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Low Level APIs

Connection

BaseParser

Plain Python parsing class

parse_error(self, response)

Parse an error response

Source code in aioredis/connection.py
def parse_error(self, response: str) -> ResponseError:
    """Parse an error response"""
    error_code = response.split(" ")[0]
    if error_code in self.EXCEPTION_CLASSES:
        response = response[len(error_code) + 1 :]
        exception_class = self.EXCEPTION_CLASSES[error_code]
        if isinstance(exception_class, dict):
            exception_class = exception_class.get(response, ResponseError)
        return exception_class(response)
    return ResponseError(response)

BlockingConnectionPool

Thread-safe blocking connection pool::

>>> from aioredis.client import Redis
>>> client = Redis(connection_pool=BlockingConnectionPool())

It performs the same function as the default 🇵🇾class:~redis.ConnectionPool implementation, in that, it maintains a pool of reusable connections that can be shared by multiple redis clients (safely across threads if required).

The difference is that, in the event that a client tries to get a connection from the pool when all of connections are in use, rather than raising a 🇵🇾class:~redis.ConnectionError (as the default 🇵🇾class:~redis.ConnectionPool implementation does), it makes the client wait (“blocks”) for a specified number of seconds until a connection becomes available.

Use max_connections to increase / decrease the pool size::

>>> pool = BlockingConnectionPool(max_connections=10)

Use timeout to tell it either how many seconds to wait for a connection to become available, or to block forever:

>>> # Block forever.
>>> pool = BlockingConnectionPool(timeout=None)

>>> # Raise a ``ConnectionError`` after five seconds if a connection is
>>> # not available.
>>> pool = BlockingConnectionPool(timeout=5)

disconnect(self, inuse_connections=True) async

Disconnects all connections in the pool.

Source code in aioredis/connection.py
async def disconnect(self, inuse_connections: bool = True):
    """Disconnects all connections in the pool."""
    self._checkpid()
    async with self._lock:
        resp = await asyncio.gather(
            *(connection.disconnect() for connection in self._connections),
            return_exceptions=True,
        )
        exc = next((r for r in resp if isinstance(r, BaseException)), None)
        if exc:
            raise exc

get_connection(self, command_name, *keys, **options) async

Get a connection, blocking for self.timeout until a connection is available from the pool.

If the connection returned is None then creates a new connection. Because we use a last-in first-out queue, the existing connections (having been returned to the pool after the initial None values were added) will be returned before None values. This means we only create new connections when we need to, i.e.: the actual number of connections will only increase in response to demand.

Source code in aioredis/connection.py
async def get_connection(self, command_name, *keys, **options):
    """
    Get a connection, blocking for ``self.timeout`` until a connection
    is available from the pool.

    If the connection returned is ``None`` then creates a new connection.
    Because we use a last-in first-out queue, the existing connections
    (having been returned to the pool after the initial ``None`` values
    were added) will be returned before ``None`` values. This means we only
    create new connections when we need to, i.e.: the actual number of
    connections will only increase in response to demand.
    """
    # Make sure we haven't changed process.
    self._checkpid()

    # Try and get a connection from the pool. If one isn't available within
    # self.timeout then raise a ``ConnectionError``.
    connection = None
    try:
        async with async_timeout.timeout(self.timeout):
            connection = await self.pool.get()
    except (asyncio.QueueEmpty, asyncio.TimeoutError):
        # Note that this is not caught by the redis client and will be
        # raised unless handled by application code. If you want never to
        raise ConnectionError("No connection available.")

    # If the ``connection`` is actually ``None`` then that's a cue to make
    # a new connection to add to the pool.
    if connection is None:
        connection = self.make_connection()

    try:
        # ensure this connection is connected to Redis
        await connection.connect()
        # connections that the pool provides should be ready to send
        # a command. if not, the connection was either returned to the
        # pool before all data has been read or the socket has been
        # closed. either way, reconnect and verify everything is good.
        try:
            if await connection.can_read():
                raise ConnectionError("Connection has data") from None
        except ConnectionError:
            await connection.disconnect()
            await connection.connect()
            if await connection.can_read():
                raise ConnectionError("Connection not ready") from None
    except BaseException:
        # release the connection back to the pool so that we don't leak it
        await self.release(connection)
        raise

    return connection

make_connection(self)

Make a fresh connection.

