refactor of channel persistence to use UUIDs

irc/bunt/bunt_datastore.go

@@ -0,0 +1,106 @@
+// Copyright (c) 2022 Shivaram Lingamneni
+// released under the MIT license
+
+package bunt
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/tidwall/buntdb"
+
+	"github.com/ergochat/ergo/irc/datastore"
+	"github.com/ergochat/ergo/irc/logger"
+	"github.com/ergochat/ergo/irc/utils"
+)
+
+// BuntKey yields a string key corresponding to a (table, UUID) pair.
+// Ideally this would not be public, but some of the migration code
+// needs it.
+func BuntKey(table datastore.Table, uuid utils.UUID) string {
+	return fmt.Sprintf("%x %s", table, uuid.String())
+}
+
+// buntdbDatastore implements datastore.Datastore using a buntdb.
+type buntdbDatastore struct {
+	db     *buntdb.DB
+	logger *logger.Manager
+}
+
+// NewBuntdbDatastore returns a datastore.Datastore backed by buntdb.
+func NewBuntdbDatastore(db *buntdb.DB, logger *logger.Manager) datastore.Datastore {
+	return &buntdbDatastore{
+		db:     db,
+		logger: logger,
+	}
+}
+
+func (b *buntdbDatastore) Backoff() time.Duration {
+	return 0
+}
+
+func (b *buntdbDatastore) GetAll(table datastore.Table) (result []datastore.KV, err error) {
+	tablePrefix := fmt.Sprintf("%x ", table)
+	err = b.db.View(func(tx *buntdb.Tx) error {
+		err := tx.AscendGreaterOrEqual("", tablePrefix, func(key, value string) bool {
+			if !strings.HasPrefix(key, tablePrefix) {
+				return false
+			}
+			uuid, err := utils.DecodeUUID(strings.TrimPrefix(key, tablePrefix))
+			if err == nil {
+				result = append(result, datastore.KV{UUID: uuid, Value: []byte(value)})
+			} else {
+				b.logger.Error("datastore", "invalid uuid", key)
+			}
+			return true
+		})
+		return err
+	})
+	return
+}
+
+func (b *buntdbDatastore) Get(table datastore.Table, uuid utils.UUID) (value []byte, err error) {
+	buntKey := BuntKey(table, uuid)
+	var result string
+	err = b.db.View(func(tx *buntdb.Tx) error {
+		result, err = tx.Get(buntKey)
+		return err
+	})
+	return []byte(result), err
+}
+
+func (b *buntdbDatastore) Set(table datastore.Table, uuid utils.UUID, value []byte, expiration time.Time) (err error) {
+	buntKey := BuntKey(table, uuid)
+	var setOptions *buntdb.SetOptions
+	if !expiration.IsZero() {
+		ttl := time.Until(expiration)
+		if ttl > 0 {
+			setOptions = &buntdb.SetOptions{Expires: true, TTL: ttl}
+		} else {
+			return nil // it already expired, i guess?
+		}
+	}
+	strVal := string(value)
+
+	err = b.db.Update(func(tx *buntdb.Tx) error {
+		_, _, err := tx.Set(buntKey, strVal, setOptions)
+		return err
+	})
+	return
+}
+
+func (b *buntdbDatastore) Delete(table datastore.Table, key utils.UUID) (err error) {
+	buntKey := BuntKey(table, key)
+	err = b.db.Update(func(tx *buntdb.Tx) error {
+		_, err := tx.Delete(buntKey)
+		return err
+	})
+	// deleting a nonexistent key is not considered an error
+	switch err {
+	case buntdb.ErrNotFound:
+		return nil
+	default:
+		return err
+	}
+}