Read-only mirror. Development happens at git.bnema.dev; issues and pull requests are closed here.

Features

• Data in memory, persisted to an append-only log with snapshots
• One writer groups commits into a single fsync
• Lock-free reads from immutable snapshots
• Conditional writes (RequireAbsent, RequireVersion)
• Standard library only, plus zerowrap for logs

Status: early development, no stable API. Linux only.

Usage

import kv "bnema.dev/ermite-kv"

db, err := kv.Open(ctx, "/var/lib/app/kv", kv.Options{})
if err != nil {
	return err
}
defer db.Close(ctx)

var b kv.Batch
b.RequireAbsent([]byte("user/alice"))
b.Put([]byte("user/alice"), []byte(`{"name":"Alice"}`))
seq, err := db.Apply(ctx, &b) // durable and visible when it returns
if errors.Is(err, kv.ErrConflict) {
	// the key already exists
}

for key, item := range db.Snapshot(ctx).Prefix(ctx, []byte("user/")) {
	fmt.Printf("%s = %s (version %d)\n", key, item.Value, item.Version)
}

Durability and visibility guarantees are in the package documentation (go doc bnema.dev/ermite-kv).

Test

go test -race ./...
ERMITE_KV_CRASH_ITERATIONS=200 go test -run TestCrash .   # SIGKILL crash test
ERMITE_KV_LOG_LEVEL=debug go test -run TestPowerLoss .    # with logs

License

MIT. See LICENSE.