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Title: Cache Manager Desc: Cache manager for aah application cache use cases. Its pluggable design as providers and caches. Keywords: cache, cache manager, cache provider, in-memory, inmemory, redis, memcache

aah Cache Manager

Introduced in v0.12.0. This document provides the insight into aah Cache Manager design and usage.


![aah-Cache-Manager-Design]({{aah_cdn_host}}/assets/img/docs/aah-cache-manager-design.svg)

Table of Contents

Registering Cache Provider

Its easy to register any cache provider into aah application that implements cache.Provider. Best spot would be at file <app-base-dir>/init.go.

Register provider

// importing aah pluggable cache provider library
import "aahframe.work/cache/provider/redis"

// import "aahframe.work/cache/provider/inmemory"
// import "aahframe.work/cache/provider/memcache"

cacheMgr := aah.App().CacheManager()

if err := cacheMgr.AddProvider("redis1", &redis.Provider{}); err != nil {
    log.Error(err) // provider might be already exists
}

if err := cacheMgr.AddProvider("redis2", &redis.Provider{}); err != nil {
    log.Error(err) // provider might be already exists
}

Configure Provider

Configuring added provider in the aah.conf under section cache { ... }.

# Sample configuration config multiple redis cache server.
cache {
    redis1 {
        provider = "redis"
        address = "localhost:6379"
    }

    redis2 {
        provider = "redis"
        address = "localhost:6380"
    }
}

Creating a Cache

aah supports to create one or more cache using each provider based on use cases. Generally it also know as cache region. aah user could create a cache anytime they want.

Note: Cache name must be unique regardless of provider is used to create a cache.

// Create a cache configuration
cacheConfig := &cache.Config{
    Name:         "app_user_ratelimit",
    ProviderName: "redis",

    // Supported eviction modes are EvictionModeTTL, EvictionModeNoTTL and EvictionModeSlide
    EvictionMode: cache.EvictionModeSlide,

    // SweepInterval only applicable to in-memory cache provider.
    // SweepInterval: time.Minute * 90, // default is 60 minutes
}

// Supply cache config to create a cache using cache manager
cacheMgr := aah.App().CacheManager()

if err := cacheMgr.CreateCache(cacheConfig); err != nil {
    log.Error(err) // error occured while creating cache
}

Using Created Cache in aah Application

Once cache is created in the application, simply get the cache instance from cache manager to perform operation supported by interface cache.Cache.

cacheMgr := aah.App().CacheManager()

// getting cache instance from cache manager
appUserRatelimitCache := cacheMgr.Cache("app_user_ratelimit")

// get value from cache
value := appUserRatelimitCache.Get("cacheId")
fmt.Println(value)

Getting underlying Cache Client from Provider

Typically interface Cache provides common set of operation methods. However in real world usage needs option to perform dedicated operations using Cache Client. aah understands the need and provides way to get the client.

// E.g.: Getting underlying Cache Client of Redis
cacheMgr := aah.App().CacheManager()
redisProvider := cacheMgr.Provider("redis2").(*redis.Provider) // provider names used during a registeration

// use the client directly to call `Incr`
result, err := redisProvider.Client().Incr("counter").Result()

Configuration: In-Memory Cache Provider

In-memory cache provider (aahframe.work/cache/provider/inmemory) is configuration free.

Configuration: Redis Cache Provider

aah user have to configure redis provider (aahframe.work/cache/provider/redis) based on no of the providers they have registered. As explained here.

Provider configuration goes into aah.conf under section cache { ... }.

cache {
    # List of supported configuration for redis cache provider
    redis1 {
        provider = "redis"

        # Redis server address
        # Default value id `:6379`.        
        address = "localhost:6379"

        # Default value is ``.
        password = ""

        # DB number
        # Default value is `0`.
        db = 0

        # Default value is `10 * No. of CPUs`
        pool_size = 20

        # Provider timeouts
        # s => seconds
        # m => minutes
        timeout {
            # Default value is `5s`.
            connect = "5s"

            # Default value is `3s`.
            read = "3s"

            # Default value is `3s`.
            write = "3s"

            # Default value is `3s`.
            pool = "3s"

            # Default value is `5m`.
            idle = "5m"
        }

        # Default value is `1m`.
        idle_check_interval = "1m"

        # Retry Backoff time limits
        # ms => milliseconds
        retry_backoff {
            # Default value is `8ms`.
            min = "8ms"

            # Default value is `512ms`.
            max = "512ms"
        }
    }
}

Configuration: Memcache Cache Provider

aah user have to configure memcache provider (aahframe.work/cache/provider/memcache) based on no of the providers they have registered. As explained here.

Provider configuration goes into aah.conf under section cache { ... }.

cache {
    memcache1 {
        # List of memcache server addresses
        # Default value is `0.0.0.0:11211`.
        addresses = [
            "0.0.0.0:11211",
            "0.0.0.0:11212",
            "0.0.0.0:11213"
        ]

        # Maximum Idle connections
        # Default value is `2`.
        max_idle_conns = 2

        # Client Timeout
        # s => seconds
        #
        # Default value is `5s`.
        timeout = "5s"
    }
}

Adding your Own Cache Provider and Cache

As you have reached, you might have pretty good guess on how to implement own cache provider. Here we go -

Then follow this documentation to register and use it. Refer to aah Redis Cache Provider and aah Memcache Cache Provider for a implementation reference.