如何让 DBD::Pg 可靠地超时？
为什么这段代码直到 $sth->execute 完成之后才执行信号处理程序？更重要的是，我该如何解决它？
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
use Sys::SigAction qw( set_sig_handler );
my $dbh = DBI->connect('dbi:Pg:dbname=dc');
eval {
my $h = set_sig_handler('ALRM', sub { die "timeout\n" });
eval {
alarm 1;
my $sth = $dbh->prepare("SELECT pg_sleep(10)");
print "Before execute\n";
$sth->execute;
print "After execute\n";
$sth->finish;
};
alarm 0;
die "$@" if $@;
};
die "$@" if $@;
print "Finished\n";
Why doesn't this code execute the signal handler until after $sth->execute completes? And more importantly, how can I fix it?
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
use Sys::SigAction qw( set_sig_handler );
my $dbh = DBI->connect('dbi:Pg:dbname=dc');
eval {
my $h = set_sig_handler('ALRM', sub { die "timeout\n" });
eval {
alarm 1;
my $sth = $dbh->prepare("SELECT pg_sleep(10)");
print "Before execute\n";
$sth->execute;
print "After execute\n";
$sth->finish;
};
alarm 0;
die "$@" if $@;
};
die "$@" if $@;
print "Finished\n";
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考虑使用 Pg 的异步查询功能。
Consider using Pg's asynchronous query feature instead.
由于 Perl 处理信号的方式发生了变化（从 5.8.0 开始称为“安全信号”），您需要使用 Perl::Unsafe::Signals 允许您的
die()在$sth-> 时工作;执行正在进行中。Due to changes in the way Perl handles signals (so-called "safe signals" as of 5.8.0), you'll need to use Perl::Unsafe::Signals to allow your
die()to work when$sth->executeis in progress.有 AnyEvent::Pg 允许异步查询 PostgreSQL，但它与 DBI 不兼容它会迫使您在 AnyEvent 之上重写您的应用程序/脚本。
There is AnyEvent::Pg that allows to query PostgreSQL asynchronously, though, it is not DBI compatible and it will force you to rewrite your app/script on top of AnyEvent.