import copy
import re
import threading
import time
import warnings
from itertools import chain
from typing import Any, Callable, Dict, List, Optional, Type, Union
from redis._cache import (
DEFAULT_BLACKLIST,
DEFAULT_EVICTION_POLICY,
DEFAULT_WHITELIST,
AbstractCache,
)
from redis._parsers.encoders import Encoder
from redis._parsers.helpers import (
_RedisCallbacks,
_RedisCallbacksRESP2,
_RedisCallbacksRESP3,
bool_ok,
)
from redis.commands import (
CoreCommands,
RedisModuleCommands,
SentinelCommands,
list_or_args,
)
from redis.connection import ConnectionPool, SSLConnection, UnixDomainSocketConnection
from redis.credentials import CredentialProvider
from redis.exceptions import (
ConnectionError,
ExecAbortError,
PubSubError,
RedisError,
ResponseError,
TimeoutError,
WatchError,
)
from redis.lock import Lock
from redis.retry import Retry
from redis.utils import (
HIREDIS_AVAILABLE,
_set_info_logger,
get_lib_version,
safe_str,
str_if_bytes,
)
SYM_EMPTY = b""
EMPTY_RESPONSE = "EMPTY_RESPONSE"
# some responses (ie. dump) are binary, and just meant to never be decoded
NEVER_DECODE = "NEVER_DECODE"
class CaseInsensitiveDict(dict):
"Case insensitive dict implementation. Assumes string keys only."
def __init__(self, data: Dict[str, str]) -> None:
for k, v in data.items():
self[k.upper()] = v
def __contains__(self, k):
return super().__contains__(k.upper())
def __delitem__(self, k):
super().__delitem__(k.upper())
def __getitem__(self, k):
return super().__getitem__(k.upper())
def get(self, k, default=None):
return super().get(k.upper(), default)
def __setitem__(self, k, v):
super().__setitem__(k.upper(), v)
def update(self, data):
data = CaseInsensitiveDict(data)
super().update(data)
class AbstractRedis:
pass
[docs]class Redis(RedisModuleCommands, CoreCommands, SentinelCommands):
"""
Implementation of the Redis protocol.
This abstract class provides a Python interface to all Redis commands
and an implementation of the Redis protocol.
Pipelines derive from this, implementing how
the commands are sent and received to the Redis server. Based on
configuration, an instance will either use a ConnectionPool, or
Connection object to talk to redis.
It is not safe to pass PubSub or Pipeline objects between threads.
"""
[docs] @classmethod
def from_url(cls, url: str, **kwargs) -> "Redis":
"""
Return a Redis client object configured from the given URL
For example::
redis://[[username]:[password]]@localhost:6379/0
rediss://[[username]:[password]]@localhost:6379/0
unix://[username@]/path/to/socket.sock?db=0[&password=password]
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.
"""
single_connection_client = kwargs.pop("single_connection_client", False)
connection_pool = ConnectionPool.from_url(url, **kwargs)
client = cls(
connection_pool=connection_pool,
single_connection_client=single_connection_client,
)
client.auto_close_connection_pool = True
return client
[docs] @classmethod
def from_pool(
cls: Type["Redis"],
connection_pool: ConnectionPool,
) -> "Redis":
"""
Return a Redis client from the given connection pool.
The Redis client will take ownership of the connection pool and
close it when the Redis client is closed.
"""
client = cls(
connection_pool=connection_pool,
)
client.auto_close_connection_pool = True
return client
def __init__(
self,
host="localhost",
port=6379,
db=0,
password=None,
socket_timeout=None,
socket_connect_timeout=None,
socket_keepalive=None,
socket_keepalive_options=None,
connection_pool=None,
unix_socket_path=None,
encoding="utf-8",
encoding_errors="strict",
charset=None,
errors=None,
decode_responses=False,
retry_on_timeout=False,
retry_on_error=None,
ssl=False,
ssl_keyfile=None,
ssl_certfile=None,
ssl_cert_reqs="required",
ssl_ca_certs=None,
ssl_ca_path=None,
ssl_ca_data=None,
ssl_check_hostname=False,
ssl_password=None,
ssl_validate_ocsp=False,
ssl_validate_ocsp_stapled=False,
ssl_ocsp_context=None,
ssl_ocsp_expected_cert=None,
max_connections=None,
single_connection_client=False,
health_check_interval=0,
client_name=None,
lib_name="redis-py",
lib_version=get_lib_version(),
username=None,
retry=None,
redis_connect_func=None,
credential_provider: Optional[CredentialProvider] = None,
protocol: Optional[int] = 2,
cache_enabled: bool = False,
client_cache: Optional[AbstractCache] = None,
cache_max_size: int = 10000,
cache_ttl: int = 0,
cache_policy: str = DEFAULT_EVICTION_POLICY,
cache_blacklist: List[str] = DEFAULT_BLACKLIST,
cache_whitelist: List[str] = DEFAULT_WHITELIST,
) -> None:
"""
Initialize a new Redis client.
To specify a retry policy for specific errors, first set
`retry_on_error` to a list of the error/s to retry on, then set
`retry` to a valid `Retry` object.
To retry on TimeoutError, `retry_on_timeout` can also be set to `True`.
Args:
single_connection_client:
if `True`, connection pool is not used. In that case `Redis`
instance use is not thread safe.
