proactor_events.py 文件源码

def write(self, data):
        if not isinstance(data, (bytes, bytearray, memoryview)):
            raise TypeError('data argument must be byte-ish (%r)',
                            type(data))
        if self._eof_written:
            raise RuntimeError('write_eof() already called')

        if not data:
            return

        if self._conn_lost:
            if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
                logger.warning('socket.send() raised exception.')
            self._conn_lost += 1
            return

        # Observable states:
        # 1. IDLE: _write_fut and _buffer both None
        # 2. WRITING: _write_fut set; _buffer None
        # 3. BACKED UP: _write_fut set; _buffer a bytearray
        # We always copy the data, so the caller can't modify it
        # while we're still waiting for the I/O to happen.
        if self._write_fut is None:  # IDLE -> WRITING
            assert self._buffer is None
            # Pass a copy, except if it's already immutable.
            self._loop_writing(data=bytes(data))
        elif not self._buffer:  # WRITING -> BACKED UP
            # Make a mutable copy which we can extend.
            self._buffer = bytearray(data)
            self._maybe_pause_protocol()
        else:  # BACKED UP
            # Append to buffer (also copies).
            self._buffer.extend(data)
            self._maybe_pause_protocol()