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=head1 NAME |
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Coro::LWP - make LWP non-blocking - as much as possible |
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=head1 SYNOPSIS |
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use Coro::LWP; # afterwards LWP should not block |
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=head1 ALTERNATIVES |
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Over the years, a number of less-invasive alternatives have popped up, |
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which you might find more acceptable than this rather invasive and fragile |
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module. All of them only support HTTP (and sometimes HTTPS). |
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=over 4 |
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=item L<AnyEvent::HTTP> |
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|
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Works fine without Coro. Requires using a very different API than |
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LWP. Probably the best choice I<iff> you can do with a completely |
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different event-based API. |
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|
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=item L<LWP::Protocol::AnyEvent::http> |
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Makes LWP use L<AnyEvent::HTTP>. Does not make LWP event-based, but allows |
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Coro threads to schedule unimpeded through its AnyEvent integration. |
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Lets you use the LWP API normally. |
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=item L<LWP::Protocol::Coro::http> |
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Basically the same as above, distinction unclear. :) |
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=item L<AnyEvent::HTTP::LWP::UserAgent> |
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A different user agent implementation, not completely transparent to |
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users, requires Coro. |
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=back |
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|
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=head1 DESCRIPTION |
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|
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This module is an L<AnyEvent> user, you need to make sure that you use and |
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run a supported event loop. |
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This module tries to make L<LWP|LWP> non-blocking with respect to other |
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coroutines as much as possible, and with whatever means it takes. |
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LWP really tries very hard to be blocking (and relies on a lot of |
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undocumented functionality in IO::Socket), so this module had to be very |
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invasive and must be loaded very early to take the proper effect. |
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|
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Note that the module L<AnyEvent::HTTP> might offer an alternative to the |
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full L<LWP> that is designed to be non-blocking. |
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Here is what it currently does (future versions of LWP might require |
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different tricks): |
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|
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=over 4 |
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=item It loads Coro::Select, overwriting the perl C<select> builtin I<globally>. |
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This is necessary because LWP calls select quite often for timeouts and |
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who-knows-what. |
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Impact: everybody else uses this (slower) version of select, too. It should be quite |
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compatible to perls builtin select, though. |
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=item It overwrites Socket::inet_aton with Coro::Util::inet_aton. |
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This is necessary because LWP might (and does) try to resolve hostnames |
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this way. |
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Impact: some code might not expect coroutine semantics, for example, when |
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you fork you might prefer the blocking variant because other coroutines |
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shouldn't actually run. |
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|
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=item It replaces the base class of Net::HTTP, Net::FTP, Net::NNTP. |
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This is necessary because LWP does not always use select to see whether |
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a filehandle can be read/written without blocking, so the base class |
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C<IO::Socket::INET> needs to be replaced by C<Coro::Socket>. |
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Impact: Coro::Socket is not at all compatible to IO::Socket::INET. While |
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it duplicates some undocumented functionality required by LWP, it does not |
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have all the methods of IO::Socket::INET and might act quite differently |
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in practise. Also, protocols other than the above mentioned will still block, |
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at least some of the time. |
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=back |
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All this likely makes other libraries than just LWP not block, but that's |
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just a side effect you cannot rely on. |
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Increases parallelism is not supported by all libraries, some might cache |
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data globally. |
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=cut |
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|
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package Coro::LWP; |
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|
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use common::sense; |
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|
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BEGIN { |
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# suppress warnings |
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local $^W = 0; |
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require Net::Config; |
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} |
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# do it as early as possible |
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use Coro::Select; |
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|
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# import these so they can grab Socket::inet_aton |
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use AnyEvent::Util (); |
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use AnyEvent::DNS (); |
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|
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use Coro::Util (); |
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use Coro::Socket (); |
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use Coro::AnyEvent (); |
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use Socket (); |
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use IO::Socket::INET (); |
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use Net::HTTP (); |
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use Net::FTP (); |
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use Net::NNTP (); |
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our $VERSION = 6.57; |
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*Socket::inet_aton = \&Coro::Util::inet_aton; |
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for (@Net::HTTP::ISA, @Net::FTP::ISA, @Net::NTTP::ISA) { |
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$_ = Coro::LWP::Socket:: if $_ eq IO::Socket::INET::; |
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} |
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package Coro::LWP::Socket; |
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no warnings; |
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use base Coro::Socket::; |
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sub new { |
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my $self = shift; |
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|
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$self->SUPER::new (@_, partial => 1) |
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} |
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1; |
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=head1 AUTHOR/SUPPORT/CONTACT |
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|
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Marc A. Lehmann <schmorp@schmorp.de> |
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http://software.schmorp.de/pkg/Coro.html |
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|
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=cut |
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