1# ermite-kv
2
3> Read-only mirror. Development happens at git.bnema.dev; issues and pull requests are closed here.
4
5An embedded key-value store for Go. Data lives in memory and is persisted to an append-only log with snapshots. One writer goroutine groups commits into a single `fsync`, and readers use immutable snapshots without locks. Standard library only, plus [zerowrap](https://github.com/bnema/zerowrap) for logs.
6
7Status: early development, no stable API. Linux only.
8
9```go
10import kv "bnema.dev/ermite-kv"
11
12db, err := kv.Open(ctx, "/var/lib/app/kv", kv.Options{})
13if err != nil {
14	return err
15}
16defer db.Close(ctx)
17
18var b kv.Batch
19b.RequireAbsent([]byte("user/alice"))
20b.Put([]byte("user/alice"), []byte(`{"name":"Alice"}`))
21seq, err := db.Apply(ctx, &b) // durable and visible when it returns
22if errors.Is(err, kv.ErrConflict) {
23	// the key already exists
24}
25
26for key, item := range db.Snapshot(ctx).Prefix(ctx, []byte("user/")) {
27	fmt.Printf("%s = %s (version %d)\n", key, item.Value, item.Version)
28}
29```
30
31The package documentation describes the durability and visibility guarantees.
32
33## Test
34
35```sh
36go test -race ./...
37ERMITE_KV_CRASH_ITERATIONS=200 go test -run TestCrash .   # SIGKILL crash test
38ERMITE_KV_LOG_LEVEL=debug go test -run TestPowerLoss .    # with logs
39```
40
41## License
42
43MIT. See [LICENSE](LICENSE).