Async cache framework with simple API to build fast and reliable applications
pip install cashews
pip install cashews[redis]
pip install cashews[diskcache]
pip install cashews[dill] # can cache in redis more types of objects
pip install cashews[speedup] # for bloom filters
Cache plays a significant role in modern applications and everybody wants to use all the power of async programming and cache. There are a few advanced techniques with cache and async programming that can help you build simple, fast, scalable and reliable applications. This library intends to make it easy to implement such techniques.
- Easy to configure and use
- Decorator-based API, decorate and play
- Different cache strategies out-of-the-box
- Support for multiple storage backends (In-memory, Redis, DiskCache)
- Set TTL as a string ("2h5m"), as
timedelta
or use a function in case TTL depends on key parameters - Transactionality
- Middlewares
- Client-side cache (10x faster than simple cache with redis)
- Bloom filters
- Different cache invalidation techniques (time-based or tags)
- Cache any objects securely with pickle (use secret)
- 2x faster than
aiocache
(with client side caching)
from cashews import cache
cache.setup("mem:https://") # configure as in-memory cache, but redis/diskcache is also supported
# use a decorator-based API
@cache(ttl="3h", key="user:{request.user.uid}")
async def long_running_function(request):
...
# or for fine-grained control, use it directly in a function
async def cache_using_function(request):
await cache.set(key=request.user.uid, value=request.user, expire="20h")
...
More examples here
- Configuration
- Available Backends
- Basic API
- Disable Cache
- Strategies
- Cache Invalidation
- Detect the source of a result
- Middleware
- Callbacks
- Transactional mode
- Contrib
cashews
provides a default cache, that you can setup in two different ways:
from cashews import cache
# via url
cache.setup("redis:https://0.0.0.0/?db=1&socket_connect_timeout=0.5&suppress=0&secret=my_secret&enable=1")
# or via kwargs
cache.setup("redis:https://0.0.0.0/", db=1, wait_for_connection_timeout=0.5, suppress=False, secret=b"my_key", enable=True)
Alternatively, you can create a cache instance yourself:
from cashews import Cache
cache = Cache()
cache.setup(...)
Optionally, you can disable cache with disable
/enable
parameter (see Disable Cache):
cache.setup("redis:https://redis/0?enable=1")
cache.setup("mem:https://?size=500", disable=True)
cache.setup("mem:https://?size=500", enable=False)
You can setup different Backends based on a prefix:
cache.setup("redis:https://redis/0")
cache.setup("mem:https://?size=500", prefix="user")
await cache.get("accounts") # will use the redis backend
await cache.get("user:1") # will use the memory backend
The in-memory cache uses fixed-sized LRU dict to store values. It checks expiration on get
and periodically purge expired keys.
cache.setup("mem:https://")
cache.setup("mem:https://?check_interval=10&size=10000")
Requires redis package.\
This will use Redis as a storage.
This backend uses pickle module to serialize values, but the cashes can store values with sha1-keyed hash.
Use secret
and digestmod
parameters to protect your application from security vulnerabilities.
The digestmod
is a hashing algorithm that can be used: sum
, md5
(default), sha1
and sha256
The secret
is a salt for a hash.
Pickle can't serialize any type of object. In case you need to store more complex types
you can use dill - set pickle_type="dill"
.
Dill is great, but less performance.
If you need complex serializer for sqlalchemy objects you can set pickle_type="sqlalchemy"
Use json
also an option to serialize/deserialize an object, but it very limited (pickle_type="json"
)
Any connection errors are suppressed, to disable it use suppress=False
- a CacheBackendInteractionError
will be raised
If you would like to use client-side cache set client_side=True
Client side cache will add cashews:
prefix for each key, to customize it use client_side_prefix
option.
cache.setup("redis:https://0.0.0.0/?db=1&minsize=10&suppress=false&secret=my_secret", prefix="func")
cache.setup("redis:https://0.0.0.0/2", password="my_pass", socket_connect_timeout=0.1, retry_on_timeout=True, secret="my_secret")
cache.setup("redis:https://0.0.0.0", client_side=True, client_side_prefix="my_prefix:", pickle_type="dill")
For using secure connections to redis (over ssl) uri should have rediss
as schema
cache.setup("rediss:https://0.0.0.0/", ssl_ca_certs="path/to/ca.crt", ssl_keyfile="path/to/client.key",ssl_certfile="path/to/client.crt",)
Requires diskcache package.
This will use local sqlite databases (with shards) as storage.
