEvents = ski.registeredEvents();
                     if (newEvents != registeredEvents) {
                         if (newEvents == 0) {
                             // remove from epoll
                             EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
                         } else {
                             if (registeredEvents == 0) {
                                 // add to epoll
                                 EPoll.ctl(epfd, EPOLL_CTL_ADD, fd, newEvents);
                             } else {
                                 // modify events
                                 EPoll.ctl(epfd, EPOLL_CTL_MOD, fd, newEvents);
                             }
                         }
                         ski.registeredEvents(newEvents);
                     }
                 }
             }
         }
     }

     /**
      * Process the polled events.
      * If the interrupt fd has been selected, drain it and clear the interrupt.
      */
     private int processEvents(int numEntries, Consumer<SelectionKey> action)
         throws IOException
     {
         assert Thread.holdsLock(this);

         boolean interrupted = false;
         int numKeysUpdated = 0;
         for (int i=0; i<numEntries; i++) {
             long event = EPoll.getEvent(pollArrayAddress, i);
             int fd = EPoll.getDescriptor(event);
             if (fd == fd0) {
                 interrupted = true;
             } else {
                 SelectionKeyImpl ski = fdToKey.get(fd);
                 if (ski != null) {
                     int rOps = EPoll.getEvents(event);
                     numKeysUpdated += processReadyEvents(rOps, ski, action);
                 }
             }
         }

         if (interrupted) {
             clearInterrupt();
         }

         return numKeysUpdated;
     }

     @Override
     protected void implClose() throws IOException {
         assert Thread.holdsLock(this);

         // prevent further wakeup
         synchronized (interruptLock) {
             interruptTriggered = true;
         }

         FileDispatcherImpl.closeIntFD(epfd);
         EPoll.freePollArray(pollArrayAddress);

         FileDispatcherImpl.closeIntFD(fd0);
         FileDispatcherImpl.closeIntFD(fd1);
     }

     @Override
     protected void implDereg(SelectionKeyImpl ski) throws IOException {
         assert !ski.isValid();
         assert Thread.holdsLock(this);

         int fd = ski.getFDVal();
         if (fdToKey.remove(fd) != null) {
             if (ski.registeredEvents() != 0) {
                 EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
                 ski.registeredEvents(0);
             }
         } else {
             assert ski.registeredEvents() == 0;
         }
     }

     @Override
     public void setEventOps(SelectionKeyImpl ski) {
         ensureOpen();
         synchronized (updateLock) {
             updateKeys.addLast(ski);
         }
     }

     @Override
     public Selector wakeup() {
         synchronized (interruptLock) {
             if (!interruptTriggered) {
                 try {
                     IOUtil.write1(fd1, (byte)0);
                 } catch (IOException ioe) {
                     throw new InternalError(ioe);
                 }
                 interruptTriggered = true;
             }
         }
         return this;
     }

     private void clearInterrupt() throws IOException {
         synchronized (interruptLock) {
             IOUtil.drain(fd0);
             interruptTriggered = false;
         }
     }
 }
	/*
	* Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.nio.ch;

	import java.io.IOException;
	import java.nio.channels.ClosedSelectorException;
	import java.nio.channels.SelectionKey;
	import java.nio.channels.Selector;
	import java.nio.channels.spi.SelectorProvider;
	import java.util.ArrayDeque;
	import java.util.Deque;
	import java.util.HashMap;
	import java.util.Map;
	import java.util.concurrent.TimeUnit;
	import java.util.function.Consumer;

	import static sun.nio.ch.EPoll.EPOLLIN;
	import static sun.nio.ch.EPoll.EPOLL_CTL_ADD;
	import static sun.nio.ch.EPoll.EPOLL_CTL_DEL;
	import static sun.nio.ch.EPoll.EPOLL_CTL_MOD;


	/**
	* Linux epoll based Selector implementation
	*/

	class EPollSelectorImpl extends SelectorImpl {

	// maximum number of events to poll in one call to epoll_wait
	private static final int NUM_EPOLLEVENTS = Math.min(IOUtil.fdLimit(), 1024);

	// epoll file descriptor
	private final int epfd;

	// address of poll array when polling with epoll_wait
	private final long pollArrayAddress;

	// file descriptors used for interrupt
	private final int fd0;
	private final int fd1;

	// maps file descriptor to selection key, synchronize on selector
	private final Map<Integer, SelectionKeyImpl> fdToKey = new HashMap<>();

	// pending new registrations/updates, queued by setEventOps
	private final Object updateLock = new Object();
	private final Deque<SelectionKeyImpl> updateKeys = new ArrayDeque<>();

	// interrupt triggering and clearing
	private final Object interruptLock = new Object();
	private boolean interruptTriggered;

	EPollSelectorImpl(SelectorProvider sp) throws IOException {
	super(sp);

	this.epfd = EPoll.create();
	this.pollArrayAddress = EPoll.allocatePollArray(NUM_EPOLLEVENTS);

	try {
	long fds = IOUtil.makePipe(false);
	this.fd0 = (int) (fds >>> 32);
	this.fd1 = (int) fds;
	} catch (IOException ioe) {
	EPoll.freePollArray(pollArrayAddress);
	FileDispatcherImpl.closeIntFD(epfd);
	throw ioe;
	}

