++ed by:
EGOR SYP PINGAN

3 PAUSE users

Author image Felipe Gasper
and 1 contributors

NAME

Net::Curl::Promiser - Asynchronous libcurl, the easy way!

DESCRIPTION

Net::Curl::Multi is powerful but tricky to use: polling, callbacks, timers, etc. This module does all of that for you and puts a Promise interface on top of it, so asynchronous I/O becomes almost as simple as synchronous I/O.

Net::Curl::Promiser itself is a base class; you’ll need to use a subclass that works with your chosen event interface.

This distribution provides the following usable subclasses:

If the event interface you want to use isn’t compatible with one of the above, you’ll need to create your own Net::Curl::Promiser subclass. This is undocumented but pretty simple; have a look at the ones above as well as another based on Linux’s epoll(7) in the distribution’s /examples.

MEMORY LEAK DETECTION

This module will, by default, warn() if its objects are DESTROY()ed during Perl’s global destruction phase. To suppress this behavior, set $Net::Curl::Promiser::IGNORE_MEMORY_LEAKS to a truthy value.

PROMISE IMPLEMENTATION

This class’s default Promise implementation is Promise::ES6. You can use a different one by overriding the PROMISE_CLASS() method in a subclass, as long as the substitute class’s new() method works the same way as Promise::ES6’s (which itself follows the ECMAScript standard).

(NB: Net::Curl::Promiser::Mojo uses Mojo::Promise instead of Promise::ES6.)

Experimental Promise::XS support

Try out experimental Promise::XS support by running with NET_CURL_PROMISER_PROMISE_ENGINE=Promise::XS in your environment. This will override PROMISE_CLASS().

DESIGN NOTES

Internally each instance of this class uses an instance of Net::Curl::Multi and an instance of Net::Curl::Promiser::Backend. (The latter, in turn, is subclassed to provide logic specific to each event interface.) These are kept separate to avoid circular references.

GENERAL-USE METHODS

The following are of interest to any code that uses this module:

CLASS->new(@ARGS)

Instantiates this class, including creation of an underlying Net::Curl::Multi object.

promise($EASY) = OBJ->add_handle( $EASY )

A passthrough to the underlying Net::Curl::Multi object’s method of the same name, but the return is given as a Promise object.

That promise resolves with the passed-in $EASY object. It rejects with either the error given to fail_handle() or the error that Net::Curl::Multi object’s info_read() returns.

IMPORTANT: As with libcurl itself, HTTP-level failures (e.g., 4xx and 5xx responses) are NOT considered failures at this level.

$obj = OBJ->cancel_handle( $EASY )

Prematurely cancels $EASY. The associated promise will be abandoned in pending state, never to resolve nor reject.

Returns OBJ.

$obj = OBJ->fail_handle( $EASY, $REASON )

Like cancel_handle() but rejects $EASY’s associated promise with the given $REASON.

Returns OBJ.

$obj = OBJ->setopt( … )

A passthrough to the underlying Net::Curl::Multi object’s method of the same name. Returns OBJ to facilitate chaining.

This class requires control of certain Net::Curl::Multi options; if you attempt to set one of these here you’ll get an exception.

$obj = OBJ->handles( … )

A passthrough to the underlying Net::Curl::Multi object’s method of the same name.

EXAMPLES

See the distribution’s /examples directory.

SEE ALSO

Net::Curl::Simple implements a similar idea to this module but doesn’t return promises. It has a more extensive interface that provides a more “perlish” experience than Net::Curl::Easy.

If you use AnyEvent, then AnyEvent::XSPromises with AnyEvent::YACurl may be a nicer fit for you.

REPOSITORY

https://github.com/FGasper/p5-Net-Curl-Promiser

LICENSE & COPYRIGHT

Copyright 2019-2020 Gasper Software Consulting.

This library is licensed under the same terms as Perl itself.