libvirt/qemud/event.h

/*
 * event.h: event loop for monitoring file handles
 *
 * Copyright (C) 2007 Daniel P. Berrange
 * Copyright (C) 2007 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 * Author: Daniel P. Berrange <berrange@redhat.com>
 */

#ifndef __VIRTD_EVENT_H__
#define __VIRTD_EVENT_H__

#include "internal.h"

/**
 * virEventAddHandleImpl: register a callback for monitoring file handle events
 *
 * @fd: file handle to monitor for events
 * @events: bitset of events to watch from POLLnnn constants
 * @cb: callback to invoke when an event occurs
 * @opaque: user data to pass to callback
 *
 * returns -1 if the file handle cannot be registered, 0 upon success
 */
int virEventAddHandleImpl(int fd, int events,
                          virEventHandleCallback cb,
                          void *opaque,
                          virFreeCallback ff);

/**
 * virEventUpdateHandleImpl: change event set for a monitored file handle
 *
 * @watch: watch whose handle to update
 * @events: bitset of events to watch from POLLnnn constants
 *
 * Will not fail if fd exists
 */
void virEventUpdateHandleImpl(int watch, int events);

/**
 * virEventRemoveHandleImpl: unregister a callback from a file handle
 *
 * @watch: watch whose handle to remove
 *
 * returns -1 if the file handle was not registered, 0 upon success
 */
int virEventRemoveHandleImpl(int watch);

/**
 * virEventAddTimeoutImpl: register a callback for a timer event
 *
 * @frequency: time between events in milliseconds
 * @cb: callback to invoke when an event occurs
 * @opaque: user data to pass to callback
 *
 * Setting frequency to -1 will disable the timer. Setting the frequency
 * to zero will cause it to fire on every event loop iteration.
 *
 * returns -1 if the file handle cannot be registered, a positive
 * integer timer id upon success
 */
int virEventAddTimeoutImpl(int frequency,
                           virEventTimeoutCallback cb,
                           void *opaque,
                           virFreeCallback ff);

/**
 * virEventUpdateTimeoutImpl: change frequency for a timer
 *
 * @timer: timer id to change
 * @frequency: time between events in milliseconds
 *
 * Setting frequency to -1 will disable the timer. Setting the frequency
 * to zero will cause it to fire on every event loop iteration.
 *
 * Will not fail if timer exists
 */
void virEventUpdateTimeoutImpl(int timer, int frequency);

/**
 * virEventRemoveTimeoutImpl: unregister a callback for a timer
 *
 * @timer: the timer id to remove
 *
 * returns -1 if the timer was not registered, 0 upon success
 */
int virEventRemoveTimeoutImpl(int timer);

/**
 * virEventInit: Initialize the event loop
 *
 * returns -1 if initialization failed
 */
int virEventInit(void);

/**
 * virEventRunOnce: run a single iteration of the event loop.
 *
 * Blocks the caller until at least one file handle has an
 * event or the first timer expires.
 *
 * returns -1 if the event monitoring failed
 */
int virEventRunOnce(void);

int
virEventHandleTypeToPollEvent(int events);
int
virPollEventToEventHandleType(int events);


/**
 * virEventInterrupt: wakeup any thread waiting in poll()
 *
 * return -1 if wakup failed
 */
int virEventInterrupt(void);


#endif /* __VIRTD_EVENT_H__ */