Feat: establish keeper registry

bitcask/reg.go

@@ -0,0 +1,11 @@
+package bitcask
+
+import "git.tcp.direct/tcp.direct/database"
+
+func init() {
+	database.Register("bitcask", func(path string) (database.Keeper, error) {
+		db := OpenDB(path)
+		err := db.init()
+		return db, err
+	})
+}

pogreb/reg.go

@@ -0,0 +1,11 @@
+package pogreb
+
+import "git.tcp.direct/tcp.direct/database"
+
+func init() {
+	database.Register("pogreb", func(path string) (database.Keeper, error) {
+		db := OpenDB(path)
+		err := db.init()
+		return db, err
+	})
+}

reg.go

@@ -0,0 +1,30 @@
+package database
+
+import (
+	"sync"
+)
+
+var (
+	keepers = make(map[string]KeeperCreator)
+	regMu   = &sync.RWMutex{}
+)
+
+func Register(name string, keeper KeeperCreator) {
+	regMu.Lock()
+	keepers[name] = keeper
+	regMu.Unlock()
+}
+
+func Get(name string) KeeperCreator {
+	regMu.RLock()
+	k := keepers[name]
+	regMu.RUnlock()
+	return k
+}
+
+func All() map[string]KeeperCreator {
+	regMu.RLock()
+	ks := keepers
+	regMu.RUnlock()
+	return ks
+}