81 lines
3.7 KiB
Markdown
81 lines
3.7 KiB
Markdown
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# go-generics-cache
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[](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)
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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.
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- a thread-safe
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- implemented with [Go Generics](https://go.dev/blog/generics-proposal)
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- TTL supported (with expiration times)
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- Simple cache is like `map[string]interface{}`
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/simple/example_test.go)
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- Cache replacement policies
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- **Least recently used (LRU)**
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- Discards the least recently used items first.
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/lru/example_test.go)
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- **Least-frequently used (LFU)**
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- Counts how often an item is needed. Those that are used least often are discarded first.
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- [An O(1) algorithm for implementing the LFU cache eviction scheme](http://dhruvbird.com/lfu.pdf)
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/lfu/example_test.go)
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- **First in first out (FIFO)**
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- Using this algorithm the cache behaves in the same way as a [FIFO queue](https://en.wikipedia.org/wiki/FIFO_(computing_and_electronics)).
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- 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.
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/fifo/example_test.go)
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- **Most recently used (MRU)**
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- In contrast to Least Recently Used (LRU), MRU discards the most recently used items first.
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/mru/example_test.go)
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- **Clock**
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- Clock is a more efficient version of FIFO than Second-chance cache algorithm.
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- See [examples](https://github.com/Code-Hex/go-generics-cache/blob/main/policy/clock/example_test.go)
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## Requirements
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Go 1.18 or later.
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## Install
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$ go get github.com/Code-Hex/go-generics-cache
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## Usage
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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)
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```go
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package main
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import (
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"context"
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"fmt"
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"time"
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cache "github.com/Code-Hex/go-generics-cache"
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)
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func main() {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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// use simple cache algorithm without options.
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c := cache.NewContext[string, int](ctx)
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c.Set("a", 1)
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gota, aok := c.Get("a")
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gotb, bok := c.Get("b")
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fmt.Println(gota, aok) // 1 true
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fmt.Println(gotb, bok) // 0 false
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// Create a cache for Number constraint. key as string, value as int.
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nc := cache.NewNumber[string, int]()
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nc.Set("age", 26, cache.WithExpiration(time.Hour))
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incremented := nc.Increment("age", 1)
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fmt.Println(incremented) // 27
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decremented := nc.Decrement("age", 1)
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fmt.Println(decremented) // 26
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}
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```
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## Articles
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- English: [Some tips and bothers for Go 1.18 Generics](https://dev.to/codehex/some-tips-and-bothers-for-go-118-generics-lc7)
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- 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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