Added Statement caching (#403)

- added parameter `stmt_cache_size` to DSN string

connection.go

@@ -109,21 +109,40 @@ func (conn *Conn) PrepareContext(ctx context.Context, query string) (driver.Stmt
 	go conn.ociBreakDone(ctx, done)
 	defer func() { close(done) }()
 
+	if conn.stmtCacheSize == 0 {
+		if rv := C.OCIStmtPrepare2(
+			conn.svc,                // service context handle
+			stmt,                    // pointer to the statement handle returned
+			conn.errHandle,          // error handle
+			queryP,                  // statement text
+			C.ub4(len(query)),       // statement text length
+			nil,                     // key to be used for searching the statement in the statement cache
+			C.ub4(0),                // length of the key
+			C.ub4(C.OCI_NTV_SYNTAX), // syntax - OCI_NTV_SYNTAX: syntax depends upon the version of the server
+			C.ub4(C.OCI_DEFAULT),    // mode
+		); rv != C.OCI_SUCCESS {
+			return nil, conn.getError(rv)
+		}
+
+		return &Stmt{conn: conn, stmt: *stmt, ctx: ctx, releaseMode: C.OCI_DEFAULT}, nil
+	}
+
 	if rv := C.OCIStmtPrepare2(
 		conn.svc,                // service context handle
 		stmt,                    // pointer to the statement handle returned
 		conn.errHandle,          // error handle
 		queryP,                  // statement text
 		C.ub4(len(query)),       // statement text length
-		nil,                     // key to be used for searching the statement in the statement cache
-		C.ub4(0),                // length of the key
+		queryP,                  // key to be used for searching the statement in the statement cache
+		C.ub4(len(query)),       // length of the key
 		C.ub4(C.OCI_NTV_SYNTAX), // syntax - OCI_NTV_SYNTAX: syntax depends upon the version of the server
 		C.ub4(C.OCI_DEFAULT),    // mode
-	); rv != C.OCI_SUCCESS {
+	); rv != C.OCI_SUCCESS && rv != C.OCI_SUCCESS_WITH_INFO {
+		// Note that C.OCI_SUCCESS_WITH_INFO is returned the first time a statement it put into the cache
 		return nil, conn.getError(rv)
 	}
 
-	return &Stmt{conn: conn, stmt: *stmt, ctx: ctx}, nil
+	return &Stmt{conn: conn, stmt: *stmt, ctx: ctx, releaseMode: C.OCI_DEFAULT, cacheKey: query}, nil
 }
 
 // Begin starts a transaction

globals.go

@@ -40,6 +40,7 @@ type (
 		transactionMode      C.ub4
 		enableQMPlaceholders bool
 		operationMode        C.ub4
+		stmtCacheSize        C.ub4
 	}
 
 	// DriverStruct is Oracle driver struct
@@ -66,6 +67,7 @@ type (
 		prefetchMemory       C.ub4
 		transactionMode      C.ub4
 		operationMode        C.ub4
+		stmtCacheSize        C.ub4
 		inTransaction        bool
 		enableQMPlaceholders bool
 		closed               bool
@@ -80,10 +82,12 @@ type (
 
 	// Stmt is Oracle statement
 	Stmt struct {
-		conn   *Conn
-		stmt   *C.OCIStmt
-		closed bool
-		ctx    context.Context
+		conn        *Conn
+		stmt        *C.OCIStmt
+		closed      bool
+		ctx         context.Context
+		cacheKey    string // if statement caching is enabled, this is the key for this statement into the cache
+		releaseMode C.ub4
 	}
 
 	// Rows is Oracle rows

oci8.go

@@ -51,6 +51,7 @@ func ParseDSN(dsnString string) (dsn *DSN, err error) {
 	dsn = &DSN{
 		prefetchRows:   0,
 		prefetchMemory: 4096,
+		stmtCacheSize:  0,
 		operationMode:  C.OCI_DEFAULT,
 		timeLocation:   time.UTC,
 	}
@@ -119,7 +120,12 @@ func ParseDSN(dsnString string) (dsn *DSN, err error) {
 			default:
 				return nil, fmt.Errorf("Invalid as: %v", v[0])
 			}
-
+		case "stmt_cache_size":
+			z, err := strconv.ParseUint(v[0], 10, 32)
+			if err != nil {
+				return nil, fmt.Errorf("invalid stmt_cache_size: %v", v[0])
+			}
+			dsn.stmtCacheSize = C.ub4(z)
 		}
 	}
 
