libvirt/src/util/event.c

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/*
* event.c: event loop for monitoring file handles
*
* Copyright (C) 2007, 2011 Red Hat, Inc.
* Copyright (C) 2007 Daniel P. Berrange
*
* 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>
*/
#include <config.h>
#include "event.h"
#include "event_poll.h"
#include "logging.h"
#include "virterror_internal.h"
#include <stdlib.h>
static virEventAddHandleFunc addHandleImpl = NULL;
static virEventUpdateHandleFunc updateHandleImpl = NULL;
static virEventRemoveHandleFunc removeHandleImpl = NULL;
static virEventAddTimeoutFunc addTimeoutImpl = NULL;
static virEventUpdateTimeoutFunc updateTimeoutImpl = NULL;
static virEventRemoveTimeoutFunc removeTimeoutImpl = NULL;
/**
* virEventAddHandle: register a callback for monitoring file handle events
*
* @fd: file handle to monitor for events
* @events: bitset of events to watch from virEventHandleType 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 virEventAddHandle(int fd,
int events,
virEventHandleCallback cb,
void *opaque,
virFreeCallback ff) {
if (!addHandleImpl)
return -1;
return addHandleImpl(fd, events, cb, opaque, ff);
}
/**
* virEventUpdateHandle: change event set for a monitored file handle
*
* @watch: watch whose file handle to update
* @events: bitset of events to watch from virEventHandleType constants
*
* Will not fail if fd exists
*/
void virEventUpdateHandle(int watch, int events) {
updateHandleImpl(watch, events);
}
/**
* virEventRemoveHandle: unregister a callback from a file handle
*
* @watch: watch whose file handle to remove
*
* returns -1 if the file handle was not registered, 0 upon success
*/
int virEventRemoveHandle(int watch) {
if (!removeHandleImpl)
return -1;
return removeHandleImpl(watch);
}
/**
* virEventAddTimeout: register a callback for a timer event
*
* @timeout: time between events in milliseconds
* @cb: callback to invoke when an event occurs
* @opaque: user data to pass to callback
*
* Setting timeout to -1 will disable the timer. Setting the timeout
* to zero will cause it to fire on every event loop iteration.
*
* returns -1 if the timer cannot be registered, a positive
* integer timer id upon success
*/
int virEventAddTimeout(int timeout,
virEventTimeoutCallback cb,
void *opaque,
virFreeCallback ff) {
if (!addTimeoutImpl)
return -1;
return addTimeoutImpl(timeout, cb, opaque, 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 virEventUpdateTimeout(int timer, int timeout) {
updateTimeoutImpl(timer, timeout);
}
/**
* virEventRemoveTimeout: unregister a callback for a timer
*
* @timer: the timer id to remove
*
* returns -1 if the timer was not registered, 0 upon success
*/
int virEventRemoveTimeout(int timer) {
if (!removeTimeoutImpl)
return -1;
return removeTimeoutImpl(timer);
}
/*****************************************************
*
* Below this point are 3 *PUBLIC* APIs for event
* loop integration with applications using libvirt.
* These API contracts cannot be changed.
*
*****************************************************/
/**
* virEventRegisterImpl:
* @addHandle: the callback to add fd handles
* @updateHandle: the callback to update fd handles
* @removeHandle: the callback to remove fd handles
* @addTimeout: the callback to add a timeout
* @updateTimeout: the callback to update a timeout
* @removeTimeout: the callback to remove a timeout
*
* Registers an event implementation, to allow integration
* with an external event loop. Applications would use this
* to integrate with the libglib2 event loop, or libevent
* or the QT event loop.
*
* If an application does not need to integrate with an
* existing event loop implementation, then the
* virEventRegisterDefaultImpl method can be used to setup
* the generic libvirt implementation.
*/
void virEventRegisterImpl(virEventAddHandleFunc addHandle,
virEventUpdateHandleFunc updateHandle,
virEventRemoveHandleFunc removeHandle,
virEventAddTimeoutFunc addTimeout,
virEventUpdateTimeoutFunc updateTimeout,
virEventRemoveTimeoutFunc removeTimeout)
{
VIR_DEBUG("addHandle=%p updateHandle=%p removeHandle=%p "
"addTimeout=%p updateTimeout=%p removeTimeout=%p",
addHandle, updateHandle, removeHandle,
addTimeout, updateTimeout, removeTimeout);
addHandleImpl = addHandle;
updateHandleImpl = updateHandle;
removeHandleImpl = removeHandle;
addTimeoutImpl = addTimeout;
updateTimeoutImpl = updateTimeout;
removeTimeoutImpl = removeTimeout;
}
/**
* virEventRegisterDefaultImpl:
*
* Registers a default event implementation based on the
* poll() system call. This is a generic implementation
* that can be used by any client application which does
* not have a need to integrate with an external event
* loop impl.
*
* Once registered, the application can invoke
* virEventRunDefaultImpl in a loop to process
* events
*
* Returns 0 on success, -1 on failure.
*/
int virEventRegisterDefaultImpl(void)
{
VIR_DEBUG("registering default event implementation");
virResetLastError();
if (virEventPollInit() < 0) {
virDispatchError(NULL);
return -1;
}
virEventRegisterImpl(
virEventPollAddHandle,
virEventPollUpdateHandle,
virEventPollRemoveHandle,
virEventPollAddTimeout,
virEventPollUpdateTimeout,
virEventPollRemoveTimeout
);
return 0;
}
/**
* virEventRunDefaultImpl:
*
* Run one iteration of the event loop. Applications
* will generally want to have a thread which invokes
* this method in an infinite loop
*
* static bool quit = false;
*
* while (!quit) {
* if (virEventRunDefaultImpl() < 0)
* ...print error...
* }
*
* Returns 0 on success, -1 on failure.
*/
int virEventRunDefaultImpl(void)
{
VIR_DEBUG("running default event implementation");
virResetLastError();
if (virEventPollRunOnce() < 0) {
virDispatchError(NULL);
return -1;
}
return 0;
}