Allow to close database in go bindings (#8793)

* Allow to close database in go bindings

bindings/go/src/fdb/database.go

@@ -42,6 +42,8 @@ import (
 // usually created and committed automatically by the (Database).Transact
 // method.
 type Database struct {
+	// String reference to the cluster file.
+	clusterFile string
 	*database
 }
 
@@ -56,6 +58,16 @@ type DatabaseOptions struct {
 	d *database
 }
 
+// Close will close the Database and clean up all resources.
+// You have to ensure that you're not resuing this database.
+func (d *Database) Close() {
+	// Remove database object from the cached databases
+	delete(openDatabases, d.clusterFile)
+
+	// Destroy the database
+	d.destroy()
+}
+
 func (opt DatabaseOptions) setOpt(code int, param []byte) error {
 	return setOpt(func(p *C.uint8_t, pl C.int) C.fdb_error_t {
 		return C.fdb_database_set_option(opt.d.ptr, C.FDBDatabaseOption(code), p, pl)
@@ -63,6 +75,10 @@ func (opt DatabaseOptions) setOpt(code int, param []byte) error {
 }
 
 func (d *database) destroy() {
+	if d.ptr == nil {
+		return
+	}
+
 	C.fdb_database_destroy(d.ptr)
 }
 

bindings/go/src/fdb/fdb.go

@@ -39,6 +39,7 @@ import (
 // Would put this in futures.go but for the documented issue with
 // exports and functions in preamble
 // (https://code.google.com/p/go-wiki/wiki/cgo#Global_functions)
+//
 //export unlockMutex
 func unlockMutex(p unsafe.Pointer) {
 	m := (*sync.Mutex)(p)
@@ -337,7 +338,7 @@ func createDatabase(clusterFile string) (Database, error) {
 	db := &database{outdb}
 	runtime.SetFinalizer(db, (*database).destroy)
 
-	return Database{db}, nil
+	return Database{clusterFile, db}, nil
 }
 
 // Deprecated: Use OpenDatabase instead.

bindings/go/src/fdb/fdb_test.go

@@ -48,7 +48,10 @@ func ExampleOpenDefault() {
 		return
 	}
 
-	_ = db
+	// Close the database after usage
+	defer db.Close()
+
+	// Do work here
 
 	// Output:
 }
@@ -313,3 +316,30 @@ func ExamplePrintable() {
 	fmt.Println(fdb.Printable([]byte{0, 1, 2, 'a', 'b', 'c', '1', '2', '3', '!', '?', 255}))
 	// Output: \x00\x01\x02abc123!?\xff
 }
+
+func TestDatabaseCloseRemovesResources(t *testing.T) {
+	err := fdb.APIVersion(API_VERSION)
+	if err != nil {
+		t.Fatalf("Unable to set API version: %v\n", err)
+	}
+
+	// OpenDefault opens the database described by the platform-specific default
+	// cluster file
+	db, err := fdb.OpenDefault()
+	if err != nil {
+		t.Fatalf("Unable to set API version: %v\n", err)
+	}
+
+	// Close the database after usage
+	db.Close()
+
+	// Open the same database again, if the database is still in the cache we would return the same object, if not we create a new object with a new pointer
+	newDB, err := fdb.OpenDefault()
+	if err != nil {
+		t.Fatalf("Unable to set API version: %v\n", err)
+	}
+
+	if db == newDB {
+		t.Fatalf("Expected a different database object, got: %v and %v\n", db, newDB)
+	}
+}