Ceph rgw CephContext的属性_service_thread

CephContext的_service_thread属性

CephContext代表这进程的上下文，该实例中几乎包含进程的所有信息。这里主要介绍他的_service_thread属性。

_service_thread代表着一个线程，主要用来完成重新打开log file和更新performance counter；GIGHUP会唤醒该线程。其主要逻辑如下：

 void *entry()  {    while (1) {      Mutex::Locker l(_lock);//heartbeat_interval==5      if (_cct->_conf->heartbeat_interval) {        utime_t interval(_cct->_conf->heartbeat_interval, 0);        _cond.WaitInterval(_cct, _lock, interval); //wait interval time      } else        _cond.Wait(_lock);      if (_exit_thread) {        break;      }      if (_reopen_logs) {        _cct->_log->reopen_log_file();        _reopen_logs = false;      }      _cct->_heartbeat_map->check_touch_file();      // refresh the perf coutners      _cct->refresh_perf_values();    }    return NULL;  }

下面是重新打开日志文件的过程：

void Log::reopen_log_file(){  pthread_mutex_lock(&m_flush_mutex);  m_flush_mutex_holder = pthread_self();  if (m_fd >= 0)    VOID_TEMP_FAILURE_RETRY(::close(m_fd));  if (m_log_file.length()) {    m_fd = ::open(m_log_file.c_str(), O_CREAT|O_WRONLY|O_APPEND, 0644);  } else {    m_fd = -1;  }  m_flush_mutex_holder = 0;  pthread_mutex_unlock(&m_flush_mutex);}