The usual.

This commit is contained in:
Guido van Rossum 1998-03-26 22:14:20 +00:00
parent 65e5399081
commit 548703a1b8
43 changed files with 2463 additions and 2323 deletions

View file

@ -3,19 +3,19 @@
This module tries to capture the various aspects of defining a server:
- address family:
- AF_INET: IP (Internet Protocol) sockets (default)
- AF_UNIX: Unix domain sockets
- others, e.g. AF_DECNET are conceivable (see <socket.h>
- AF_INET: IP (Internet Protocol) sockets (default)
- AF_UNIX: Unix domain sockets
- others, e.g. AF_DECNET are conceivable (see <socket.h>
- socket type:
- SOCK_STREAM (reliable stream, e.g. TCP)
- SOCK_DGRAM (datagrams, e.g. UDP)
- SOCK_STREAM (reliable stream, e.g. TCP)
- SOCK_DGRAM (datagrams, e.g. UDP)
- client address verification before further looking at the request
(This is actually a hook for any processing that needs to look
at the request before anything else, e.g. logging)
(This is actually a hook for any processing that needs to look
at the request before anything else, e.g. logging)
- how to handle multiple requests:
- synchronous (one request is handled at a time)
- forking (each request is handled by a new process)
- threading (each request is handled by a new thread)
- synchronous (one request is handled at a time)
- forking (each request is handled by a new process)
- threading (each request is handled by a new thread)
The classes in this module favor the server type that is simplest to
write: a synchronous TCP/IP server. This is bad class design, but
@ -25,14 +25,14 @@ slows down method lookups.)
There are four classes in an inheritance diagram that represent
synchronous servers of four types:
+-----------+ +------------------+
| TCPServer |------->| UnixStreamServer |
+-----------+ +------------------+
|
v
+-----------+ +--------------------+
| UDPServer |------->| UnixDatagramServer |
+-----------+ +--------------------+
+-----------+ +------------------+
| TCPServer |------->| UnixStreamServer |
+-----------+ +------------------+
|
v
+-----------+ +--------------------+
| UDPServer |------->| UnixDatagramServer |
+-----------+ +--------------------+
Note that UnixDatagramServer derives from UDPServer, not from
UnixStreamServer -- the only difference between an IP and a Unix
@ -43,7 +43,7 @@ Forking and threading versions of each type of server can be created
using the ForkingServer and ThreadingServer mix-in classes. For
instance, a threading UDP server class is created as follows:
class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
The Mix-in class must come first, since it overrides a method defined
in UDPServer!
@ -119,8 +119,8 @@ class TCPServer:
- __init__(server_address, RequestHandlerClass)
- serve_forever()
- handle_request() # if you don't use serve_forever()
- fileno() -> int # for select()
- handle_request() # if you don't use serve_forever()
- fileno() -> int # for select()
Methods that may be overridden:
@ -157,42 +157,42 @@ class TCPServer:
request_queue_size = 5
def __init__(self, server_address, RequestHandlerClass):
"""Constructor. May be extended, do not override."""
self.server_address = server_address
self.RequestHandlerClass = RequestHandlerClass
self.socket = socket.socket(self.address_family,
self.socket_type)
self.server_bind()
self.server_activate()
"""Constructor. May be extended, do not override."""
self.server_address = server_address
self.RequestHandlerClass = RequestHandlerClass
self.socket = socket.socket(self.address_family,
self.socket_type)
self.server_bind()
self.server_activate()
def server_bind(self):
"""Called by constructor to bind the socket.
"""Called by constructor to bind the socket.
May be overridden.
May be overridden.
"""
self.socket.bind(self.server_address)
"""
self.socket.bind(self.server_address)
def server_activate(self):
"""Called by constructor to activate the server.
"""Called by constructor to activate the server.
May be overridden.
May be overridden.
"""
self.socket.listen(self.request_queue_size)
"""
self.socket.listen(self.request_queue_size)
def fileno(self):
"""Return socket file number.
"""Return socket file number.
Interface required by select().
Interface required by select().
"""
return self.socket.fileno()
"""
return self.socket.fileno()
def serve_forever(self):
"""Handle one request at a time until doomsday."""
while 1:
self.handle_request()
"""Handle one request at a time until doomsday."""
while 1:
self.handle_request()
# The distinction between handling, getting, processing and
# finishing a request is fairly arbitrary. Remember:
@ -206,54 +206,54 @@ class TCPServer:
# this constructor will handle the request all by itself
def handle_request(self):
"""Handle one request, possibly blocking."""
request, client_address = self.get_request()
if self.verify_request(request, client_address):
try:
self.process_request(request, client_address)
except:
self.handle_error(request, client_address)
"""Handle one request, possibly blocking."""
request, client_address = self.get_request()
if self.verify_request(request, client_address):
try:
self.process_request(request, client_address)
except:
self.handle_error(request, client_address)
def get_request(self):
"""Get the request and client address from the socket.
"""Get the request and client address from the socket.
May be overridden.
May be overridden.
"""
return self.socket.accept()
"""
return self.socket.accept()
