fceabb2498
This is a fairly intrusive change, but outside of the moving of opal/event to opal/mca/event, the only changes involved (a) changing all calls to opal_event functions to reflect the new framework instead, and (b) ensuring that all opal_event_t objects are properly constructed since they are now true opal_objects. Note: Shiqing has just returned from vacation and has not yet had a chance to complete the Windows integration. Thus, this commit almost certainly breaks Windows support on the trunk. However, I want this to have a chance to soak for as long as possible before I become less available a week from today (going to be at a class for 5 days, and thus will only be sparingly available) so we can find and fix any problems. Biggest change is moving the libevent code from opal/event to a new opal/mca/event framework. This was done to make it much easier to update libevent in the future. New versions can be inserted as a new component and tested in parallel with the current version until validated, then we can remove the earlier version if we so choose. This is a statically built framework ala installdirs, so only one component will build at a time. There is no selection logic - the sole compiled component simply loads its function pointers into the opal_event struct. I have gone thru the code base and converted all the libevent calls I could find. However, I cannot compile nor test every environment. It is therefore quite likely that errors remain in the system. Please keep an eye open for two things: 1. compile-time errors: these will be obvious as calls to the old functions (e.g., opal_evtimer_new) must be replaced by the new framework APIs (e.g., opal_event.evtimer_new) 2. run-time errors: these will likely show up as segfaults due to missing constructors on opal_event_t objects. It appears that it became a typical practice for people to "init" an opal_event_t by simply using memset to zero it out. This will no longer work - you must either OBJ_NEW or OBJ_CONSTRUCT an opal_event_t. I tried to catch these cases, but may have missed some. Believe me, you'll know when you hit it. There is also the issue of the new libevent "no recursion" behavior. As I described on a recent email, we will have to discuss this and figure out what, if anything, we need to do. This commit was SVN r23925.
207 строки
8.0 KiB
C
207 строки
8.0 KiB
C
/*
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* Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
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* Copyright (c) 2007-2010 Niels Provos and Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _EVENT_H_
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#define _EVENT_H_
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/** @mainpage
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@section intro Introduction
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libevent is an event notification library for developing scalable network
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servers. The libevent API provides a mechanism to execute a callback
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function when a specific event occurs on a file descriptor or after a
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timeout has been reached. Furthermore, libevent also support callbacks due
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to signals or regular timeouts.
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libevent is meant to replace the event loop found in event driven network
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servers. An application just needs to call event_dispatch() and then add or
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remove events dynamically without having to change the event loop.
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Currently, libevent supports /dev/poll, kqueue(2), select(2), poll(2) and
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epoll(4). It also has experimental support for real-time signals. The
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internal event mechanism is completely independent of the exposed event API,
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and a simple update of libevent can provide new functionality without having
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to redesign the applications. As a result, Libevent allows for portable
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application development and provides the most scalable event notification
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mechanism available on an operating system. Libevent can also be used for
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multi-threaded applications; see Steven Grimm's explanation. Libevent should
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compile on Linux, *BSD, Mac OS X, Solaris and Windows.
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@section usage Standard usage
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Every program that uses libevent must include the <event.h> header, and pass
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the -levent flag to the linker. Before using any of the functions in the
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library, you must call event_init() or event_base_new() to perform one-time
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initialization of the libevent library.
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@section event Event notification
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For each file descriptor that you wish to monitor, you must declare an event
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structure and call event_set() to initialize the members of the structure.
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To enable notification, you add the structure to the list of monitored
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events by calling event_add(). The event structure must remain allocated as
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long as it is active, so it should be allocated on the heap. Finally, you
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call event_dispatch() to loop and dispatch events.
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@section bufferevent I/O Buffers
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libevent provides an abstraction on top of the regular event callbacks. This
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abstraction is called a buffered event. A buffered event provides input and
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output buffers that get filled and drained automatically. The user of a
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buffered event no longer deals directly with the I/O, but instead is reading
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from input and writing to output buffers.