@@ -162,6 +168,7 @@ func (drv *DriverStruct) Open(dsnString string) (driver.Conn, error) {
 
 	conn := Conn{
 		operationMode: dsn.operationMode,
+		stmtCacheSize: dsn.stmtCacheSize,
 		logger:        drv.Logger,
 	}
 	if conn.logger == nil {
@@ -353,6 +360,14 @@ func (drv *DriverStruct) Open(dsnString string) (driver.Conn, error) {
 			return nil, fmt.Errorf("authentication context attribute set error: %v", err)
 		}
 
+		if dsn.stmtCacheSize > 0 {
+			stmtCacheSize := dsn.stmtCacheSize
+			err = conn.ociAttrSet(unsafe.Pointer(conn.svc), C.OCI_HTYPE_SVCCTX, unsafe.Pointer(&stmtCacheSize), 0, C.OCI_ATTR_STMTCACHESIZE)
+			if err != nil {
+				return nil, fmt.Errorf("stmt cache size attribute set error: %v", err)
+			}
+		}
+
 	} else {
 
 		var svcCtxP *C.OCISvcCtx

oci8_sql_go_113_test.go

@@ -0,0 +1,84 @@
+// +build go1.13
+
+package oci8
+
+import (
+	"context"
+	"testing"
+)
+
+// TestStatementCaching tests to ensure statement caching is working
+func TestStatementCaching(t *testing.T) {
+	if TestDisableDatabase {
+		t.SkipNow()
+	}
+
+	t.Parallel()
+
+	var err error
+
+	db := testGetDB("?stmt_cache_size=10")
+	if db == nil {
+		t.Fatal("db is null")
+	}
+
+	defer func() {
+		err = db.Close()
+		if err != nil {
+			t.Fatal("db close error:", err)
+		}
+	}()
+
+	ctx, cancel := context.WithTimeout(context.Background(), TestContextTimeout)
+	conn, err := db.Conn(ctx)
+	cancel()
+	// we need to get access to the raw connection so we can access the different fields on the oci8.Stmt
+	var rawConn *Conn
+	// NOTE that conn.Raw() is only available with Go >= 1.13
+	_ = conn.Raw(func(driverConn interface{}) error {
+		rawConn = driverConn.(*Conn)
+		return nil
+	})
+
+	ctx, cancel = context.WithTimeout(context.Background(), TestContextTimeout)
+	stmt, err := rawConn.PrepareContext(ctx, "select ?, ?, ? from dual")
+	cancel()
+	if err != nil {
+		t.Fatal("prepare error:", err)
+	}
+
+	rawStmt := stmt.(*Stmt)
+	if rawStmt.cacheKey != "select ?, ?, ? from dual" {
+		err := stmt.Close()
+		if err != nil {
+			t.Fatal("stmt close error:", err)
+		}
+		t.Fatalf("cacheKey not equal: expected %s, but got %s", "select ?, ?, ? from dual", rawStmt.cacheKey)
+	}
+
+	// closing the statement should put the statement into the cache
+	err = stmt.Close()
+	if err != nil {
+		t.Fatal("stmt close error:", err)
+	}
+
+	ctx, cancel = context.WithTimeout(context.Background(), TestContextTimeout)
+	stmt, err = rawConn.PrepareContext(ctx, "select ?, ?, ? from dual")
+	cancel()
+	if err != nil {
+		t.Fatal("prepare error:", err)
+	}
+
+	rawStmt = stmt.(*Stmt)
+	if rawStmt.cacheKey != "select ?, ?, ? from dual" {
+		err := stmt.Close()
+		if err != nil {
+			t.Fatal("stmt close error:", err)
+		}
+		t.Fatalf("cacheKey not equal: expected %s, but got %s", "select ?, ?, ? from dual", rawStmt.cacheKey)
+	}
+	err = stmt.Close()
+	if err != nil {
+		t.Fatal("stmt close error:", err)
+	}
+}

oci8_sql_test.go

@@ -66,7 +66,7 @@ func testExecQuery(t *testing.T, query string, args []interface{}) {
 }
 