"""
if not connection_pool:
if charset is not None:
warnings.warn(
DeprecationWarning(
'"charset" is deprecated. Use "encoding" instead'
)
)
encoding = charset
if errors is not None:
warnings.warn(
DeprecationWarning(
'"errors" is deprecated. Use "encoding_errors" instead'
)
)
encoding_errors = errors
if not retry_on_error:
retry_on_error = []
if retry_on_timeout is True:
retry_on_error.append(TimeoutError)
kwargs = {
"db": db,
"username": username,
"password": password,
"socket_timeout": socket_timeout,
"encoding": encoding,
"encoding_errors": encoding_errors,
"decode_responses": decode_responses,
"retry_on_error": retry_on_error,
"retry": copy.deepcopy(retry),
"max_connections": max_connections,
"health_check_interval": health_check_interval,
"client_name": client_name,
"lib_name": lib_name,
"lib_version": lib_version,
"redis_connect_func": redis_connect_func,
"credential_provider": credential_provider,
"protocol": protocol,
"cache_enabled": cache_enabled,
"client_cache": client_cache,
"cache_max_size": cache_max_size,
"cache_ttl": cache_ttl,
"cache_policy": cache_policy,
"cache_blacklist": cache_blacklist,
"cache_whitelist": cache_whitelist,
}
# based on input, setup appropriate connection args
if unix_socket_path is not None:
kwargs.update(
{
"path": unix_socket_path,
"connection_class": UnixDomainSocketConnection,
}
)
else:
# TCP specific options
kwargs.update(
{
"host": host,
"port": port,
"socket_connect_timeout": socket_connect_timeout,
"socket_keepalive": socket_keepalive,
"socket_keepalive_options": socket_keepalive_options,
}
)
if ssl:
kwargs.update(
{
"connection_class": SSLConnection,
"ssl_keyfile": ssl_keyfile,
"ssl_certfile": ssl_certfile,
"ssl_cert_reqs": ssl_cert_reqs,
"ssl_ca_certs": ssl_ca_certs,
"ssl_ca_data": ssl_ca_data,
"ssl_check_hostname": ssl_check_hostname,
"ssl_password": ssl_password,
"ssl_ca_path": ssl_ca_path,
"ssl_validate_ocsp_stapled": ssl_validate_ocsp_stapled,
"ssl_validate_ocsp": ssl_validate_ocsp,
"ssl_ocsp_context": ssl_ocsp_context,
"ssl_ocsp_expected_cert": ssl_ocsp_expected_cert,
}
)
connection_pool = ConnectionPool(**kwargs)
self.auto_close_connection_pool = True
else:
self.auto_close_connection_pool = False
self.connection_pool = connection_pool
self.connection = None
if single_connection_client:
self.connection = self.connection_pool.get_connection("_")
self.response_callbacks = CaseInsensitiveDict(_RedisCallbacks)
if self.connection_pool.connection_kwargs.get("protocol") in ["3", 3]:
self.response_callbacks.update(_RedisCallbacksRESP3)
else:
self.response_callbacks.update(_RedisCallbacksRESP2)
def __repr__(self) -> str:
return (
f"<{type(self).__module__}.{type(self).__name__}"
f"({repr(self.connection_pool)})>"
)
[docs] def get_encoder(self) -> "Encoder":
"""Get the connection pool's encoder"""
return self.connection_pool.get_encoder()
[docs] def get_connection_kwargs(self) -> Dict:
"""Get the connection's key-word arguments"""
return self.connection_pool.connection_kwargs
def get_retry(self) -> Optional["Retry"]:
return self.get_connection_kwargs().get("retry")
def set_retry(self, retry: "Retry") -> None:
self.get_connection_kwargs().update({"retry": retry})
self.connection_pool.set_retry(retry)
[docs] def set_response_callback(self, command: str, callback: Callable) -> None:
"""Set a custom Response Callback"""
self.response_callbacks[command] = callback
[docs] def load_external_module(self, funcname, func) -> None:
"""
This function can be used to add externally defined redis modules,
and their namespaces to the redis client.
funcname - A string containing the name of the function to create
func - The function, being added to this class.
ex: Assume that one has a custom redis module named foomod that
creates command named 'foo.dothing' and 'foo.anotherthing' in redis.
To load function functions into this namespace:
from redis import Redis
from foomodule import F
r = Redis()
r.load_external_module("foo", F)
r.foo().dothing('your', 'arguments')
For a concrete example see the reimport of the redisjson module in
tests/test_connection.py::test_loading_external_modules
"""
setattr(self, funcname, func)
[docs] def pipeline(self, transaction=True, shard_hint=None) -> "Pipeline":
"""
Return a new pipeline object that can queue multiple commands for
later execution. ``transaction`` indicates whether all commands
should be executed atomically. Apart from making a group of operations
atomic, pipelines are useful for reducing the back-and-forth overhead
between the client and server.
"""
return Pipeline(
self.connection_pool, self.response_callbacks, transaction, shard_hint
)
[docs] def transaction(
self, func: Callable[["Pipeline"], None], *watches, **kwargs
) -> None:
"""
Convenience method for executing the callable `func` as a transaction
while watching all keys specified in `watches`. The 'func' callable
should expect a single argument which is a Pipeline object.
"""
shard_hint = kwargs.pop("shard_hint", None)
value_from_callable = kwargs.pop("value_from_callable", False)
watch_delay = kwargs.pop("watch_delay", None)
with self.pipeline(True, shard_hint) as pipe:
while True:
try:
if watches:
pipe.watch(*watches)
func_value = func(pipe)
exec_value = pipe.execute()
return func_value if value_from_callable else exec_value
except WatchError:
if watch_delay is not None and watch_delay > 0:
time.sleep(watch_delay)
continue
[docs] def lock(
self,
name: str,
timeout: Optional[float] = None,
sleep: float = 0.1,
blocking: bool = True,
blocking_timeout: Optional[float] = None,
lock_class: Union[None, Any] = None,
thread_local: bool = True,
):
"""
Return a new Lock object using key ``name`` that mimics
the behavior of threading.Lock.
