data

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

Installation

go get git.akyoto.dev/go/data

Usage

// User type
type User struct { Name string }

// Create ~/.data/myapp/User.dat
users := data.NewFile[User]("myapp")

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

// Read
a, err := users.Get("1")
b, err := users.Get("2")
c, err := users.Get("3")

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

Format

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

Tests

PASS: TestCollection
PASS: TestCollection/All
PASS: TestCollection/Filter
PASS: TestCollection/Get
PASS: TestCollection/Exists
PASS: TestCollection/Parallel_Get_and_Set
PASS: TestCollection/Delete
PASS: TestFilePersistence
coverage: 84.1% of statements

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

When you initiate a new collection via data.New you can specify a storage system. data.NewFile is a useful shortcut to create a collection with the data.File storage.

nil

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

data.File

data.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 data.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 writes would require n * io time to complete all writes but the async behavior makes it a constant io.

You should use data.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.

License

Please see the license documentation.

Copyright

© 2023 Eduard Urbach