mirror of
https://github.com/python/cpython.git
synced 2025-11-04 15:41:43 +00:00
220 lines
7 KiB
Python
220 lines
7 KiB
Python
"""Abstract Protocol base classes."""
|
|
|
|
__all__ = (
|
|
'BaseProtocol', 'Protocol', 'DatagramProtocol',
|
|
'SubprocessProtocol', 'BufferedProtocol',
|
|
)
|
|
|
|
|
|
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
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
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()
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
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 BufferedProtocol(BaseProtocol):
|
|
"""Interface for stream protocol with manual buffer control.
|
|
|
|
Important: this has been added to asyncio in Python 3.7
|
|
*on a provisional basis*! Consider it as an experimental API that
|
|
might be changed or removed in Python 3.8.
|
|
|
|
Event methods, such as `create_server` and `create_connection`,
|
|
accept factories that return protocols that implement this interface.
|
|
|
|
The idea of BufferedProtocol is that it allows to manually allocate
|
|
and control the receive buffer. Event loops can then use the buffer
|
|
provided by the protocol to avoid unnecessary data copies. This
|
|
can result in noticeable performance improvement for protocols that
|
|
receive big amounts of data. Sophisticated protocols can allocate
|
|
the buffer only once at creation time.
|
|
|
|
State machine of calls:
|
|
|
|
start -> CM [-> GB [-> BU?]]* [-> ER?] -> CL -> end
|
|
|
|
* CM: connection_made()
|
|
* GB: get_buffer()
|
|
* BU: buffer_updated()
|
|
* ER: eof_received()
|
|
* CL: connection_lost()
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
def get_buffer(self, sizehint):
|
|
"""Called to allocate a new receive buffer.
|
|
|
|
*sizehint* is a recommended minimal size for the returned
|
|
buffer. When set to -1, the buffer size can be arbitrary.
|
|
|
|
Must return an object that implements the
|
|
:ref:`buffer protocol <bufferobjects>`.
|
|
It is an error to return a zero-sized buffer.
|
|
"""
|
|
|
|
def buffer_updated(self, nbytes):
|
|
"""Called when the buffer was updated with the received data.
|
|
|
|
*nbytes* is the total number of bytes that were written to
|
|
the buffer.
|
|
"""
|
|
|
|
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."""
|
|
|
|
__slots__ = ()
|
|
|
|
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."""
|
|
|
|
__slots__ = ()
|
|
|
|
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."""
|
|
|
|
|
|
def _feed_data_to_buffered_proto(proto, data):
|
|
data_len = len(data)
|
|
while data_len:
|
|
buf = proto.get_buffer(data_len)
|
|
buf_len = len(buf)
|
|
if not buf_len:
|
|
raise RuntimeError('get_buffer() returned an empty buffer')
|
|
|
|
if buf_len >= data_len:
|
|
buf[:data_len] = data
|
|
proto.buffer_updated(data_len)
|
|
return
|
|
else:
|
|
buf[:buf_len] = data[:buf_len]
|
|
proto.buffer_updated(buf_len)
|
|
data = data[buf_len:]
|
|
data_len = len(data)
|