Source code in aioredis/connection.py
def make_connection(self):
    """Make a fresh connection."""
    connection = self.connection_class(**self.connection_kwargs)
    self._connections.append(connection)
    return connection

release(self, connection) async

Releases the connection back to the pool.

Source code in aioredis/connection.py
async def release(self, connection: Connection):
    """Releases the connection back to the pool."""
    # Make sure we haven't changed process.
    self._checkpid()
    if not self.owns_connection(connection):
        # pool doesn't own this connection. do not add it back
        # to the pool. instead add a None value which is a placeholder
        # that will cause the pool to recreate the connection if
        # its needed.
        await connection.disconnect()
        self.pool.put_nowait(None)
        return

    # Put the connection back into the pool.
    try:
        self.pool.put_nowait(connection)
    except asyncio.QueueFull:
        # perhaps the pool has been reset() after a fork? regardless,
        # we don't want this connection
        pass

Connection

Manages TCP communication to and from a Redis server

can_read(self, timeout=0) async

Poll the socket to see if there’s data that can be read.

Source code in aioredis/connection.py
async def can_read(self, timeout: float = 0):
    """Poll the socket to see if there's data that can be read."""
    if not self.is_connected:
        await self.connect()
    return await self._parser.can_read(timeout)

check_health(self) async

Check the health of the connection with a PING/PONG

Source code in aioredis/connection.py
async def check_health(self):
    """Check the health of the connection with a PING/PONG"""
    if (
        self.health_check_interval
        and asyncio.get_event_loop().time() > self.next_health_check
    ):
        try:
            await self.send_command("PING", check_health=False)
            if str_if_bytes(await self.read_response()) != "PONG":
                raise ConnectionError("Bad response from PING health check")
        except (ConnectionError, TimeoutError) as err:
            await self.disconnect()
            try:
                await self.send_command("PING", check_health=False)
                if str_if_bytes(await self.read_response()) != "PONG":
                    raise ConnectionError(
                        "Bad response from PING health check"
                    ) from None
            except BaseException as err2:
                raise err2 from err

connect(self) async

Connects to the Redis server if not already connected

Source code in aioredis/connection.py
async def connect(self):
    """Connects to the Redis server if not already connected"""
    if self.is_connected:
        return
    try:
        await self._connect()
    except asyncio.CancelledError:
        raise
    except (socket.timeout, asyncio.TimeoutError):
        raise TimeoutError("Timeout connecting to server")
    except OSError as e:
        raise ConnectionError(self._error_message(e))
    except Exception as exc:
        raise ConnectionError(exc) from exc

    try:
        await self.on_connect()
    except RedisError:
        # clean up after any error in on_connect
        await self.disconnect()
        raise

    # run any user callbacks. right now the only internal callback
    # is for pubsub channel/pattern resubscription
    for callback in self._connect_callbacks:
        task = callback(self)
        if task and inspect.isawaitable(task):
            await task

disconnect(self) async

Disconnects from the Redis server

Source code in aioredis/connection.py
async def disconnect(self):
    """Disconnects from the Redis server"""
    try:
        async with async_timeout.timeout(self.socket_connect_timeout):
            self._parser.on_disconnect()
            if not self.is_connected:
                return
            try:
                if os.getpid() == self.pid:
                    self._writer.close()
                    # py3.6 doesn't have this method
                    if hasattr(self._writer, "wait_closed"):
                        await self._writer.wait_closed()
            except OSError:
                pass
            self._reader = None
            self._writer = None
    except asyncio.TimeoutError:
        raise TimeoutError(
            f"Timed out closing connection after {self.socket_connect_timeout}"
        ) from None

on_connect(self) async

Initialize the connection, authenticate and select a database

Source code in aioredis/connection.py
async def on_connect(self):
    """Initialize the connection, authenticate and select a database"""
    self._parser.on_connect(self)

