diff --git a/src/buffered_file_writer.c b/src/buffered_file_writer.c
new file mode 100644
index 0000000..ad53d31
--- /dev/null
+++ b/src/buffered_file_writer.c
@@ -0,0 +1,214 @@
+/**
+* Copyright (C) 2008 Happy Fish / YuQing
+*
+* FastDFS may be copied only under the terms of the GNU General
+* Public License V3, which may be found in the FastDFS source kit.
+* Please visit the FastDFS Home Page http://www.fastken.com/ for more detail.
+**/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include "shared_func.h"
+#include "logger.h"
+#include "buffered_file_writer.h"
+
+int buffered_file_writer_open_ex(BufferedFileWriter *writer,
+        const char *filename, const int buffer_size,
+        const int max_written_once, const int mode)
+{
+    int result;
+    int written_once;
+
+    writer->buffer_size = (buffer_size > 0) ? buffer_size : 64 * 1024;
+    written_once = (max_written_once > 0) ? max_written_once : 256;
+    if (written_once > writer->buffer_size)
+    {
+        logError("file: "__FILE__", line: %d, "
+                "max_written_once: %d > buffer_size: %d",
+                __LINE__, written_once, writer->buffer_size);
+        return EINVAL;
+    }
+
+    writer->buff = (char *)malloc(writer->buffer_size);
+    if (writer->buff == NULL)
+    {
+        logError("file: "__FILE__", line: %d, "
+                "malloc %d bytes fail",
+                __LINE__, writer->buffer_size);
+        return ENOMEM;
+    }
+
+    snprintf(writer->filename, sizeof(writer->filename), "%s", filename);
+    writer->fd = open(writer->filename, O_WRONLY | O_CREAT | O_TRUNC, mode);
+    if (writer->fd < 0)
+    {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, "
+                "open file %s fail, "
+                "errno: %d, error info: %s",
+                __LINE__, writer->filename,
+                result, STRERROR(result));
+
+        free(writer->buff);
+        writer->buff = NULL;
+        return result;
+    }
+
+    writer->current = writer->buff;
+    writer->buff_end = writer->buff + writer->buffer_size;
+    writer->water_mark = writer->buff_end - written_once;
+
+    return 0;
+}
+
+int buffered_file_writer_close(BufferedFileWriter *writer)
+{
+    int result;
+
+    if (writer->buff == NULL)
+    {
+        return EINVAL;
+    }
+
+    result = buffered_file_writer_flush(writer);
+    if (result == 0 && fsync(writer->fd) != 0)
+    {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, "
+                "fsync file %s fail, "
+                "errno: %d, error info: %s",
+                __LINE__, writer->filename,
+                result, STRERROR(result));
+    }
+
+    if (close(writer->fd) != 0)
+    {
+        if (result == 0)
+        {
+            result = errno != 0 ? errno : EIO;
+        }
+        logError("file: "__FILE__", line: %d, "
+                "close file %s fail, "
+                "errno: %d, error info: %s",
+                __LINE__, writer->filename,
+                errno, STRERROR(errno));
+    }
+
+    free(writer->buff);
+    writer->buff = NULL;
+
+    return result;
+}
+
+int buffered_file_writer_flush(BufferedFileWriter *writer)
+{
+    int result;
+    int len;
+
+    len = writer->current - writer->buff;
+    if (len == 0)
+    {
+        return 0;
+    }
+
+    if (fc_safe_write(writer->fd, writer->buff, len) != len)
+    {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, "
+                "write to file %s fail, "
+                "errno: %d, error info: %s", __LINE__,
+                writer->filename, result, STRERROR(result));
+        return result;
+    }
+
+    writer->current = writer->buff;
+    return 0;
+}
+
+int buffered_file_writer_append(BufferedFileWriter *writer,
+        const char *format, ...)