It is a good choice if you don't want to use redis, but you need a shared storage, or your cache takes a lot of local memory. Also, it is a good choice for client side local storage.
You can setup disk cache with FanoutCache parameters
** Warning ** cache.scan
and cache.get_match
does not work with this storage (works only if shards are disabled)
cache.setup("disk:https://")
cache.setup("disk:https://?directory=/tmp/cache&timeout=1&shards=0") # disable shards
Gb = 1073741824
cache.setup("disk:https://", size_limit=3 * Gb, shards=12)
There are a few basic methods to work with cache:
from cashews import cache
cache.setup("mem:https://") # configure as in-memory cache
await cache.set(key="key", value=90, expire="2h", exist=None) # -> bool
await cache.set_raw(key="key", value="str") # -> bool
await cache.set_many({"key1": value, "key2": value}) # -> None
await cache.get("key", default=None) # -> Any
await cache.get_or_set("key", default=awaitable_or_callable, expire="1h") # -> Any
await cache.get_raw("key") # -> Any
await cache.get_many("key1", "key2", default=None) # -> tuple[Any]
async for key, value in cache.get_match("pattern:*", batch_size=100):
...
await cache.incr("key") # -> int
await cache.exists("key") # -> bool
await cache.delete("key")
await cache.delete_many("key1", "key2")
await cache.delete_match("pattern:*")
async for key in cache.scan("pattern:*"):
...
await cache.expire("key", timeout=10)
await cache.get_expire("key") # -> int seconds to expire
await cache.ping(message=None) # -> bytes
await cache.clear()
await cache.is_locked("key", wait=60) # -> bool
async with cache.lock("key", expire=10):
...
await cache.set_lock("key", value="value", expire=60) # -> bool
await cache.unlock("key", "value") # -> bool
await cache.get_keys_count() # -> int - total number of keys in cache
await cache.close()
Cache can be disabled not only at setup, but also in runtime. Cashews allow you to disable/enable any call of cache or specific commands:
from cashews import cache, Command
cache.setup("mem:https://") # configure as in-memory cache
cache.disable(Command.DELETE)
cache.disable()
cache.enable(Command.GET, Command.SET)
cache.enable()
with cache.disabling():
...
- Simple cache
- Fail cache (Failover cache)
- Hit cache
- Early
- Soft
- Async Iterators
- Locked
- Rate limit
- Circuit breaker
This is a typical cache strategy: execute, store and return from cache until it expires.
from datetime import timedelta
from cashews import cache
cache.setup("mem:https://")
@cache(ttl=timedelta(hours=3), key="user:{request.user.uid}")
async def long_running_function(request):
...
Return cache result, if one of the given exceptions is raised (at least one function call should succeed prior to that).
from cashews import cache
cache.setup("mem:https://")
# note: the key will be "__module__.get_status:name:{name}"
@cache.failover(ttl="2h", exceptions=(ValueError, MyException))
async def get_status(name):
value = await api_call()
return {"status": value}
If exceptions didn't get will catch all exceptions or use default if it is set by:
cache.set_default_fail_exceptions(ValueError, MyException)
Expire cache after given numbers of call cache_hits
.
from cashews import cache
cache.setup("mem:https://")
@cache.hit(ttl="2h", cache_hits=100, update_after=2)
async def get(name):
value = await api_call()
return {"status": value}
Cache strategy that tries to solve Cache stampede problem with a hot cache recalculating result in a background.
from cashews import cache # or: from cashews import early
# if you call this function after 7 min, cache will be updated in a background
@cache.early(ttl="10m", early_ttl="7m")
async def get(name):
value = await api_call()
return {"status": value}
Like a simple cache, but with a fail protection base on soft ttl.
from cashews import cache
cache.setup("mem:https://")
# if you call this function after 7 min, cache will be updated and return a new result.
# If it fail on recalculation will return current cached value (if it is not more than 10 min old)
@cache.soft(ttl="10m", soft_ttl="7m")
async def get(name):
value = await api_call()
return {"status": value}
All upper decorators can be used only with coroutines. Cashing async iterators works differently.
To cache async iterators use iterator
decorator
from cashews import cache
cache.setup("mem:https://")
@cache.iterator(ttl="10m", key="get:{name}")
async def get(name):
async for item in get_pages(name):
yield ...
Decorator that can help you to solve Cache stampede problem. Lock the following function calls until the first one is finished. This guarantees exactly one function call for given ttl.