    # if username and/or password are set, authenticate
    if self.username or self.password:
        if self.username:
            auth_args = (self.username, self.password or "")
        else:
            auth_args = (self.password,)
        # avoid checking health here -- PING will fail if we try
        # to check the health prior to the AUTH
        await self.send_command("AUTH", *auth_args, check_health=False)

        try:
            auth_response = await self.read_response()
        except AuthenticationWrongNumberOfArgsError:
            # a username and password were specified but the Redis
            # server seems to be < 6.0.0 which expects a single password
            # arg. retry auth with just the password.
            # https://github.com/andymccurdy/redis-py/issues/1274
            await self.send_command("AUTH", self.password, check_health=False)
            auth_response = await self.read_response()

        if str_if_bytes(auth_response) != "OK":
            raise AuthenticationError("Invalid Username or Password")

    # if a client_name is given, set it
    if self.client_name:
        await self.send_command("CLIENT", "SETNAME", self.client_name)
        if str_if_bytes(await self.read_response()) != "OK":
            raise ConnectionError("Error setting client name")

    # if a database is specified, switch to it
    if self.db:
        await self.send_command("SELECT", self.db)
        if str_if_bytes(await self.read_response()) != "OK":
            raise ConnectionError("Invalid Database")

pack_command(self, *args)

Pack a series of arguments into the Redis protocol

Source code in aioredis/connection.py
def pack_command(self, *args: EncodableT) -> List[bytes]:
    """Pack a series of arguments into the Redis protocol"""
    output = []
    # the client might have included 1 or more literal arguments in
    # the command name, e.g., 'CONFIG GET'. The Redis server expects these
    # arguments to be sent separately, so split the first argument
    # manually. These arguments should be bytestrings so that they are
    # not encoded.
    if isinstance(args[0], str):
        args = tuple(args[0].encode().split()) + args[1:]
    elif b" " in args[0]:
        args = tuple(args[0].split()) + args[1:]

    buff = SYM_EMPTY.join((SYM_STAR, str(len(args)).encode(), SYM_CRLF))

    buffer_cutoff = self._buffer_cutoff
    for arg in map(self.encoder.encode, args):
        # to avoid large string mallocs, chunk the command into the
        # output list if we're sending large values or memoryviews
        arg_length = len(arg)
        if (
            len(buff) > buffer_cutoff
            or arg_length > buffer_cutoff
            or isinstance(arg, memoryview)
        ):
            buff = SYM_EMPTY.join(
                (buff, SYM_DOLLAR, str(arg_length).encode(), SYM_CRLF)
            )
            output.append(buff)
            output.append(arg)
            buff = SYM_CRLF
        else:
            buff = SYM_EMPTY.join(
                (
                    buff,
                    SYM_DOLLAR,
                    str(arg_length).encode(),
                    SYM_CRLF,
                    arg,
                    SYM_CRLF,
                )
            )
    output.append(buff)
    return output

pack_commands(self, commands)

Pack multiple commands into the Redis protocol

Source code in aioredis/connection.py
def pack_commands(self, commands: Iterable[Iterable[EncodableT]]) -> List[bytes]:
    """Pack multiple commands into the Redis protocol"""
    output: List[bytes] = []
    pieces: List[bytes] = []
    buffer_length = 0
    buffer_cutoff = self._buffer_cutoff

    for cmd in commands:
        for chunk in self.pack_command(*cmd):
            chunklen = len(chunk)
            if (
                buffer_length > buffer_cutoff
                or chunklen > buffer_cutoff
                or isinstance(chunk, memoryview)
            ):
                output.append(SYM_EMPTY.join(pieces))
                buffer_length = 0
                pieces = []

            if chunklen > buffer_cutoff or isinstance(chunk, memoryview):
                output.append(chunk)
            else:
                pieces.append(chunk)
                buffer_length += chunklen

