twisted的tcp.py分析

#每个connector都有一个 Connection对象
@implementer(interfaces.ITCPTransport, interfaces.ISystemHandle)
class Connection(_TLSConnectionMixin, abstract.FileDescriptor, _SocketCloser,
                 _AbortingMixin):
    """
    Superclass of all socket-based FileDescriptors.

    This is an abstract superclass of all objects which represent a TCP/IP
    connection based socket.

    @ivar logstr: prefix used when logging events related to this connection.
    @type logstr: C{str}
    """

    def __init__(self, skt, protocol, reactor=None):
        abstract.FileDescriptor.__init__(self, reactor=reactor)
        self.socket = skt
        self.socket.setblocking(0)
        self.fileno = skt.fileno
        self.protocol = protocol

    def getHandle(self):
        """Return the socket for this connection."""
        return self.socket

    def doRead(self):
        """Calls self.protocol.dataReceived with all available data.

        This reads up to self.bufferSize bytes of data from its socket, then
        calls self.dataReceived(data) to process it.  If the connection is not
        lost through an error in the physical recv(), this function will return
        the result of the dataReceived call.
        """
        try:
            data = self.socket.recv(self.bufferSize)#recv读取数据
        except socket.error as se:
            if se.args[0] == EWOULDBLOCK:
                return
            else:
                return main.CONNECTION_LOST

        return self._dataReceived(data)#调用内部方法

    def _dataReceived(self, data):
        if not data:
            return main.CONNECTION_DONE
        rval = self.protocol.dataReceived(data)#调用-协议提供的数据接收方法
        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

    def writeSomeData(self, data):
        """
        Write as much as possible of the given data to this TCP connection.

        This sends up to C{self.SEND_LIMIT} bytes from C{data}.  If the
        connection is lost, an exception is returned.  Otherwise, the number
        of bytes successfully written is returned.
        """
        # Limit length of buffer to try to send, because some OSes are too
        # stupid to do so themselves (ahem windows)
        limitedData = lazyByteSlice(data, 0, self.SEND_LIMIT)

        try:
            return untilConcludes(self.socket.send, limitedData)
        except socket.error as se:
            if se.args[0] in (EWOULDBLOCK, ENOBUFS):
                return 0
            else:
                return main.CONNECTION_LOST

    def _closeWriteConnection(self):
        try:
            self.socket.shutdown(1)
        except socket.error:
            pass
        p = interfaces.IHalfCloseableProtocol(self.protocol, None)
        if p:
            try:
                p.writeConnectionLost()
            except:
                f = failure.Failure()
                log.err()
                self.connectionLost(f)

    def readConnectionLost(self, reason):
        p = interfaces.IHalfCloseableProtocol(self.protocol, None)
        if p:
            try:
                p.readConnectionLost()
            except:
                log.err()
                self.connectionLost(failure.Failure())
        else:
            self.connectionLost(reason)

    def connectionLost(self, reason):
        """See abstract.FileDescriptor.connectionLost().
        """
        # Make sure we're not called twice, which can happen e.g. if
        # abortConnection() is called from protocol's dataReceived and then
        # code immediately after throws an exception that reaches the
        # reactor. We can't rely on "disconnected" attribute for this check
        # since twisted.internet._oldtls does evil things to it:
        if not hasattr(self, "socket"):
            return
        abstract.FileDescriptor.connectionLost(self, reason)
        self._closeSocket(not reason.check(error.ConnectionAborted))
        protocol = self.protocol
        del self.protocol
        del self.socket
        del self.fileno
        protocol.connectionLost(reason)

    logstr = "Uninitialized"

    def logPrefix(self):
        """Return the prefix to log with when I own the logging thread.
        """
        return self.logstr

    def getTcpNoDelay(self):
        return operator.truth(self.socket.getsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY))

    def setTcpNoDelay(self, enabled):
        self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, enabled)

    def getTcpKeepAlive(self):
        return operator.truth(self.socket.getsockopt(socket.SOL_SOCKET,
                                                     socket.SO_KEEPALIVE))

    def setTcpKeepAlive(self, enabled):
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, enabled)