add stmt garbage recycle

orm/db_alias.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	lru "github.com/hashicorp/golang-lru"
 	"reflect"
 	"sync"
 	"time"
@@ -106,8 +107,8 @@ func (ac *_dbCache) getDefault() (al *alias) {
 
 type DB struct {
 	*sync.RWMutex
-	DB    *sql.DB
-	stmts map[string]*sql.Stmt
+	DB             *sql.DB
+	stmtDecorators *lru.Cache
 }
 
 func (d *DB) Begin() (*sql.Tx, error) {
@@ -118,19 +119,22 @@ func (d *DB) BeginTx(ctx context.Context, opts *sql.TxOptions) (*sql.Tx, error)
 	return d.DB.BeginTx(ctx, opts)
 }
 
-func (d *DB) getStmt(query string) (*sql.Stmt, error) {
+//su must call release to release *sql.Stmt after using
+func (d *DB) getStmtDecorator(query string) (*stmtDecorator, error) {
 	d.RLock()
-	c, ok := d.stmts[query]
+	c, ok := d.stmtDecorators.Get(query)
 	d.RUnlock()
 	if ok {
-		return c, nil
+		c.(*stmtDecorator).acquire()
+		return c.(*stmtDecorator), nil
 	}
 
 	d.Lock()
-	c, ok = d.stmts[query]
+	c, ok = d.stmtDecorators.Get(query)
 	if ok {
 		d.Unlock()
-		return c, nil
+		c.(*stmtDecorator).acquire()
+		return c.(*stmtDecorator), nil
 	}
 
 	stmt, err := d.Prepare(query)
@@ -138,9 +142,12 @@ func (d *DB) getStmt(query string) (*sql.Stmt, error) {
 		d.Unlock()
 		return nil, err
 	}
-	d.stmts[query] = stmt
+	sd := newStmtDecorator(stmt)
+	d.stmtDecorators.Add(query, sd)
 	d.Unlock()
-	return stmt, nil
+
+	sd.acquire()
+	return sd, nil
 }
 
 func (d *DB) Prepare(query string) (*sql.Stmt, error) {
@@ -152,52 +159,63 @@ func (d *DB) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error
 }
 
 func (d *DB) Exec(query string, args ...interface{}) (sql.Result, error) {
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		return nil, err
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.Exec(args...)
 }
 
 func (d *DB) ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error) {
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		return nil, err
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.ExecContext(ctx, args...)
 }
 
 func (d *DB) Query(query string, args ...interface{}) (*sql.Rows, error) {
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		return nil, err
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.Query(args...)
 }
 
 func (d *DB) QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error) {
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		return nil, err
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.QueryContext(ctx, args...)
 }
 
 func (d *DB) QueryRow(query string, args ...interface{}) *sql.Row {
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		panic(err)
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.QueryRow(args...)
 
 }
 
 func (d *DB) QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row {
-
-	stmt, err := d.getStmt(query)
+	sd, err := d.getStmtDecorator(query)
 	if err != nil {
 		panic(err)
 	}
+	stmt := sd.getStmt()
+	defer sd.release()
 	return stmt.QueryRowContext(ctx, args)
 }
 
@@ -275,9 +293,9 @@ func addAliasWthDB(aliasName, driverName string, db *sql.DB) (*alias, error) {
 	al.Name = aliasName
 	al.DriverName = driverName
 	al.DB = &DB{
-		RWMutex: new(sync.RWMutex),
-		DB:      db,
-		stmts:   make(map[string]*sql.Stmt),
+		RWMutex:        new(sync.RWMutex),
+		DB:             db,
+		stmtDecorators: newStmtDecoratorLruWithEvict(),
 	}
 
 	if dr, ok := drivers[driverName]; ok {
@@ -402,3 +420,39 @@ func GetDB(aliasNames ...string) (*sql.DB, error) {
 	}
 	return nil, fmt.Errorf("DataBase of alias name `%s` not found", name)
 }
+
+type stmtDecorator struct {
+	wg sync.WaitGroup
+	stmt *sql.Stmt
+}
+
+func (s *stmtDecorator) getStmt() *sql.Stmt {
+	return s.stmt
+}
+
+func (s *stmtDecorator) acquire() {
+	s.wg.Add(1)
+}
+
+func (s *stmtDecorator) release() {
+	s.wg.Done()
+}
+
+//garbage recycle for stmt
+func (s *stmtDecorator) destroy() {
+	s.wg.Wait()
+	_ = s.stmt.Close()
+}
+
+func newStmtDecorator(sqlStmt *sql.Stmt) *stmtDecorator {
+	return &stmtDecorator{
+		stmt: sqlStmt,
+	}
+}
+
+func newStmtDecoratorLruWithEvict() *lru.Cache {
+	cache, _ := lru.NewWithEvict(1000, func(key interface{}, value interface{}) {
+		value.(*stmtDecorator).destroy()
+	})
+	return cache
+}

orm/orm.go

@@ -559,9 +559,9 @@ func NewOrmWithDB(driverName, aliasName string, db *sql.DB) (Ormer, error) {
 	al.Name = aliasName
 	al.DriverName = driverName
 	al.DB = &DB{
-		RWMutex: new(sync.RWMutex),
-		DB:      db,
-		stmts:   make(map[string]*sql.Stmt),
+		RWMutex:        new(sync.RWMutex),
+		DB:             db,
+		stmtDecorators: newStmtDecoratorLruWithEvict(),
 	}
 
 	detectTZ(al)