CGI output gzip compression module

Question

Edit: How should I interpret the silence? On a scale from 0 to 10 where 0 means "Bloody awful" and 10 means "Nothing to complain about".

I'm mainly concerned about readability and things I don't seem to be aware of. If the code is readable, I won't need to explain it.

#!/usr/bin/python
import os
import sys
import subprocess
assert __name__ != '__main__'
max_load_avg1 = 3.5
'''
compressout
===========
Simple CGI output module.
Uses gzip compression on the output stream if the client accepts it.
NOTICE: The `cgitb` module will write to stdout if the script crashes,
you should use a browser that does not accept gzip, when you are
testing your scripts.
NOTICE: In the beginning of this file `max_load_avg1` is defined.
This is the maximum allowed load average under one minute.
If the one minute load average exceeds this value, compressout will
abort.
Functions
=========
init(write_headers=True)
------------------------
 Initialize the module. This function will detect if the client
 supports gzip.
 If `write_headers`, write a 'Vary' and (if used)
 'Content-Encdoing' header.
write_h(s)
----------
 Write part of header.
 Write `s` to standard output, will never go through gzip.
write_b(s)
----------
 Write part of body.
 gzip is supported by the client
 -------------------------------
 `s` will be appended to a local buffer
 which `done` will compress and print.
 gzip is not supported
 ---------------------
 `s` will go straight to stdout.
done()
------
 Done writing output.
 This function will invoke gzip.
Dos and don'ts
==============
## ## ##
if __name__ == '__main__':
 compressout.init()
 main()
 compressout.done()
## ## ##
 * Never call `write_h` after any call to `write_b`
 * Always call `done` when your done.
 * Use only compressout to write output
 * NOTICE: The `cgitb` module will write to stdout if the script
 crashes, you should use a browser that does not accept gzip,
 when you are testing your scripts.
'''
http503_body = '''
Service temporarily unavailable!
Wait at least two minutes before trying again.
Re-attempting prematurely may result in banning your IP address.
-- END OF TRANSMISSION --
'''
def init(write_headers=True):
 '''
 Initialize the module. This function will detect if the client
 support gzip.
 If `write_headers`, write a 'Vary' and (if used)
 'Content-Encoding' header.
 '''
 global use_gzip
 global body
 # This is the only place where sending a 503 message will work.
 # write_h:
 # - Message body may need to be compressed.
 # - Possibility of conflicting Status headers.
 # write_b:
 # - Message body may need to be compressed.
 # - Message body may be application/xhtml+xml
 # done:
 # - Message body needs to be compressed if `use_gzip`.
 # - Body has already been written if not `use_gzip`.
 if os.getloadavg()[0] > max_load_avg1:
 sys.stdout.write('Status: 503\n')
 sys.stdout.write('Content-Type: text/plain\n')
 sys.stdout.write('Retry-After: 90\n')
 sys.stdout.write(http503_body)
 sys.stdout.flush()
 os.abort()
 use_gzip = 'gzip' in os.getenv('HTTP_ACCEPT_ENCODING', '')
 body = ''
 if write_headers:
 sys.stdout.write('Vary: Accept-Encoding\n')
 if use_gzip:
 sys.stdout.write('Content-Encoding: gzip\n')
def write_h(s):
 '''
 Write part of header.
 Write `s` to standard output, will never go through gzip.
 '''
 if os.getloadavg()[0] > max_load_avg1: os.abort()
 sys.stdout.write(s)
def write_b(s):
 '''
 Write part of body.
 gzip is supported by the client
 -------------------------------
 `s` will be appended to a local buffer
 which `done` will compress and print.
 gzip is not supported
 ---------------------
 `s` will go straight to stdout.
 '''
 global body
 if os.getloadavg()[0] > max_load_avg1: os.abort()
 if use_gzip:
 body += s
 else:
 sys.stdout.write(s)
def done():
 '''
 Done writing output.
 This function will invoke gzip.
 '''
 if os.getloadavg()[0] > max_load_avg1: os.abort()
 if use_gzip:
 gzip = subprocess.Popen(
 ['gzip'],
 stdin=subprocess.PIPE,
 stdout=subprocess.PIPE
 )
 sys.stdout.write(gzip.communicate(body)[0])
use_gzip = True or False
body = ''

I realize there are a few things I should have commented when I edited this module a while ago. But for "correctness" sake, I won't change the code in the question.

The current code can be found at: https://oskog97.com/read/?path=/compressout.py

• Oskar Skog: Is there any other way than adding for spaces before every line of code? It's a pain in the ass to insert code in posts here.
• 200_success: The easiest way to post code is to paste it, highlight it, and press Ctrl-K to mark it as a code block.

Answer 1

A few things I've noticed from a quick skim:

• The assert is kinda useless.
• write_h and write_b?? Documentation isn't an excuse for giving your functions useless names. Name them write_header and write_body or something.
• Globals? Just no. Especially when they're defined AFTER the functions. Took me like 5 minutes to find them.
• You've copied if os.getloadavg()[0] > max_load_avg1: os.abort() tons of times. Might be a good idea to export them to a function.
• use_gzip = True or False. ?????????????????????? What ????????????????????????

• Oskar Skog: Do you have any suggestion what I could use instead of globals? I know about classes and objects, but I'm trying to get away with "transparent" changes as I've got lots of code that uses this module.
• Oskar Skog: As a temporary workaround, I've moved them up to right below the doc string and added big shouting warning labels. ... Just for the LOLs: electricstuff.co.uk/reallydangerous.gif
• Tom: Using an object is probably the best solution here, but since you don't want that, just pass the body and gzip as parameters and return tuples from the functions.
• Oskar Skog: Using an object would actually be easier than doing that. I'm basically using the entire module as if it was an object.