twisted reactor implementation source code parsing
1. reactor Source resolve
1.1 Case Study Code:
from twisted.internet import protocol
from twisted.internet.protocol import Factory
from twisted.protocols.basic import LineReceiver
from twisted.internet import reactor
class Chat(LineReceiver):
def __init__(self, users):
self.users = users
self.name = None
self.state = "GETNAME"
def connectionMade(self):
self.sendLine(b'Whats your name')
def connectionLost(self, reason):
if self.name in self.users:
del self.users[self.name]
def lineReceived(self, line):
if self.state == "GETNAME":
self.handle_GETNAME(line)
else:
self.handle_CHAT(line)
def handle_GETNAME(self, name):
if name in self.users:
self.sendLine(b"Name taken, please choose another.")
return
self.sendLine(b"Welcome, %s!" % (name,))
self.name = name
self.users[name] = self
self.state = "CHAT"
def handle_CHAT(self, message):
message = "<%s> %s" % (self.name, message)
pr_type(message)
print(self.users)
for name, protocol in self.users.items():
if protocol != self:
protocol.sendLine(message.encode())
class ChatFactory(Factory):
def __init__(self):
self.users = {} # maps user names to Chat instances
def buildProtocol(self, addr):
return Chat(self.users)
def main():
# 监听端口
reactor.listenTCP(8123, ChatFactory())
reactor.run()
if __name__ == '__main__':
main()
1.2. Reactor code analysis
Documents have been traced to reactor.run (), so the front part is not repeated here.
reactor has been found, the following look at what it does after running:
res = reactor.run
pr_type(res)
result:
<bound method _SignalReactorMixin.run of <twisted.internet.selectreactor.SelectReactor object at 0x000000C61740B6D8>> <class 'method'>
Look at github get: twisted / internet / base.py
class _SignalReactorMixin(object):
def startRunning(self, installSignalHandlers=True):
"""
PosixReactorBase _SignalReactorMixin parent class and has the function ReactorBase, but _SignalReactorMixin front mounting mro order, then, will the first call _SignalReactorMixin.
"""
self._installSignalHandlers = installSignalHandlers
ReactorBase.startRunning(self)
def run(self, installSignalHandlers=True):
self.startRunning(installSignalHandlers=installSignalHandlers)
self.mainLoop ()
def MAINLOOP (self):
while self._started:
try:
while self._started:
# Advance simulation time in delayed event
# processors.
self.runUntilCurrent()
t2 = self.timeout()
t = self.running and t2
self.doIteration (t) # monitor cycle to achieve Affairs
except:
log.msg("Unexpected error in main loop.")
log.err()
else:
log.msg('Main loop terminated.')
Here is the main loop.
The main loop to do a few things:
- Listener: self.doIteration (t)
Monitor realization: self.doIteration (t)
#twisted/src/twisted/internet/selectreactor.py
@implementer(IReactorFDSet)
class SelectReactor(posixbase.PosixReactorBase, _extraBase):
"""
A select() based reactor - runs on all POSIX platforms and on Win32.
@ivar _reads: A set containing L{FileDescriptor} instances which will be
checked for read events.
@ivar _writes: A set containing L{FileDescriptor} instances which will be
checked for writability.
"""
def __init__(self):
"""
Initialize file descriptor tracking dictionaries and the base class.
"""
self._reads = set()
self._writes = set()
posixbase.PosixReactorBase.__init__(self)
def doSelect(self, timeout):
"""
Run one iteration of the I/O monitor loop.
This will run all selectables who had input or output readiness
waiting for them.
"""
try:
r, w, ignored = _select(self._reads,
self._writes,
[], timeout)
except ValueError:
# Possibly a file descriptor has gone negative?
self._preenDescriptors()
return
except TypeError:
# Something *totally* invalid (object w/o fileno, non-integral
# result) was passed
log.err()
self._preenDescriptors()
return
except (select.error, socket.error, IOError) as se:
# select(2) encountered an error, perhaps while calling the fileno()
# method of a socket. (Python 2.6 socket.error is an IOError
# subclass, but on Python 2.5 and earlier it is not.)
if se.args[0] in (0, 2):
# windows does this if it got an empty list
if (not self._reads) and (not self._writes):
return
else:
raise
elif se.args[0] == EINTR:
return
elif se.args[0] == EBADF:
self._preenDescriptors()
return
else:
# OK, I really don't know what's going on. Blow up.
raise
_drdw = self._doReadOrWrite
_logrun = log.callWithLogger
for selectables, method, fdset in ((r, "doRead", self._reads),
(w,"doWrite", self._writes)):
for selectable in selectables:
