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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef CEPH_PAXOS_FSMAP_H
#define CEPH_PAXOS_FSMAP_H
#include <chrono>
#include "mds/FSMap.h"
#include "mds/MDSMap.h"
#include "include/ceph_assert.h"
class PaxosFSMap {
public:
virtual ~PaxosFSMap() {}
const FSMap &get_pending_fsmap() const { ceph_assert(is_leader()); return pending_fsmap; }
const FSMap &get_fsmap() const { return fsmap; }
virtual bool is_leader() const = 0;
protected:
FSMap &get_pending_fsmap_writeable() { ceph_assert(is_leader()); return pending_fsmap; }
FSMap &create_pending() {
ceph_assert(is_leader());
pending_fsmap = fsmap;
pending_fsmap.inc_epoch();
return pending_fsmap;
}
void prune_fsmap_history() {
auto now = real_clock::now();
for (auto it = history.begin(); it != history.end(); ) {
auto since = now - it->second.get_btime();
/* Be sure to not make the map empty */
auto itnext = std::next(it);
if (itnext == history.end()) {
break;
}
/* Keep the map just before the prune time threshold:
* [ e-1 (lifetime > history_prune_time) | e (lifetime 1s) ]
* If an mds was removed in (e), then we want to be able to say it was
* last seen 1 second ago.
*/
auto since2 = now - itnext->second.get_btime();
if (since > history_prune_time && since2 > history_prune_time) {
it = history.erase(it);
} else {
break;
}
}
}
void put_fsmap_history(const FSMap& _fsmap) {
auto now = real_clock::now();
auto since = now - _fsmap.get_btime();
if (since < history_prune_time) {
history.emplace(std::piecewise_construct, std::forward_as_tuple(_fsmap.get_epoch()), std::forward_as_tuple(_fsmap));
}
}
void set_fsmap_history_threshold(std::chrono::seconds t) {
history_prune_time = t;
}
std::chrono::seconds get_fsmap_history_threshold() const {
return history_prune_time;
}
const auto& get_fsmap_history() const {
return history;
}
void decode(ceph::buffer::list &bl) {
fsmap.decode(bl);
put_fsmap_history(fsmap);
pending_fsmap = FSMap(); /* nuke it to catch invalid access */
}
private:
/* Keep these PRIVATE to prevent unprotected manipulation. */
std::map<epoch_t, FSMap> history;
std::chrono::seconds history_prune_time = std::chrono::seconds(0);
FSMap fsmap; /* the current epoch */
FSMap pending_fsmap; /* the next epoch */
};
#endif
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