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>