/**
* Copyright (C) 2009-2013 Barchart, Inc. <http://www.barchart.com/>
*
* All rights reserved. Licensed under the OSI BSD License.
*
* http://www.opensource.org/licenses/bsd-license.php
*/
package com.barchart.udt;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* UDT Epoll Manager
*
* @see <a href="http://en.wikipedia.org/wiki/Epoll">Epoll</a>
* @see <a href="http://udt.sourceforge.net/udt4/doc/epoll.htm">UDT Epoll</a>
*/
public class EpollUDT {
/**
* poll interest option mask
* <p>
* see udt.h enum - EPOLLOpt
*
* <pre>
* UDT_EPOLL_IN = 0x1,
* UDT_EPOLL_OUT = 0x4,
* UDT_EPOLL_ERR = 0x8
* </pre>
*
* this is subset adapted to jdk select pattern
*/
public static enum Opt {
/**
* not interested
*/
NONE(0x0), //
/**
* UDT_EPOLL_IN : interested in read
*/
READ(0x1), //
/**
* UDT_EPOLL_OUT: interested in write
*/
WRITE(0x4), //
/**
* UDT_EPOLL_ERR: interested in exceptions
*/
ERROR(0x8), //
BOTH(WRITE.code | READ.code), //
ERROR_READ(ERROR.code | READ.code), //
ERROR_WRITE(ERROR.code | WRITE.code), //
ALL(ERROR.code | WRITE.code | READ.code), //
UNKNOWN(-1);
;
private static final Opt[] ENUM_VALS = Opt.values();
public static Opt from(final int code) {
for (final Opt known : ENUM_VALS) {
if (known.code == code) {
return known;
}
}
return UNKNOWN;
}
/**
* poll event mask;
* <p>
* used for both requesting interest and reporting readiness
*/
public final int code;
Opt(final int code) {
this.code = code;
}
public boolean hasError() {
return (code & ERROR.code) != 0;
}
public boolean hasRead() {
return (code & READ.code) != 0;
}
public boolean hasWrite() {
return (code & WRITE.code) != 0;
}
/**
* Non-empty mask of 3 parts.
*/
public boolean isValidInterestRequest() {
switch (this) {
case NONE:
case READ:
case WRITE:
case ERROR:
case BOTH:
case ERROR_WRITE:
case ERROR_READ:
case ALL:
return true;
default:
return false;
}
}
}
protected static final Logger log = LoggerFactory.getLogger(EpollUDT.class);
protected final int id;
protected volatile boolean isActive;
/**
* place holder socket to work around logic in epoll.h CEPoll::wait() which
* expects at least one socket being monitored with non empty interest
*/
private final SocketUDT socketUDT;
/**
* allocate poll
*/
public EpollUDT() throws ExceptionUDT {
id = SocketUDT.epollCreate0();
isActive = true;
socketUDT = new SocketUDT(TypeUDT.DATAGRAM);
SocketUDT.epollAdd0(id, socketUDT.id(), Opt.BOTH.code);
log.debug("ep {} create", id());
}
/**
* deallocate poll; called on {@link #finalize()}
*/
public void destroy() throws ExceptionUDT {
SocketUDT.epollRemove0(id(), socketUDT.id());
socketUDT.close();
isActive = false;
SocketUDT.epollRelease0(id());
log.debug("ep {} delete", id());
}
/**
* poll descriptor id
*/
public int id() {
return id;
}
/**
* poll becomes active after instance creation and inactive after
* {@link #destroy()}
*/
public boolean isActive() {
return isActive;
}
/**
* deallocate poll
* <p>
* NOTE: catch all exceptions; else prevents GC
* <p>
* NOTE: do not leak "this" references; else prevents GC
*/
@Override
protected void finalize() {
try {
destroy();
super.finalize();
} catch (final Throwable e) {
log.error("failed to destroy id=" + id(), e);
}
}
/**
* register socket into event processing poll
*/
public void add(final SocketUDT socket, final Opt option)
throws ExceptionUDT {
log.debug("ep {} add {} {}", id(), socket, option);
// assert option.isValidInterestRequest();
SocketUDT.epollAdd0(id(), socket.id(), option.code);
}
/**
* unregister socket from event processing poll
*/
public void remove(final SocketUDT socket) throws ExceptionUDT {
log.debug("ep {} rem {}", id(), socket);
SocketUDT.epollRemove0(id(), socket.id());
}
/**
* update existing poll/socket registration with changed interest
*/
public void update(final SocketUDT socket, final Opt option)
throws ExceptionUDT {
log.debug("ep {} mod {} {}", id(), socket, option);
assert option.isValidInterestRequest();
SocketUDT.epollUpdate0(id(), socket.id(), option.code);
}
/** report current poll/socket readiness */
public Opt verify(final SocketUDT socket) throws ExceptionUDT {
final int code = SocketUDT.epollVerify0(id(), socket.id());
return Opt.from(code);
}
}