If specified, ``timeout`` indicates a maximum life for the lock.
By default, it will remain locked until release() is called.
``sleep`` indicates the amount of time to sleep per loop iteration
when the lock is in blocking mode and another client is currently
holding the lock.
``blocking`` indicates whether calling ``acquire`` should block until
the lock has been acquired or to fail immediately, causing ``acquire``
to return False and the lock not being acquired. Defaults to True.
Note this value can be overridden by passing a ``blocking``
argument to ``acquire``.
``blocking_timeout`` indicates the maximum amount of time in seconds to
spend trying to acquire the lock. A value of ``None`` indicates
continue trying forever. ``blocking_timeout`` can be specified as a
float or integer, both representing the number of seconds to wait.
``lock_class`` forces the specified lock implementation. Note that as
of redis-py 3.0, the only lock class we implement is ``Lock`` (which is
a Lua-based lock). So, it's unlikely you'll need this parameter, unless
you have created your own custom lock class.
``thread_local`` indicates whether the lock token is placed in
thread-local storage. By default, the token is placed in thread local
storage so that a thread only sees its token, not a token set by
another thread. Consider the following timeline:
time: 0, thread-1 acquires `my-lock`, with a timeout of 5 seconds.
thread-1 sets the token to "abc"
time: 1, thread-2 blocks trying to acquire `my-lock` using the
Lock instance.
time: 5, thread-1 has not yet completed. redis expires the lock
key.
time: 5, thread-2 acquired `my-lock` now that it's available.
thread-2 sets the token to "xyz"
time: 6, thread-1 finishes its work and calls release(). if the
token is *not* stored in thread local storage, then
thread-1 would see the token value as "xyz" and would be
able to successfully release the thread-2's lock.
In some use cases it's necessary to disable thread local storage. For
example, if you have code where one thread acquires a lock and passes
that lock instance to a worker thread to release later. If thread
local storage isn't disabled in this case, the worker thread won't see
the token set by the thread that acquired the lock. Our assumption
is that these cases aren't common and as such default to using
thread local storage."""
if lock_class is None:
lock_class = Lock
return lock_class(
self,
name,
timeout=timeout,
sleep=sleep,
blocking=blocking,
blocking_timeout=blocking_timeout,
thread_local=thread_local,
)
[docs] def pubsub(self, **kwargs):
"""
Return a Publish/Subscribe object. With this object, you can
subscribe to channels and listen for messages that get published to
them.
"""
return PubSub(self.connection_pool, **kwargs)
def monitor(self):
return Monitor(self.connection_pool)
def client(self):
return self.__class__(
connection_pool=self.connection_pool, single_connection_client=True
)
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def __del__(self):
self.close()
def close(self):
# In case a connection property does not yet exist
# (due to a crash earlier in the Redis() constructor), return
# immediately as there is nothing to clean-up.
if not hasattr(self, "connection"):
return
conn = self.connection
if conn:
self.connection = None
self.connection_pool.release(conn)
if self.auto_close_connection_pool:
self.connection_pool.disconnect()
def _send_command_parse_response(self, conn, command_name, *args, **options):
"""
Send a command and parse the response
"""
conn.send_command(*args)
return self.parse_response(conn, command_name, **options)
def _disconnect_raise(self, conn, error):
"""
Close the connection and raise an exception
if retry_on_error is not set or the error
is not one of the specified error types
"""
conn.disconnect()
if (
conn.retry_on_error is None
or isinstance(error, tuple(conn.retry_on_error)) is False
):
raise error
# COMMAND EXECUTION AND PROTOCOL PARSING
[docs] def execute_command(self, *args, **options):
"""Execute a command and return a parsed response"""
command_name = args[0]
keys = options.pop("keys", None)
pool = self.connection_pool
conn = self.connection or pool.get_connection(command_name, **options)
response_from_cache = conn._get_from_local_cache(args)
if response_from_cache is not None:
return response_from_cache
else:
try:
response = conn.retry.call_with_retry(
lambda: self._send_command_parse_response(
conn, command_name, *args, **options
),
lambda error: self._disconnect_raise(conn, error),
)
conn._add_to_local_cache(args, response, keys)
return response
finally:
if not self.connection:
pool.release(conn)
[docs] def parse_response(self, connection, command_name, **options):
"""Parses a response from the Redis server"""
try:
if NEVER_DECODE in options:
response = connection.read_response(disable_decoding=True)
options.pop(NEVER_DECODE)
else:
response = connection.read_response()
except ResponseError:
if EMPTY_RESPONSE in options:
return options[EMPTY_RESPONSE]
raise
if EMPTY_RESPONSE in options:
options.pop(EMPTY_RESPONSE)
if command_name in self.response_callbacks:
return self.response_callbacks[command_name](response, **options)
return response
def flush_cache(self):
try:
if self.connection:
self.connection.client_cache.flush()
else:
self.connection_pool.flush_cache()
except AttributeError:
pass
def delete_command_from_cache(self, command):
try:
if self.connection:
self.connection.client_cache.delete_command(command)
else:
self.connection_pool.delete_command_from_cache(command)
except AttributeError:
pass
def invalidate_key_from_cache(self, key):
try:
if self.connection:
self.connection.client_cache.invalidate_key(key)
else:
self.connection_pool.invalidate_key_from_cache(key)
except AttributeError:
pass
StrictRedis = Redis
class Monitor:
"""
Monitor is useful for handling the MONITOR command to the redis server.
next_command() method returns one command from monitor
listen() method yields commands from monitor.
