Simple use cases for PHP libevent extensions

The PHP libevent extension has a very powerful feature. The following excerpt from Baidu Encyclopedia:

Libevent is a C language, lightweight open-source high-performance network library, mainly has the following several highlights: event-driven (Event-driven), high-performance, lightweight, focus on the network, not as large as ACE;

The source code is quite refined, easy to read, cross-platform, support Windows, Linux, *bsd and Mac Os, support multiple I/O multiplexing technology, Epoll, poll, Dev/poll, select and Kqueue, etc., support I/O,

Events such as timers and signals; Register event priority.

The libevent extension in PHP has the following functions:

Event_base_free () frees the resource, which cannot destroy the binding event
Event_base_loop () Handles events and handles event loops based on the specified base
Event_base_loopbreak () immediately cancels the event loop, with the same behavior as the break statement
Event_base_loopexit () exits the loop after a specified time
Event_base_new () creation and initial events
Event_base_priority_init () Sets the priority of the event
Event_base_set () Associating events to event base
Event_buffer_base_set () Associating cached events to Event_base
Event_buffer_disable () disabling a cached event
Event_buffer_enable () enable a specified cached event
Event_buffer_fd_set () Change the file system description of a cache
Event_buffer_free () releasing cache events
Event_buffer_new () to create a new cache event
Event_buffer_priority_set () Priority setting for cache events
Event_buffer_read () reading data from a cache event
Event_buffer_set_callback () Sets or resets the callback Hansh function to the cached event
Event_buffer_timeout_set () sets the read and write time to timeout for a cached event
Event_buffer_watermark_set setting watermark flags for read and write events
Event_buffer_write () writes data to the cache event
Event_add () Adds an execution event to the specified settings
Event_del () Removing events from the set events
Event_free () empty event handle
Event_new () Create a new event
Event_set () Prepare to add an event in Event_add

Event_set explanation of some parameters:

(a) Ev_timeout: timeout
(b) Ev_read: As long as there is data in the network buffer, the callback function is triggered
(c) Ev_write: The callback function is triggered whenever the data that is plugged into the network buffer is written out
(d) ev_signal:posix signal volume
(e) Ev_persist: If this attribute is not specified, the event will be deleted after the callback function is triggered
(f) Ev_et:edge-trigger edge triggering

Let's take a look at a simple use case:

123456789101112131415161718192021222324

<?php$socket = stream_socket_server("tcp://0.0.0.0:8000", $errno, $errstr);$base= event_base_new();$event= event_new();functionread_cb($socket, $flag, $base) {　　fread($socket);   fwrite("hello world\n");}functionaccept_cb($socket, $flag, $base) {    $conn= stream_socket_accept($socket, 0);    stream_set_blocking($conn, 0);    $event= event_new();    event_set($event, $conn, EV_READ | EV_PERSIST, ‘read_cb‘, $base);    event_base_set($event, $base);    event_add($event);}event_set($event, $socket, EV_READ | EV_PERSIST, ‘accept_cb‘, $base);event_base_set($event, $base);event_add($event);event_base_loop($base);

This paragraph is a simple use case of a PPT from Hantian, let me explain to you:

First, create a TCP service that binds 8000 ports. Create a event_base, and then create an event that allows the event to listen to the newly created socket via the Event_set settings and set the properties for the event, and you can see that the callback function is specified ACCEPT_CB

This event is then bound to base and added to the listener event to initiate the events loop.

It can be found that ACCEPT_CB has accepted the client link and created an event to do the same thing as before, and the callback function that specifies the event is READ_CB. The READ_CB function does a read and write operation.

Below I myself by finishing writing a client client.php

123456789101112131415

<?php/** * author: NickBai * createTime: 2016/12/17 0017 下午 3:00 */$socket_client= stream_socket_client(‘tcp://127.0.0.1:2000‘, $errno, $errstr, 30);fwrite($socket_client, "hello world!");sleep(1);$return= fread($socket_client, 1024);echo"come from server : ". $return. PHP_EOL;sleep(2);fwrite($socket_client, "send again!");$return= fread($socket_client, 1024);echo"come from server : ". $return. PHP_EOL;

I've re-organized a server service-side code with actual operations as follows

server.php

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162

<?php/** * Created by PhpStorm. * User: Administrator * Date: 2016/12/17 * Time: 20:59 */$socket= stream_socket_server("tcp://0.0.0.0:2000", $errno, $errstr);$base= event_base_new();$event= event_new();event_set($event, $socket, EV_READ | EV_PERSIST, ‘accept_cb‘, $base);event_base_set($event, $base);event_add($event);event_base_loop($base);functionread_cb($buffer){    static$ct= 0;     $ct_last= $ct;     $ct_data= ‘‘;     while($read = event_buffer_read($buffer, 1024)) {         $ct+= strlen($read);         $ct_data.= $read;     }    $ct_size= ($ct- $ct_last) * 8;     echo"client say : ". $ct_data.PHP_EOL;     event_buffer_write($buffer, "Received $ct_size byte data");}functionwrite_cb($buffer){    echo"我在打酱油 ". PHP_EOL;} functionerror_cb($buffer, $error){    // 客户端断开连接之后,清除    event_buffer_disable($GLOBALS[‘buffer‘], EV_READ | EV_WRITE);     event_buffer_free($GLOBALS[‘buffer‘]);     fclose($GLOBALS[‘connection‘]);     unset($GLOBALS[‘buffer‘], $GLOBALS[‘connection‘]); }functionaccept_cb($socket, $flag, $base){    $connection= stream_socket_accept($socket);    stream_set_blocking($connection, 0);    $buffer= event_buffer_new($connection, ‘read_cb‘, ‘write_cb‘, ‘error_cb‘);     event_buffer_base_set($buffer, $base);     event_buffer_timeout_set($buffer, 30, 30);     event_buffer_watermark_set($buffer, EV_READ, 0, 0xffffff);     event_buffer_priority_set($buffer, 10);     event_buffer_enable($buffer, EV_READ | EV_PERSIST);     // 必须将 $connection 和 $buffer 赋值给一个全局变量，否则无法生效    $GLOBALS[‘connection‘] = $connection;    $GLOBALS[‘buffer‘] = $buffer; }

Simple use cases for PHP libevent extensions