    if pieces:
        output.append(SYM_EMPTY.join(pieces))
    return output

read_response(self) async

Read the response from a previously sent command

Source code in aioredis/connection.py
async def read_response(self):
    """Read the response from a previously sent command"""
    try:
        async with self._lock:
            async with async_timeout.timeout(self.socket_timeout):
                response = await self._parser.read_response()
    except asyncio.TimeoutError:
        await self.disconnect()
        raise TimeoutError(f"Timeout reading from {self.host}:{self.port}")
    except BaseException:
        await self.disconnect()
        raise

    if self.health_check_interval:
        self.next_health_check = (
            asyncio.get_event_loop().time() + self.health_check_interval
        )

    if isinstance(response, ResponseError):
        raise response from None
    return response

send_command(self, *args, **kwargs) async

Pack and send a command to the Redis server

Source code in aioredis/connection.py
async def send_command(self, *args, **kwargs):
    """Pack and send a command to the Redis server"""
    if not self.is_connected:
        await self.connect()
    await self.send_packed_command(
        self.pack_command(*args), check_health=kwargs.get("check_health", True)
    )

send_packed_command(self, command, check_health=True) async

Send an already packed command to the Redis server

Source code in aioredis/connection.py
async def send_packed_command(
    self,
    command: Union[bytes, str, Iterable[Union[bytes, str]]],
    check_health: bool = True,
):
    """Send an already packed command to the Redis server"""
    if not self._writer:
        await self.connect()
    # guard against health check recursion
    if check_health:
        await self.check_health()
    try:
        if isinstance(command, str):
            command = command.encode()
        if isinstance(command, bytes):
            command = [command]
        await asyncio.wait_for(
            self._send_packed_command(command),
            self.socket_timeout,
        )
    except asyncio.TimeoutError:
        await self.disconnect()
        raise TimeoutError("Timeout writing to socket") from None
    except OSError as e:
        await self.disconnect()
        if len(e.args) == 1:
            err_no, errmsg = "UNKNOWN", e.args[0]
        else:
            err_no = e.args[0]
            errmsg = e.args[1]
        raise ConnectionError(
            f"Error {err_no} while writing to socket. {errmsg}."
        ) from e
    except BaseException:
        await self.disconnect()
        raise

ConnectionPool

Create a connection pool. If max_connections is set, then this object raises 🇵🇾class:~redis.ConnectionError when the pool’s limit is reached.

By default, TCP connections are created unless connection_class is specified. Use 🇵🇾class:~redis.UnixDomainSocketConnection for unix sockets.

Any additional keyword arguments are passed to the constructor of connection_class.

disconnect(self, inuse_connections=True) async

Disconnects connections in the pool

If inuse_connections is True, disconnect connections that are current in use, potentially by other tasks. Otherwise only disconnect connections that are idle in the pool.

Source code in aioredis/connection.py
async def disconnect(self, inuse_connections: bool = True):
    """
    Disconnects connections in the pool

    If ``inuse_connections`` is True, disconnect connections that are
    current in use, potentially by other tasks. Otherwise only disconnect
    connections that are idle in the pool.
    """
    self._checkpid()
    async with self._lock:
        if inuse_connections:
            connections = chain(
                self._available_connections, self._in_use_connections
            )
        else:
            connections = self._available_connections
        resp = await asyncio.gather(
            *(connection.disconnect() for connection in connections),
            return_exceptions=True,
        )
        exc = next((r for r in resp if isinstance(r, BaseException)), None)
        if exc:
            raise exc

from_url(url, **kwargs) classmethod

Return a connection pool configured from the given URL.

For example::

redis://[[username]:[password]]@localhost:6379/0
rediss://[[username]:[password]]@localhost:6379/0
unix://[[username]:[password]]@/path/to/socket.sock?db=0

Three URL schemes are supported:

The username, password, hostname, path and all querystring values are passed through urllib.parse.unquote in order to replace any percent-encoded values with their corresponding characters.

There are several ways to specify a database number. The first value found will be used: 1. A db querystring option, e.g. redis://localhost?db=0 2. If using the redis:// or rediss:// schemes, the path argument of the url, e.g. redis://localhost/0 3. A db keyword argument to this function.