"""
monitor_re = re.compile(r"\[(\d+) (.*?)\] (.*)")
command_re = re.compile(r'"(.*?)(?<!\\)"')
def __init__(self, connection_pool):
self.connection_pool = connection_pool
self.connection = self.connection_pool.get_connection("MONITOR")
def __enter__(self):
self.connection.send_command("MONITOR")
# check that monitor returns 'OK', but don't return it to user
response = self.connection.read_response()
if not bool_ok(response):
raise RedisError(f"MONITOR failed: {response}")
return self
def __exit__(self, *args):
self.connection.disconnect()
self.connection_pool.release(self.connection)
def next_command(self):
"""Parse the response from a monitor command"""
response = self.connection.read_response()
if isinstance(response, bytes):
response = self.connection.encoder.decode(response, force=True)
command_time, command_data = response.split(" ", 1)
m = self.monitor_re.match(command_data)
db_id, client_info, command = m.groups()
command = " ".join(self.command_re.findall(command))
# Redis escapes double quotes because each piece of the command
# string is surrounded by double quotes. We don't have that
# requirement so remove the escaping and leave the quote.
command = command.replace('\\"', '"')
if client_info == "lua":
client_address = "lua"
client_port = ""
client_type = "lua"
elif client_info.startswith("unix"):
client_address = "unix"
client_port = client_info[5:]
client_type = "unix"
else:
# use rsplit as ipv6 addresses contain colons
client_address, client_port = client_info.rsplit(":", 1)
client_type = "tcp"
return {
"time": float(command_time),
"db": int(db_id),
"client_address": client_address,
"client_port": client_port,
"client_type": client_type,
"command": command,
}
def listen(self):
"""Listen for commands coming to the server."""
while True:
yield self.next_command()
class PubSub:
"""
PubSub provides publish, subscribe and listen support to Redis channels.
After subscribing to one or more channels, the listen() method will block
until a message arrives on one of the subscribed channels. That message
will be returned and it's safe to start listening again.
"""
PUBLISH_MESSAGE_TYPES = ("message", "pmessage", "smessage")
UNSUBSCRIBE_MESSAGE_TYPES = ("unsubscribe", "punsubscribe", "sunsubscribe")
HEALTH_CHECK_MESSAGE = "redis-py-health-check"
def __init__(
self,
connection_pool,
shard_hint=None,
ignore_subscribe_messages: bool = False,
encoder: Optional["Encoder"] = None,
push_handler_func: Union[None, Callable[[str], None]] = None,
):
self.connection_pool = connection_pool
self.shard_hint = shard_hint
self.ignore_subscribe_messages = ignore_subscribe_messages
self.connection = None
self.subscribed_event = threading.Event()
# we need to know the encoding options for this connection in order
# to lookup channel and pattern names for callback handlers.
self.encoder = encoder
self.push_handler_func = push_handler_func
if self.encoder is None:
self.encoder = self.connection_pool.get_encoder()
self.health_check_response_b = self.encoder.encode(self.HEALTH_CHECK_MESSAGE)
if self.encoder.decode_responses:
self.health_check_response = ["pong", self.HEALTH_CHECK_MESSAGE]
else:
self.health_check_response = [b"pong", self.health_check_response_b]
if self.push_handler_func is None:
_set_info_logger()
self.reset()
def __enter__(self) -> "PubSub":
return self
def __exit__(self, exc_type, exc_value, traceback) -> None:
self.reset()
def __del__(self) -> None:
try:
# if this object went out of scope prior to shutting down
# subscriptions, close the connection manually before
# returning it to the connection pool
self.reset()
except Exception:
pass
def reset(self) -> None:
if self.connection:
self.connection.disconnect()
self.connection.deregister_connect_callback(self.on_connect)
self.connection_pool.release(self.connection)
self.connection = None
self.health_check_response_counter = 0
self.channels = {}
self.pending_unsubscribe_channels = set()
self.shard_channels = {}
self.pending_unsubscribe_shard_channels = set()
self.patterns = {}
self.pending_unsubscribe_patterns = set()
self.subscribed_event.clear()
def close(self) -> None:
self.reset()
def on_connect(self, connection) -> None:
"Re-subscribe to any channels and patterns previously subscribed to"