⚠️ **Warning: this decorator will not cache the result To do it you can combine this decorator with any cache decorator or use parameterlock=True
with@cache()
from cashews import cache
cache.setup("mem:https://")
@cache.locked(ttl="10s")
async def get(name):
value = await api_call()
return {"status": value}
Rate limit for a function call: if rate limit is reached raise an RateLimitError
exception.
⚠️ **Warning: this decorator will not cache the result To do it you can combine this decorator with any cache failover decorator`
from cashews import cache, RateLimitError
cache.setup("mem:https://")
# no more than 10 calls per minute or ban for 10 minutes - raise RateLimitError
@cache.rate_limit(limit=10, period="1m", ttl="10m")
async def get(name):
value = await api_call()
return {"status": value}
# no more than 100 calls in 10 minute window. if rate limit will rich -> return from cache
@cache.failover(ttl="10m", exceptions=(RateLimitError, ))
@cache.slice_rate_limit(limit=100, period="10m")
async def get_next(name):
value = await api_call()
return {"status": value}
Circuit breaker pattern. Count the number of failed calls and if the error rate reaches the specified value, it will raise CircuitBreakerOpen
exception
⚠️ **Warning: this decorator will not cache the result To do it you can combine this decorator with any cache failover decorator`
from cashews import cache, CircuitBreakerOpen
cache.setup("mem:https://")
@cache.circuit_breaker(errors_rate=10, period="1m", ttl="5m")
async def get(name):
...
@cache.failover(ttl="10m", exceptions=(CircuitBreakerOpen, ))
@cache.circuit_breaker(errors_rate=10, period="10m", ttl="5m", half_open_ttl="1m")
async def get_next(name):
...
Simple Bloom filter:
from cashews import cache
cache.setup("mem:https://")
@cache.bloom(capacity=10_000, false_positives=1)
async def email_exists(email: str) -> bool:
...
for email in all_users_emails:
await email_exists.set(email)
await email_exists("[email protected]")
By default, any successful result of the function call is stored, even if it is a None
.
Caching decorators have the parameter - condition
, which can be:
- a callable object that receives the result of a function call or an exception, args, kwargs and a cache key
- a string: "not_none" or "skip_none" to do not cache
None
values in
from cashews import cache, NOT_NONE
cache.setup("mem:https://")
@cache(ttl="1h", condition=NOT_NONE)
async def get():
...
def skit_test_result(result, args, kwargs, key=None) -> bool:
return result and result != "test"
@cache(ttl="1h", condition=skit_test_result)
async def get():
...
It is also possible to cache an exception that the function can raise, to do so use special conditions (only for simple, hit and early)
from cashews import cache, with_exceptions, only_exceptions
cache.setup("mem:https://")
@cache(ttl="1h", condition=with_exceptions(MyException, TimeoutError))
async def get():
...
@cache(ttl="1h", condition=only_exceptions(MyException, TimeoutError))
async def get():
...
Also caching decorators have the parameter time_condition
- min latency in seconds (can be set like ttl
)
of getting the result of a function call to be cached.
from cashews import cache
cache.setup("mem:https://")
@cache(ttl="1h", time_condition="3s") # to cache for 1 hour if execution takes more than 3 seconds
async def get():
...
Often, to compose a cache key, you need all the parameters of the function call. By default, Cashews will generate a key using the function name, module names and parameters
from cashews import cache
cache.setup("mem:https://")
@cache(ttl=timedelta(hours=3))
async def get_name(user, *args, version="v1", **kwargs):
...
# a key template will be "__module__.get_name:user:{user}:{__args__}:version:{version}:{__kwargs__}"
await get_name("me", version="v2")
# a key will be "__module__.get_name:user:me::version:v2"
await get_name("me", version="v1", foo="bar")
# a key will be "__module__.get_name:user:me::version:v1:foo:bar"
await get_name("me", "opt", "attr", opt="opt", attr="attr")
# a key will be "__module__.get_name:user:me:opt:attr:version:v1:attr:attr:opt:opt"
For more advanced usage it better to define a cache key manually:
from cashews import cache
cache.setup("mem:https://")
@cache(ttl="2h", key="user_info:{user_id}")
async def get_info(user_id: str):
...
You may use objects in a key and access to an attribute through a template:
@cache(ttl="2h", key="user_info:{user.uuid}")
async def get_info(user: User):
...
You may use built-in functions to format template values (lower
, upper
, len
, jwt
, hash
)
@cache(ttl="2h", key="user_info:{user.name:lower}:{password:hash(sha1)}")
async def get_info(user: User, password: str):
...
