immutable db for query

modules/stake/db.go

@@ -30,6 +30,14 @@ func getDb() *sql.DB {
 	return db
 }
 
+func getImmuDb() *sql.DB {
+	db, err := dbm.Sqliter.GetImmuDB()
+	if err != nil {
+		panic(err)
+	}
+	return db
+}
+
 type SqlTxWrapper struct {
 	tx        *sql.Tx
 	withBlock bool

modules/stake/query.go

@@ -6,14 +6,14 @@ import (
 )
 
 func QueryCandidates() (candidates Candidates) {
-	db := getDb()
+	db := getImmuDb()
 	cond := make(map[string]interface{})
 	cond["active"] = "Y"
 	return queryCandidates(db, cond)
 }
 
 func QueryCandidateByAddress(address common.Address) *Candidate {
-	db := getDb()
+	db := getImmuDb()
 	cond := make(map[string]interface{})
 	cond["address"] = address.String()
 	candidates := queryCandidates(db, cond)
@@ -25,7 +25,7 @@ func QueryCandidateByAddress(address common.Address) *Candidate {
 }
 
 func QueryCandidateById(id int64) *Candidate {
-	db := getDb()
+	db := getImmuDb()
 	cond := make(map[string]interface{})
 	cond["id"] = id
 	candidates := queryCandidates(db, cond)
@@ -37,7 +37,7 @@ func QueryCandidateById(id int64) *Candidate {
 }
 
 func QueryDelegationsByAddress(delegatorAddress common.Address) (delegations []*Delegation) {
-	db := getDb()
+	db := getImmuDb()
 	cond := make(map[string]interface{})
 	cond["delegator_address"] = delegatorAddress.String()
 	return queryDelegations(db, cond)

sdk/dbm/sqliter.go

@@ -15,6 +15,7 @@ import (
 type sqliter struct{
 	dbPath string
 	db *sql.DB
+	immuDb *sql.DB
 }
 
 var Sqliter = &sqliter{}
@@ -50,14 +51,41 @@ func (s *sqliter) GetDB() (*sql.DB, error) {
 	return db, nil
 }
 
+func (s *sqliter) GetImmuDB() (*sql.DB, error) {
+	if strings.Compare(s.dbPath, "")  == 0 {
+		return nil, errors.ErrInternal("Sqlite database path is not set.")
+	}
+	if s.immuDb != nil {
+		if s.immuDb.Stats().OpenConnections > 0 {
+			return s.immuDb, nil
+		}
+	}
+	db, err := sql.Open("sqlite3", s.dbPath)
+	if err != nil {
+		return nil, errors.ErrInternal("Open database: " + err.Error())
+	}
+	if db.Ping(); err != nil {
+		return nil, errors.ErrInternal("Open database: " + err.Error())
+	}
+	db.Exec("PRAGMA journal_mode=WAL;")
+	s.immuDb = db
+	return db, nil
+}
+
 func (s *sqliter) CloseDB() {
 	if s.db != nil {
 		if err := s.db.Close(); err != nil {
-			log.Warn("Failed to close sqlite db: " + s.dbPath)
+			log.Warn("Failed to close sqlite db connection: " + s.dbPath)
 		}
-		log.Info("Sqlite db closed successfully！")
 		s.db = nil
 	}
+	if s.immuDb != nil {
+		if err := s.immuDb.Close(); err != nil {
+			log.Warn("Failed to close sqlite immutable connection: " + s.dbPath)
+		}
+		s.immuDb = nil
+	}
+	log.Info("Sqlite db closed successfully！")
 }