# NOTE: for python3, we can't pass bytestrings as keyword arguments
# so we need to decode channel/pattern names back to unicode strings
# before passing them to [p]subscribe.
self.pending_unsubscribe_channels.clear()
self.pending_unsubscribe_patterns.clear()
self.pending_unsubscribe_shard_channels.clear()
if self.channels:
channels = {
self.encoder.decode(k, force=True): v for k, v in self.channels.items()
}
self.subscribe(**channels)
if self.patterns:
patterns = {
self.encoder.decode(k, force=True): v for k, v in self.patterns.items()
}
self.psubscribe(**patterns)
if self.shard_channels:
shard_channels = {
self.encoder.decode(k, force=True): v
for k, v in self.shard_channels.items()
}
self.ssubscribe(**shard_channels)
@property
def subscribed(self) -> bool:
"""Indicates if there are subscriptions to any channels or patterns"""
return self.subscribed_event.is_set()
def execute_command(self, *args):
"""Execute a publish/subscribe command"""
# NOTE: don't parse the response in this function -- it could pull a
# legitimate message off the stack if the connection is already
# subscribed to one or more channels
if self.connection is None:
self.connection = self.connection_pool.get_connection(
"pubsub", self.shard_hint
)
# register a callback that re-subscribes to any channels we
# were listening to when we were disconnected
self.connection.register_connect_callback(self.on_connect)
if self.push_handler_func is not None and not HIREDIS_AVAILABLE:
self.connection._parser.set_pubsub_push_handler(self.push_handler_func)
connection = self.connection
kwargs = {"check_health": not self.subscribed}
if not self.subscribed:
self.clean_health_check_responses()
self._execute(connection, connection.send_command, *args, **kwargs)
def clean_health_check_responses(self) -> None:
"""
If any health check responses are present, clean them
"""
ttl = 10
conn = self.connection
while self.health_check_response_counter > 0 and ttl > 0:
if self._execute(conn, conn.can_read, timeout=conn.socket_timeout):
response = self._execute(conn, conn.read_response)
if self.is_health_check_response(response):
self.health_check_response_counter -= 1
else:
raise PubSubError(
"A non health check response was cleaned by "
"execute_command: {0}".format(response)
)
ttl -= 1
def _disconnect_raise_connect(self, conn, error) -> None:
"""
Close the connection and raise an exception
if retry_on_timeout is not set or the error
is not a TimeoutError. Otherwise, try to reconnect
"""
conn.disconnect()
if not (conn.retry_on_timeout and isinstance(error, TimeoutError)):
raise error
conn.connect()
def _execute(self, conn, command, *args, **kwargs):
"""
Connect manually upon disconnection. If the Redis server is down,
this will fail and raise a ConnectionError as desired.
After reconnection, the ``on_connect`` callback should have been
called by the # connection to resubscribe us to any channels and
patterns we were previously listening to
"""
return conn.retry.call_with_retry(
lambda: command(*args, **kwargs),
lambda error: self._disconnect_raise_connect(conn, error),
)
def parse_response(self, block=True, timeout=0):
"""Parse the response from a publish/subscribe command"""
conn = self.connection
if conn is None:
raise RuntimeError(
"pubsub connection not set: "
"did you forget to call subscribe() or psubscribe()?"
)
self.check_health()
def try_read():
if not block:
if not conn.can_read(timeout=timeout):
return None
else:
conn.connect()
return conn.read_response(disconnect_on_error=False, push_request=True)
response = self._execute(conn, try_read)
if self.is_health_check_response(response):
# ignore the health check message as user might not expect it
self.health_check_response_counter -= 1
return None
return response
def is_health_check_response(self, response) -> bool:
"""
Check if the response is a health check response.
If there are no subscriptions redis responds to PING command with a
bulk response, instead of a multi-bulk with "pong" and the response.
"""
return response in [
self.health_check_response, # If there was a subscription
self.health_check_response_b, # If there wasn't
]
def check_health(self) -> None:
conn = self.connection
if conn is None:
raise RuntimeError(
"pubsub connection not set: "
"did you forget to call subscribe() or psubscribe()?"
)
if conn.health_check_interval and time.time() > conn.next_health_check:
conn.send_command("PING", self.HEALTH_CHECK_MESSAGE, check_health=False)
self.health_check_response_counter += 1
def _normalize_keys(self, data) -> Dict:
"""
normalize channel/pattern names to be either bytes or strings
based on whether responses are automatically decoded. this saves us
from coercing the value for each message coming in.
"""
encode = self.encoder.encode
decode = self.encoder.decode
return {decode(encode(k)): v for k, v in data.items()}
def psubscribe(self, *args, **kwargs):
"""
Subscribe to channel patterns. Patterns supplied as keyword arguments
expect a pattern name as the key and a callable as the value. A
pattern's callable will be invoked automatically when a message is
received on that pattern rather than producing a message via
``listen()``.
"""
if args:
args = list_or_args(args[0], args[1:])
new_patterns = dict.fromkeys(args)
new_patterns.update(kwargs)
ret_val = self.execute_command("PSUBSCRIBE", *new_patterns.keys())
# update the patterns dict AFTER we send the command. we don't want to
# subscribe twice to these patterns, once for the command and again
# for the reconnection.
new_patterns = self._normalize_keys(new_patterns)
self.patterns.update(new_patterns)
if not self.subscribed:
# Set the subscribed_event flag to True
self.subscribed_event.set()
# Clear the health check counter
self.health_check_response_counter = 0
self.pending_unsubscribe_patterns.difference_update(new_patterns)
return ret_val
def punsubscribe(self, *args):
"""
Unsubscribe from the supplied patterns. If empty, unsubscribe from
all patterns.
"""
if args:
args = list_or_args(args[0], args[1:])
patterns = self._normalize_keys(dict.fromkeys(args))
else:
patterns = self.patterns
self.pending_unsubscribe_patterns.update(patterns)
return self.execute_command("PUNSUBSCRIBE", *args)
def subscribe(self, *args, **kwargs):
"""
Subscribe to channels. Channels supplied as keyword arguments expect
a channel name as the key and a callable as the value. A channel's
callable will be invoked automatically when a message is received on
that channel rather than producing a message via ``listen()`` or
``get_message()``.