@cache(ttl="2h", key="user:{token:jwt(client_id)}")
async def get_user_by_token(token: str) -> User:
...
Or define your own transformation functions:
from cashews import default_formatter, cache
cache.setup("mem:https://")
@default_formatter.register("prefix")
def _prefix(value, chars=3):
return value[:chars].upper()
@cache(ttl="2h", key="servers-user:{user.index:prefix(4)}") # a key will be "servers-user:DWQS"
async def get_user_servers(user):
...
or register type formatters:
from decimal import Decimal
from cashews import default_formatter, cache
@default_formatter.type_format(Decimal)
def _decimal(value: Decimal) -> str:
return str(value.quantize(Decimal("0.00")))
@cache(ttl="2h", key="price-{item.price}:{item.currency:upper}") # a key will be "price-10.00:USD"
async def convert_price(item):
...
Not only function arguments can participate in a key formation. Cashews have a template_context
. You may use any variable registered in it:
from cashews import cache, key_context, register_key_context
cache.setup("mem:https://")
register_key_context("client_id")
@cache(ttl="2h", key="user:{client_id}")
async def get_current_user():
pass
...
with key_context(client_id=135356):
await get_current_user()
from cashews import cache
cache.setup("mem:https://")
class MyClass:
@cache(ttl="2h")
async def get_name(self, user, version="v1"):
...
# a key template will be "__module__:MyClass.get_name:self:{self}:user:{user}:version:{version}
await MyClass().get_name("me", version="v2")
# a key will be "__module__:MyClass.get_name:self:<__module__.MyClass object at 0x105edd6a0>:user:me:version:v1"
As you can see, there is an ugly reference to the instance in the key. That is not what we expect to see. That cache will not work properly. There are 3 solutions to avoid it:
- define
__str__
magic method in our class
class MyClass:
@cache(ttl="2h")
async def get_name(self, user, version="v1"):
...
def __str__(self) -> str:
return self._host
await MyClass(host="http:https://example.com").get_name("me", version="v2")
# a key will be "__module__:MyClass.get_name:self:http:https://example.com:user:me:version:v1"
- Set a key template
class MyClass:
@cache(ttl="2h", key="{self._host}:name:{user}:{version}")
async def get_name(self, user, version="v1"):
...
await MyClass(host="http:https://example.com").get_name("me", version="v2")
# a key will be "http:https://example.com:name:me:v1"
- Use
noself
ornoself_cache
if you want to excludeself
from a key
from cashews import cache, noself, noself_cache
cache.setup("mem:https://")
class MyClass:
@noself(cache)(ttl="2h")
async def get_name(self, user, version="v1"):
...
@noself_cache(ttl="2h") # for python <= 3.8
async def get_name(self, user, version="v1"):
...
# a key template will be "__module__:MyClass.get_name:user:{user}:version:{version}
await MyClass().get_name("me", version="v2")
# a key will be "__module__:MyClass.get_name:user:me:version:v1"
Cache time to live (ttl
) is a required parameter for all cache decorators. TTL can be:
- an integer as the number of seconds
- a
timedelta
- a string like in golang e.g
1d2h3m50s
- a callable object like a function that receives
args
andkwargs
of the decorated function and returns one of the previous format for TTL
Examples:
from cashews import cache
from datetime import timedelta
cache.setup("mem:https://")
@cache(ttl=60 * 10)
async def get(item_id: int) -> Item:
pass
@cache(ttl=timedelta(minutes=10))
async def get(item_id: int) -> Item:
pass
@cache(ttl="10m")
async def get(item_id: int) -> Item:
pass
def _ttl(item_id: int) -> str:
return "2h" if item_id > 10 else "1h"
@cache(ttl=_ttl)
async def get(item_id: int) -> Item:
pass
Cashews mostly use built-in pickle to store data but also support other pickle-like serialization like dill. Some types of objects are not picklable, in this case, cashews has API to define custom encoding/decoding:
from cashews.serialize import register_type
async def my_encoder(value: CustomType, *args, **kwargs) -> bytes:
...
async def my_decoder(value: bytes, *args, **kwargs) -> CustomType:
...
register_type(CustomType, my_encoder, my_decoder)
Cache invalidation - one of the main Computer Science well-known problems.
Sometimes, you want to invalidate the cache after some action is triggered. Consider this example:
from cashews import cache
cache.setup("mem:https://")
@cache(ttl="1h", key="items:page:{page}")
async def items(page=1):
...
