Lock free multipart backend implementation for FS (#5401)

pkg/ioutil/append-file_windows.go

@@ -0,0 +1,43 @@
+/*
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ioutil
+
+import (
+	"io"
+	"os"
+
+	"github.com/minio/minio/pkg/lock"
+)
+
+// AppendFile - appends the file "src" to the file "dst"
+func AppendFile(dst string, src string) error {
+	appendFile, err := lock.Open(dst, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	defer appendFile.Close()
+
+	srcFile, err := lock.Open(src, os.O_RDONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer srcFile.Close()
+	// Allocate staging buffer.
+	var buf = make([]byte, defaultAppendBufferSize)
+	_, err = io.CopyBuffer(appendFile, srcFile, buf)
+	return err
+}