# if this was disconnected in another thread, kill it.
# ^^^^ --- what the !@#*? serious! -exarkun
if selectable not in fdset:
continue
# This for pausing input when we're not ready for more.
_logrun(selectable, _drdw, selectable, method)
doIteration = doSelect
def _doReadOrWrite(self, selectable, method):
try:
why = getattr(selectable, method)()
except:
why = sys.exc_info()[1]
log.err()
if why:
self._disconnectSelectable(selectable, why, method == "doRead")
Description:
Experimental platform is win so here call is selectReactor
There is a package, performed in the win platform doIteration = doSelect
In the Unix platform is doIteration = doPoll
Of course, you can manually choose, as long as the platform support.
Further _select essence is a package, as long as the selector, and a final bottom are select.select (), particularly visible twisted / internet / selectreactor.py
r, w, e = select.select(r, w, w, timeout)
return r, w + e, []
Here, in essence, it was returned to readable, writable queue to perform read and write.
So if the client requests a connection, doRead method will be invoked;
Here, selectable substantially Port class instance
@implementer(interfaces.IListeningPort)
class Port(base.BasePort, _SocketCloser):
"""
A TCP server port, listening for connections.
"""
def doRead(self):
"""
Called when my socket is ready for reading.
This accepts a connection and calls self.protocol() to handle the
wire-level protocol.
"""
try:
if platformType == "posix":
numAccepts = self.numberAccepts
else:
# win32 event loop breaks if we do more than one accept()
# in an iteration of the event loop.
numAccepts = 1
with _BuffersLogs(self._logger.namespace,
self._logger.observer) as bufferingLogger:
accepted = 0
clients = _accept(bufferingLogger,
range(numAccepts),
self.socket,
_reservedFD)
for accepted, (skt, addr) in enumerate(clients, 1):
fdesc._setCloseOnExec(skt.fileno())
if len(addr) == 4:
# IPv6, make sure we get the scopeID if it
# exists
host = socket.getnameinfo(
addr,
socket.NI_NUMERICHOST | socket.NI_NUMERICSERV)
addr = tuple([host[0]] + list(addr[1:]))
protocol = self.factory.buildProtocol(
self._buildAddr(addr))
if protocol is None:
skt.close()
continue
s = self.sessionno
self.sessionno = s + 1
transport = self.transport(
skt, protocol, addr, self, s, self.reactor)
protocol.makeConnection(transport)
# Scale our synchronous accept loop according to traffic
# Reaching our limit on consecutive accept calls indicates
# there might be still more clients to serve the next time
# the reactor calls us. Prepare to accept some more.
if accepted == self.numberAccepts:
self.numberAccepts += 20
# Otherwise, don't attempt to accept any more clients than
# we just accepted or any less than 1.
else:
self.numberAccepts = max(1, accepted)
except BaseException:
# Note that in TLS mode, this will possibly catch SSL.Errors
# raised by self.socket.accept()
#
# There is no "except SSL.Error:" above because SSL may be
# None if there is no SSL support. In any case, all the
# "except SSL.Error:" suite would probably do is log.deferr()
# and return, so handling it here works just as well.
log.deferr()
Resolution:
clients = _accept(bufferingLogger,range(numAccepts),self.socket,_reservedFD)
Returns the client, addr.
def _accept(logger, accepts, listener, reservedFD):
"""
Return a generator that yields client sockets from the provided
listening socket until there are none left or an unrecoverable
error occurs.
"""
client, address = listener.accept()
yield client, address
then
transport = self.transport(skt, protocol, addr, self, s, self.reactor)
protocol.makeConnection(transport)
The actual transport is to call a method
def _makeTransport(self):
"""
Create a L{Client} bound to this L{Connector}.
@return: a new L{Client}
@rtype: L{Client}
"""
return Client(self.host, self.port, self.bindAddress, self, self.reactor)
In summary, the CLIENT Transport point, it is an example of Port, comprising host, port, bindaddress socket information and the like.
Further, reactor.listenTCP (8123, ChatFactory ())
It will call its def startListening (self):
In which calls self.startReading (), the port is added to the instance of the read sequence reactor, as summarized below section
class _BaseTCPClient(object):
"""
Code shared with other (non-POSIX) reactors for management of outgoing TCP
connections (both TCPv4 and TCPv6).
@note: In order to be functional, this class must be mixed into the same
hierarchy as L{_BaseBaseClient}. It would subclass L{_BaseBaseClient}
directly, but the class hierarchy here is divided in strange ways out
of the need to share code along multiple axes; specifically, with the
IOCP reactor and also with UNIX clients in other reactors.
