From 9fc36171d0a89f659884504128a272db7cff4606 Mon Sep 17 00:00:00 2001
From: Anton Evangelatov <anton.evangelatov@gmail.com>
Date: Mon, 17 Sep 2018 13:04:46 +0200
Subject: [PATCH] swarm: schemas and migrations

---
 swarm/storage/database.go   |  9 ++-------
 swarm/storage/ldbstore.go   | 22 ++++++++++++++++++++++
 swarm/storage/localstore.go | 27 +++++++++++++++++++++++++++
 swarm/storage/schema.go     |  6 ++++++
 swarm/swarm.go              |  5 +++++
 5 files changed, 62 insertions(+), 7 deletions(-)
 create mode 100644 swarm/storage/schema.go

diff --git a/swarm/storage/database.go b/swarm/storage/database.go
index 3b5d003de1..e25fce31fb 100644
--- a/swarm/storage/database.go
+++ b/swarm/storage/database.go
@@ -20,8 +20,6 @@ package storage
 // no need for queueing/caching
 
 import (
-	"fmt"
-
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/iterator"
@@ -46,13 +44,10 @@ func NewLDBDatabase(file string) (*LDBDatabase, error) {
 	return database, nil
 }
 
-func (db *LDBDatabase) Put(key []byte, value []byte) {
+func (db *LDBDatabase) Put(key []byte, value []byte) error {
 	metrics.GetOrRegisterCounter("ldbdatabase.put", nil).Inc(1)
 
-	err := db.db.Put(key, value, nil)
-	if err != nil {
-		fmt.Println("Error put", err)
-	}
+	return db.db.Put(key, value, nil)
 }
 
 func (db *LDBDatabase) Get(key []byte) ([]byte, error) {
diff --git a/swarm/storage/ldbstore.go b/swarm/storage/ldbstore.go
index bde627394e..84d7c195bd 100644
--- a/swarm/storage/ldbstore.go
+++ b/swarm/storage/ldbstore.go
@@ -730,6 +730,28 @@ func (s *LDBStore) tryAccessIdx(ikey []byte, index *dpaDBIndex) bool {
 	return true
 }
 
+func (s *LDBStore) GetSchema() (string, error) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	data, err := s.db.Get([]byte(`schema`))
+	if err != nil {
+		if err == leveldb.ErrNotFound {
+			return "", nil
+		}
+		return "", err
+	}
+
+	return string(data), nil
+}
+
+func (s *LDBStore) PutSchema(schema string) error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	return s.db.Put([]byte(`schema`), []byte(schema))
+}
+
 func (s *LDBStore) Get(_ context.Context, addr Address) (chunk Chunk, err error) {
 	metrics.GetOrRegisterCounter("ldbstore.get", nil).Inc(1)
 	log.Trace("ldbstore.get", "key", addr)
diff --git a/swarm/storage/localstore.go b/swarm/storage/localstore.go
index 04701ee69a..05bf829d5b 100644
--- a/swarm/storage/localstore.go
+++ b/swarm/storage/localstore.go
@@ -184,3 +184,30 @@ func (ls *LocalStore) Iterator(from uint64, to uint64, po uint8, f func(Address,
 func (ls *LocalStore) Close() {
 	ls.DbStore.Close()
 }
+
+func (ls *LocalStore) Migrate() error {
+	schema, err := ls.DbStore.GetSchema()
+	if err != nil {
+		log.Error(err.Error())
+		return err
+	}
+
+	log.Debug("found schema", "schema", schema, "runtime-schema", CurrentDbSchema)
+	if schema != CurrentDbSchema {
+		// run migrations
+
+		if schema == "" {
+			log.Debug("running migrations for", "schema", schema, "runtime-schema", CurrentDbSchema)
+
+			ls.DbStore.Cleanup()
+
+			err := ls.DbStore.PutSchema(DbSchemaHive)
+			if err != nil {
+				log.Error(err.Error())
+				return err
+			}
+		}
+	}
+
+	return nil
+}
diff --git a/swarm/storage/schema.go b/swarm/storage/schema.go
new file mode 100644
index 0000000000..3006c114df
--- /dev/null
+++ b/swarm/storage/schema.go
@@ -0,0 +1,6 @@
+package storage
+
+// "hive" is the first formal schema of LevelDB we release together with Swarm 0.3.4
+const DbSchemaHive = "hive"
+
+const CurrentDbSchema = DbSchemaHive
diff --git a/swarm/swarm.go b/swarm/swarm.go
index 13aa1125d3..eaf5b1147e 100644
--- a/swarm/swarm.go
+++ b/swarm/swarm.go
@@ -169,6 +169,11 @@ func NewSwarm(config *api.Config, mockStore *mock.NodeStore) (self *Swarm, err e
 		return nil, err
 	}
 
+	err = lstore.Migrate()
+	if err != nil {
+		return nil, err
+	}
+
 	self.netStore, err = storage.NewNetStore(lstore, nil)
 	if err != nil {
 		return nil, err