Entry.h

// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab

#ifndef __CEPH_LOG_ENTRY_H
#define __CEPH_LOG_ENTRY_H

#include "include/utime.h"
#include "common/PrebufferedStreambuf.h"
#include <pthread.h>
#include <string>


namespace ceph {
namespace log {

struct Entry {
  utime_t m_stamp;
  pthread_t m_thread;
  short m_prio, m_subsys;
  Entry *m_next;

  PrebufferedStreambuf m_streambuf;
  size_t m_buf_len;
  size_t* m_exp_len;
  char m_static_buf[1];

  Entry()
    : m_thread(0), m_prio(0), m_subsys(0),
      m_next(NULL),
      m_streambuf(m_static_buf, sizeof(m_static_buf)),
      m_buf_len(sizeof(m_static_buf)),
      m_exp_len(NULL)
  {}
  Entry(utime_t s, pthread_t t, short pr, short sub,
  const char *msg = NULL)
      : m_stamp(s), m_thread(t), m_prio(pr), m_subsys(sub),
        m_next(NULL),
        m_streambuf(m_static_buf, sizeof(m_static_buf)),
        m_buf_len(sizeof(m_static_buf)),
        m_exp_len(NULL)
    {
      if (msg) {
        ostream os(&m_streambuf);
        os << msg;
      }
    }
  Entry(utime_t s, pthread_t t, short pr, short sub, char* buf, size_t buf_len, size_t* exp_len,
	const char *msg = NULL)
    : m_stamp(s), m_thread(t), m_prio(pr), m_subsys(sub),
      m_next(NULL),
      m_streambuf(buf, buf_len),
      m_buf_len(buf_len),
      m_exp_len(exp_len)
  {
    if (msg) {
      ostream os(&m_streambuf);
      os << msg;
    }
  }

  // function improves estimate for expected size of message
  void hint_size() {
    if (m_exp_len != NULL) {
      size_t size = m_streambuf.size();
      if (size > __atomic_load_n(m_exp_len, __ATOMIC_RELAXED)) {
        //log larger then expected, just expand
        __atomic_store_n(m_exp_len, size + 10, __ATOMIC_RELAXED);
      }
      else {
        //asymptotically adapt expected size to message size
        __atomic_store_n(m_exp_len, (size + 10 + m_buf_len*31) / 32, __ATOMIC_RELAXED);
      }
    }
  }

  void set_str(const std::string &s) {
    ostream os(&m_streambuf);
    os << s;
  }

  std::string get_str() const {
    return m_streambuf.get_str();
  }

  // returns current size of content
  size_t size() const {
    return m_streambuf.size();
  }

  // extracts up to avail chars of content
  int snprintf(char* dst, size_t avail) const {
    return m_streambuf.snprintf(dst, avail);
  }
};

}
}

#endif