@cache.invalidate("items:page:*")
async def create_item(item):
...
Here, the cache for items
will be invalidated every time create_item
is called
There are two problems:
- with redis backend you cashews will scan a full database to get a key that match a pattern (
items:page:*
) - not good for performance reasons - what if we do not specify a key for cache:
@cache(ttl="1h")
async def items(page=1):
...
Cashews provide the tag system: you can tag cache keys, so they will be stored in a separate SET to avoid high load on redis storage. To use the tags in a more efficient way please use it with the client side feature.
⚠️ **Warning: Tags require setting up default cache or cache for tags prefixfrom cashews import cache cache.setup(...) # or cache.setup_tags_backend(...)
from cashews import cache
cache.setup("redis:https://", client_side=True)
@cache(ttl="1h", tags=["items", "page:{page}"])
async def items(page=1):
...
await cache.delete_tags("page:1")
await cache.delete_tags("items")
# low level api
cache.register_tag("my_tag", key_template="key{i}")
await cache.set("key1", "value", expire="1d", tags=["my_tag"])
You can invalidate future call of cache request by context manager:
from cashews import cache, invalidate_further
@cache(ttl="3h")
async def items():
...
async def add_item(item: Item) -> List[Item]:
...
with invalidate_further():
await items
Often, you may face a problem with an invalid cache after the code is changed. For example:
@cache(ttl=timedelta(days=1), key="user:{user_id}")
async def get_user(user_id):
return {"name": "Dmitry", "surname": "Krykov"}
Then, the returned value was changed to:
- return {"name": "Dmitry", "surname": "Krykov"}
+ return {"full_name": "Dmitry Krykov"}
Since the function returns a dict, there is no simple way to automatically detect that kind of cache invalidity
One way to solve the problem is to add a prefix for this cache:
@cache(ttl=timedelta(days=1), prefix="v2")
async def get_user(user_id):
return {"full_name": "Dmitry Krykov"}
but it is so easy to forget to do it...
The best defense against this problem is to use your own datacontainers, like
dataclasses,
with defined __repr__
method.
This will add distinctness and cashews
can detect changes in such structures automatically
by checking object representation.
from dataclasses import dataclass
from cashews import cache
cache.setup("mem:https://")
@dataclass
class User:
name: str
surname: str
# or define your own class with __repr__ method
class User:
def __init__(self, name, surname):
self.name, self.surname = name, surname
def __repr__(self):
return f"{self.name} {self.surname}"
# Will detect changes of a structure
@cache(ttl="1d", prefix="v2")
async def get_user(user_id):
return User("Dima", "Krykov")
Decorators give us a very simple API but also make it difficult to understand where the result is coming from - cache or direct call.
To solve this problem cashews
has detect
context manager:
from cashews import cache
with cache.detect as detector:
response = await something_that_use_cache()
calls = detector.calls
print(calls)
# >>> {"my:key": [{"ttl": 10, "name": "simple", "backend": "redis"}, ], "fail:key": [{"ttl": 10, "exc": RateLimit}, "name": "fail", "backend": "mem"],}
E.g. A simple middleware to use it in a web app:
@app.middleware("http")
async def add_from_cache_headers(request: Request, call_next):
with cache.detect as detector:
response = await call_next(request)
if detector.calls:
key = list(detector.calls.keys())[0]
response.headers["X-From-Cache"] = key
expire = await cache.get_expire(key)
response.headers["X-From-Cache-Expire-In-Seconds"] = str(expire)
return response
Cashews provide the interface for a "middleware" pattern:
import logging
from cashews import cache
logger = logging.getLogger(__name__)
async def logging_middleware(call, cmd: Command, backend: Backend, *args, **kwargs):
key = args[0] if args else kwargs.get("key", kwargs.get("pattern", ""))
logger.info("=> Cache request: %s ", cmd.value, extra={"args": args, "cache_key": key})
return await call(*args, **kwargs)
cache.setup("mem:https://", middlewares=(logging_middleware, ))
One of the middleware that is preinstalled in cache instance is CallbackMiddleware
.