def verify_request(self, request, client_address):
"""Verify the request. May be overridden.
"""Verify the request. May be overridden.
Return true if we should proceed with this request.
Return true if we should proceed with this request.
"""
return 1
"""
return 1
def process_request(self, request, client_address):
"""Call finish_request.
"""Call finish_request.
Overridden by ForkingMixIn and ThreadingMixIn.
Overridden by ForkingMixIn and ThreadingMixIn.
"""
self.finish_request(request, client_address)
"""
self.finish_request(request, client_address)
def finish_request(self, request, client_address):
"""Finish one request by instantiating RequestHandlerClass."""
self.RequestHandlerClass(request, client_address, self)
"""Finish one request by instantiating RequestHandlerClass."""
self.RequestHandlerClass(request, client_address, self)
def handle_error(self, request, client_address):
"""Handle an error gracefully. May be overridden.
"""Handle an error gracefully. May be overridden.
The default is to print a traceback and continue.
The default is to print a traceback and continue.
"""
print '-'*40
print 'Exception happened during processing of request from',
print client_address
import traceback
traceback.print_exc()
print '-'*40
"""
print '-'*40
print 'Exception happened during processing of request from',
print client_address
import traceback
traceback.print_exc()
print '-'*40
class UDPServer(TCPServer):
@ -265,19 +265,19 @@ class UDPServer(TCPServer):
max_packet_size = 8192
def get_request(self):
return self.socket.recvfrom(self.max_packet_size)
return self.socket.recvfrom(self.max_packet_size)
if hasattr(socket, 'AF_UNIX'):
class UnixStreamServer(TCPServer):
address_family = socket.AF_UNIX
address_family = socket.AF_UNIX
class UnixDatagramServer(UDPServer):
address_family = socket.AF_UNIX
address_family = socket.AF_UNIX
class ForkingMixIn:
@ -287,34 +287,34 @@ class ForkingMixIn:
active_children = None
def collect_children(self):
"""Internal routine to wait for died children."""
while self.active_children:
pid, status = os.waitpid(0, os.WNOHANG)
if not pid: break
self.active_children.remove(pid)
"""Internal routine to wait for died children."""
while self.active_children:
pid, status = os.waitpid(0, os.WNOHANG)
if not pid: break
self.active_children.remove(pid)
def process_request(self, request, client_address):
"""Fork a new subprocess to process the request."""
self.collect_children()
pid = os.fork()
if pid:
# Parent process
if self.active_children is None:
self.active_children = []
self.active_children.append(pid)
return
else:
# Child process.
# This must never return, hence os._exit()!
try:
self.finish_request(request, client_address)
os._exit(0)
except:
try:
self.handle_error(request,
client_address)
finally:
os._exit(1)
"""Fork a new subprocess to process the request."""
self.collect_children()
pid = os.fork()
if pid:
# Parent process
if self.active_children is None:
self.active_children = []
self.active_children.append(pid)
return
else:
# Child process.
# This must never return, hence os._exit()!
try:
self.finish_request(request, client_address)
os._exit(0)
except:
try:
self.handle_error(request,
client_address)
finally:
os._exit(1)
class ThreadingMixIn:
@ -322,10 +322,10 @@ class ThreadingMixIn:
"""Mix-in class to handle each request in a new thread."""
def process_request(self, request, client_address):
"""Start a new thread to process the request."""
import thread
thread.start_new_thread(self.finish_request,
(request, client_address))
"""Start a new thread to process the request."""
import thread
thread.start_new_thread(self.finish_request,
(request, client_address))
class ForkingUDPServer(ForkingMixIn, UDPServer): pass
@ -354,27 +354,27 @@ class BaseRequestHandler:
"""
def __init__(self, request, client_address, server):
self.request = request
self.client_address = client_address
self.server = server
try:
self.setup()
self.handle()
self.finish()
finally:
sys.exc_traceback = None # Help garbage collection
self.request = request
self.client_address = client_address
self.server = server
try:
self.setup()
self.handle()
self.finish()
finally:
sys.exc_traceback = None # Help garbage collection
def setup(self):
pass
pass
def __del__(self):
pass
pass
def handle(self):
pass
pass
def finish(self):
pass
pass
# The following two classes make it possible to use the same service
@ -390,12 +390,12 @@ class StreamRequestHandler(BaseRequestHandler):
"""Define self.rfile and self.wfile for stream sockets."""
def setup(self):
self.connection = self.request
self.rfile = self.connection.makefile('rb', 0)
self.wfile = self.connection.makefile('wb', 0)
self.connection = self.request
self.rfile = self.connection.makefile('rb', 0)
self.wfile = self.connection.makefile('wb', 0)
def finish(self):
self.wfile.flush()
self.wfile.flush()
class DatagramRequestHandler(BaseRequestHandler):
@ -403,10 +403,10 @@ class DatagramRequestHandler(BaseRequestHandler):
"""Define self.rfile and self.wfile for datagram sockets."""
def setup(self):
import StringIO
self.packet, self.socket = self.request
self.rfile = StringIO.StringIO(self.packet)
self.wfile = StringIO.StringIO(self.packet)
import StringIO
self.packet, self.socket = self.request
self.rfile = StringIO.StringIO(self.packet)
self.wfile = StringIO.StringIO(self.packet)
def finish(self):
self.socket.send(self.wfile.getvalue())
self.socket.send(self.wfile.getvalue())