137 lines
4.4 KiB
Python
137 lines
4.4 KiB
Python
"""Abstract Protocol base classes."""
|
|
|
|
__all__ = (
|
|
'BaseProtocol', 'Protocol', 'DatagramProtocol',
|
|
'SubprocessProtocol',
|
|
)
|
|
|
|
|
|
class BaseProtocol:
|
|
"""Common base class for protocol interfaces.
|
|
|
|
Usually user implements protocols that derived from BaseProtocol
|
|
like Protocol or ProcessProtocol.
|
|
|
|
The only case when BaseProtocol should be implemented directly is
|
|
write-only transport like write pipe
|
|
"""
|
|
|
|
def connection_made(self, transport):
|
|
"""Called when a connection is made.
|
|
|
|
The argument is the transport representing the pipe connection.
|
|
To receive data, wait for data_received() calls.
|
|
When the connection is closed, connection_lost() is called.
|
|
"""
|
|
|
|
def connection_lost(self, exc):
|
|
"""Called when the connection is lost or closed.
|
|
|
|
The argument is an exception object or None (the latter
|
|
meaning a regular EOF is received or the connection was
|
|
aborted or closed).
|
|
"""
|
|
|
|
def pause_writing(self):
|
|
"""Called when the transport's buffer goes over the high-water mark.
|
|
|
|
Pause and resume calls are paired -- pause_writing() is called
|
|
once when the buffer goes strictly over the high-water mark
|
|
(even if subsequent writes increases the buffer size even
|
|
more), and eventually resume_writing() is called once when the
|
|
buffer size reaches the low-water mark.
|
|
|
|
Note that if the buffer size equals the high-water mark,
|
|
pause_writing() is not called -- it must go strictly over.
|
|
Conversely, resume_writing() is called when the buffer size is
|
|
equal or lower than the low-water mark. These end conditions
|
|
are important to ensure that things go as expected when either
|
|
mark is zero.
|
|
|
|
NOTE: This is the only Protocol callback that is not called
|
|
through EventLoop.call_soon() -- if it were, it would have no
|
|
effect when it's most needed (when the app keeps writing
|
|
without yielding until pause_writing() is called).
|
|
"""
|
|
|
|
def resume_writing(self):
|
|
"""Called when the transport's buffer drains below the low-water mark.
|
|
|
|
See pause_writing() for details.
|
|
"""
|
|
|
|
|
|
class Protocol(BaseProtocol):
|
|
"""Interface for stream protocol.
|
|
|
|
The user should implement this interface. They can inherit from
|
|
this class but don't need to. The implementations here do
|
|
nothing (they don't raise exceptions).
|
|
|
|
When the user wants to requests a transport, they pass a protocol
|
|
factory to a utility function (e.g., EventLoop.create_connection()).
|
|
|
|
When the connection is made successfully, connection_made() is
|
|
called with a suitable transport object. Then data_received()
|
|
will be called 0 or more times with data (bytes) received from the
|
|
transport; finally, connection_lost() will be called exactly once
|
|
with either an exception object or None as an argument.
|
|
|
|
State machine of calls:
|
|
|
|
start -> CM [-> DR*] [-> ER?] -> CL -> end
|
|
|
|
* CM: connection_made()
|
|
* DR: data_received()
|
|
* ER: eof_received()
|
|
* CL: connection_lost()
|
|
"""
|
|
|
|
def data_received(self, data):
|
|
"""Called when some data is received.
|
|
|
|
The argument is a bytes object.
|
|
"""
|
|
|
|
def eof_received(self):
|
|
"""Called when the other end calls write_eof() or equivalent.
|
|
|
|
If this returns a false value (including None), the transport
|
|
will close itself. If it returns a true value, closing the
|
|
transport is up to the protocol.
|
|
"""
|
|
|
|
|
|
class DatagramProtocol(BaseProtocol):
|
|
"""Interface for datagram protocol."""
|
|
|
|
def datagram_received(self, data, addr):
|
|
"""Called when some datagram is received."""
|
|
|
|
def error_received(self, exc):
|
|
"""Called when a send or receive operation raises an OSError.
|
|
|
|
(Other than BlockingIOError or InterruptedError.)
|
|
"""
|
|
|
|
|
|
class SubprocessProtocol(BaseProtocol):
|
|
"""Interface for protocol for subprocess calls."""
|
|
|
|
def pipe_data_received(self, fd, data):
|
|
"""Called when the subprocess writes data into stdout/stderr pipe.
|
|
|
|
fd is int file descriptor.
|
|
data is bytes object.
|
|
"""
|
|
|
|
def pipe_connection_lost(self, fd, exc):
|
|
"""Called when a file descriptor associated with the child process is
|
|
closed.
|
|
|
|
fd is the int file descriptor that was closed.
|
|
"""
|
|
|
|
def process_exited(self):
|
|
"""Called when subprocess has exited."""
|