This middleware also add to a cache a new interface that allow to add a function that will be called before given command will be triggered
from cashews import cache, Command
def callback(key, result):
print(f"GET key={key}")
with cache.callback(callback, cmd=Command.GET):
await cache.get("test") # also will print "GET key=test"
Applications are more often based on a database with transaction (OLTP) usage. Usually cache supports transactions poorly. Here is just a simple example of how we can make our cache inconsistent:
async def my_handler():
async with db.transaction():
await db.insert(user)
await cache.set(f"key:{user.id}", user)
await api.service.register(user)
Here the API call may fail, the database transaction will rollback, but the cache will not. Of course, in this code, we can solve it by moving the cache call outside transaction, but in real code it may not so easy. Another case: we want to make bulk operations with a group of keys to keep it consistent:
async def login(user, token, session):
...
old_session = await cache.get(f"current_session:{user.id}")
await cache.incr(f"sessions_count:{user.id}")
await cache.set(f"current_session:{user.id}", session)
await cache.set(f"token:{token.id}", user)
return old_session
Here we want to have some way to protect our code from race conditions and do operations with cache simultaneously.
Cashews support transaction operations:
⚠️ **Warning: transaction operations areset
,set_many
,delete
,delete_many
,delete_match
andincr
from cashews import cache
...
@cache.transaction()
async def my_handler():
async with db.transaction():
await db.insert(user)
await cache.set(f"key:{user.id}", user)
await api.service.register(user)
# or
async def login(user, token, session):
async with cache.transaction() as tx:
old_session = await cache.get(f"current_session:{user.id}")
await cache.incr(f"sessions_count:{user.id}")
await cache.set(f"current_session:{user.id}", session)
await cache.set(f"token:{token.id}", user)
if ...:
tx.rollback()
return old_session
Transactions in cashews support different modes of "isolation"
- fast (0-7% overhead) - memory based, can't protect of race conditions, but may use for atomicity
- locked (default - 4-9% overhead) - use kind of shared lock per cache key (in case of redis or disk backend), protect of race conditions
- serializable (7-50% overhead) - use global shared lock - one transaction per time (almost useless)
from cashews import cache, TransactionMode
...
@cache.transaction(TransactionMode.SERIALIZABLE, timeout=1)
async def my_handler():
...
This library is framework agnostic, but includes several "batteries" for most popular tools.
You may find a few middlewares useful that can help you to control a cache in you web application based on fastapi.
CacheEtagMiddleware
- middleware add Etag and check 'If-None-Match' header based on EtagCacheRequestControlMiddleware
- middleware check and addCache-Control
headerCacheDeleteMiddleware
- clear cache for an endpoint based onClear-Site-Data
header
⚠️ **Warning: CacheEtagMiddleware requires setting up default cache or cache with prefix "fastapi:"from cashews import cache cache.setup(...) # or cache.setup(..., prefix="fastapi:")
Example:
from fastapi import FastAPI, Header, Query
from fastapi.responses import StreamingResponse
from cashews import cache
from cashews.contrib.fastapi import (
CacheDeleteMiddleware,
CacheEtagMiddleware,
CacheRequestControlMiddleware,
cache_control_ttl,
)
app = FastAPI()
app.add_middleware(CacheDeleteMiddleware)
app.add_middleware(CacheEtagMiddleware)
app.add_middleware(CacheRequestControlMiddleware)
metrics_middleware = create_metrics_middleware()
cache.setup(os.environ.get("CACHE_URI", "redis:https://"))
@app.get("/")
@cache.failover(ttl="1h")
@cache(ttl=cache_control_ttl(default="4m"), key="simple:{user_agent:hash}", time_condition="1s")
async def simple(user_agent: str = Header("No")):
...
@app.get("/stream")
@cache(ttl="1m", key="stream:{file_path}")
async def stream(file_path: str = Query(__file__)):
return StreamingResponse(_read_file(file_path=file_path))
async def _read_file(_read_file):
...
Also cashews can cache stream responses
You can easily provide metrics using the Prometheus middleware.
from cashews import cache
from cashews.contrib.prometheus import create_metrics_middleware
metrics_middleware = create_metrics_middleware(with_tag=False)
cache.setup("redis:https://", middlewares=(metrics_middleware,))
- Clone the project.
- After creating a virtual environment, install pre-commit:
pip install pre-commit && pre-commit install --install-hooks
To run tests you can use tox
:
pip install tox
tox -e py // tests for inmemory backend
tox -e py-diskcache // tests for diskcache backend
tox -e py-redis // tests for redis backend - you need to run redis
tox -e py-integration // tests for integrations with aiohttp and fastapi
tox // to run all tests for all python that is installed on your machine
Or use pytest
, but 2 tests always fail, it is OK:
pip install .[tests,redis,diskcache,speedup] fastapi aiohttp requests httpx SQLAlchemy prometheus-client
pytest // run all tests with all backends
pytest -m "not redis" // all tests without tests for redis backend