NAME AnyEvent::Open3::Simple - interface to open3 under AnyEvent VERSION version 0.74 SYNOPSIS use v5.10; use AnyEvent; use AnyEvent::Open3::Simple; my $done = AnyEvent->condvar; my $ipc = AnyEvent::Open3::Simple->new( on_start => sub { my $proc = shift; # isa AnyEvent::Open3::Simple::Process say 'child PID: ', $proc->pid; }, on_stdout => sub { my $proc = shift; # isa AnyEvent::Open3::Simple::Process my $line = shift; # string say 'out: ', $string; }, on_stderr => sub { my $proc = shift; # isa AnyEvent::Open3::Simple::Process my $line = shift; # string say 'err: ', $line; }, on_exit => sub { my $proc = shift; # isa AnyEvent::Open3::Simple::Process my $exit_value = shift; # integer my $signal = shift; # integer say 'exit value: ', $exit_value; say 'signal: ', $signal; $done->send; }, on_error => sub { my $error = shift; # the exception thrown by IPC::Open3::open3 warn "error: $error"; $done->send; }, ); $ipc->run('echo', 'hello there'); $done->recv; DESCRIPTION This module provides an interface to open3 while running under AnyEvent that delivers data from stdout and stderr as lines are written by the subprocess. The interface is reminiscent of IPC::Open3::Simple, although this module does provides a somewhat different API, so it cannot be used a drop in replacement for that module. There are already a number of interfaces for interacting with subprocesses in the context of AnyEvent, but this one is the most convenient for my usage. Note the modules listed in the SEE ALSO section below for other interfaces that may be more or less appropriate. CONSTRUCTOR Constructor takes a hash or hashref of event callbacks and attributes. Event callbacks have an "on_" prefix, attributes do not. ATTRIBUTES * implementation The implementation to use for detecting process termination. This should be one of "child" or "idle". On all platforms except for Microsoft Windows (but not Cygwin) the default is "child". You can change the default by setting the "ANYEVENT_OPEN3_SIMPLE" environment variable, like this: % export ANYEVENT_OPEN3_SIMPLE=idle EVENTS These events will be triggered by the subprocess when the run method is called. Each event callback (except "on_error") gets passed in an instance of AnyEvent::Open3::Simple::Process as its first argument which can be used to get the PID of the subprocess, or to write to it. "on_error" does not get a process object because it indicates an error in the creation of the process. Not all of these events will fire depending on the execution of the child process. In the very least exactly one of "on_start" or "on_error" will be called. * "on_start" ($proc) Called after the process is created, but before the run method returns (that is, it does not wait to re-enter the event loop first). * "on_error" ($error) Called when there is an execution error, for example, if you ask to run a program that does not exist. No process is passed in because the process failed to create. The error passed in is the error thrown by IPC::Open3 (typically a string which begins with "open3: ..."). In some environments open3 is unable to detect exec errors in the child, so you may not be able to rely on this event. It does seem to work consistently on Perl 5.14 or better though. Different environments have different ways of handling it when you ask to run a program that doesn't exist. On Linux and Cygwin, this will raise an "on_error" event, on "MSWin32" it will not trigger a "on_error" and instead cause a normal exit with a exit value of 1. * "on_stdout" ($proc, $line) Called on every line printed to stdout by the child process. * "on_stderr" ($proc, $line) Called on every line printed to stderr by the child process. * "on_exit" ($proc, $exit_value, $signal) Called when the processes completes, either because it called exit, or if it was killed by a signal. * "on_success" ($proc) Called when the process returns zero exit value and is not terminated by a signal. * "on_signal" ($proc, $signal) Called when the processes is terminated by a signal. * "on_fail" ($proc, $exit_value) Called when the process returns a non-zero exit value. METHODS $ipc->run($program, @arguments) Start the given program with the given arguments. Returns immediately. Any events that have been specified in the constructor (except for "on_start") will not be called until the process re-enters the event loop. CAVEATS Some AnyEvent implementations may not work properly with the method used by AnyEvent::Open3::Simple to wait for the child process to terminate. See "CHILD-PROCESS-WATCHERS" in AnyEvent for details. This module uses an idle watcher instead of a child watcher to detect program termination on Microsoft Windows (but not Cygwin). This is because the child watchers are unsupported by AnyEvent on Windows. The idle watcher implementation seems to pass the test suite, but there may be some traps for the unwary. There may be other platforms or event loops where this is the appropriate choice, and you can use the "ANYEVENT_OPEN3_SIMPLE" environment variable or the "implementation" attribute to force it use an idle watcher instead. Patches for detecting environments where idle watchers should be used are welcome and encouraged. The pure perl implementation that comes with Perl (AnyEvent::Impl::Perl) does not seem to work with this module on Microsoft Windows so I make EV a prereq on that platform (which does work). Writing to a subprocesses stdin via AnyEvent::Open3::Simple::Process's "print" method is unsupported on Microsoft Windows (it does work under Cygwin though). There are some traps for the unwary relating to buffers and deadlocks, IPC::Open3 is recommended reading. If you register a call back for "on_exit", but not "on_error" then use a condition variable to wait for the process to complete as in this: my $cv = AnyEvent->condvar; my $ipc = AnyEvent::Open3::Simple->new( on_exit => sub { $cv->send }, ); $ipc->run('command_not_found'); $cv->recv; You might be waiting forever if there is an error starting the process (if for example you give it a bad command). To handle this situation you might use croak on the condition variable in the event of error: my $cv = AnyEvent->condvar; my $ipc = AnyEvent::Open3::Simple->new( on_exit => sub { $cv->send }, on_error => sub { my $error = shift; $cv->croak($error); }, ); $ipc->run('command_not_found'); $cv->recv; This will cause the "recv" to die, printing a useful diagnostic if the exception isn't caught somewhere else. SEE ALSO AnyEvent::Subprocess, AnyEvent::Util, AnyEvent::Run. AUTHOR author: Graham Ollis contributors: Stephen R. Scaffidi COPYRIGHT AND LICENSE This software is copyright (c) 2012 by Graham Ollis. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.