ObjFW  Artifact [8f646c7ee8]

Artifact 8f646c7ee8437c6c9729a87bc8f1b2c571d88a74f8815dc48f40a5a39acd8f39:

• File src/OFKernelEventObserver_epoll.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: 5754) [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 <fcntl.h>
#include <unistd.h>

#include <sys/epoll.h>

#import "OFKernelEventObserver.h"
#import "OFKernelEventObserver+Private.h"
#import "OFKernelEventObserver_epoll.h"
#import "OFMapTable.h"
#import "OFNull.h"

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

#define EVENTLIST_SIZE 64

static const of_map_table_functions_t mapFunctions = { NULL };

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

	@try {
		struct epoll_event event;

#ifdef HAVE_EPOLL_CREATE1
		if ((_epfd = epoll_create1(EPOLL_CLOEXEC)) == -1)
			@throw [OFInitializationFailedException exception];
#else
		int flags;

		if ((_epfd = epoll_create(1)) == -1)
			@throw [OFInitializationFailedException exception];

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

		_FDToEvents = [[OFMapTable alloc]
		    initWithKeyFunctions: mapFunctions
			  valueFunctions: mapFunctions];

		memset(&event, 0, sizeof(event));
		event.events = EPOLLIN;
		event.data.ptr = [OFNull null];

		if (epoll_ctl(_epfd, EPOLL_CTL_ADD, _cancelFD[0], &event) == -1)
			@throw [OFInitializationFailedException exception];
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (void)dealloc
{
	close(_epfd);

	[_FDToEvents release];

	[super dealloc];
}

- (void)OF_addObject: (id)object
      fileDescriptor: (int)fd
	      events: (int)addEvents
{
	intptr_t events;

	events = (intptr_t)[_FDToEvents valueForKey: (void*)(intptr_t)fd];
	if (events == 0) {
		struct epoll_event event;

		memset(&event, 0, sizeof(event));
		event.events = addEvents;
		event.data.ptr = object;

		if (epoll_ctl(_epfd, EPOLL_CTL_ADD, fd, &event) == -1)
			@throw [OFObserveFailedException
			    exceptionWithObserver: self
					    errNo: errno];

		[_FDToEvents setValue: (void*)(intptr_t)addEvents
			       forKey: (void*)(intptr_t)fd];
	} else {
		struct epoll_event event;

		memset(&event, 0, sizeof(event));
		event.events = (int)events | addEvents;
		event.data.ptr = object;

		if (epoll_ctl(_epfd, EPOLL_CTL_MOD, fd, &event) == -1)
			@throw [OFObserveFailedException
			    exceptionWithObserver: self
					    errNo: errno];

		[_FDToEvents setValue: (void*)(events | addEvents)
			       forKey: (void*)(intptr_t)fd];
	}
}

- (void)OF_removeObject: (id)object
	 fileDescriptor: (int)fd
		 events: (int)removeEvents
{
	intptr_t events;

	events = (intptr_t)[_FDToEvents valueForKey: (void*)(intptr_t)fd];
	events &= ~removeEvents;

	if (events == 0) {
		if (epoll_ctl(_epfd, EPOLL_CTL_DEL, fd, NULL) == -1)
			@throw [OFObserveFailedException
			    exceptionWithObserver: self
					    errNo: errno];

		[_FDToEvents removeValueForKey: (void*)(intptr_t)fd];
	} else {
		struct epoll_event event;

		memset(&event, 0, sizeof(event));
		event.events = (int)events;
		event.data.ptr = object;

		if (epoll_ctl(_epfd, EPOLL_CTL_MOD, fd, &event) == -1)
			@throw [OFObserveFailedException
			    exceptionWithObserver: self
					    errNo: errno];

		[_FDToEvents setValue: (void*)events
			       forKey: (void*)(intptr_t)fd];
	}
}

- (void)OF_addObjectForReading: (id)object
{
	[self OF_addObject: object
	    fileDescriptor: [object fileDescriptorForReading]
		    events: EPOLLIN];
}

- (void)OF_addObjectForWriting: (id)object
{
	[self OF_addObject: object
	    fileDescriptor: [object fileDescriptorForWriting]
		    events: EPOLLOUT];
}

- (void)OF_removeObjectForReading: (id)object
{
	[self OF_removeObject: object
	       fileDescriptor: [object fileDescriptorForReading]
		       events: EPOLLIN];
}

- (void)OF_removeObjectForWriting: (id)object
{
	[self OF_removeObject: object
	       fileDescriptor: [object fileDescriptorForWriting]
		       events: EPOLLOUT];
}

- (void)observeForTimeInterval: (of_time_interval_t)timeInterval
{
	OFNull *nullObject = [OFNull null];
	void *pool = objc_autoreleasePoolPush();
	struct epoll_event eventList[EVENTLIST_SIZE];
	int i, events;

	[self OF_processQueueAndStoreRemovedIn: nil];
	[self OF_processReadBuffers];

	objc_autoreleasePoolPop(pool);

	events = epoll_wait(_epfd, eventList, EVENTLIST_SIZE,
	    (timeInterval != -1 ? timeInterval * 1000 : -1));

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

	for (i = 0; i < events; i++) {
		if (eventList[i].data.ptr == nullObject) {
			char buffer;

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

			continue;
		}

		if (eventList[i].events & EPOLLIN) {
			pool = objc_autoreleasePoolPush();

			if ([_delegate respondsToSelector:
			    @selector(objectIsReadyForReading:)])
				[_delegate objectIsReadyForReading:
				    eventList[i].data.ptr];

			objc_autoreleasePoolPop(pool);
		}

		if (eventList[i].events & EPOLLOUT) {
			pool = objc_autoreleasePoolPush();

			if ([_delegate respondsToSelector:
			    @selector(objectIsReadyForWriting:)])
				[_delegate objectIsReadyForWriting:
				    eventList[i].data.ptr];

			objc_autoreleasePoolPop(pool);
		}

		assert((eventList[i].events & ~(EPOLLIN | EPOLLOUT)) == 0);
	}
}
@end