ipc/chromium/src/third_party/libevent/changelist-internal.h@6474c204b198 (annotated)
ipc/chromium/src/third_party/libevent/changelist-internal.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson |
| michael@0 | 3 | * |
| michael@0 | 4 | * Redistribution and use in source and binary forms, with or without |
| michael@0 | 5 | * modification, are permitted provided that the following conditions |
| michael@0 | 6 | * are met: |
| michael@0 | 7 | * 1. Redistributions of source code must retain the above copyright |
| michael@0 | 8 | * notice, this list of conditions and the following disclaimer. |
| michael@0 | 9 | * 2. Redistributions in binary form must reproduce the above copyright |
| michael@0 | 10 | * notice, this list of conditions and the following disclaimer in the |
| michael@0 | 11 | * documentation and/or other materials provided with the distribution. |
| michael@0 | 12 | * 3. The name of the author may not be used to endorse or promote products |
| michael@0 | 13 | * derived from this software without specific prior written permission. |
| michael@0 | 14 | * |
| michael@0 | 15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| michael@0 | 16 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| michael@0 | 17 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| michael@0 | 18 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| michael@0 | 19 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| michael@0 | 20 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| michael@0 | 21 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| michael@0 | 22 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| michael@0 | 23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| michael@0 | 24 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 25 | */ |
| michael@0 | 26 | #ifndef _CHANGELIST_H_ |
| michael@0 | 27 | #define _CHANGELIST_H_ |
| michael@0 | 28 | |
| michael@0 | 29 | /* |
| michael@0 | 30 | A "changelist" is a list of all the fd status changes that should be made |
| michael@0 | 31 | between calls to the backend's dispatch function. There are a few reasons |
| michael@0 | 32 | that a backend would want to queue changes like this rather than processing |
| michael@0 | 33 | them immediately. |
| michael@0 | 34 | |
| michael@0 | 35 | 1) Sometimes applications will add and delete the same event more than |
| michael@0 | 36 | once between calls to dispatch. Processing these changes immediately |
| michael@0 | 37 | is needless, and potentially expensive (especially if we're on a system |
| michael@0 | 38 | that makes one syscall per changed event). |
| michael@0 | 39 | |
| michael@0 | 40 | 2) Sometimes we can coalesce multiple changes on the same fd into a single |
| michael@0 | 41 | syscall if we know about them in advance. For example, epoll can do an |
| michael@0 | 42 | add and a delete at the same time, but only if we have found out about |
| michael@0 | 43 | both of them before we tell epoll. |
| michael@0 | 44 | |
| michael@0 | 45 | 3) Sometimes adding an event that we immediately delete can cause |
| michael@0 | 46 | unintended consequences: in kqueue, this makes pending events get |
| michael@0 | 47 | reported spuriously. |
| michael@0 | 48 | */ |
| michael@0 | 49 | |
| michael@0 | 50 | #include "event2/util.h" |
| michael@0 | 51 | |
| michael@0 | 52 | /** Represents a */ |
| michael@0 | 53 | struct event_change { |
| michael@0 | 54 | /** The fd or signal whose events are to be changed */ |
| michael@0 | 55 | evutil_socket_t fd; |
| michael@0 | 56 | /* The events that were enabled on the fd before any of these changes |
| michael@0 | 57 | were made. May include EV_READ or EV_WRITE. */ |
| michael@0 | 58 | short old_events; |
| michael@0 | 59 | |
| michael@0 | 60 | /* The changes that we want to make in reading and writing on this fd. |
| michael@0 | 61 | * If this is a signal, then read_change has EV_CHANGE_SIGNAL set, |
| michael@0 | 62 | * and write_change is unused. */ |
| michael@0 | 63 | ev_uint8_t read_change; |
| michael@0 | 64 | ev_uint8_t write_change; |
| michael@0 | 65 | }; |
| michael@0 | 66 | |
| michael@0 | 67 | /* Flags for read_change and write_change. */ |
| michael@0 | 68 | |
| michael@0 | 69 | /* If set, add the event. */ |
| michael@0 | 70 | #define EV_CHANGE_ADD 0x01 |
| michael@0 | 71 | /* If set, delete the event. Exclusive with EV_CHANGE_ADD */ |
| michael@0 | 72 | #define EV_CHANGE_DEL 0x02 |
| michael@0 | 73 | /* If set, this event refers a signal, not an fd. */ |
| michael@0 | 74 | #define EV_CHANGE_SIGNAL EV_SIGNAL |
| michael@0 | 75 | /* Set for persistent events. Currently not used. */ |
| michael@0 | 76 | #define EV_CHANGE_PERSIST EV_PERSIST |
| michael@0 | 77 | /* Set for adding edge-triggered events. */ |
| michael@0 | 78 | #define EV_CHANGE_ET EV_ET |
| michael@0 | 79 | |
| michael@0 | 80 | /* The value of fdinfo_size that a backend should use if it is letting |
| michael@0 | 81 | * changelist handle its add and delete functions. */ |
| michael@0 | 82 | #define EVENT_CHANGELIST_FDINFO_SIZE sizeof(int) |
| michael@0 | 83 | |
| michael@0 | 84 | /** Set up the data fields in a changelist. */ |
| michael@0 | 85 | void event_changelist_init(struct event_changelist *changelist); |
| michael@0 | 86 | /** Remove every change in the changelist, and make corresponding changes |
| michael@0 | 87 | * in the event maps in the base. This function is generally used right |
| michael@0 | 88 | * after making all the changes in the changelist. */ |
| michael@0 | 89 | void event_changelist_remove_all(struct event_changelist *changelist, |
| michael@0 | 90 | struct event_base *base); |
| michael@0 | 91 | /** Free all memory held in a changelist. */ |
| michael@0 | 92 | void event_changelist_freemem(struct event_changelist *changelist); |
| michael@0 | 93 | |
| michael@0 | 94 | /** Implementation of eventop_add that queues the event in a changelist. */ |
| michael@0 | 95 | int event_changelist_add(struct event_base *base, evutil_socket_t fd, short old, short events, |
| michael@0 | 96 | void *p); |
| michael@0 | 97 | /** Implementation of eventop_del that queues the event in a changelist. */ |
| michael@0 | 98 | int event_changelist_del(struct event_base *base, evutil_socket_t fd, short old, short events, |
| michael@0 | 99 | void *p); |
| michael@0 | 100 | |
| michael@0 | 101 | #endif |