"""
if args:
args = list_or_args(args[0], args[1:])
new_channels = dict.fromkeys(args)
new_channels.update(kwargs)
ret_val = self.execute_command("SUBSCRIBE", *new_channels.keys())
# update the channels dict AFTER we send the command. we don't want to
# subscribe twice to these channels, once for the command and again
# for the reconnection.
new_channels = self._normalize_keys(new_channels)
self.channels.update(new_channels)
if not self.subscribed:
# Set the subscribed_event flag to True
self.subscribed_event.set()
# Clear the health check counter
self.health_check_response_counter = 0
self.pending_unsubscribe_channels.difference_update(new_channels)
return ret_val
def unsubscribe(self, *args):
"""
Unsubscribe from the supplied channels. If empty, unsubscribe from
all channels
"""
if args:
args = list_or_args(args[0], args[1:])
channels = self._normalize_keys(dict.fromkeys(args))
else:
channels = self.channels
self.pending_unsubscribe_channels.update(channels)
return self.execute_command("UNSUBSCRIBE", *args)
def ssubscribe(self, *args, target_node=None, **kwargs):
"""
Subscribes the client to the specified shard channels.
Channels supplied as keyword arguments expect a channel name as the key
and a callable as the value. A channel's callable will be invoked automatically
when a message is received on that channel rather than producing a message via
``listen()`` or ``get_sharded_message()``.
"""
if args:
args = list_or_args(args[0], args[1:])
new_s_channels = dict.fromkeys(args)
new_s_channels.update(kwargs)
ret_val = self.execute_command("SSUBSCRIBE", *new_s_channels.keys())
# update the s_channels dict AFTER we send the command. we don't want to
# subscribe twice to these channels, once for the command and again
# for the reconnection.
new_s_channels = self._normalize_keys(new_s_channels)
self.shard_channels.update(new_s_channels)
if not self.subscribed:
# Set the subscribed_event flag to True
self.subscribed_event.set()
# Clear the health check counter
self.health_check_response_counter = 0
self.pending_unsubscribe_shard_channels.difference_update(new_s_channels)
return ret_val
def sunsubscribe(self, *args, target_node=None):
"""
Unsubscribe from the supplied shard_channels. If empty, unsubscribe from
all shard_channels
"""
if args:
args = list_or_args(args[0], args[1:])
s_channels = self._normalize_keys(dict.fromkeys(args))
else:
s_channels = self.shard_channels
self.pending_unsubscribe_shard_channels.update(s_channels)
return self.execute_command("SUNSUBSCRIBE", *args)
def listen(self):
"Listen for messages on channels this client has been subscribed to"
while self.subscribed:
response = self.handle_message(self.parse_response(block=True))
if response is not None:
yield response
def get_message(
self, ignore_subscribe_messages: bool = False, timeout: float = 0.0
):
"""
Get the next message if one is available, otherwise None.
If timeout is specified, the system will wait for `timeout` seconds
before returning. Timeout should be specified as a floating point
number, or None, to wait indefinitely.
"""
if not self.subscribed:
# Wait for subscription
start_time = time.time()
if self.subscribed_event.wait(timeout) is True:
# The connection was subscribed during the timeout time frame.
# The timeout should be adjusted based on the time spent
# waiting for the subscription
time_spent = time.time() - start_time
timeout = max(0.0, timeout - time_spent)
else:
# The connection isn't subscribed to any channels or patterns,
# so no messages are available
return None
response = self.parse_response(block=(timeout is None), timeout=timeout)
if response:
return self.handle_message(response, ignore_subscribe_messages)
return None
get_sharded_message = get_message
def ping(self, message: Union[str, None] = None) -> bool:
"""
Ping the Redis server
"""
args = ["PING", message] if message is not None else ["PING"]
return self.execute_command(*args)
def handle_message(self, response, ignore_subscribe_messages=False):
"""
Parses a pub/sub message. If the channel or pattern was subscribed to
with a message handler, the handler is invoked instead of a parsed
message being returned.
"""
if response is None:
return None
if isinstance(response, bytes):
response = [b"pong", response] if response != b"PONG" else [b"pong", b""]
message_type = str_if_bytes(response[0])
if message_type == "pmessage":
message = {
"type": message_type,
"pattern": response[1],
"channel": response[2],
"data": response[3],
}
elif message_type == "pong":
message = {
"type": message_type,
"pattern": None,
"channel": None,
"data": response[1],
}
else:
message = {
"type": message_type,
"pattern": None,
"channel": response[1],
"data": response[2],
}
# if this is an unsubscribe message, remove it from memory
if message_type in self.UNSUBSCRIBE_MESSAGE_TYPES:
if message_type == "punsubscribe":
pattern = response[1]
if pattern in self.pending_unsubscribe_patterns:
self.pending_unsubscribe_patterns.remove(pattern)
self.patterns.pop(pattern, None)
elif message_type == "sunsubscribe":
s_channel = response[1]
if s_channel in self.pending_unsubscribe_shard_channels:
self.pending_unsubscribe_shard_channels.remove(s_channel)
self.shard_channels.pop(s_channel, None)
else:
channel = response[1]
if channel in self.pending_unsubscribe_channels:
self.pending_unsubscribe_channels.remove(channel)
self.channels.pop(channel, None)
if not self.channels and not self.patterns and not self.shard_channels:
# There are no subscriptions anymore, set subscribed_event flag
# to false
self.subscribed_event.clear()
if message_type in self.PUBLISH_MESSAGE_TYPES:
# if there's a message handler, invoke it
if message_type == "pmessage":
handler = self.patterns.get(message["pattern"], None)
elif message_type == "smessage":
handler = self.shard_channels.get(message["channel"], None)
else:
handler = self.channels.get(message["channel"], None)
if handler:
handler(message)
return None
elif message_type != "pong":
# this is a subscribe/unsubscribe message. ignore if we don't
# want them
if ignore_subscribe_messages or self.ignore_subscribe_messages:
return None
return message
def run_in_thread(
self,
sleep_time: float = 0.0,
daemon: bool = False,
exception_handler: Optional[Callable] = None,
) -> "PubSubWorkerThread":
for channel, handler in self.channels.items():
if handler is None:
raise PubSubError(f"Channel: '{channel}' has no handler registered")
for pattern, handler in self.patterns.items():
if handler is None:
raise PubSubError(f"Pattern: '{pattern}' has no handler registered")
for s_channel, handler in self.shard_channels.items():
if handler is None:
raise PubSubError(
f"Shard Channel: '{s_channel}' has no handler registered"
)
thread = PubSubWorkerThread(
self, sleep_time, daemon=daemon, exception_handler=exception_handler
)
thread.start()
return thread
class PubSubWorkerThread(threading.Thread):
def __init__(
self,
pubsub,
sleep_time: float,
daemon: bool = False,
exception_handler: Union[
Callable[[Exception, "PubSub", "PubSubWorkerThread"], None], None
] = None,
):
super().__init__()
self.daemon = daemon
self.pubsub = pubsub
self.sleep_time = sleep_time
self.exception_handler = exception_handler
self._running = threading.Event()
def run(self) -> None:
if self._running.is_set():
return
self._running.set()
pubsub = self.pubsub
sleep_time = self.sleep_time
while self._running.is_set():
try:
pubsub.get_message(ignore_subscribe_messages=True, timeout=sleep_time)
except BaseException as e:
if self.exception_handler is None:
raise
self.exception_handler(e, pubsub, self)
pubsub.close()
def stop(self) -> None:
