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# go-generics-cache
[](https://github.com/Code-Hex/go-generics-cache/actions/workflows/test.yml) [](https://codecov.io/gh/Code-Hex/go-generics-cache) [](https://pkg.go.dev/github.com/Code-Hex/go-generics-cache)
go-generics-cache is an in-memory key:value store/cache that is suitable for applications running on a single machine. This in-memory cache uses [Go Generics](https://go.dev/blog/generics-proposal) which is introduced in 1.18.
- a thread-safe
- implemented with [Go Generics](https://go.dev/blog/generics-proposal)
- TTL supported (with expiration times)
- Simple cache is like `map[string]interface{}`
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/simple/example_test.go)
- Cache replacement policies
- **Least recently used (LRU)**
- Discards the least recently used items first.
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/lru/example_test.go)
- **Least-frequently used (LFU)**
- Counts how often an item is needed. Those that are used least often are discarded first.
- [An O(1) algorithm for implementing the LFU cache eviction scheme](http://dhruvbird.com/lfu.pdf)
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/lfu/example_test.go)
- **First in first out (FIFO)**
- Using this algorithm the cache behaves in the same way as a [FIFO queue](https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics)).
- The cache evicts the blocks in the order they were added, without any regard to how often or how many times they were accessed before.
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/fifo/example_test.go)
- **Most recently used (MRU)**
- In contrast to Least Recently Used (LRU), MRU discards the most recently used items first.
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/mru/example_test.go)
- **Clock**
- Clock is a more efficient version of FIFO than Second-chance cache algorithm.
- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/clock/example_test.go)
## Requirements
Go 1.18 or later.
## Install
$ go get github.com/Code-Hex/go-generics-cache
## Usage
See also [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/example_test.go) or [go playground](https://go.dev/play/p/kDs-6wpRAcX)
```go
package main
import (
"context"
"fmt"
"time"
cache "github.com/Code-Hex/go-generics-cache"
)
func main() {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// use simple cache algorithm without options.
c := cache.NewContext[string, int](ctx)
c.Set("a", 1)
gota, aok := c.Get("a")
gotb, bok := c.Get("b")
fmt.Println(gota, aok) // 1 true
fmt.Println(gotb, bok) // 0 false
// Create a cache for Number constraint. key as string, value as int.
nc := cache.NewNumber[string, int]()
nc.Set("age", 26, cache.WithExpiration(time.Hour))
incremented := nc.Increment("age", 1)
fmt.Println(incremented) // 27
decremented := nc.Decrement("age", 1)
fmt.Println(decremented) // 26
}
```
## Articles
- English: [Some tips and bothers for Go 1.18 Generics](https://dev.to/codehex/some-tips-and-bothers-for-go-118-generics-lc7)
- Japanese: [Go 1.18 の Generics を使ったキャッシュライブラリを作った時に見つけた tips と微妙な点](https://zenn.dev/codehex/articles/3e6935ee6d853e)
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