ceph/src/mon/PaxosFSMap.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef CEPH_PAXOS_FSMAP_H
  16 #define CEPH_PAXOS_FSMAP_H
  17
  18 #include "mds/FSMap.h"
  19 #include "mds/MDSMap.h"
  20
  21 #include "include/assert.h"
  22
  23 class PaxosFSMap {
  24 public:
  25   virtual ~PaxosFSMap() {}
  26
  27   const FSMap &get_pending_fsmap() const { assert(is_leader()); return pending_fsmap; }
  28   const FSMap &get_fsmap() const { return fsmap; }
  29
  30   virtual bool is_leader() const = 0;
  31
  32 protected:
  33   FSMap &get_pending_fsmap_writeable() { assert(is_leader()); return pending_fsmap; }
  34
  35   /* get_working_fsmap returns the "relevant" version of the fsmap (see MDSMonitor.cc history)
  36    * used depending in helper methods of MDSMonitor.cc.
  37    *
  38    * This is technically evil and will be removed in the future.
  39    *
  40    * See discussion: https://github.com/ceph/ceph/pull/21458#discussion_r182081366
  41    */
  42   const FSMap &get_working_fsmap() const { return is_leader() ? pending_fsmap : fsmap; }
  43
  44   FSMap &create_pending() {
  45     assert(is_leader());
  46     pending_fsmap = fsmap;
  47     pending_fsmap.epoch++;
  48     return pending_fsmap;
  49   }
  50
  51   void decode(bufferlist &bl) {
  52     fsmap.decode(bl);
  53     pending_fsmap = FSMap(); /* nuke it to catch invalid access */
  54   }
  55
  56 private:
  57   /* Keep these PRIVATE to prevent unprotected manipulation. */
  58   FSMap fsmap; /* the current epoch */
  59   FSMap pending_fsmap; /* the next epoch */
  60 };
  61
  62
  63 #endif