ObjFW  Artifact [306f8337d7]

Artifact 306f8337d76bcd3e89cd30bae64a677194f313fd8ad2c729e4e28701fc09e40c:

• File src/OFKernelEventObserver_kqueue.m — part of check-in [220513a3f5] at 2015-05-09 18:13:19 on branch trunk — More OFKernelEventObserver refactoring

  This was necessary because select(), poll() and kevent() on FreeBSD and
  OS X would sometimes return 0 events, even if there are some, and
  sometimes return the correct number of events that were pending, meaning
  the number of events returned is unreliable. To make things worse,
  whether it returns 0 or the number of events that were pending is
  completely non-deterministic on both FreeBSD and OS X (running the same
  tests multiple times in a row would make it sometimes work and sometimes
  fail).

  In order to prevent code from depending on the return value of
  -[observeForTimeInterval:] (which would depend on select(), poll() and
  kevent() returning the correct number), OFKernelObserver no longer
  returns whether there were pending events. It is expected that
  -[observe] or -[observeForTimeInterval:] is just called in a loop as
  long as events should be handled.

  The tests have been changed as well to reflect this. What they do now is
  set a deadline and call -[observeForTimeInterval:] with a small timeout
  in a loop until the deadline is reached or all events have been handled.

  Note: DragonFlyBSD has not been tested, but will most likely behave like
  FreeBSD and OS X. (user: js, size: 5089) [annotate] [blame] [check-ins using]

/*
 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015
 *   Jonathan Schleifer <js@webkeks.org>
 *
 * All rights reserved.
 *
 * This file is part of ObjFW. It may be distributed under the terms of the
 * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
 * the packaging of this file.
 *
 * Alternatively, it may be distributed under the terms of the GNU General
 * Public License, either version 2 or 3, which can be found in the file
 * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
 * file.
 */

#include "config.h"

#include <assert.h>
#include <errno.h>
#include <math.h>

#include <fcntl.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>

#import "OFKernelEventObserver.h"
#import "OFKernelEventObserver+Private.h"
#import "OFKernelEventObserver_kqueue.h"
#import "OFDataArray.h"
#import "OFArray.h"

#import "OFInitializationFailedException.h"
#import "OFObserveFailedException.h"
#import "OFOutOfRangeException.h"

#define EVENTLIST_SIZE 64

@implementation OFKernelEventObserver_kqueue
- init
{
	self = [super init];

	@try {
		struct kevent event;

#ifdef HAVE_KQUEUE1
		if ((_kernelQueue = kqueue1(O_CLOEXEC)) == -1)
			@throw [OFInitializationFailedException
			    exceptionWithClass: [self class]];
#else
		int flags;

		if ((_kernelQueue = kqueue()) == -1)
			@throw [OFInitializationFailedException
			    exceptionWithClass: [self class]];

		if ((flags = fcntl(_kernelQueue, F_GETFD, 0)) != -1)
			fcntl(_kernelQueue, F_SETFD, flags | FD_CLOEXEC);
#endif

		_changeList = [[OFDataArray alloc] initWithItemSize:
		    sizeof(struct kevent)];
		EV_SET(&event, _cancelFD[0], EVFILT_READ, EV_ADD, 0, 0, 0);
		[_changeList addItem: &event];

		_removedArray = [[OFMutableArray alloc] init];
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (void)dealloc
{
	close(_kernelQueue);

	[_changeList release];
	[_removedArray release];

	[super dealloc];
}

- (void)OF_addObjectForReading: (id)object
{
	struct kevent event;

	if ([_changeList count] >= INT_MAX)
		@throw [OFOutOfRangeException exception];

	memset(&event, 0, sizeof(event));
	event.ident = [object fileDescriptorForReading];
	event.filter = EVFILT_READ;
	event.flags = EV_ADD;
#ifndef __NetBSD__
	event.udata = object;
#else
	event.udata = (intptr_t)object;
#endif

	[_changeList addItem: &event];
}

- (void)OF_addObjectForWriting: (id)object
{
	struct kevent event;

	if ([_changeList count] >= INT_MAX)
		@throw [OFOutOfRangeException exception];

	memset(&event, 0, sizeof(event));
	event.ident = [object fileDescriptorForWriting];
	event.filter = EVFILT_WRITE;
	event.flags = EV_ADD;
#ifndef __NetBSD__
	event.udata = object;
#else
	event.udata = (intptr_t)object;
#endif

	[_changeList addItem: &event];
}

- (void)OF_removeObjectForReading: (id)object
{
	struct kevent event;

	memset(&event, 0, sizeof(event));
	event.ident = [object fileDescriptorForReading];
	event.filter = EVFILT_READ;
	event.flags = EV_DELETE;
	[_changeList addItem: &event];
}

- (void)OF_removeObjectForWriting: (id)object
{
	struct kevent event;

	memset(&event, 0, sizeof(event));
	event.ident = [object fileDescriptorForWriting];
	event.filter = EVFILT_WRITE;
	event.flags = EV_DELETE;
	[_changeList addItem: &event];
}

- (void)observeForTimeInterval: (of_time_interval_t)timeInterval
{
	void *pool = objc_autoreleasePoolPush();
	struct timespec timeout;
	struct kevent eventList[EVENTLIST_SIZE];
	int i, events;

	timeout.tv_sec = (time_t)timeInterval;
	timeout.tv_nsec = lrint((timeInterval - timeout.tv_sec) * 1000000000);

	/*
	 * Make sure to keep the streams retained and thus the file descriptors
	 * valid until the actual change has been performed.
	 */
	[self OF_processQueueAndStoreRemovedIn: _removedArray];

	[self OF_processReadBuffers];

	objc_autoreleasePoolPop(pool);

	events = kevent(_kernelQueue, [_changeList items],
	    (int)[_changeList count], eventList, EVENTLIST_SIZE,
	    (timeInterval != -1 ? &timeout : NULL));

	if (events < 0)
		@throw [OFObserveFailedException exceptionWithObserver: self
								 errNo: errno];

	[_changeList removeAllItems];
	[_removedArray removeAllObjects];

	for (i = 0; i < events; i++) {
		if (eventList[i].flags & EV_ERROR)
			@throw [OFObserveFailedException
			    exceptionWithObserver: self
					    errNo: (int)eventList[i].data];

		if (eventList[i].ident == _cancelFD[0]) {
			char buffer;

			assert(eventList[i].filter == EVFILT_READ);
			OF_ENSURE(read(_cancelFD[0], &buffer, 1) == 1);

			continue;
		}

		pool = objc_autoreleasePoolPush();

		switch (eventList[i].filter) {
		case EVFILT_READ:
			if ([_delegate respondsToSelector:
			    @selector(objectIsReadyForReading:)])
				[_delegate objectIsReadyForReading:
				    (id)eventList[i].udata];
			break;
		case EVFILT_WRITE:
			if ([_delegate respondsToSelector:
			    @selector(objectIsReadyForWriting:)])
				[_delegate objectIsReadyForWriting:
				    (id)eventList[i].udata];
			break;
		default:
			assert(0);
		}

		objc_autoreleasePoolPop(pool);
	}
}
@end