Woodgnome's profile - activity

I only just figured out how to run Sage in a daemon/service-like kind of state - see http://ask.sagemath.org/question/2343... for the Sage script.

Now I'm trying to rewrite it to Python with Sage imports, so I can automatically start it with sage -python [PATH TO PYTHON FILE] as opposed to manually starting Sage and loading the script.

The fails with the following stack trace

Traceback (most recent call last):
  File "socket.py", line 1, in <module>
    import socket
  File "/var/www/lingapps/assets/sage/socket.py", line 4, in <module>
    import sage.all
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/all.py", line 54, in <module>
    from sage.env import SAGE_ROOT, SAGE_DOC, SAGE_LOCAL, DOT_SAGE, SAGE_ENV
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/env.py", line 84, in <module>
    _add_variable_or_fallback('HOSTNAME',        socket.gethostname())
AttributeError: 'module' object has no attribute 'gethostname'

This also happens when I have just a single line in the script: import sage.all.

It also fails with the following error if I just start sage -python and type import sage.all:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/all.py", line 54, in <module>
    from sage.env import SAGE_ROOT, SAGE_DOC, SAGE_LOCAL, DOT_SAGE, SAGE_ENV
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/env.py", line 20, in <module>
    import os, socket
  File "socket.py", line 6, in <module>
    import sage.calculus.predefined
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/calculus/__init__.py", line 1, in <module>
    import all
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/calculus/all.py", line 1, in <module>
    from calculus import maxima as maxima_calculus
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/calculus/calculus.py", line 400, in <module>
    from sage.rings.all import RR, Integer, CC, QQ, RealDoubleElement, algdep
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/rings/all.py", line 21, in <module>
    from ring import Ring
  File "ring.pyx", line 1, in init sage.rings.ring (sage/rings/ring.c:18156)
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/structure/__init__.py", line 1, in <module>
    import dynamic_class # allows for sage.structure.dynamic_class?
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/structure/dynamic_class.py", line 119, in <module>
    from sage.misc.cachefunc import weak_cached_function
  File "cachefunc.pyx", line 421, in init sage.misc.cachefunc (sage/misc/cachefunc.c:17825)
  File "function_mangling.pyx", line 39, in init sage.misc.function_mangling (sage/misc/function_mangling.c:3106)
  File "/var/www/lingapps/assets/sage/local/lib/python2.7/site-packages/sage/misc/sageinspect.py", line 131, in <module>
    from sage.env import SAGE_SRC
ImportError: cannot import name SAGE_SRC

It doesn't work with sage [PATH TO SAGE FILE]either:

Traceback (most recent call last):
  File "socket ...

I finally realised that the Sage shell is a Python shell and that it's possible to run Sage inside a Python script. With this knowledge I was able to write a Python script that can execute Sage commands and uses sockets for inter-process communication.

I decided to write the script to act as much like running sage -c 'commmand' as possible. I copied most of the code from sage/local/sage-eval and paired it up with a Python socket example and ended with the following Python script:

import socket
import sys
from cStringIO import StringIO
from sage.all import *
from sage.calculus.predefined import x
from sage.misc.preparser import preparse

SHUTDOWN = False
HOST = 'localhost'
PORT = 8888
MAX_MSG_LENGTH = 102400

# Create socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
print 'Socket created'

# Bind socket to localhost and port
try:
  s.bind((HOST, PORT))
except socket.error , msg:
  print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
  sys.exit()

print 'Socket bind complete'

# Start listening on socket
s.listen(10)
print 'Socket now listening'

# Loop listener for new connections
while not SHUTDOWN:
  # Wait to accept a new client connection
  conn, addr = s.accept()
  print 'Connected with ' + addr[0] + ':' + str(addr[1])

  # Receive message from client
  msg = conn.recv(MAX_MSG_LENGTH)
  if msg:
    if msg == "stop":
      SHUTDOWN = True
    else:
      parsed = preparse(msg)
      if parsed.startswith('load') or parsed.startswith('attach'):
        os.system('sage "' + os.path.join(os.getcwd(), parsed.split(None, 1)[1]) + '"')
      else:
        # Redirect stdout to my stdout to capture into a string
        sys.stdout = mystdout = StringIO()

        # Evalutate msg
        try:
          eval(compile(parsed,'<cmdline>','exec'))
          result = mystdout.getvalue() # Get result from mystdout
        except Exception as e:
          result = "ERROR: " + str(type(e)) + " " + str(e)

        # Restore stdout
        sys.stdout = sys.__stdout__

        # Send response to connected client
        if result == "":
          conn.sendall("Empty result, did you remember to print?")
        else:
          conn.sendall(result)

  # Close client connection
  conn.close()

# Close listener
s.close()

I saved the script to a file called sage-daemon.py in my Sage root folder. The stopmessage handler isn't really neccessary, but it's useful if anyone can "properly" daemonize the script (and also to avoid interrupting the script with CTRL+C, because that will leave the socket as in-use for a while after the script has been interrupted). See my other question http://ask.sagemath.org/question/2350... .

To run the script: sage -python sage-daemon.py This will leave the Sage shell waiting for socket input.

Here's a PHP script I used to test the functionality with:

<?php

$socket = socket_create(AF_INET, SOCK_STREAM, getprotobyname("tcp"));
if (!$socket) die("Could not create socket\n");

$connected = socket_connect($socket, "localhost", 8888);
if (!$connected) echo "Not connected\n";
else {
  $msg = "print solve(5*x==3,x)";

  $sent = socket_send($socket, $msg, strlen($msg), 0);
  if (!$sent) echo "Error sending message\n";
  else {
    if ($msg != "stop"){
      $response = socket_read($socket, 1024);
      if (!$response) echo "Error receiving response\n";
      else echo $response . "\n";
    }
  }
}

socket_close($socket);

If successfull this should print ... (more)