1 """Abstract Protocol class.""" 2 3 __all__ = ['BaseProtocol', 'Protocol', 'DatagramProtocol', 4 'SubprocessProtocol'] 5 6 7 class BaseProtocol: 8 """Common base class for protocol interfaces. 9 10 Usually user implements protocols that derived from BaseProtocol 11 like Protocol or ProcessProtocol. 12 13 The only case when BaseProtocol should be implemented directly is 14 write-only transport like write pipe 15 """ 16 17 def connection_made(self, transport): 18 """Called when a connection is made. 19 20 The argument is the transport representing the pipe connection. 21 To receive data, wait for data_received() calls. 22 When the connection is closed, connection_lost() is called. 23 """ 24 25 def connection_lost(self, exc): 26 """Called when the connection is lost or closed. 27 28 The argument is an exception object or None (the latter 29 meaning a regular EOF is received or the connection was 30 aborted or closed). 31 """ 32 33 def pause_writing(self): 34 """Called when the transport's buffer goes over the high-water mark. 35 36 Pause and resume calls are paired -- pause_writing() is called 37 once when the buffer goes strictly over the high-water mark 38 (even if subsequent writes increases the buffer size even 39 more), and eventually resume_writing() is called once when the 40 buffer size reaches the low-water mark. 41 42 Note that if the buffer size equals the high-water mark, 43 pause_writing() is not called -- it must go strictly over. 44 Conversely, resume_writing() is called when the buffer size is 45 equal or lower than the low-water mark. These end conditions 46 are important to ensure that things go as expected when either 47 mark is zero. 48 49 NOTE: This is the only Protocol callback that is not called 50 through EventLoop.call_soon() -- if it were, it would have no 51 effect when it's most needed (when the app keeps writing 52 without yielding until pause_writing() is called). 53 """ 54 55 def resume_writing(self): 56 """Called when the transport's buffer drains below the low-water mark. 57 58 See pause_writing() for details. 59 """ 60 61 62 class Protocol(BaseProtocol): 63 """Interface for stream protocol. 64 65 The user should implement this interface. They can inherit from 66 this class but don't need to. The implementations here do 67 nothing (they don't raise exceptions). 68 69 When the user wants to requests a transport, they pass a protocol 70 factory to a utility function (e.g., EventLoop.create_connection()). 71 72 When the connection is made successfully, connection_made() is 73 called with a suitable transport object. Then data_received() 74 will be called 0 or more times with data (bytes) received from the 75 transport; finally, connection_lost() will be called exactly once 76 with either an exception object or None as an argument. 77 78 State machine of calls: 79 80 start -> CM [-> DR*] [-> ER?] -> CL -> end 81 82 * CM: connection_made() 83 * DR: data_received() 84 * ER: eof_received() 85 * CL: connection_lost() 86 """ 87 88 def data_received(self, data): 89 """Called when some data is received. 90 91 The argument is a bytes object. 92 """ 93 94 def eof_received(self): 95 """Called when the other end calls write_eof() or equivalent. 96 97 If this returns a false value (including None), the transport 98 will close itself. If it returns a true value, closing the 99 transport is up to the protocol. 100 """ 101 102 103 class DatagramProtocol(BaseProtocol): 104 """Interface for datagram protocol.""" 105 106 def datagram_received(self, data, addr): 107 """Called when some datagram is received.""" 108 109 def error_received(self, exc): 110 """Called when a send or receive operation raises an OSError. 111 112 (Other than BlockingIOError or InterruptedError.) 113 """ 114 115 116 class SubprocessProtocol(BaseProtocol): 117 """Interface for protocol for subprocess calls.""" 118 119 def pipe_data_received(self, fd, data): 120 """Called when the subprocess writes data into stdout/stderr pipe. 121 122 fd is int file descriptor. 123 data is bytes object. 124 """ 125 126 def pipe_connection_lost(self, fd, exc): 127 """Called when a file descriptor associated with the child process is 128 closed. 129 130 fd is the int file descriptor that was closed. 131 """ 132 133 def process_exited(self): 134 """Called when subprocess has exited.""" 135