If none of these options are specified, the default db=0 is used.

All querystring options are cast to their appropriate Python types. Boolean arguments can be specified with string values “True”/”False” or “Yes”/”No”. Values that cannot be properly cast cause a ValueError to be raised. Once parsed, the querystring arguments and keyword arguments are passed to the ConnectionPool‘s class initializer. In the case of conflicting arguments, querystring arguments always win.

Source code in aioredis/connection.py
@classmethod
def from_url(cls: Type[_CP], url: str, **kwargs) -> _CP:
    """
    Return a connection pool configured from the given URL.

    For example::

        redis://[[username]:[password]]@localhost:6379/0
        rediss://[[username]:[password]]@localhost:6379/0
        unix://[[username]:[password]]@/path/to/socket.sock?db=0

    Three URL schemes are supported:

    - `redis://` creates a TCP socket connection. See more at:
      <https://www.iana.org/assignments/uri-schemes/prov/redis>
    - `rediss://` creates a SSL wrapped TCP socket connection. See more at:
      <https://www.iana.org/assignments/uri-schemes/prov/rediss>
    - ``unix://``: creates a Unix Domain Socket connection.

    The username, password, hostname, path and all querystring values
    are passed through urllib.parse.unquote in order to replace any
    percent-encoded values with their corresponding characters.

    There are several ways to specify a database number. The first value
    found will be used:
        1. A ``db`` querystring option, e.g. redis://localhost?db=0
        2. If using the redis:// or rediss:// schemes, the path argument
           of the url, e.g. redis://localhost/0
        3. A ``db`` keyword argument to this function.

    If none of these options are specified, the default db=0 is used.

    All querystring options are cast to their appropriate Python types.
    Boolean arguments can be specified with string values "True"/"False"
    or "Yes"/"No". Values that cannot be properly cast cause a
    ``ValueError`` to be raised. Once parsed, the querystring arguments
    and keyword arguments are passed to the ``ConnectionPool``'s
    class initializer. In the case of conflicting arguments, querystring
    arguments always win.
    """
    url_options = parse_url(url)
    kwargs.update(url_options)
    return cls(**kwargs)

get_connection(self, command_name, *keys, **options) async

Get a connection from the pool

Source code in aioredis/connection.py
async def get_connection(self, command_name, *keys, **options):
    """Get a connection from the pool"""
    self._checkpid()
    async with self._lock:
        try:
            connection = self._available_connections.pop()
        except IndexError:
            connection = self.make_connection()
        self._in_use_connections.add(connection)

    try:
        # ensure this connection is connected to Redis
        await connection.connect()
        # connections that the pool provides should be ready to send
        # a command. if not, the connection was either returned to the
        # pool before all data has been read or the socket has been
        # closed. either way, reconnect and verify everything is good.
        try:
            if await connection.can_read():
                raise ConnectionError("Connection has data") from None
        except ConnectionError:
            await connection.disconnect()
            await connection.connect()
            if await connection.can_read():
                raise ConnectionError("Connection not ready") from None
    except BaseException:
        # release the connection back to the pool so that we don't
        # leak it
        await self.release(connection)
        raise

    return connection

get_encoder(self)

Return an encoder based on encoding settings

Source code in aioredis/connection.py
def get_encoder(self):
    """Return an encoder based on encoding settings"""
    kwargs = self.connection_kwargs
    return self.encoder_class(
        encoding=kwargs.get("encoding", "utf-8"),
        encoding_errors=kwargs.get("encoding_errors", "strict"),
        decode_responses=kwargs.get("decode_responses", False),
    )

make_connection(self)