	// register one end of the socket pair for wakeups
	EPoll.ctl(epfd, EPOLL_CTL_ADD, fd0, EPOLLIN);
	}

	private void ensureOpen() {
	if (!isOpen())
	throw new ClosedSelectorException();
	}

	@Override
	protected int doSelect(Consumer<SelectionKey> action, long timeout)
	throws IOException
	{
	assert Thread.holdsLock(this);

	// epoll_wait timeout is int
	int to = (int) Math.min(timeout, Integer.MAX_VALUE);
	boolean blocking = (to != 0);
	boolean timedPoll = (to > 0);

	int numEntries;
	processUpdateQueue();
	processDeregisterQueue();
	try {
	begin(blocking);

	do {
	long startTime = timedPoll ? System.nanoTime() : 0;
	numEntries = EPoll.wait(epfd, pollArrayAddress, NUM_EPOLLEVENTS, to);
	if (numEntries == IOStatus.INTERRUPTED && timedPoll) {
	// timed poll interrupted so need to adjust timeout
	long adjust = System.nanoTime() - startTime;
	to -= TimeUnit.MILLISECONDS.convert(adjust, TimeUnit.NANOSECONDS);
	if (to <= 0) {
	// timeout expired so no retry
	numEntries = 0;
	}
	}
	} while (numEntries == IOStatus.INTERRUPTED);
	assert IOStatus.check(numEntries);

	} finally {
	end(blocking);
	}
	processDeregisterQueue();
	return processEvents(numEntries, action);
	}

	/**
	* Process changes to the interest ops.
	*/
	private void processUpdateQueue() {
	assert Thread.holdsLock(this);

	synchronized (updateLock) {
	SelectionKeyImpl ski;
	while ((ski = updateKeys.pollFirst()) != null) {
	if (ski.isValid()) {
	int fd = ski.getFDVal();
	// add to fdToKey if needed
	SelectionKeyImpl previous = fdToKey.putIfAbsent(fd, ski);
	assert (previous == null) \|\| (previous == ski);

	int newEvents = ski.translateInterestOps();
	int registeredEvents = ski.registeredEvents();
	if (newEvents != registeredEvents) {
	if (newEvents == 0) {
	// remove from epoll
	EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
	} else {
	if (registeredEvents == 0) {
	// add to epoll
	EPoll.ctl(epfd, EPOLL_CTL_ADD, fd, newEvents);
	} else {
	// modify events
	EPoll.ctl(epfd, EPOLL_CTL_MOD, fd, newEvents);
	}
	}
	ski.registeredEvents(newEvents);
	}
	}
	}
	}
	}

	/**
	* Process the polled events.
	* If the interrupt fd has been selected, drain it and clear the interrupt.
	*/
	private int processEvents(int numEntries, Consumer<SelectionKey> action)
	throws IOException
	{
	assert Thread.holdsLock(this);

	boolean interrupted = false;
	int numKeysUpdated = 0;
	for (int i=0; i<numEntries; i++) {
	long event = EPoll.getEvent(pollArrayAddress, i);
	int fd = EPoll.getDescriptor(event);
	if (fd == fd0) {
	interrupted = true;
	} else {
	SelectionKeyImpl ski = fdToKey.get(fd);
	if (ski != null) {
	int rOps = EPoll.getEvents(event);
	numKeysUpdated += processReadyEvents(rOps, ski, action);
	}
	}
	}

	if (interrupted) {
	clearInterrupt();
	}

	return numKeysUpdated;
	}

	@Override
	protected void implClose() throws IOException {
	assert Thread.holdsLock(this);

	// prevent further wakeup
	synchronized (interruptLock) {
	interruptTriggered = true;
	}

	FileDispatcherImpl.closeIntFD(epfd);
	EPoll.freePollArray(pollArrayAddress);

	FileDispatcherImpl.closeIntFD(fd0);
	FileDispatcherImpl.closeIntFD(fd1);
	}

	@Override
	protected void implDereg(SelectionKeyImpl ski) throws IOException {
	assert !ski.isValid();
	assert Thread.holdsLock(this);

	int fd = ski.getFDVal();
	if (fdToKey.remove(fd) != null) {
	if (ski.registeredEvents() != 0) {
	EPoll.ctl(epfd, EPOLL_CTL_DEL, fd, 0);
	ski.registeredEvents(0);
	}
	} else {
	assert ski.registeredEvents() == 0;
	}
	}

	@Override
	public void setEventOps(SelectionKeyImpl ski) {
	ensureOpen();
	synchronized (updateLock) {
	updateKeys.addLast(ski);
	}
	}

	@Override
	public Selector wakeup() {
	synchronized (interruptLock) {
	if (!interruptTriggered) {
	try {
	IOUtil.write1(fd1, (byte)0);
	} catch (IOException ioe) {
	throw new InternalError(ioe);
	}
	interruptTriggered = true;
	}
	}
	return this;
	}

	private void clearInterrupt() throws IOException {
	synchronized (interruptLock) {
	IOUtil.drain(fd0);
	interruptTriggered = false;
	}
	}
	}