Auto refreshing cache

A golang package that provides auto refreshing cache interface for various data sources.

To use library:

import "github.com/mhrabovcin/cache/pkg/cache"

Concepts

A library work around a concept of a global Cache that consists of multiple Sources. Each Source is independent cache that can be configured with different source and refresh frequency.

Interface

The library provides basic interface for accessing cached data:

c := cache.New(source1, source2, ...)
item, err := c.Get("source_name", "key")
item.Value()

Each source is independent and can be configured with own data source and refresh frequency. A general Source usage:

source1 := cache.NewSource(
    "source_name",
    cache.WithDefaultData(map[string]string{
        "intial_key": "inital_value",
    }),
)
// Required to stop automatic fetching goroutine
defer source1.Stop()

item, err := source1.Get("cache_key")
item.Value()

Source always returns a Item that includes Metadata. If cache refresh fails the cache source will serve stale data. To check when data was refreshed use Item methods:

item, err := source1.Get("cache_key")

// When the item was last refreshed
item.LastRefreshed()

// If the item is stale
item.IsStale()

// When the chace will be refreshed again
item.NextRefresh()

Data sources

Redis and Database sources are supported.

cache.NewRedisSource(...)
cache.NewDbSource(...)
cache.NewStaticSource(...)

Custom data sources

It is possible to provide custom data fetcher to general cache Source. A data fetcher must implement FetchFunc interface.

func myFetcher() (map[string]string, error) {
    return map[string]string{}, nil
}

customSource := cache.NewSource(
    "custom_source",
    // Refresh every 1 hour
    cache.WithFetchFunc(myFetcher, 1*time.Hour),
)

Development

A library was built with Go 1.12 version and uses go modules.

To run tests:

make coverage

To run benchmark

make bench