nfstest.rexec (3) - Linux Manuals

nfstest.rexec: Remote procedure module

NAME

nfstest.rexec - Remote procedure module

DESCRIPTION

Provides a set of tools for executing a wide range commands, statements, expressions or functions on a remote host by running a server process on the remote host serving requests without disconnecting. This allows for a sequence of operations to be done remotely and not losing state. A file could be opened remotely, do some other things and then write to the same opened file without opening the file again.

In order to use this module the user id must be able to 'ssh' to the remote host without the need for a password.

CLASSES

class Rexec(baseobj.BaseObj)

Rexec object

       Rexec() -> New remote procedure object

       Arguments:
           servername:
               Name or IP address of remote server
           logfile:
               Name of logfile to create on remote server

       Usage:
           from nfstest.rexec import Rexec

           # Function to be defined at remote host
           def add_one(n):
               return n + 1

           # Function to be defined at remote host
           def get_time(delay=0):
               time.sleep(delay)
               return time.time()

           # Create remote procedure object
           x = Rexec("192.168.0.85")

           # Define function at remote host
           x.rcode(add_one)

           # Evaluate the expression calling add_one()
           out = x.reval("add_one(67)")

           # Run the function with the given argument
           out = x.run("add_one", 7)

           # Run built-in functions
           import time
           out = x.run(time.time)

           # Import libraries and symbols
           x.rimport("time", ["sleep"])
           x.run("sleep", 2)

           # Define function at remote host -- since function uses the
           # time module, this module must be first imported
           x.rimport("time")
           x.rcode(get_time)

           # Evaluate the expression calling get_time()
           out = x.reval("get_time()")

           # Run the function with the given argument
           out = x.run("get_time", 10)

           # Open file on remote host
           fd = x.run(os.open, "/tmp/testfile", os.O_WRONLY|os.O_CREAT|os.O_TRUNC)
           count = x.run(os.write, fd, "hello there
	")
           x.run(os.close, fd)

           # Use of positional arguments
           out = x.run('get_time', 2)

           # Use of named arguments
           out = x.run('get_time', delay=2)

           # Use of NOWAIT option for long running functions so other things
           # can be done while waiting
           x.run('get_time', 2, NOWAIT=True)
           while True:
               # Poll every 0.1 secs to see if function has finished
               if x.poll(0.1):
                   # Get results
                   out = x.results()
                   break


Methods defined here:
---------------------

__del__(self)
Destructor

__init__(self, servername='', logfile=None, sync_timeout=0.10000000000000001)
Constructor

Initialize object's private data.


servername:
Host name or IP address of host where remote server will run
logfile:
Pathname of log file to be created on remote host
[Default: "/dev/null"]
sync_timeout:
Timeout used for synchronizing the connection stream
[Default: 0.1]



poll(self, timeout=0)
Return whether there is any data available to be read


timeout:
Maximum time in seconds to block, if timeout is None then
an infinite timeout is used



rcode(self, code)
Define function on remote server

results(self)
Return pending results

reval(self, expr)
Evaluate expression on remote server

rexec(self, expr)
Execute statement on remote server

rimport(self, module, symbols=[])
Import module on remote server


module:
Module to import in the remote server
symbols:
If given, import only these symbols from the module



run(self, *kwts, **kwds)
Run function on remote server

The first positional argument is the function to be executed.
All other positional arguments and any named arguments are treated
as arguments to the function

wait(self, objlist=None, timeout=0)
Return a list of Rexec objects where data is available to be read


objlist:
List of Rexec objects to poll, if not given use current object
timeout:
Maximum time in seconds to block, if timeout is None then
an infinite timeout is used

FUNCTIONS

bare_server(port, logfile)

Bare-bones remote server

proc_requests(fd, conn)

Main remote procedure server

fd:

File descriptor for logfile

conn:

Connection object

write_log(fd, msg, nl=')

Return timestamp

BUGS

No known bugs.

AUTHOR

Jorge Mora (mora [at] netapp.com)