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import socket
import os
import select
import sys
class SocketFileWrapper:
"""Wraps a socket to a wsgi-compliant file-like object."""
def __init__(self, sock):
"""@param sock: is a socket.socket()"""
self.sock = sock
self.buff = ""
def read(self, size=None):
"""see pep333"""
if size is None:
try:
return self.buff + self.sock.recv()
except: raise # Yes, this is necessary.
else:
self.buff = ""
if size <= len(self.buff):
ret, self.buff = self.buff[:size], self.buff[size:]
return ret
try:
return self.buff + self.sock.recv(size)
except: raise # Yes, this is necessary.
else:
self.buff = ""
def readline(self):
"""see pep333"""
while True:
try:
split = self.buff.index('\n') + 1
ret, self.buff = self.buff[:split], self.buff[split:]
return ret
except ValueError:
data = self.sock.recv(4096)
if not data:
ret, self.buff = self.buff, ""
return ret
self.buff += data
def readlines(self):
"""see pep333"""
data = self.readline()
while data:
yield data
data = self.readline()
def __iter__(self):
"""see pep333"""
return self
def next(self):
"""see pep333"""
data = self.read(4096)
if not data:
raise StopIteration
return data
def flush(self):
"""see pep333"""
pass
def write(self, data):
"""see pep333"""
assert isinstance(data, str)
self.sock.send(data)
def writelines(self, lines):
"""see pep333"""
map(self.write, lines)
class SCGIServer:
"""Usage: create an SCGIServer object and invoke the run method which will
then turn this process into an scgi server."""
class WorkerState:
"""state: 0 means idle and 1 means working.
These values are also sent as strings '0' and '1' over the socket."""
def __init__(self, pid, sock, state):
self.pid = pid
self.sock = sock
self.state = state
def __init__(self, wsgiapp, port, interface="localhost", error=sys.stderr,
minworkers=2, maxworkers=32, maxrequests=1000):
"""
@param wsgiapp: is the WSGI application to be run.
@type port: number
@param port: is the tcp port to listen on
@type interface: str
@param interface: is the interface to bind to (default: "localhost")
@param error: is a filelike object beeing passed as wsgi.error in
environ
@type minworkers: number
@param minworkers: is the number of worker processes to spawn
@type maxworkers: number
@param maxworkers: is the maximum number of workers that can be spawned
on demand
@type maxrequests: number
@param maxrequests: is the number of requests a worker processes before
dying
"""
assert hasattr(error, "write")
self.wsgiapp = wsgiapp
self.port = port
self.interface = interface
self.minworkers = minworkers
self.maxworkers = maxworkers
self.maxrequests = maxrequests
self.error = error
self.server = None # becomes a socket
# maps filedescriptors to WorkerStates
self.workers = {}
def run(self):
"""
Serve the wsgi application.
"""
self.server = socket.socket()
self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.server.bind((self.interface, self.port))
self.server.listen(5)
while True:
while (len(self.workers) < self.minworkers or # less than min
(len(self.workers) < self.maxworkers and # less than max
not len([w for w in # no inctive
self.workers.values() if w.state == 0]))):
self.spawnworker()
rs, _, _ = select.select(self.workers.keys(), [], [])
for s in rs:
data = self.workers[s].sock.recv(1)
if data == '':
self.workers[s].sock.close()
del self.workers[s]
elif data in ('0', '1'):
self.workers[s].state = int(data)
else:
raise RuntimeError, "unexpected data from worker"
try:
pid = 1
while pid > 0:
pid, _ = os.waitpid(0, os.WNOHANG)
except OSError:
pass
def spawnworker(self):
"""
internal! spawns a single worker
"""
srvsock, worksock = socket.socketpair()
pid = os.fork()
if pid == 0:
# close unneeded sockets
srvsock.close()
for worker in self.workers.values():
worker.sock.close()
del self.workers
self.work(worksock)
sys.exit()
elif pid > 0:
# close unneeded sockets
worksock.close()
self.workers[srvsock.fileno()] = SCGIServer.\
WorkerState(pid, srvsock, 0)
else:
raise RuntimeError, "fork failed"
def work(self, worksock):
"""
internal! serves maxrequests times
"""
for _ in range(self.maxrequests):
(con, addr) = self.server.accept()
worksock.send('1') # tell server we're working
self.process(con)
worksock.send('0') # tell server we've finished
def process(self, con):
"""
internal! processes a single request on the connection con.
"""
# This is a little bit ugly:
# The server has to send the length of the request followed by a colon.
# We assume that 1. the colon is within the first seven bytes.
# 2. the packet isn't fragmented.
# Furthermore 1 implies that the request isn't longer than 999999 bytes.
# This method however works. :-)
data = con.recv(7)
if not ':' in data:
con.close()
return
length, data = data.split(':', 1)
if not length.isdigit(): # clear protocol violation
con.close()
return
length = long(length)
while len(data) != length + 1: # read one byte beyond
t = con.recv(length + 1 - len(data))
if not t: # request too short
con.close()
return
data += t
# netstrings!
data = data.split('\0')
# the byte beyond has to be a ','.
# and the number of netstrings excluding the final ',' has to be even
if data.pop() != ',' or len(data) % 2 != 0:
con.close()
return
environ = {}
while data:
key = data.pop(0)
value = data.pop(0)
environ[key] = value
def start_response(status, headers, exc_info=None):
con.send('Status: %s\r\n%s\r\n\r\n' % (status,
'\r\n'.join(map("%s: %s".__mod__, headers))))
return con.send
environ.update({
"wsgi.version": (1, 0),
"wsgi.input": SocketFileWrapper(con),
"wsgi.errors": self.error,
"wsgi.url_scheme": "http",
"wsgi.multithread": False,
"wsgi.multiprocess": True,
"wsgi.run_once": False})
if environ.get("HTTPS", "no").lower() in ('yes', 'y', '1'):
environ["wsgi.url_scheme"] = "https"
if "HTTP_CONTENT_TYPE" in environ:
environ["CONTENT_TYPE"] = environ.pop("HTTP_CONTENT_TYPE")
if "HTTP_CONTENT_LENGTH" in environ:
del environ["HTTP_CONTENT_LENGTH"] # TODO: better way?
result = self.wsgiapp(environ, start_response)
assert hasattr(result, "__iter__")
for data in result:
assert isinstance(data, str)
con.send(data)
if hasattr(result, "close"):
result.close()
con.close()
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