1"""Abstract Protocol base classes."""
2
3__all__ = (
4    'BaseProtocol', 'Protocol', 'DatagramProtocol',
5    'SubprocessProtocol', 'BufferedProtocol',
6)
7
8
9class BaseProtocol:
10    """Common base class for protocol interfaces.
11
12    Usually user implements protocols that derived from BaseProtocol
13    like Protocol or ProcessProtocol.
14
15    The only case when BaseProtocol should be implemented directly is
16    write-only transport like write pipe
17    """
18
19    __slots__ = ()
20
21    def connection_made(self, transport):
22        """Called when a connection is made.
23
24        The argument is the transport representing the pipe connection.
25        To receive data, wait for data_received() calls.
26        When the connection is closed, connection_lost() is called.
27        """
28
29    def connection_lost(self, exc):
30        """Called when the connection is lost or closed.
31
32        The argument is an exception object or None (the latter
33        meaning a regular EOF is received or the connection was
34        aborted or closed).
35        """
36
37    def pause_writing(self):
38        """Called when the transport's buffer goes over the high-water mark.
39
40        Pause and resume calls are paired -- pause_writing() is called
41        once when the buffer goes strictly over the high-water mark
42        (even if subsequent writes increases the buffer size even
43        more), and eventually resume_writing() is called once when the
44        buffer size reaches the low-water mark.
45
46        Note that if the buffer size equals the high-water mark,
47        pause_writing() is not called -- it must go strictly over.
48        Conversely, resume_writing() is called when the buffer size is
49        equal or lower than the low-water mark.  These end conditions
50        are important to ensure that things go as expected when either
51        mark is zero.
52
53        NOTE: This is the only Protocol callback that is not called
54        through EventLoop.call_soon() -- if it were, it would have no
55        effect when it's most needed (when the app keeps writing
56        without yielding until pause_writing() is called).
57        """
58
59    def resume_writing(self):
60        """Called when the transport's buffer drains below the low-water mark.
61
62        See pause_writing() for details.
63        """
64
65
66class Protocol(BaseProtocol):
67    """Interface for stream protocol.
68
69    The user should implement this interface.  They can inherit from
70    this class but don't need to.  The implementations here do
71    nothing (they don't raise exceptions).
72
73    When the user wants to requests a transport, they pass a protocol
74    factory to a utility function (e.g., EventLoop.create_connection()).
75
76    When the connection is made successfully, connection_made() is
77    called with a suitable transport object.  Then data_received()
78    will be called 0 or more times with data (bytes) received from the
79    transport; finally, connection_lost() will be called exactly once
80    with either an exception object or None as an argument.
81
82    State machine of calls:
83
84      start -> CM [-> DR*] [-> ER?] -> CL -> end
85
86    * CM: connection_made()
87    * DR: data_received()
88    * ER: eof_received()
89    * CL: connection_lost()
90    """
91
92    __slots__ = ()
93
94    def data_received(self, data):
95        """Called when some data is received.
96
97        The argument is a bytes object.
98        """
99
100    def eof_received(self):
101        """Called when the other end calls write_eof() or equivalent.
102
103        If this returns a false value (including None), the transport
104        will close itself.  If it returns a true value, closing the
105        transport is up to the protocol.
106        """
107
108
109class BufferedProtocol(BaseProtocol):
110    """Interface for stream protocol with manual buffer control.
111
112    Event methods, such as `create_server` and `create_connection`,
113    accept factories that return protocols that implement this interface.
114
115    The idea of BufferedProtocol is that it allows to manually allocate
116    and control the receive buffer.  Event loops can then use the buffer
117    provided by the protocol to avoid unnecessary data copies.  This
118    can result in noticeable performance improvement for protocols that
119    receive big amounts of data.  Sophisticated protocols can allocate
120    the buffer only once at creation time.
121
122    State machine of calls:
123
124      start -> CM [-> GB [-> BU?]]* [-> ER?] -> CL -> end
125
126    * CM: connection_made()
127    * GB: get_buffer()
128    * BU: buffer_updated()
129    * ER: eof_received()
130    * CL: connection_lost()
131    """
132
133    __slots__ = ()
134
135    def get_buffer(self, sizehint):
136        """Called to allocate a new receive buffer.
137
138        *sizehint* is a recommended minimal size for the returned
139        buffer.  When set to -1, the buffer size can be arbitrary.
140
141        Must return an object that implements the
142        :ref:`buffer protocol <bufferobjects>`.
143        It is an error to return a zero-sized buffer.
144        """
145
146    def buffer_updated(self, nbytes):
147        """Called when the buffer was updated with the received data.
148
149        *nbytes* is the total number of bytes that were written to
150        the buffer.
151        """
152
153    def eof_received(self):
154        """Called when the other end calls write_eof() or equivalent.
155
156        If this returns a false value (including None), the transport
157        will close itself.  If it returns a true value, closing the
158        transport is up to the protocol.
159        """
160
161
162class DatagramProtocol(BaseProtocol):
163    """Interface for datagram protocol."""
164
165    __slots__ = ()
166
167    def datagram_received(self, data, addr):
168        """Called when some datagram is received."""
169
170    def error_received(self, exc):
171        """Called when a send or receive operation raises an OSError.
172
173        (Other than BlockingIOError or InterruptedError.)
174        """
175
176
177class SubprocessProtocol(BaseProtocol):
178    """Interface for protocol for subprocess calls."""
179
180    __slots__ = ()
181
182    def pipe_data_received(self, fd, data):
183        """Called when the subprocess writes data into stdout/stderr pipe.
184
185        fd is int file descriptor.
186        data is bytes object.
187        """
188
189    def pipe_connection_lost(self, fd, exc):
190        """Called when a file descriptor associated with the child process is
191        closed.
192
193        fd is the int file descriptor that was closed.
194        """
195
196    def process_exited(self):
197        """Called when subprocess has exited."""
198
199
200def _feed_data_to_buffered_proto(proto, data):
201    data_len = len(data)
202    while data_len:
203        buf = proto.get_buffer(data_len)
204        buf_len = len(buf)
205        if not buf_len:
206            raise RuntimeError('get_buffer() returned an empty buffer')
207
208        if buf_len >= data_len:
209            buf[:data_len] = data
210            proto.buffer_updated(data_len)
211            return
212        else:
213            buf[:buf_len] = data[:buf_len]
214            proto.buffer_updated(buf_len)
215            data = data[buf_len:]
216            data_len = len(data)
217