# ocean

In-memory key value store that saves your data to disk using JSON.

## Installation

```shell
go get git.akyoto.dev/go/ocean
```

## Example

```go
// Define the User type
type User struct { Name string }

// Create a collection in ~/.ocean/myapp/User.dat
users := ocean.New[User]("myapp", &storage.File[User]{})

// Store some data
users.Set("1", &User{Name: "User 1"})
users.Set("2", &User{Name: "User 2"})
users.Set("3", &User{Name: "User 3"})

// Read from memory
first, err := users.Get("1")

// Iterate over all users
for user := range users.All() {
    fmt.Println(user.Name)
}
```

## File format

```json
1
{"name":"User 1"}
2
{"name":"User 2"}
3
{"name":"User 3"}
```

## Benchmarks

```
BenchmarkGet-12         275126157                4.462 ns/op           0 B/op          0 allocs/op
BenchmarkSet-12          4796011               251.0 ns/op            32 B/op          2 allocs/op
BenchmarkDelete-12      471913158                2.530 ns/op           0 B/op          0 allocs/op
BenchmarkNew-12         48838576                22.89 ns/op           80 B/op          1 allocs/op
```

## Storage systems

### nil

You can specify `nil` as the storage system which will keep data in RAM only.

### storage.File

`storage.File` uses a single file to store all records.
Writes using `Set(key, value)` are async and only mark the collection as "dirty" which is very quick.
The sync to disk happens shortly afterwards.
Every collection uses one goroutine to check the "dirty" flag, write the new contents to disk and reset the flag.

The biggest advantage of `storage.File` is that it scales well with the number of requests:

Suppose `n` is the number of write requests and `io` is the time it takes for one write. Immediate storage would require `O(n * io)` time to complete all writes but the async behavior makes it `O(n)`.

You should use `storage.File` if you have a permanently running process such as a web server where end users expect quick responses and background work can happen after the user request has already been dealt with.

Make sure you `defer collection.Sync()` to ensure that queued writes will be handled when the process ends.

### storage.Directory

`storage.Directory` creates a directory for your records and saves each record in a separate file.
The performance of this method heavily depends on the file system you are using but in general `storage.File` should be preferred as it provides much better performance.