 // testGetRows runs a statement and returns the rows as [][]interface{}
-func testGetRows(t *testing.T, stmt *sql.Stmt, args []interface{}) ([][]interface{}, error) {
+func testGetRows(t testing.TB, stmt *sql.Stmt, args []interface{}) ([][]interface{}, error) {
 	// get rows
 	ctx, cancel := context.WithTimeout(context.Background(), TestContextTimeout)
 	defer cancel()
@@ -468,7 +468,7 @@ end;
 	_, err = stmt.ExecContext(ctx)
 	cancel()
 	expected := "ORA-01013"
-	if err == nil || len(err.Error()) < len(expected) || err.Error()[:len(expected)] != expected {
+	if err == nil || len(err.Error()) < len(expected) || !strings.Contains(err.Error(), expected) {
 		t.Fatalf("stmt exec - expected: %v - received: %v", expected, err)
 	}
 
@@ -488,7 +488,7 @@ end;
 	ctx, cancel = context.WithTimeout(context.Background(), 200*time.Millisecond)
 	_, err = stmt.QueryContext(ctx)
 	cancel()
-	if err == nil || len(err.Error()) < len(expected) || err.Error()[:len(expected)] != expected {
+	if err == nil || len(err.Error()) < len(expected) || !strings.Contains(err.Error(), expected) {
 		t.Fatalf("stmt query - expected: %v - received: %v", expected, err)
 	}
 
@@ -1475,6 +1475,104 @@ func benchmarkPrefetchSelect(b *testing.B, prefetchRows int64, prefetchMemory in
 	}
 }
 
+// TestSelectParallelWithStatementCaching checks parallel select from dual but with statement caching enabled
+func TestSelectParallelWithStatementCaching(t *testing.T) {
+	if TestDisableDatabase {
+		t.SkipNow()
+	}
+	db := testGetDB("?stmt_cache_size=100")
+	if db == nil {
+		t.Fatal("db is null")
+	}
+
+	var waitGroup sync.WaitGroup
+	waitGroup.Add(50)
+
+	for i := 0; i < 50; i++ {
+		go func(num int) {
+			defer waitGroup.Done()
+
+			selectNumFromDual(t, db, float64(num))
+		}(i)
+	}
+
+	waitGroup.Wait()
+}
+
+// selectNumFromDual will execute a "select :1 from dual" where the parameter is the num param of this function
+func selectNumFromDual(t testing.TB, db *sql.DB, num float64) {
+	ctx, cancel := context.WithTimeout(context.Background(), TestContextTimeout)
+	stmt, err := db.PrepareContext(ctx, "select :1 from dual")
+	cancel()
+	if err != nil {
+		t.Fatal("prepare error:", err)
+	}
+	defer func() {
+		if stmt != nil {
+			err := stmt.Close()
+			if err != nil {
+				t.Fatal("stmt close error:", err)
+			}
+		}
+	}()
+
+	var result [][]interface{}
+	result, err = testGetRows(t, stmt, []interface{}{num})
+	if err != nil {
+		t.Fatal("get rows error:", err)
+	}
+	if result == nil {
+		t.Fatal("result is nil")
+	}
+	if len(result) != 1 {
+		t.Fatal("len result not equal to 1")
+	}
+	if len(result[0]) != 1 {
+		t.Fatal("len result[0] not equal to 1")
+	}
+	data, ok := result[0][0].(float64)
+	if !ok {
+		t.Fatal("result not float64")
+	}
+	if data != num {
+		t.Fatal("result not equal to:", num)
+	}
+}
+
+func BenchmarkSelectNoCaching(b *testing.B) {
+	if TestDisableDatabase || TestDisableDestructive {
+		b.SkipNow()
+	}
+	for i := 0; i < b.N; i++ {
+		selectNumFromDual(b, TestDB, float64(i))
+	}
+}
+
+func BenchmarkSelectWithCaching(b *testing.B) {
+	b.StopTimer()
+
+	if TestDisableDatabase || TestDisableDestructive {
+		b.SkipNow()
+	}
+
+	db := testGetDB("?stmt_cache_size=100")
+	if db == nil {
+		b.Fatal("db is null")
+	}
+
+	defer func() {
+		err := db.Close()
+		if err != nil {
+			b.Fatal("db close error:", err)
+		}
+	}()
+
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		selectNumFromDual(b, db, float64(i))
+	}
+}
+
 func BenchmarkPrefetchR0M32768(b *testing.B) {
 	b.StopTimer()
 

