py-libp2p/libp2p/protocol_muxer/multiselect_communicator.py

from libp2p.abc import (
    IMultiselectCommunicator,
)
from libp2p.exceptions import (
    ParseError,
)
from libp2p.io.abc import (
    ReadWriteCloser,
)
from libp2p.io.exceptions import (
    IOException,
)
from libp2p.utils import (
    encode_delim,
    read_delim,
)

from .exceptions import (
    MultiselectCommunicatorError,
)


class MultiselectCommunicator(IMultiselectCommunicator):
    read_writer: ReadWriteCloser

    def __init__(self, read_writer: ReadWriteCloser) -> None:
        self.read_writer = read_writer

    async def write(self, msg_str: str) -> None:
        """
        :raise MultiselectCommunicatorError: raised when failed to write to underlying reader
        """  # noqa: E501
        msg_bytes = encode_delim(msg_str.encode())
        try:
            await self.read_writer.write(msg_bytes)
        except IOException as error:
            raise MultiselectCommunicatorError(
                "fail to write to multiselect communicator"
            ) from error

    async def read(self) -> str:
        """
        :raise MultiselectCommunicatorError: raised when failed to read from underlying reader
        """  # noqa: E501
        try:
            data = await read_delim(self.read_writer)
        # `IOException` includes `IncompleteReadError` and `StreamError`
        except (ParseError, IOException) as error:
            raise MultiselectCommunicatorError(
                "fail to read from multiselect communicator"
            ) from error
        return data.decode()