@ivar _addressType: The Twisted _IPAddress implementation for this client
@type _addressType: L{IPv4Address} or L{IPv6Address}
@ivar connector: The L{Connector} which is driving this L{_BaseTCPClient}'s
connection attempt.
@ivar addr: The address that this socket will be connecting to.
@type addr: If IPv4, a 2-C{tuple} of C{(str host, int port)}. If IPv6, a
4-C{tuple} of (C{str host, int port, int ignored, int scope}).
@ivar createInternetSocket: Subclasses must implement this as a method to
create a python socket object of the appropriate address family and
socket type.
@type createInternetSocket: 0-argument callable returning
C{socket._socketobject}.
"""
_addressType = address.IPv4Address
def __init__(self, host, port, bindAddress, connector, reactor=None):
# BaseClient.__init__ is invoked later
self.connector = connector
self.addr = (host, port)
whenDone = self.resolveAddress
err = None
skt = None
if abstract.isIPAddress(host):
self._requiresResolution = False
elif abstract.isIPv6Address(host):
self._requiresResolution = False
self.addr = _resolveIPv6(host, port)
self.addressFamily = socket.AF_INET6
self._addressType = address.IPv6Address
else:
self._requiresResolution = True
try:
skt = self.createInternetSocket()
except socket.error as se:
err = error.ConnectBindError(se.args[0], se.args[1])
whenDone = None
if whenDone and bindAddress is not None:
try:
if abstract.isIPv6Address(bindAddress[0]):
bindinfo = _resolveIPv6(*bindAddress)
else:
bindinfo = bindAddress
skt.bind(bindinfo)
except socket.error as se:
err = error.ConnectBindError(se.args[0], se.args[1])
whenDone = None
self._finishInit(whenDone, skt, err, reactor)
Look again at the protocol
protocol.makeConnection(transport)
protocol = self.factory.buildProtocol(self._buildAddr(addr))
protocol used here is LineReceiver, look at its makeConnection
# /twisted/internet/protocol.py
@_oldStyle
class BaseProtocol:
"""
This is the abstract superclass of all protocols.
Some methods have helpful default implementations here so that they can
easily be shared, but otherwise the direct subclasses of this class are more
interesting, L{Protocol} and L{ProcessProtocol}.
"""
connected = 0
transport = None
def makeConnection(self, transport):
"""
Make a connection to a transport and a server.
This sets the 'transport' attribute of this Protocol, and calls the
connectionMade() callback.
"""
self.connected = 1
self.transport = transport
self.connectionMade()
Call self.connectionMade ()
This is to write the code, send a message.
def connectionMade(self):
self.sendLine(b'Whats your name')
# /twisted/protocols/basic.py
class LineReceiver(protocol.Protocol, _PauseableMixin):
"""
A protocol that receives lines and/or raw data, depending on mode.
"""
def sendLine(self, line):
"""
Sends a line to the other end of the connection.
@param line: The line to send, not including the delimiter.
@type line: C{bytes}
"""
return self.transport.write(line + self.delimiter)
1.3. listenTCP()
Back to the example.
DEF main ():
# listening port
reactor.listenTCP (8123, ChatFactory ())
reactor.run ()
reactor.listenTCP () registered a listener event, it is the parent class PosixReactorBase methods.
# twisted/internet/posixbase.py
@implementer(IReactorTCP, IReactorUDP, IReactorMulticast)
class PosixReactorBase(_SignalReactorMixin, _DisconnectSelectableMixin,
ReactorBase):
"""
A basis for reactors that use file descriptors.
@ivar _childWaker: L{None} or a reference to the L{_SIGCHLDWaker}
which is used to properly notice child process termination.
"""
# IReactorTCP
def listenTCP(self, port, factory, backlog=50, interface=''):
p = tcp.Port(port, factory, backlog, interface, self)
p.startListening()
return p
# twisted/internet/tcp.py
@implementer(interfaces.IListeningPort)
class Port(base.BasePort, _SocketCloser):
"""
A TCP server port, listening for connections.
"""
def startListening(self):
"""Create and bind my socket, and begin listening on it.
创建套接字，开始监听。
This is called on unserialization, and must be called after creating a
server to begin listening on the specified port.
