处理WWW :: Mechanize中的GET错误

Question

我正在使用一个脚本，该脚本使用WWW :: Mechanize从网站上抓取数据，并且除了网站本身之外，其他所有功能都运行良好。 有时它只是暂时没有响应，并且对于给定的my $url = 'http://www.somesite.com/more/url/text'我在$mech->get($url) ：

Error GETing http://www.somesite.com/more/url/text: Can't connect to www.somesite.com:443 at ./trackSomesite.pl line 34.

此错误有时会以无法识别的模式偶尔发生，并且根据我与我正在处理的网站的经验，这是由于服务器不稳定。

我希望能够明确知道发生此错误，而不是其他错误（例如Too many requests 。 我的问题是如何使我的脚本处理该错误而不死？

Answer 1

将$mech->get(...)请求包装在一个eval块中，或者使用autocheck => 0 ，然后检查$mech->status代码和/或$mech->status_line来决定要做什么。

这是一个例子：

#!/usr/bin/env perl

use WWW::Mechanize;

use constant RETRY_MAX => 5;

my $url = 'http://www.xxsomesite.com/more/url/text'; # Cannot connect

my $mech = WWW::Mechanize->new( autocheck => 0 );

my $content = fetch($url);

sub fetch {
    my ($url) = @_;

    for my $retry (0 .. RETRY_MAX-1) {
        my $message = "Attempting to fetch [ $url ]";
        $message .= $retry ? " - retry $retry\n" : "\n";
        warn $message;

        my $response = $mech->get($url);
        return $response->content() if $response->is_success();

        my $status = $response->status;
        warn "status = $status\n";

        if ($response->status_line =~ /Can['']t connect/) {
            $retry++;
            warn "cannot connect...will retry after $retry seconds\n";
            sleep $retry;
        } elsif ($status == 429) {
            warn "too many requests...ignoring\n";
            return undef;
        } else {
            warn "something else...\n";
            return undef;
        }
    }

    warn "giving up...\n";
    return undef;
}

产量

Attempting to fetch [ http://www.xxsomesite.com/more/url/text ]
status = 500
cannot connect...will retry after 1 seconds
Attempting to fetch [ http://www.xxsomesite.com/more/url/text ] - retry 1
status = 500
cannot connect...will retry after 2 seconds
Attempting to fetch [ http://www.xxsomesite.com/more/url/text ] - retry 2
status = 500
cannot connect...will retry after 3 seconds
Attempting to fetch [ http://www.xxsomesite.com/more/url/text ] - retry 3
status = 500
cannot connect...will retry after 4 seconds
Attempting to fetch [ http://www.xxsomesite.com/more/url/text ] - retry 4
status = 500
cannot connect...will retry after 5 seconds
giving up...