[编程好习惯] 青睐小粒度锁

example.c
00096: typedef struct tag_timer
00097: {
00098:     dll_node_t node_;
00106:     ...
00107: } timer_instance_t, *timer_handler_t;
00108:
00109: // guard for initialized timer
00110: static const csize_t TIMER_MARK = 0x20091026;
00111:
00112: error_t timer_init (timer_handler_t _handler, msecond_t _duration,
00113:     expiration_cb_t _cb, const char *_name)
00114: {
00122:     ...
00123:     timer_lock ();
00124:     if (TIMER_MARK == _handler->mark_) {
00125:         // if it has been initialized then failing it
00126:         timer_unlock ();
00127:         return ERROR_T (ERROR_TIMER_INIT_INITIALIZED);
00128:     }
00129:
00130:     // convert to TICK_DURATION_IN_MSEC unit
00131:     _handler->ticks_ = _duration / TICK_DURATION_IN_MSEC;
00132:     if (0 == _handler->ticks_) {
00133:         _handler->ticks_ ++;
00134:     }
00135:     _handler->cb_ = _cb;
00136:     _handler->state_ = TIMER_INITIALIZED;
00137:     dll_node_init (&_handler->node_);
00138:     if (0 == _name) {
00139:         _handler->name_ [0] = 0;
00140:     }
00141:     else {
00142:         strncpy (_handler->name_, _name, sizeof (_handler->name_));
00143:     }
00144:     _handler->mark_ = TIMER_MARK;
00145:     timer_unlock ();
00146:
00147:     return 0;
00148: }

example.c
00112: error_t timer_init (timer_handler_t _handler, msecond_t _duration,
00113:     expiration_cb_t _cb, const char *_name)
00114: {
00122:     ...
00123: &n