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package sun.nio.ch;

import java.io.IOException;
import java.nio.channels.*;
import java.nio.channels.spi.*;
import java.util.*;

An implementation of Selector for Linux 2.6+ kernels that uses the epoll event notification facility.
/** * An implementation of Selector for Linux 2.6+ kernels that uses * the epoll event notification facility. */
class EPollSelectorImpl extends SelectorImpl { // File descriptors used for interrupt protected int fd0; protected int fd1; // The poll object EPollArrayWrapper pollWrapper; // Maps from file descriptors to keys private Map<Integer,SelectionKeyImpl> fdToKey; // True if this Selector has been closed private volatile boolean closed; // Lock for interrupt triggering and clearing private final Object interruptLock = new Object(); private boolean interruptTriggered = false;
Package private constructor called by factory method in the abstract superclass Selector.
/** * Package private constructor called by factory method in * the abstract superclass Selector. */
EPollSelectorImpl(SelectorProvider sp) throws IOException { super(sp); long pipeFds = IOUtil.makePipe(false); fd0 = (int) (pipeFds >>> 32); fd1 = (int) pipeFds; try { pollWrapper = new EPollArrayWrapper(); pollWrapper.initInterrupt(fd0, fd1); fdToKey = new HashMap<>(); } catch (Throwable t) { try { FileDispatcherImpl.closeIntFD(fd0); } catch (IOException ioe0) { t.addSuppressed(ioe0); } try { FileDispatcherImpl.closeIntFD(fd1); } catch (IOException ioe1) { t.addSuppressed(ioe1); } throw t; } } protected int doSelect(long timeout) throws IOException { if (closed) throw new ClosedSelectorException(); processDeregisterQueue(); try { begin(); pollWrapper.poll(timeout); } finally { end(); } processDeregisterQueue(); int numKeysUpdated = updateSelectedKeys(); if (pollWrapper.interrupted()) { // Clear the wakeup pipe pollWrapper.putEventOps(pollWrapper.interruptedIndex(), 0); synchronized (interruptLock) { pollWrapper.clearInterrupted(); IOUtil.drain(fd0); interruptTriggered = false; } } return numKeysUpdated; }
Update the keys whose fd's have been selected by the epoll. Add the ready keys to the ready queue.
/** * Update the keys whose fd's have been selected by the epoll. * Add the ready keys to the ready queue. */
private int updateSelectedKeys() { int entries = pollWrapper.updated; int numKeysUpdated = 0; for (int i=0; i<entries; i++) { int nextFD = pollWrapper.getDescriptor(i); SelectionKeyImpl ski = fdToKey.get(Integer.valueOf(nextFD)); // ski is null in the case of an interrupt if (ski != null) { int rOps = pollWrapper.getEventOps(i); if (selectedKeys.contains(ski)) { if (ski.channel.translateAndSetReadyOps(rOps, ski)) { numKeysUpdated++; } } else { ski.channel.translateAndSetReadyOps(rOps, ski); if ((ski.nioReadyOps() & ski.nioInterestOps()) != 0) { selectedKeys.add(ski); numKeysUpdated++; } } } } return numKeysUpdated; } protected void implClose() throws IOException { if (closed) return; closed = true; // prevent further wakeup synchronized (interruptLock) { interruptTriggered = true; } FileDispatcherImpl.closeIntFD(fd0); FileDispatcherImpl.closeIntFD(fd1); pollWrapper.closeEPollFD(); // it is possible selectedKeys = null; // Deregister channels Iterator<SelectionKey> i = keys.iterator(); while (i.hasNext()) { SelectionKeyImpl ski = (SelectionKeyImpl)i.next(); deregister(ski); SelectableChannel selch = ski.channel(); if (!selch.isOpen() && !selch.isRegistered()) ((SelChImpl)selch).kill(); i.remove(); } fd0 = -1; fd1 = -1; } protected void implRegister(SelectionKeyImpl ski) { if (closed) throw new ClosedSelectorException(); SelChImpl ch = ski.channel; int fd = Integer.valueOf(ch.getFDVal()); fdToKey.put(fd, ski); pollWrapper.add(fd); keys.add(ski); } protected void implDereg(SelectionKeyImpl ski) throws IOException { assert (ski.getIndex() >= 0); SelChImpl ch = ski.channel; int fd = ch.getFDVal(); fdToKey.remove(Integer.valueOf(fd)); pollWrapper.remove(fd); ski.setIndex(-1); keys.remove(ski); selectedKeys.remove(ski); deregister((AbstractSelectionKey)ski); SelectableChannel selch = ski.channel(); if (!selch.isOpen() && !selch.isRegistered()) ((SelChImpl)selch).kill(); } public void putEventOps(SelectionKeyImpl ski, int ops) { if (closed) throw new ClosedSelectorException(); SelChImpl ch = ski.channel; pollWrapper.setInterest(ch.getFDVal(), ops); } public Selector wakeup() { synchronized (interruptLock) { if (!interruptTriggered) { pollWrapper.interrupt(); interruptTriggered = true; } } return this; } }