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Once initialized via bufferevent_new(), the bufferevent structure can be
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used repeatedly with bufferevent_enable() and bufferevent_disable().
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Instead of reading and writing directly to a socket, you would call
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bufferevent_read() and bufferevent_write().
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When read enabled the bufferevent will try to read from the file descriptor
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and call the read callback. The write callback is executed whenever the
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output buffer is drained below the write low watermark, which is 0 by
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default.
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@section timers Timers
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libevent can also be used to create timers that invoke a callback after a
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certain amount of time has expired. The evtimer_set() function prepares an
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event struct to be used as a timer. To activate the timer, call
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evtimer_add(). Timers can be deactivated by calling evtimer_del().
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@section timeouts Timeouts
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In addition to simple timers, libevent can assign timeout events to file
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descriptors that are triggered whenever a certain amount of time has passed
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with no activity on a file descriptor. The timeout_set() function
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initializes an event struct for use as a timeout. Once initialized, the
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event must be activated by using timeout_add(). To cancel the timeout, call
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timeout_del().
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@section evdns Asynchronous DNS resolution
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libevent provides an asynchronous DNS resolver that should be used instead
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of the standard DNS resolver functions. These functions can be imported by
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including the <evdns.h> header in your program. Before using any of the
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resolver functions, you must call evdns_init() to initialize the library. To
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convert a hostname to an IP address, you call the evdns_resolve_ipv4()
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function. To perform a reverse lookup, you would call the
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evdns_resolve_reverse() function. All of these functions use callbacks to
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avoid blocking while the lookup is performed.
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@section evhttp Event-driven HTTP servers
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libevent provides a very simple event-driven HTTP server that can be
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embedded in your program and used to service HTTP requests.
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To use this capability, you need to include the <evhttp.h> header in your
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program. You create the server by calling evhttp_new(). Add addresses and
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ports to listen on with evhttp_bind_socket(). You then register one or more
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callbacks to handle incoming requests. Each URI can be assigned a callback
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via the evhttp_set_cb() function. A generic callback function can also be
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registered via evhttp_set_gencb(); this callback will be invoked if no other
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callbacks have been registered for a given URI.
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@section evrpc A framework for RPC servers and clients
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libevent provides a framework for creating RPC servers and clients. It
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takes care of marshaling and unmarshaling all data structures.
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@section api API Reference
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To browse the complete documentation of the libevent API, click on any of
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the following links.
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event2/event.h
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The primary libevent header
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event2/buffer.h
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Buffer management for network reading and writing
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event2/dns.h
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Asynchronous DNS resolution
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event2/http.h
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An embedded libevent-based HTTP server
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evrpc.h
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A framework for creating RPC servers and clients
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*/
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/** @file libevent/event.h
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A library for writing event-driven network servers
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <event2/event-config.h>
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#ifdef _EVENT_HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef _EVENT_HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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#ifdef _EVENT_HAVE_STDINT_H
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#include <stdint.h>
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#endif
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#include <stdarg.h>
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/* For int types. */
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#include <evutil.h>
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#ifdef WIN32
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#ifndef WIN32_LEAN_AND_MEAN
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#define WIN32_LEAN_AND_MEAN
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#endif
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#include <winsock2.h>
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#include <windows.h>
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#undef WIN32_LEAN_AND_MEAN
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typedef unsigned char u_char;
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typedef unsigned short u_short;
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#endif
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#include <event2/event_struct.h>
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#include <event2/event.h>
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#include <event2/event_compat.h>
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#include <event2/buffer.h>
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#include <event2/buffer_compat.h>
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#include <event2/bufferevent.h>
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#include <event2/bufferevent_struct.h>
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#include <event2/bufferevent_compat.h>
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#include <event2/tag.h>
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#include <event2/tag_compat.h>
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#ifdef __cplusplus
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}
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#endif
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#endif /* _EVENT_H_ */
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