diff --git a/display_bar.h b/display_bar.h
index 7bdc170..46b1d10 100644
--- a/display_bar.h
+++ b/display_bar.h
@@ -1,29 +1,30 @@
 #include<stdio.h>
 #include<time.h>
 #include<stdbool.h>
+#include<stddef.h>
 
 #ifndef _DISPLAY_BAR_H_
 #define _DISPLAY_BAR_H_
 
+//declare for raw operation
 typedef unsigned raw_progress_bar_t;
 
 void lock_scrolled();
-
 void unlock_scrolled();
-
-void ready_progress_bar();
-
-void quit_progress_bar();
-
 void add_scrolled_unlocked(unsigned int i);
-
 raw_progress_bar_t create_raw_progress_bar();
-
 void RawDisplayProgressBar(raw_progress_bar_t bar,size_t offset,size_t total,const char * filename);
 
+//you should call before using progrees bar.
+void ready_progress_bar();
+//quit progress bar system.
+void quit_progress_bar();
+//same as isatty
 bool isatty_file(FILE * file);
 
+//
 void myd_perror(const char * msg);
+int myd_vfprintf(int line,FILE * f,const char * msg,va_list arg);
 
 typedef struct {
     raw_progress_bar_t bar;
diff --git a/server.c b/server.c
index 40915c4..d65cf02 100644
--- a/server.c
+++ b/server.c
@@ -301,9 +301,9 @@ int parse_args(int argc,const char * argv[] , in_port_t * port){
 typedef struct SharedState{
     //empty if less than 0
     queue_struct(int,WORK_QUEUE_SIZE) socks;
-#ifdef USE_TRACE
+    #ifdef USE_TRACE
     queue_struct(struct timespec,WORK_QUEUE_SIZE) trace_timer;
-#endif
+    #endif
     pthread_mutex_t sock_mutex;
     pthread_cond_t ready;
     //int progress[MAX_THREAD_NUMBER];
@@ -311,14 +311,14 @@ typedef struct SharedState{
 
 void init_shared_state(shared_state_t * state) {
     queue_init(&state->socks);
-#ifdef USE_TRACE
+    #ifdef USE_TRACE
     queue_init(&state->trace_timer);
-#endif
+    #endif
     pthread_mutex_init(&state->sock_mutex,NULL);
     pthread_cond_init(&state->ready,NULL);
 }
 #endif
-//
+//argument for thread worker
 typedef struct WorkerArgument
 {
     int id;
@@ -365,10 +365,11 @@ void * worker_proc(void * data){
     #endif
     for(;;){
         pthread_mutex_lock(&globalState.sock_mutex);
+        //wait until request come.
         while (queue_isempty(&globalState.socks)){
             pthread_cond_wait(&globalState.ready,&globalState.sock_mutex);
         }
-        csock = dequeue(&globalState.socks);
+        csock = dequeue(&globalState.socks); //dequeue socket descriptor for request.
     #ifdef USE_TRACE
         ts_top_begin = dequeue(&globalState.trace_timer);
     #endif
@@ -377,6 +378,7 @@ void * worker_proc(void * data){
         clock_gettime(Top_Trace_Timer_ID,&ts_top_end);
         clock_gettime(Bottom_Trace_Timer_ID,&ts_bottom_begin);
     #endif
+        //process request.
         if((fd = read_request(csock,args->buf,args->bufsize)) > 0){
             send_response(csock,fd,args->buf,args->bufsize);
             close(fd);
@@ -454,7 +456,7 @@ int main(int argc, const char *argv[]){
     if(use_gui)
         ready_progress_bar();
     #ifdef USE_TRACE
-        report_resolution();
+    report_resolution();
     #endif
     sock = socket(AF_INET,SOCK_STREAM,0);
     atexit(safe_exit);
diff --git a/timerhelper.h b/timerhelper.h
index ae90e96..fc4ae26 100644
--- a/timerhelper.h
+++ b/timerhelper.h
@@ -2,6 +2,10 @@
 #define _TIMERHELPER_H_
 #include <sys/time.h>
 
+#ifndef __always_inline
+#define __always_inline
+#endif
+
 __always_inline struct timespec timespec_sub(struct timespec a,struct timespec b){
     struct timespec ret;
     ret.tv_sec = a.tv_sec - b.tv_sec;