Ceph rgw CephContext _log属性

Ceph rgw CephContext _log属性

_log是CephContext类的属性,他代表一个线程实例，主要用于日志的处理，在CephContext的对象的实例化过程中会初始化该对象并开启该线程。

log线程的主要逻辑如下：

void *Log::entry()
{
  pthread_mutex_lock(&m_queue_mutex);
  m_queue_mutex_holder = pthread_self();//获取线程自身的ID
  //log线程在运行且有新的日志记录写入到m_new中才刷新日志（持久化）
  while (!m_stop) {
    if (!m_new.empty()) {
      m_queue_mutex_holder = 0;
      pthread_mutex_unlock(&m_queue_mutex);
      flush();
      pthread_mutex_lock(&m_queue_mutex);
      m_queue_mutex_holder = pthread_self();
      continue;
    }

    pthread_cond_wait(&m_cond_flusher, &m_queue_mutex);
  }
  m_queue_mutex_holder = 0;
  pthread_mutex_unlock(&m_queue_mutex);
  flush();
  return NULL;
}

void Log::flush()
{
  pthread_mutex_lock(&m_flush_mutex);
  m_flush_mutex_holder = pthread_self();
  pthread_mutex_lock(&m_queue_mutex);
  m_queue_mutex_holder = pthread_self();
  EntryQueue t;
  t.swap(m_new);
  pthread_cond_broadcast(&m_cond_loggers);
  m_queue_mutex_holder = 0;
  pthread_mutex_unlock(&m_queue_mutex);
  _flush(&t, &m_recent, false);

  // trim
  while (m_recent.m_len > m_max_recent) {
    delete m_recent.dequeue();
  }

  m_flush_mutex_holder = 0;
  pthread_mutex_unlock(&m_flush_mutex);
}

void Log::_flush(EntryQueue *t, EntryQueue *requeue, bool crash)
{
  Entry *e;
  char buf[80];
  while ((e = t->dequeue()) != NULL) {
    unsigned sub = e->m_subsys;

    bool should_log = crash || m_subs->get_log_level(sub) >= e->m_prio;
    bool do_fd = m_fd >= 0 && should_log;
    bool do_syslog = m_syslog_crash >= e->m_prio && should_log;
    bool do_stderr = m_stderr_crash >= e->m_prio && should_log;

    if (do_fd || do_syslog || do_stderr) {
      int buflen = 0;

      if (crash)
    buflen += snprintf(buf, sizeof(buf), "%6d> ", -t->m_len);
      buflen += e->m_stamp.sprintf(buf + buflen, sizeof(buf)-buflen);
      buflen += snprintf(buf + buflen, sizeof(buf)-buflen, " %lx %2d ",
            (unsigned long)e->m_thread, e->m_prio);

      // FIXME: this is slow
      string s = e->get_str();
//写到日志文件中
      if (do_fd) {
    int r = safe_write(m_fd, buf, buflen);
    if (r >= 0)
      r = safe_write(m_fd, s.data(), s.size());
    if (r >= 0)
      r = write(m_fd, "\n", 1);
    if (r < 0)
      cerr << "problem writing to " << m_log_file << ": " << cpp_strerror(r) << std::endl;
      }
//调用系统日志，系统调用写日志
      if (do_syslog) {
    syslog(LOG_USER, "%s%s", buf, s.c_str());
      }
//日志打印到标准错误终端。
      if (do_stderr) {
    cerr << buf << s << std::endl;
      }
    }
//把打印的日志条目，保存到Mrecent队列中。
    requeue->enqueue(e);
  }
}