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Diffstat (limited to 'gnu/java/nio/EpollSelectorImpl.java')
| -rw-r--r-- | gnu/java/nio/EpollSelectorImpl.java | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/gnu/java/nio/EpollSelectorImpl.java b/gnu/java/nio/EpollSelectorImpl.java new file mode 100644 index 000000000..2b3c9bbb1 --- /dev/null +++ b/gnu/java/nio/EpollSelectorImpl.java @@ -0,0 +1,399 @@ +/* EpollSelectorImpl.java -- selector implementation using epoll + Copyright (C) 2006 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath 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, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.java.nio; + +import gnu.classpath.Configuration; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.nio.channels.SelectableChannel; +import java.nio.channels.SelectionKey; +import java.nio.channels.Selector; +import java.nio.channels.spi.AbstractSelectableChannel; +import java.nio.channels.spi.AbstractSelector; +import java.nio.channels.spi.SelectorProvider; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Set; + +/** + * An implementation of {@link Selector} that uses the epoll event + * notification mechanism on GNU/Linux. + * + * @author Casey Marshall (csm@gnu.org) + */ +public class EpollSelectorImpl extends AbstractSelector +{ + // XXX is this reasonable? Does it matter? + private static final int DEFAULT_EPOLL_SIZE = 128; + private static final int sizeof_struct_epoll_event; + + private static final int OP_ACCEPT = SelectionKey.OP_ACCEPT; + private static final int OP_CONNECT = SelectionKey.OP_CONNECT; + private static final int OP_READ = SelectionKey.OP_READ; + private static final int OP_WRITE = SelectionKey.OP_WRITE; + + /** our epoll file descriptor. */ + private int epoll_fd; + + private final HashMap keys; + private Set selectedKeys; + private Thread waitingThread; + private ByteBuffer events; + + private static final int INITIAL_CAPACITY; + private static final int MAX_DOUBLING_CAPACITY; + private static final int CAPACITY_INCREMENT; + + static + { + if (Configuration.INIT_LOAD_LIBRARY) + System.loadLibrary("javanio"); + + if (epoll_supported()) + sizeof_struct_epoll_event = sizeof_struct(); + else + sizeof_struct_epoll_event = -1; + + INITIAL_CAPACITY = 64 * sizeof_struct_epoll_event; + MAX_DOUBLING_CAPACITY = 1024 * sizeof_struct_epoll_event; + CAPACITY_INCREMENT = 128 * sizeof_struct_epoll_event; + } + + public EpollSelectorImpl(SelectorProvider provider) + throws IOException + { + super(provider); + epoll_fd = epoll_create(DEFAULT_EPOLL_SIZE); + keys = new HashMap(); + selectedKeys = null; + events = ByteBuffer.allocateDirect(INITIAL_CAPACITY); + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#keys() + */ + public Set keys() + { + return new HashSet(keys.values()); + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#select() + */ + public int select() throws IOException + { + return doSelect(-1); + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#select(long) + */ + public int select(long timeout) throws IOException + { + if (timeout > Integer.MAX_VALUE) + throw new IllegalArgumentException("timeout is too large"); + if (timeout < 0) + throw new IllegalArgumentException("invalid timeout"); + return doSelect((int) timeout); + } + + private int doSelect(int timeout) throws IOException + { + synchronized (keys) + { + Set cancelledKeys = cancelledKeys(); + synchronized (cancelledKeys) + { + for (Iterator it = cancelledKeys.iterator(); it.hasNext(); ) + { + EpollSelectionKeyImpl key = (EpollSelectionKeyImpl) it.next(); + epoll_delete(epoll_fd, key.fd); + key.valid = false; + keys.remove(Integer.valueOf(key.fd)); + it.remove(); + deregister(key); + } + + // Clear out closed channels. The fds are removed from the epoll + // fd when closed, so there is no need to remove them manually. + for (Iterator it = keys.values().iterator(); it.hasNext(); ) + { + EpollSelectionKeyImpl key = (EpollSelectionKeyImpl) it.next(); + SelectableChannel ch = key.channel(); + if (ch instanceof VMChannelOwner) + { + if (!((VMChannelOwner) ch).getVMChannel().getState().isValid()) + it.remove(); + } + } + + // Don't bother if we have nothing to select. + if (keys.isEmpty()) + return 0; + + int ret; + try + { + begin(); + waitingThread = Thread.currentThread(); + ret = epoll_wait(epoll_fd, events, keys.size(), timeout); + } + finally + { + Thread.interrupted(); + waitingThread = null; + end(); + } + + HashSet s = new HashSet(ret); + for (int i = 0; i < ret; i++) + { + events.position(i * sizeof_struct_epoll_event); + ByteBuffer b = events.slice(); + int fd = selected_fd(b); + EpollSelectionKeyImpl key + = (EpollSelectionKeyImpl) keys.get(Integer.valueOf(fd)); + if (key == null) + throw new IOException("fd was selected, but no key found"); + key.selectedOps = selected_ops(b) & key.interestOps; + s.add(key); + } + + reallocateBuffer(); + + selectedKeys = s; + return ret; + } + } + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#selectedKeys() + */ + public Set