# trip the flag so the run loop exits. the run loop will
# close the pubsub connection, which disconnects the socket
# and returns the connection to the pool.
self._running.clear()
class Pipeline(Redis):
"""
Pipelines provide a way to transmit multiple commands to the Redis server
in one transmission. This is convenient for batch processing, such as
saving all the values in a list to Redis.
All commands executed within a pipeline are wrapped with MULTI and EXEC
calls. This guarantees all commands executed in the pipeline will be
executed atomically.
Any command raising an exception does *not* halt the execution of
subsequent commands in the pipeline. Instead, the exception is caught
and its instance is placed into the response list returned by execute().
Code iterating over the response list should be able to deal with an
instance of an exception as a potential value. In general, these will be
ResponseError exceptions, such as those raised when issuing a command
on a key of a different datatype.
"""
UNWATCH_COMMANDS = {"DISCARD", "EXEC", "UNWATCH"}
def __init__(self, connection_pool, response_callbacks, transaction, shard_hint):
self.connection_pool = connection_pool
self.connection = None
self.response_callbacks = response_callbacks
self.transaction = transaction
self.shard_hint = shard_hint
self.watching = False
self.reset()
def __enter__(self) -> "Pipeline":
return self
def __exit__(self, exc_type, exc_value, traceback):
self.reset()
def __del__(self):
try:
self.reset()
except Exception:
pass
def __len__(self) -> int:
return len(self.command_stack)
def __bool__(self) -> bool:
"""Pipeline instances should always evaluate to True"""
return True
def reset(self) -> None:
self.command_stack = []
self.scripts = set()
# make sure to reset the connection state in the event that we were
# watching something
if self.watching and self.connection:
try:
# call this manually since our unwatch or
# immediate_execute_command methods can call reset()
self.connection.send_command("UNWATCH")
self.connection.read_response()
except ConnectionError:
# disconnect will also remove any previous WATCHes
self.connection.disconnect()
# clean up the other instance attributes
self.watching = False
self.explicit_transaction = False
# we can safely return the connection to the pool here since we're
# sure we're no longer WATCHing anything
if self.connection:
self.connection_pool.release(self.connection)
self.connection = None
def close(self) -> None:
"""Close the pipeline"""
self.reset()
def multi(self) -> None:
"""
Start a transactional block of the pipeline after WATCH commands
are issued. End the transactional block with `execute`.
"""
if self.explicit_transaction:
raise RedisError("Cannot issue nested calls to MULTI")
if self.command_stack:
raise RedisError(
"Commands without an initial WATCH have already been issued"
)
self.explicit_transaction = True
def execute_command(self, *args, **kwargs):
kwargs.pop("keys", None) # the keys are used only for client side caching
if (self.watching or args[0] == "WATCH") and not self.explicit_transaction:
return self.immediate_execute_command(*args, **kwargs)
return self.pipeline_execute_command(*args, **kwargs)
def _disconnect_reset_raise(self, conn, error) -> None:
"""
Close the connection, reset watching state and
raise an exception if we were watching,
retry_on_timeout is not set,
or the error is not a TimeoutError
"""
conn.disconnect()
# if we were already watching a variable, the watch is no longer
# valid since this connection has died. raise a WatchError, which
# indicates the user should retry this transaction.
if self.watching:
self.reset()
raise WatchError(
"A ConnectionError occurred on while watching one or more keys"
)
# if retry_on_timeout is not set, or the error is not
# a TimeoutError, raise it
if not (conn.retry_on_timeout and isinstance(error, TimeoutError)):
self.reset()
raise
def immediate_execute_command(self, *args, **options):
"""
Execute a command immediately, but don't auto-retry on a
ConnectionError if we're already WATCHing a variable. Used when
issuing WATCH or subsequent commands retrieving their values but before
MULTI is called.
"""
command_name = args[0]
conn = self.connection
# if this is the first call, we need a connection
if not conn:
conn = self.connection_pool.get_connection(command_name, self.shard_hint)
self.connection = conn
return conn.retry.call_with_retry(
lambda: self._send_command_parse_response(
conn, command_name, *args, **options
),
lambda error: self._disconnect_reset_raise(conn, error),
)
def pipeline_execute_command(self, *args, **options) -> "Pipeline":
"""
Stage a command to be executed when execute() is next called
Returns the current Pipeline object back so commands can be
chained together, such as:
pipe = pipe.set('foo', 'bar').incr('baz').decr('bang')
At some other point, you can then run: pipe.execute(),
which will execute all commands queued in the pipe.