+{
+    va_list ap;
+    int result;
+    int remain_size;
+    int len;
+    int i;
+
+    result = 0;
+    for (i=0; i<2; i++)
+    {
+        remain_size = writer->buff_end - writer->current;
+        va_start(ap, format);
+        len = vsnprintf(writer->current, remain_size, format, ap);
+        va_end(ap);
+
+        if (len  < remain_size)
+        {
+            writer->current += len;
+            if (writer->current > writer->water_mark)
+            {
+                result = buffered_file_writer_flush(writer);
+            }
+
+            break;
+        }
+
+        if (len > writer->buffer_size)
+        {
+            result = ENOSPC;
+            logError("file: "__FILE__", line: %d, "
+                    "too large output buffer, %d > %d!",
+                    __LINE__, len, writer->buffer_size);
+            break;
+        }
+
+        //maybe full, try again
+        if ((result=buffered_file_writer_flush(writer)) != 0)
+        {
+            break;
+        }
+    }
+
+    return result;
+}
+
+int buffered_file_writer_append_buff(BufferedFileWriter *writer,
+        const char *buff, const int len)
+{
+    int result;
+
+    if (len >= writer->water_mark - writer->current)
+    {
+        if ((result=buffered_file_writer_flush(writer)) != 0)
+        {
+            return result;
+        }
+
+        if (fc_safe_write(writer->fd, buff, len) != len)
+        {
+            result = errno != 0 ? errno : EIO;
+            logError("file: "__FILE__", line: %d, "
+                    "write to file %s fail, "
+                    "errno: %d, error info: %s", __LINE__,
+                    writer->filename, result, STRERROR(result));
+            return result;
+        }
+
+        return 0;
+    }
+
+    memcpy(writer->current, buff, len);
+    writer->current += len;
+    if (writer->current > writer->water_mark)
+    {
+        return buffered_file_writer_flush(writer);
+    }
+
+    return 0;
+}
+
diff --git a/src/buffered_file_writer.h b/src/buffered_file_writer.h
new file mode 100644
index 0000000..988229f
--- /dev/null
+++ b/src/buffered_file_writer.h
@@ -0,0 +1,72 @@
+/**
+* Copyright (C) 2008 Happy Fish / YuQing
+*
+* FastDFS may be copied only under the terms of the GNU General
+* Public License V3, which may be found in the FastDFS source kit.
+* Please visit the FastDFS Home Page http://www.fastken.com/ for more detail.
+**/
+
+#ifndef BUFFERED_FILE_WRITER_H
+#define BUFFERED_FILE_WRITER_H
+
+#include "common_define.h"
+
+typedef struct
+{
+    int fd;
+    int buffer_size;
+    char filename[MAX_PATH_SIZE];
+    char *buff;
+    char *current;
+    char *buff_end;
+    char *water_mark;
+} BufferedFileWriter;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** open buffered file writer
+ *  parameters:
+ *         writer: the writer
+ *         filename: the filename to write
+ *         buffer_size: the buffer size, <= 0 for recommend 64KB
+ *         max_written_once: max written bytes per call, <= 0 for 256
+ *         mode: the file privilege such as 0644
+ *  return: error code, 0 for success, != 0 for errno
+ */
+int buffered_file_writer_open_ex(BufferedFileWriter *writer,
+        const char *filename, const int buffer_size,
+        const int max_written_once, const int mode);
+
+static inline int buffered_file_writer_open(BufferedFileWriter *writer,
+        const char *filename)
+{
+    const int buffer_size = 0;
+    const int max_written_once = 0;
+    const int mode = 0644;
+    return buffered_file_writer_open_ex(writer, filename,
+            buffer_size, max_written_once, mode);
+}
+
+/** close buffered file writer
+ * parameters:
+ *         writer: the writer
+ *  return: error code, 0 for success, != 0 for errno
+ */
+int buffered_file_writer_close(BufferedFileWriter *writer);
+
+int buffered_file_writer_append(BufferedFileWriter *writer,
+        const char *format, ...);
+
+int buffered_file_writer_append_buff(BufferedFileWriter *writer,
+        const char *buff, const int len);
+
+int buffered_file_writer_flush(BufferedFileWriter *writer);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+