# go-memoize
There wasn't a decent [memoizer](https://wikipedia.org/wiki/Memoization) for Golang out there, so I lashed two nice libraries together and made one.
Dead-simple. Safe for concurrent use.
[](https://pkg.go.dev/github.com/kofalt/go-memoize)
[](https://goreportcard.com/report/github.com/kofalt/go-memoize)
[](https://github.com/kofalt/go-memoize/actions)
## Project status
**Complete.** Latest commit timestamp might be old - that's okay.
Go-memoize has been in production for a few years, and has yet to burn the house down.
## Usage
Cache expensive function calls in memory, with a configurable timeout and purge interval:
```golang
import (
"time"
"github.com/kofalt/go-memoize"
)
// Any expensive call that you wish to cache
expensive := func() (any, error) {
time.Sleep(3 * time.Second)
return "some data", nil
}
// Cache expensive calls in memory for 90 seconds, purging old entries every 10 minutes.
cache := memoize.NewMemoizer(90*time.Second, 10*time.Minute)
// This will call the expensive func
result, err, cached := cache.Memoize("key1", expensive)
// This will be cached
result, err, cached = cache.Memoize("key1", expensive)
// This uses a new cache key, so expensive is called again
result, err, cached = cache.Memoize("key2", expensive)
```
In the example above, `result` is:
1. the return value from your function if `cached` is false, or
1. a previously stored value if `cached` is true.
All the hard stuff is punted to [go-cache](https://github.com/patrickmn/go-cache) and [sync/singleflight](https://github.com/golang/sync), I just lashed them together.
Note that `cache.Storage` is exported, so you can use underlying features such as [Flush](https://godoc.org/github.com/patrickmn/go-cache#Cache.Flush) or [SaveFile](https://godoc.org/github.com/patrickmn/go-cache#Cache.SaveFile).
### Type safety
The default usage stores and returns an `any` type.
If you wants to store & retrieve a specific type, use `Call` instead:
```golang
import (
"time"
"github.com/kofalt/go-memoize"
)
// Same example as above, but this func returns a string!
expensive := func() (string, error) {
time.Sleep(3 * time.Second)
return "some data", nil
}
// Same as before
cache := memoize.NewMemoizer(90*time.Second, 10*time.Minute)
// This will call the expensive func, and return a string.
result, err, cached := memoize.Call(cache, "key1", expensive)
// This will be cached
result, err, cached = memoize.Call(cache, "key1", expensive)
// This uses a new cache key, so expensive is called again
result, err, cached = memoize.Call(cache, "key2", expensive)
```