Create a new connection

Source code in aioredis/connection.py
def make_connection(self):
    """Create a new connection"""
    if self._created_connections >= self.max_connections:
        raise ConnectionError("Too many connections")
    self._created_connections += 1
    return self.connection_class(**self.connection_kwargs)

release(self, connection) async

Releases the connection back to the pool

Source code in aioredis/connection.py
async def release(self, connection: Connection):
    """Releases the connection back to the pool"""
    self._checkpid()
    async with self._lock:
        try:
            self._in_use_connections.remove(connection)
        except KeyError:
            # Gracefully fail when a connection is returned to this pool
            # that the pool doesn't actually own
            pass

        if self.owns_connection(connection):
            self._available_connections.append(connection)
        else:
            # pool doesn't own this connection. do not add it back
            # to the pool and decrement the count so that another
            # connection can take its place if needed
            self._created_connections -= 1
            await connection.disconnect()
            return

DefaultParser

Plain Python parsing class

on_connect(self, connection)

Called when the stream connects

Source code in aioredis/connection.py
def on_connect(self, connection: "Connection"):
    """Called when the stream connects"""
    self._stream = connection._reader
    self._buffer = SocketBuffer(
        self._stream, self._read_size, connection.socket_timeout
    )
    self.encoder = connection.encoder

on_disconnect(self)

Called when the stream disconnects

Source code in aioredis/connection.py
def on_disconnect(self):
    """Called when the stream disconnects"""
    if self._stream is not None:
        self._stream = None
    if self._buffer is not None:
        self._buffer.close()
        self._buffer = None
    self.encoder = None

Encoder

Encode strings to bytes-like and decode bytes-like to strings

decode(self, value, force=False)

Return a unicode string from the bytes-like representation

Source code in aioredis/connection.py
def decode(self, value: EncodableT, force=False) -> EncodableT:
    """Return a unicode string from the bytes-like representation"""
    if self.decode_responses or force:
        if isinstance(value, memoryview):
            return value.tobytes().decode(self.encoding, self.encoding_errors)
        if isinstance(value, bytes):
            return value.decode(self.encoding, self.encoding_errors)
    return value

encode(self, value)

Return a bytestring or bytes-like representation of the value

Source code in aioredis/connection.py
def encode(self, value: EncodableT) -> EncodedT:
    """Return a bytestring or bytes-like representation of the value"""
    if isinstance(value, (bytes, memoryview)):
        return value
    if isinstance(value, bool):
        # special case bool since it is a subclass of int
        raise DataError(
            "Invalid input of type: 'bool'. "
            "Convert to a bytes, string, int or float first."
        )
    if isinstance(value, (int, float)):
        return repr(value).encode()
    if not isinstance(value, str):
        # a value we don't know how to deal with. throw an error
        typename = value.__class__.__name__
        raise DataError(
            f"Invalid input of type: {typename!r}. "
            "Convert to a bytes, string, int or float first."
        )
    if isinstance(value, str):
        return value.encode(self.encoding, self.encoding_errors)
    return value

HiredisParser

Parser class for connections using Hiredis

PythonParser

Plain Python parsing class

on_connect(self, connection)

Called when the stream connects

Source code in aioredis/connection.py
def on_connect(self, connection: "Connection"):
    """Called when the stream connects"""
    self._stream = connection._reader
    self._buffer = SocketBuffer(
        self._stream, self._read_size, connection.socket_timeout
    )
    self.encoder = connection.encoder

on_disconnect(self)

Called when the stream disconnects

Source code in aioredis/connection.py
def on_disconnect(self):
    """Called when the stream disconnects"""
    if self._stream is not None:
        self._stream = None
    if self._buffer is not None:
        self._buffer.close()
        self._buffer = None
    self.encoder = None

SocketBuffer

Async-friendly re-impl of redis-py’s SocketBuffer.

TODO: We’re currently passing through two buffers, the asyncio.StreamReader and this. I imagine we can reduce the layers here while maintaining compliance with prior art.

Utils

from_url(url, **kwargs)

Returns an active Redis client generated from the given database URL.

Will attempt to extract the database id from the path url fragment, if none is provided.

Source code in aioredis/utils.py
def from_url(url, **kwargs):
    """
    Returns an active Redis client generated from the given database URL.

    Will attempt to extract the database id from the path url fragment, if
    none is provided.
    """
    from aioredis.client import Redis

    return Redis.from_url(url, **kwargs)