Memcached

This extension provides support for connecting to Memcached servers. It registers the aiomcache.Client service.

Usage

First install the memcached extra:

pip install selva[memcached]

Define the configuration properties:

configuration/settings.yaml

extensions:
  - selva.ext.data.memcached # (1)

data:
  memcached:
    default: # (2)
      address: "localhost:11211"
    other: # (3)
      address: "localhost:11212"

1. Activate the extension
2. "default" connection will be registered without a name
3. Connection registered with name "other"

Inject the aiomcache.Client service:

from typing import Annotated
from aiomcache import Client as Memcached
from selva.di import service, Inject


@service
class MyService:
    # default service
    memcached: Annotated[Memcached, Inject]

    # named service
    other_memcached: Annotated[Memcached, Inject(name="other")]

Using environment variables

configuration/settings.yaml

data:
  memcached:
    default:
      address: "${MEMCACHED_ADDR}" # (1)

1. Can be define with just the environment variable SELVA__DATA__MEMCACHED__DEFAULT__ADDRESS

Example

application/handler.pyconfiguration/settings.yaml

from typing import Annotated

from aiomcache import Client as Memcached

from asgikit.responses import respond_json

from selva.di import Inject
from selva.web import get

@get
async def index(request, memcached: Annotated[Memcached, Inject]):
    if not await memcached.get(b"number"):
        await memcached.set(b"number", b"0")
    number = await memcached.incr("number")
    await respond_json(request.response, {"number": number})

data:
  memcached:
    default:
      address: "localhost:11211"

Configuration options

Selva offers several options to configure Memcached. If you need more control over the Memcached service, you can create your own aiomcache.Client service.

The available options are shown below:

data:
  memcached:
    default:
      address: ""
      options:
        pool_size: 10
        pool_minsize: 1
        get_flat_handler: "package.module.function" # (1)
        set_flat_handler: "package.module.function" # (2)
        conn_args: "package.module:variable" # (3)

1. dotted path to a python function
2. dotted path to a python function
3. dotted path to a python variable