"""
self.command_stack.append((args, options))
return self
def _execute_transaction(self, connection, commands, raise_on_error) -> List:
cmds = chain([(("MULTI",), {})], commands, [(("EXEC",), {})])
all_cmds = connection.pack_commands(
[args for args, options in cmds if EMPTY_RESPONSE not in options]
)
connection.send_packed_command(all_cmds)
errors = []
# parse off the response for MULTI
# NOTE: we need to handle ResponseErrors here and continue
# so that we read all the additional command messages from
# the socket
try:
self.parse_response(connection, "_")
except ResponseError as e:
errors.append((0, e))
# and all the other commands
for i, command in enumerate(commands):
if EMPTY_RESPONSE in command[1]:
errors.append((i, command[1][EMPTY_RESPONSE]))
else:
try:
self.parse_response(connection, "_")
except ResponseError as e:
self.annotate_exception(e, i + 1, command[0])
errors.append((i, e))
# parse the EXEC.
try:
response = self.parse_response(connection, "_")
except ExecAbortError:
if errors:
raise errors[0][1]
raise
# EXEC clears any watched keys
self.watching = False
if response is None:
raise WatchError("Watched variable changed.")
# put any parse errors into the response
for i, e in errors:
response.insert(i, e)
if len(response) != len(commands):
self.connection.disconnect()
raise ResponseError(
"Wrong number of response items from pipeline execution"
)
# find any errors in the response and raise if necessary
if raise_on_error:
self.raise_first_error(commands, response)
# We have to run response callbacks manually
data = []
for r, cmd in zip(response, commands):
if not isinstance(r, Exception):
args, options = cmd
command_name = args[0]
if command_name in self.response_callbacks:
r = self.response_callbacks[command_name](r, **options)
data.append(r)
return data
def _execute_pipeline(self, connection, commands, raise_on_error):
# build up all commands into a single request to increase network perf
all_cmds = connection.pack_commands([args for args, _ in commands])
connection.send_packed_command(all_cmds)
response = []
for args, options in commands:
try:
response.append(self.parse_response(connection, args[0], **options))
except ResponseError as e:
response.append(e)
if raise_on_error:
self.raise_first_error(commands, response)
return response
def raise_first_error(self, commands, response):
for i, r in enumerate(response):
if isinstance(r, ResponseError):
self.annotate_exception(r, i + 1, commands[i][0])
raise r
def annotate_exception(self, exception, number, command):
cmd = " ".join(map(safe_str, command))
msg = (
f"Command # {number} ({cmd}) of pipeline "
f"caused error: {exception.args[0]}"
)
exception.args = (msg,) + exception.args[1:]
def parse_response(self, connection, command_name, **options):
result = Redis.parse_response(self, connection, command_name, **options)
if command_name in self.UNWATCH_COMMANDS:
self.watching = False
elif command_name == "WATCH":
self.watching = True
return result
def load_scripts(self):
# make sure all scripts that are about to be run on this pipeline exist
scripts = list(self.scripts)
immediate = self.immediate_execute_command
shas = [s.sha for s in scripts]
# we can't use the normal script_* methods because they would just
# get buffered in the pipeline.
exists = immediate("SCRIPT EXISTS", *shas)
if not all(exists):
for s, exist in zip(scripts, exists):
if not exist:
s.sha = immediate("SCRIPT LOAD", s.script)
def _disconnect_raise_reset(self, conn: Redis, error: Exception) -> None:
"""
Close the connection, raise an exception if we were watching,
and raise an exception if TimeoutError is not part of retry_on_error,
or the error is not a TimeoutError
"""
conn.disconnect()
# if we were watching a variable, the watch is no longer valid
# since this connection has died. raise a WatchError, which
# indicates the user should retry this transaction.
if self.watching:
raise WatchError(
"A ConnectionError occurred on while watching one or more keys"
)
# if TimeoutError is not part of retry_on_error, or the error
# is not a TimeoutError, raise it
if not (
TimeoutError in conn.retry_on_error and isinstance(error, TimeoutError)
):
self.reset()
raise error
def execute(self, raise_on_error=True):
"""Execute all the commands in the current pipeline"""
stack = self.command_stack
if not stack and not self.watching:
return []
if self.scripts:
self.load_scripts()
if self.transaction or self.explicit_transaction:
execute = self._execute_transaction
else:
execute = self._execute_pipeline
conn = self.connection
if not conn:
conn = self.connection_pool.get_connection("MULTI", self.shard_hint)
# assign to self.connection so reset() releases the connection
# back to the pool after we're done
self.connection = conn
try:
return conn.retry.call_with_retry(
lambda: execute(conn, stack, raise_on_error),
lambda error: self._disconnect_raise_reset(conn, error),
)
finally:
self.reset()
def discard(self):
"""
Flushes all previously queued commands
See: https://redis.io/commands/DISCARD
"""
self.execute_command("DISCARD")
def watch(self, *names):
"""Watches the values at keys ``names``"""
if self.explicit_transaction:
raise RedisError("Cannot issue a WATCH after a MULTI")
return self.execute_command("WATCH", *names)
def unwatch(self) -> bool:
"""Unwatches all previously specified keys"""
return self.watching and self.execute_command("UNWATCH") or True