"""
_reservedFD.reserve()
if self._preexistingSocket is None:
# Create a new socket and make it listen
try:
# 声明一个非阻塞socket
skt = self.createInternetSocket()
if self.addressFamily == socket.AF_INET6:
addr = _resolveIPv6(self.interface, self.port)
else:
addr = (self.interface, self.port)
# 绑定
skt.bind(addr)
except socket.error as le:
raise CannotListenError(self.interface, self.port, le)
# 监听
skt.listen(self.backlog)
else:
# Re-use the externally specified socket
skt = self._preexistingSocket
self._preexistingSocket = None
# Avoid shutting it down at the end.
self._shouldShutdown = False
# Make sure that if we listened on port 0, we update that to
# reflect what the OS actually assigned us.
self._realPortNumber = skt.getsockname()[1]
log.msg("%s starting on %s" % (
self._getLogPrefix(self.factory), self._realPortNumber))
# The order of the next 5 lines is kind of bizarre. If no one
# can explain it, perhaps we should re-arrange them.
self.factory.doStart()
self.connected = True
self.socket = skt
self.fileno = self.socket.fileno
self.numberAccepts = 100
self.startReading()
def createInternetSocket(self):
"""(internal) Create a non-blocking socket using
self.addressFamily, self.socketType.
"""
s = socket.socket(self.addressFamily, self.socketType)
s.setblocking(0)
fdesc._setCloseOnExec(s.fileno())
return s
The whole logic is simple, and the server-side as normal, creates a socket, bind, listen. Except that socket descriptor added to the read set of reactor. So if the connection with the client over the words, reactor will be monitored, then the event handler is triggered.
Look self.startReading ()
# /twisted/internet/abstract.py
@implementer(
interfaces.IPushProducer, interfaces.IReadWriteDescriptor,
interfaces.IConsumer, interfaces.ITransport,
interfaces.IHalfCloseableDescriptor)
class FileDescriptor(_ConsumerMixin, _LogOwner):
"""
An object which can be operated on by select().
This is an abstract superclass of all objects which may be notified when
they are readable or writable; e.g. they have a file-descriptor that is
valid to be passed to select(2).
"""
def startReading(self):
"""Start waiting for read availability.
"""
self.reactor.addReader(self)
def addReader(self, reader):
"""
Add a FileDescriptor for notification of data available to read.
"""
self._reads.add(reader)
In this sequence will transport added _reads
SOCKET and then the corresponding message will be treated at each select, is to call the doRead transport () method in class tcp.py/Connection.
# twisted/internet/tcp.py
@implementer(interfaces.ITCPTransport, interfaces.ISystemHandle)
class Connection(_TLSConnectionMixin, abstract.FileDescriptor, _SocketCloser,
_AbortingMixin):
def doRead(self):
try:
# 接收数据
data = self.socket.recv(self.bufferSize)
except socket.error as se:
if se.args[0] == EWOULDBLOCK:
return
else:
return main.CONNECTION_LOST
return self._dataReceived(data)
def _dataReceived(self, data):
if not data:
return main.CONNECTION_DONE
# 调用我们自定义protocol的dataReceived方法处理数据
rval = self.protocol.dataReceived(data)
if rval is not None:
offender = self.protocol.dataReceived
warningFormat = (
'Returning a value other than None from %(fqpn)s is '
'deprecated since %(version)s.')
warningString = deprecate.getDeprecationWarningString(
offender, versions.Version('Twisted', 11, 0, 0),
format=warningFormat)
deprecate.warnAboutFunction(offender, warningString)
return rval
In which the calling custom protocol
rval = self.protocol.dataReceived(data)
At this point, the whole cycle be run up.
2. Other
2.1. implementer(IReactorFDSet)
This is a decorator interface, concrete and tangible https://www.cnblogs.com/wodeboke-y/p/11216029.html
# twisted/internet/selectreactor.py
@implementer(IReactorFDSet)
class SelectReactor(posixbase.PosixReactorBase, _extraBase)
implementer expressed SelectReactor implements methods IReactorFDSet interface used here zope.interface , it is the interface in python.
IReactorFDSet interfaces mainly acquisition descriptor, add, or delete method of operation. These methods will be able to see the name to know the meaning of, Skip.
# twisted/internet/interfaces.py
class IReactorFDSet(Interface):
def addReader(reader):
def addWriter(writer):
def removeReader(reader):
def removeWriter(writer):
def removeAll():
def getReaders():
def getWriters():
3. Summary
Simply described, then, twisted to create two socket, respectively, port number port, port + 1, select the use of the system (or other IO multiplexing function) as a polling body;
Then, the upper layer processor encapsulated form and protocol factory, reactor cycle responsible.
PS: do not read the code architecture diagram of the pit too. . . . .