perl中recv介绍

今天才发现perl中的recv函数竟然不会因为没有满足指定长度而阻塞！这要是在C中，必须将socket设置成了non-block以后，才会在没有满足指定数据长度也会返回，通过fcntl可以判断在recv前后，socket描述符前后都是block状态的， 所以应该是perl在封装recv的时候，将socket先设置成non-block， 返回数据之前又将socket设置成block，而且socket buffer中的数据至少为1个字节，否则才会阻塞。

 

recv SOCKET,SCALAR,LENGTH,FLAGS

Receives a message on a socket. Attempts to receive LENGTH charactersof data into variable SCALAR from the specified SOCKET filehandle.SCALAR will be grown or shrunk to the length actually read.

 

fcntl FILEHANDLE,FUNCTION,SCALAR

 

===========================================FILE: server.pl===========================================#!/usr/bin/perl -wuse strict;use IO::Socket;my $message = undef;my $server = undef;my $ret = undef;my $lsock = IO::Socket::INET->new(LocalPort => 4444, Type => SOCK_STREAM, Reuse => 1, Listen => 10 ) or die "Couldn't be a tcp server on port 4444 : $@/n";$server = $lsock->accept();while(1) { $ret = $server->recv($message, 4000); printf "$message: %d/n", length($message);}close($server);close($lsock);===========================================FILE: client.pl===========================================#!/usr/bin/perl -wuse strict;use IO::Socket;my $message = undef;my $client = undef;$client = IO::Socket::INET->new(PeerAddr => "localhost", PeerPort => 4444, Proto => "tcp", Type => SOCK_STREAM) or die "Couldn't connect to localhost:4444 : $@/n";while(<STDIN>) { $message = $_; chomp($message); $client->send($message);}close($client);