如何使用“管道”来促进 Perl 中的进程间通信？

Question

谁能解释我如何成功地让我的流程进行通信？我发现 IPC 上的 perldoc 令人困惑。

到目前为止我所拥有的是：

$| = 1;
$SIG{CHLD} = {wait};
my $parentPid = $$;

if ($pid = fork();) ) {
    if ($pid == 0) {
       pipe($parentPid, $$);
       open PARENT, "<$parentPid";
       while (<PARENT>) {
           print $_;
       }
       close PARENT;
       exit();
    } else {

       pipe($parentPid, $pid);
       open CHILD, ">$pid";
          or error("\nError opening: childPid\nRef: $!\n");
       open (FH, "<list")
          or error("\nError opening: list\nRef: $!\n");

       while(<FH>) {
          print CHILD, $_;
       }

       close FH
          or error("\nError closing: list\nRef: $!\n");
       close CHILD
          or error("\nError closing: childPid\nRef: $!\n);
    } else {
    error("\nError forking\nRef: $!\n");
}

• 首先：perldoc pipe 中的READHANDLE、WRITEHANDLE 是什么意思？

• 第二：我能否在不依赖 CPAN 或其他模块的情况下实施解决方案？

_{（来源：wellho.net）}

Answer 1

这是一个基于perldoc perlipc 中的代码的简化示例：

#!/usr/bin/perl

use strict; use warnings;

$SIG{CHLD} = sub { wait };

pipe my $reader, my $writer;

my $pid = fork;
defined $pid or die "fork failed: $!";

if ( $pid ) { # parent
    close $reader;
    for my $n ( 1 .. 5 ) {
        select $writer;
        $| = 1;
        print $writer "Message $n\n"
            or die "Failed to pass message to child: $!";
        sleep 1;
    }
    close $writer;
    exit;
}
else { # child
    close $writer;
    while ( my $msg = <$reader> ) {
        print "Child received: $msg";
        last if rand > 0.5; # to check error handling in parent
    }
    close $reader;
    exit;
}