oci8_test.go

@@ -185,16 +185,18 @@ func TestParseDSN(t *testing.T) {
 
 	const prefetchRows = 0
 	const prefetchMemory = 4096
+	const stmtCacheSize = 0
 
 	var dsnTests = []struct {
 		dsnString   string
 		expectedDSN *DSN
 	}{
-		{"oracle://xxmc:[email protected]:1521/ORCL?loc=America%2FPhoenix", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, timeLocation: timeLocations[5]}},
-		{"xxmc/[email protected]:1521/ORCL?loc=America%2FPhoenix", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, timeLocation: timeLocations[5]}},
-		{"sys/[email protected]:1521/ORCL?loc=America%2FPhoenix&as=sysdba", &DSN{Username: "sys", Password: "syspwd", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, timeLocation: timeLocations[5], operationMode: 0x00000002}}, // with operationMode: 0x00000002 = C.OCI_SYDBA
-		{"xxmc/[email protected]:1521/ORCL", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, timeLocation: time.UTC}},
-		{"xxmc/[email protected]/ORCL", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, timeLocation: time.UTC}},
+		{"oracle://xxmc:[email protected]:1521/ORCL?loc=America%2FPhoenix", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: stmtCacheSize, timeLocation: timeLocations[5]}},
+		{"xxmc/[email protected]:1521/ORCL?loc=America%2FPhoenix", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: stmtCacheSize, timeLocation: timeLocations[5]}},
+		{"sys/[email protected]:1521/ORCL?loc=America%2FPhoenix&as=sysdba", &DSN{Username: "sys", Password: "syspwd", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: stmtCacheSize, timeLocation: timeLocations[5], operationMode: 0x00000002}}, // with operationMode: 0x00000002 = C.OCI_SYDBA
+		{"xxmc/[email protected]:1521/ORCL", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169:1521/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: stmtCacheSize, timeLocation: time.UTC}},
+		{"xxmc/[email protected]/ORCL", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: stmtCacheSize, timeLocation: time.UTC}},
+		{"xxmc/[email protected]/ORCL?stmt_cache_size=50", &DSN{Username: "xxmc", Password: "xxmc", Connect: "107.20.30.169/ORCL", prefetchRows: prefetchRows, prefetchMemory: prefetchMemory, stmtCacheSize: 50, timeLocation: time.UTC}},
 	}
 
 	for _, tt := range dsnTests {

rows.go

@@ -202,7 +202,7 @@ func (rows *Rows) Next(dest []driver.Value) error {
 		// SQLT_RSET - ref cursor
 		case C.SQLT_RSET:
 			stmtP := (**C.OCIStmt)(rows.defines[i].pbuf)
-			subStmt := &Stmt{conn: rows.stmt.conn, stmt: *stmtP, ctx: rows.stmt.ctx}
+			subStmt := &Stmt{conn: rows.stmt.conn, stmt: *stmtP, ctx: rows.stmt.ctx, releaseMode: C.ub4(C.OCI_DEFAULT)}
 			if rows.defines[i].subDefines == nil {
 				var err error
 				rows.defines[i].subDefines, err = subStmt.makeDefines()