selectedKeys() + { + if (selectedKeys == null) + return Collections.EMPTY_SET; + return selectedKeys; + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#selectNow() + */ + public int selectNow() throws IOException + { + return doSelect(0); + } + + /* (non-Javadoc) + * @see java.nio.channels.Selector#wakeup() + */ + public Selector wakeup() + { + try + { + waitingThread.interrupt(); + } + catch (NullPointerException npe) + { + // Ignored, thrown if we are not in a blocking op. + } + return this; + } + + /* (non-Javadoc) + * @see java.nio.channels.spi.AbstractSelector#implCloseSelector() + */ + protected void implCloseSelector() throws IOException + { + VMChannel.close(epoll_fd); + } + + /* (non-Javadoc) + * @see java.nio.channels.spi.AbstractSelector#register(java.nio.channels.spi.AbstractSelectableChannel, int, java.lang.Object) + */ + protected SelectionKey register(AbstractSelectableChannel ch, int ops, Object att) + { + if (!(ch instanceof VMChannelOwner)) + throw new IllegalArgumentException("unsupported channel type"); + + VMChannel channel = ((VMChannelOwner) ch).getVMChannel(); + try + { + int native_fd = channel.getState().getNativeFD(); + synchronized (keys) + { + if (keys.containsKey(Integer.valueOf(native_fd))) + throw new IllegalArgumentException("channel already registered"); + EpollSelectionKeyImpl result = + new EpollSelectionKeyImpl(this, ch, native_fd); + if ((ops & ~(ch.validOps())) != 0) + throw new IllegalArgumentException("invalid ops for channel"); + result.interestOps = ops; + result.selectedOps = 0; + result.valid = true; + result.attach(att); + result.key = System.identityHashCode(result); + epoll_add(epoll_fd, result.fd, ops); + keys.put(Integer.valueOf(native_fd), result); + reallocateBuffer(); + return result; + } + } + catch (IOException ioe) + { + throw new IllegalArgumentException(ioe); + } + } + + private void reallocateBuffer() + { + // Ensure we have enough space for all potential events that may be + // returned. + if (events.capacity() < keys.size() * sizeof_struct_epoll_event) + { + int cap = events.capacity(); + if (cap < MAX_DOUBLING_CAPACITY) + cap <<= 1; + else + cap += CAPACITY_INCREMENT; + events = ByteBuffer.allocateDirect(cap); + } + // Ensure that the events buffer is not too large, given the number of + // events registered. + else if (events.capacity() > keys.size() * sizeof_struct_epoll_event * 2 + 1 + && events.capacity() > INITIAL_CAPACITY) + { + int cap = events.capacity() >>> 1; + events = ByteBuffer.allocateDirect(cap); + } + } + + void epoll_modify(EpollSelectionKeyImpl key, int ops) throws IOException + { + epoll_modify(epoll_fd, key.fd, ops); + } + + /** + * Tell if epoll is supported by this system, and support was compiled in. + * + * @return True if this system supports event notification with epoll. + */ + public static native boolean epoll_supported(); + + + /** + * Returns the size of `struct epoll_event'. + * + * @return The size of `struct epoll_event'. + */ + private static native int sizeof_struct(); + + + /** + * Open a new epoll file descriptor. + * + * @param size The size hint for the new epoll descriptor. + * @return The new file descriptor integer. + * @throws IOException If allocating a new epoll descriptor fails. + */ + private static native int epoll_create(int size) throws IOException; + + /** + * Add a file descriptor to this selector. + * + * @param efd The epoll file descriptor. + * @param fd The file descriptor to add (or modify). + * @param ops The interest opts. + */ + private static native void epoll_add(int efd, int fd, int ops) + throws IOException; + + /** + * Modify the interest ops of the key selecting for the given FD. + * + * @param efd The epoll file descriptor. + * @param fd The file descriptor to modify. + * @param ops The ops. + * @throws IOException + */ + private static native void epoll_modify(int efd, int fd, int ops) + throws IOException; + + /** + * Remove a file descriptor from this selector. + * + * @param efd The epoll file descriptor. + * @param fd The file descriptor. + * @throws IOException + */ + private static native void epoll_delete(int efd, int fd) throws IOException; + + /** + * Select events. + * + * @param efd The epoll file descriptor. + * @param state The buffer to hold selected events. + * @param n The number of events that may be put in `state'. + * @param timeout The timeout. + * @return The number of events selected. + * @throws IOException + */ + private static native int epoll_wait(int efd, ByteBuffer state, int n, int timeout) + throws IOException; + + /** + * Fetch the fd value from a selected struct epoll_event. + * + * @param struct The direct buffer holding the struct. + * @return The fd value. + */ + private static native int selected_fd(ByteBuffer struct); + + /** + * Fetch the enabled operations from a selected struct epoll_event. + * + * @param struct The direct buffer holding the struct. + * @return The selected operations. + */ + private static native int selected_ops(ByteBuffer struct); +} |