Perl AnyEvent中的watcher实例

这几天看了下perl的事件编程框架AnyEvent,重点参考了一下几篇文章:

http://search.cpan.org/~mlehmann/AnyEvent-7.05/lib/AnyEvent.pm

http://search.cpan.org/~mlehmann/AnyEvent-7.05/lib/AnyEvent/Intro.pod

//www.jb51.net/article/55278.htm

1、什么是事件编程?

举个简单的例子,你浏览网页的时候,你点击一个图片,蹭的弹出一个东西,你不点,那就在那里,等待一个人来点它。如果你写过js,其实就是,你注册了很多的时间比如click,dbclick,keybord,submit等,那么浏览器就起到帮我们去监听这些事件的发生(Loop)。当有对应的事件发生的时候,我们也一般也设置了callback,比如onclick,onsubmit等,去响应这些事件,这基本就是事件编程的一个缩影了。

2、perl AnyEvent中的watcher

在AnyEvent中有5中watcher,分别是IO,timer,signal, child, idle.

2.1 io watcher

代码如下:

#!/usr/bin/perl

 

use AnyEvent;

my $cv = AnyEvent->condvar;

 

#open my $file , '<' , 'test.txt' or die "$!" ;

open F , '<' , 'test.txt' or die "$!" ;

my $io_watcher = AnyEvent->io (

      fh   => *F,

      poll => 'r',

      cb   => sub {

         chomp (my $input = sysread F ,my $buf ,1024); # read a line

 

         warn "read: $buf\n"  if $input >0 ;       # output what has been read

         #$cv->send if /quit/ ; # quit program if /quit/i

      },

   );

 

$cv->recv; # wait until user enters /quit/i

timer watcher

AnyEvent 的timer的一部分其实像javascript的setInterval :

代码如下:

#!/usr/bin/perl

 

use 5.016;

use AnyEvent ;

 

my $cv = AnyEvent->condvar ;

 

my $w = AnyEvent->timer(

    after => 0 ,  #多少秒之后触发事件

    interval => 2 ,  #多少秒触发事件

    cb => sub {

        say AnyEvent->time ," ",AnyEvent->now ;

 

    }

);

 

$cv->recv;

signal watcher

前面我们在的文章中写到了perl中对于信号的处理 《perl信号处理简单学习》,这里主要是AnyEvent中对于这些事件的处理。

代码如下:

#!/usr/bin/perl

 

use 5.016;

use AnyEvent ;

#say for keys %SIG; 看一下又多少信号

my $cv = AnyEvent->condvar ;

 

my $w = AnyEvent->signal(

    signal => 'INT',

    cb => sub {

        say AnyEvent->time ," ",AnyEvent->now ;

        exit 1 ;

 

    }

);

 

$cv->recv;

child watcher

代码如下:

#!/usr/bin/perl

use AnyEvent;

   my $done = AnyEvent->condvar;

 

   my $pid = fork or exit 5;

 

   my $w = AnyEvent->child (

      pid => $pid,

      cb  => sub {

         my ($pid, $status) = @_;

         warn "pid $pid exited with status $status";

         $done->send;

      },

   );

 

   # do something else, then wait for process exit

   $done->recv;

idle watcher

就是如果main loop在空闲的时候做些什么呢?

代码如下:

#!/usr/bin/perl 

use AnyEvent;

   my @lines; # read data

   my $idle_w;

   $cv = AnyEvent->condvar;

   my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {

      push @lines, scalar <STDIN>;

 

      # start an idle watcher, if not already done

      $idle_w ||= AnyEvent->idle (cb => sub {

         # handle only one line, when there are lines left

         if (my $line = shift @lines) {

            print "handled when idle: $line";

         } else {

            # otherwise disable the idle watcher again

            undef $idle_w;

         }

      });

   });

 

   $cv->recv;

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