Paul Evans > IPC-PerlSSH-Async-0.07 > IPC::PerlSSH::Async

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Module Version: 0.07   Source  

NAME ^

IPC::PerlSSH::Async - Asynchronous wrapper around IPC::PerlSSH

SYNOPSIS ^

Note: the constructor has changed since version 0.03.

 use IO::Async::Loop;
 use IPC::PerlSSH::Async;

 my $loop = IO::Async::Loop->new();

 my $ips = IPC::PerlSSH::Async->new(
    on_exception => sub { die "Failed - $_[0]\n" },

    Host => "over.there",
 );

 $loop->add( $ips );

 $ips->eval(
    code => "use POSIX qw( uname ); uname()",
    on_result => sub { print "Remote uname is ".join( ",", @_ )."\n"; },
 );

 # We can pass arguments
 $ips->eval( 
    code => 'open FILE, ">", shift; print FILE shift; close FILE;',
    args => [ "foo.txt", "Hello, world!" ],
    on_result => sub { print "Wrote foo.txt\n" },
 );

 # We can load pre-defined libraries
 $ips->use_library(
    library => "FS",
    funcs   => [qw( unlink )],
    on_loaded => sub {
       $ips->call(
          name => "unlink",
          args => [ "foo.txt" ],
          on_result => sub { print "Removed foo.txt\n" },
       );
    },
 );

 $loop->loop_forever;

DESCRIPTION ^

This module provides an object class that implements the IPC::PerlSSH behaviour in an asynchronous way, suitable for use in an IO::Async-based program.

Briefly, IPC::PerlSSH is a module that allows execution of perl code in a remote perl instance, usually accessed via ssh, with the notable distinction that the module does not need to be present in the remote end, nor does any special server need to be running, besides ssh itself. For more detail, see the IPC::PerlSSH documentation.

INITIAL PARAMETERS ^

As well as the "PARAMETERS" named below, the constructor will take any of the constructor arguments named by IPC::PerlSSH, to set up the connection.

PARAMETERS ^

The following named parameters may be passed to new or configure:

on_exception => CODE

Optional. A default callback to use if a call to eval(), store() or call() does not provide one. If it is changed while a result it outstanding, the handler that was in place at the time it was invoked will be used in case of errors. Changes will only affect new eval(), store() or call() calls made after the change.

on_exit => CODE

Optional. A callback to invoke if the remote perl process exits. Will be passed directly to the IO::Async::Process on_finish method.

METHODS ^

$ips->eval( %args )

This method evaluates code in the remote host, passing arguments and returning the result.

The %args hash takes the following keys:

code => STRING

The perl code to execute, in a string. (i.e. NOT a CODE reference).

args => ARRAY

Optional. An ARRAY reference containing arguments to pass to the code.

on_result => CODE

Continuation to invoke when the code returns a result.

on_exception => CODE

Optional. Continuation to invoke if the code throws an exception.

The code should be passed in a string, and is evaluated using a string eval in the remote host, in list context. If this method is called in scalar context, then only the first element of the returned list is returned. Only string scalar values are supported in either the arguments or the return values; no deeply-nested structures can be passed.

To pass or return a more complex structure, consider using a module such as Storable, which can serialise the structure into a plain string, to be deserialised on the remote end.

If the remote code threw an exception, then this function propagates it as a plain string. If the remote process exits before responding, this will be propagated as an exception.

$ips->store( %args )

This method sends code to the remote host to store in a named procedure which can be executed later.

The %args hash takes the following keys:

name => STRING

A name for the stored procedure.

code => STRING

The perl code to store, in a string. (i.e. NOT a CODE reference).

on_stored => CODE

Continuation to invoke when the code is successfully stored.

on_exception => CODE

Optional. Continuation to invoke if compiling the code throws an exception.

The code should be passed in a string, along with a name which can later be called by the call method.

While the code is not executed, it will still be compiled into a CODE reference in the remote host. Any compile errors that occur will still invoke the on_exception continuation. If the remote process exits before responding, this will be propagated as an exception.

$ips->call( %args )

This method invokes a stored procedure that has earlier been defined using the store method. The arguments are passed and the result is returned in the same way as with the eval method.

The %params hash takes the following keys:

name => STRING

The name of the stored procedure.

args => ARRAY

Optional. An ARRAY reference containing arguments to pass to the code.

on_result => CODE

Continuation to invoke when the code returns a result.

on_exception => CODE

Optional. Continuation to invoke if the code throws an exception or exits.

$ips->use_library( %args )

This method loads a library of code from a module, and stores them to the remote perl by calling store on each one.

The %params hash takes the following keys:

library => STRING

Name of the library to load

funcs => ARRAY

Optional. Reference to an array containing names of functions to load.

on_loaded => CODE

Continuation to invoke when all the functions are stored.

on_exception => CODE

Optional. Continuation to invoke if storing a function throws an exception or exits.

The library name may be a full class name, or a name within the IPC::PerlSSH::Library:: space.

If the funcs list is non-empty, then only those named functions are stored (analogous to the use perl statement). This may be useful in large libraries that define many functions, only a few of which are actually used.

For more information, see IPC::PerlSSH::Library.

AUTHOR ^

Paul Evans <leonerd@leonerd.org.uk>

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