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comparison: ipc/chromium/src/third_party/libevent/changelist-internal.h
ipc/chromium/src/third_party/libevent/changelist-internal.h
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| -1:000000000000 | 0:8b60fb40a29e |
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| 1 /* | |
| 2 * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson | |
| 3 * | |
| 4 * Redistribution and use in source and binary forms, with or without | |
| 5 * modification, are permitted provided that the following conditions | |
| 6 * are met: | |
| 7 * 1. Redistributions of source code must retain the above copyright | |
| 8 * notice, this list of conditions and the following disclaimer. | |
| 9 * 2. Redistributions in binary form must reproduce the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer in the | |
| 11 * documentation and/or other materials provided with the distribution. | |
| 12 * 3. The name of the author may not be used to endorse or promote products | |
| 13 * derived from this software without specific prior written permission. | |
| 14 * | |
| 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
| 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
| 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
| 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
| 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
| 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 25 */ | |
| 26 #ifndef _CHANGELIST_H_ | |
| 27 #define _CHANGELIST_H_ | |
| 28 | |
| 29 /* | |
| 30 A "changelist" is a list of all the fd status changes that should be made | |
| 31 between calls to the backend's dispatch function. There are a few reasons | |
| 32 that a backend would want to queue changes like this rather than processing | |
| 33 them immediately. | |
| 34 | |
| 35 1) Sometimes applications will add and delete the same event more than | |
| 36 once between calls to dispatch. Processing these changes immediately | |
| 37 is needless, and potentially expensive (especially if we're on a system | |
| 38 that makes one syscall per changed event). | |
| 39 | |
| 40 2) Sometimes we can coalesce multiple changes on the same fd into a single | |
| 41 syscall if we know about them in advance. For example, epoll can do an | |
| 42 add and a delete at the same time, but only if we have found out about | |
| 43 both of them before we tell epoll. | |
| 44 | |
| 45 3) Sometimes adding an event that we immediately delete can cause | |
| 46 unintended consequences: in kqueue, this makes pending events get | |
| 47 reported spuriously. | |
| 48 */ | |
| 49 | |
| 50 #include "event2/util.h" | |
| 51 | |
| 52 /** Represents a */ | |
| 53 struct event_change { | |
| 54 /** The fd or signal whose events are to be changed */ | |
| 55 evutil_socket_t fd; | |
| 56 /* The events that were enabled on the fd before any of these changes | |
| 57 were made. May include EV_READ or EV_WRITE. */ | |
| 58 short old_events; | |
| 59 | |
| 60 /* The changes that we want to make in reading and writing on this fd. | |
| 61 * If this is a signal, then read_change has EV_CHANGE_SIGNAL set, | |
| 62 * and write_change is unused. */ | |
| 63 ev_uint8_t read_change; | |
| 64 ev_uint8_t write_change; | |
| 65 }; | |
| 66 | |
| 67 /* Flags for read_change and write_change. */ | |
| 68 | |
| 69 /* If set, add the event. */ | |
| 70 #define EV_CHANGE_ADD 0x01 | |
| 71 /* If set, delete the event. Exclusive with EV_CHANGE_ADD */ | |
| 72 #define EV_CHANGE_DEL 0x02 | |
| 73 /* If set, this event refers a signal, not an fd. */ | |
| 74 #define EV_CHANGE_SIGNAL EV_SIGNAL | |
| 75 /* Set for persistent events. Currently not used. */ | |
| 76 #define EV_CHANGE_PERSIST EV_PERSIST | |
| 77 /* Set for adding edge-triggered events. */ | |
| 78 #define EV_CHANGE_ET EV_ET | |
| 79 | |
| 80 /* The value of fdinfo_size that a backend should use if it is letting | |
| 81 * changelist handle its add and delete functions. */ | |
| 82 #define EVENT_CHANGELIST_FDINFO_SIZE sizeof(int) | |
| 83 | |
| 84 /** Set up the data fields in a changelist. */ | |
| 85 void event_changelist_init(struct event_changelist *changelist); | |
| 86 /** Remove every change in the changelist, and make corresponding changes | |
| 87 * in the event maps in the base. This function is generally used right | |
| 88 * after making all the changes in the changelist. */ | |
| 89 void event_changelist_remove_all(struct event_changelist *changelist, | |
| 90 struct event_base *base); | |
| 91 /** Free all memory held in a changelist. */ | |
| 92 void event_changelist_freemem(struct event_changelist *changelist); | |
| 93 | |
| 94 /** Implementation of eventop_add that queues the event in a changelist. */ | |
| 95 int event_changelist_add(struct event_base *base, evutil_socket_t fd, short old, short events, | |
| 96 void *p); | |
| 97 /** Implementation of eventop_del that queues the event in a changelist. */ | |
| 98 int event_changelist_del(struct event_base *base, evutil_socket_t fd, short old, short events, | |
| 99 void *p); | |
| 100 | |
| 101 #endif |
