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Diffstat (limited to 'libs/libevent/src/changelist-internal.h')
| -rw-r--r-- | libs/libevent/src/changelist-internal.h | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/libs/libevent/src/changelist-internal.h b/libs/libevent/src/changelist-internal.h new file mode 100644 index 0000000000..98fc52aebf --- /dev/null +++ b/libs/libevent/src/changelist-internal.h @@ -0,0 +1,102 @@ +/* + * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#ifndef CHANGELIST_INTERNAL_H_INCLUDED_ +#define CHANGELIST_INTERNAL_H_INCLUDED_ + +/* + A "changelist" is a list of all the fd status changes that should be made + between calls to the backend's dispatch function. There are a few reasons + that a backend would want to queue changes like this rather than processing + them immediately. + + 1) Sometimes applications will add and delete the same event more than + once between calls to dispatch. Processing these changes immediately + is needless, and potentially expensive (especially if we're on a system + that makes one syscall per changed event). + + 2) Sometimes we can coalesce multiple changes on the same fd into a single + syscall if we know about them in advance. For example, epoll can do an + add and a delete at the same time, but only if we have found out about + both of them before we tell epoll. + + 3) Sometimes adding an event that we immediately delete can cause + unintended consequences: in kqueue, this makes pending events get + reported spuriously. + */ + +#include "event2/util.h" + +/** Represents a */ +struct event_change { + /** The fd or signal whose events are to be changed */ + evutil_socket_t fd; + /* The events that were enabled on the fd before any of these changes + were made. May include EV_READ or EV_WRITE. */ + short old_events; + + /* The changes that we want to make in reading and writing on this fd. + * If this is a signal, then read_change has EV_CHANGE_SIGNAL set, + * and write_change is unused. */ + ev_uint8_t read_change; + ev_uint8_t write_change; + ev_uint8_t close_change; +}; + +/* Flags for read_change and write_change. */ + +/* If set, add the event. */ +#define EV_CHANGE_ADD 0x01 +/* If set, delete the event. Exclusive with EV_CHANGE_ADD */ +#define EV_CHANGE_DEL 0x02 +/* If set, this event refers a signal, not an fd. */ +#define EV_CHANGE_SIGNAL EV_SIGNAL +/* Set for persistent events. Currently not used. */ +#define EV_CHANGE_PERSIST EV_PERSIST +/* Set for adding edge-triggered events. */ +#define EV_CHANGE_ET EV_ET + +/* The value of fdinfo_size that a backend should use if it is letting + * changelist handle its add and delete functions. */ +#define EVENT_CHANGELIST_FDINFO_SIZE sizeof(int) + +/** Set up the data fields in a changelist. */ +void event_changelist_init_(struct event_changelist *changelist); +/** Remove every change in the changelist, and make corresponding changes + * in the event maps in the base. This function is generally used right + * after making all the changes in the changelist. */ +void event_changelist_remove_all_(struct event_changelist *changelist, + struct event_base *base); +/** Free all memory held in a changelist. */ +void event_changelist_freemem_(struct event_changelist *changelist); + +/** Implementation of eventop_add that queues the event in a changelist. */ +int event_changelist_add_(struct event_base *base, evutil_socket_t fd, short old, short events, + void *p); +/** Implementation of eventop_del that queues the event in a changelist. */ +int event_changelist_del_(struct event_base *base, evutil_socket_t fd, short old, short events, + void *p); + +#endif |