Simplified distributed block storage with strong consistency, like in Ceph
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// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.1 (see README.md for details)
#include <map>
#include <vector>
#include <algorithm>
#include "cpp-btree/btree_map.h"
#include "object_id.h"
#include "osd_ops.h"
#include "pg_states.h"
#define PG_EPOCH_BITS 48
struct pg_obj_loc_t
{
uint64_t role;
osd_num_t osd_num;
bool outdated;
};
typedef std::vector<pg_obj_loc_t> pg_osd_set_t;
struct pg_osd_set_state_t
{
// (role -> osd_num_t) map, as in pg.target_set and pg.cur_set
std::vector<osd_num_t> read_target;
// full OSD set including additional OSDs where the object is misplaced
pg_osd_set_t osd_set;
uint64_t state = 0;
uint64_t object_count = 0;
};
struct pg_list_result_t
{
obj_ver_id *buf = NULL;
uint64_t total_count;
uint64_t stable_count;
};
struct osd_op_t;
struct pg_peering_state_t
{
// osd_num -> list result
std::map<osd_num_t, osd_op_t*> list_ops;
std::map<osd_num_t, pg_list_result_t> list_results;
pool_id_t pool_id = 0;
pg_num_t pg_num = 0;
};
struct obj_piece_id_t
{
object_id oid;
uint64_t osd_num;
};
struct obj_ver_osd_t
{
uint64_t osd_num;
object_id oid;
uint64_t version;
};
struct flush_action_t
{
bool rollback = false, make_stable = false;
uint64_t stable_to = 0, rollback_to = 0;
bool submitted = false;
};
struct pg_flush_batch_t
{
std::map<osd_num_t, std::vector<obj_ver_id>> rollback_lists;
std::map<osd_num_t, std::vector<obj_ver_id>> stable_lists;
int flush_ops = 0, flush_done = 0;
int flush_objects = 0;
};
struct pg_t
{
int state = 0;
uint64_t scheme = 0;
uint64_t pg_cursize = 0, pg_size = 0, pg_minsize = 0, pg_data_size = 0;
pool_id_t pool_id = 0;
pg_num_t pg_num = 0;
uint64_t clean_count = 0, total_count = 0;
// epoch number - should increase with each non-clean activation of the PG
uint64_t epoch = 0, reported_epoch = 0;
// target history and all potential peers
std::vector<std::vector<osd_num_t>> target_history;
std::vector<osd_num_t> all_peers;
bool history_changed = false;
// peer list from the last peering event
std::vector<osd_num_t> cur_peers;
// target_set is the "correct" peer OSD set for this PG
std::vector<osd_num_t> target_set;
// cur_set is the current set of connected peer OSDs for this PG
// cur_set = (role => osd_num or UINT64_MAX if missing). role numbers begin with zero
std::vector<osd_num_t> cur_set;
// same thing in state_dict-like format
pg_osd_set_t cur_loc_set;
// moved object map. by default, each object is considered to reside on cur_set.
// this map stores all objects that differ.
// it may consume up to ~ (raw storage / object size) * 24 bytes in the worst case scenario
// which is up to ~192 MB per 1 TB in the worst case scenario
std::map<pg_osd_set_t, pg_osd_set_state_t> state_dict;
btree::btree_map<object_id, pg_osd_set_state_t*> incomplete_objects, misplaced_objects, degraded_objects;
std::map<obj_piece_id_t, flush_action_t> flush_actions;
std::vector<obj_ver_osd_t> copies_to_delete_after_sync;
btree::btree_map<object_id, uint64_t> ver_override;
pg_peering_state_t *peering_state = NULL;
pg_flush_batch_t *flush_batch = NULL;
int inflight = 0; // including write_queue
std::multimap<object_id, osd_op_t*> write_queue;
void calc_object_states(int log_level);
void print_state();
};
inline bool operator < (const pg_obj_loc_t &a, const pg_obj_loc_t &b)
{
return a.outdated < b.outdated ||
a.outdated == b.outdated && a.role < b.role ||
a.outdated == b.outdated && a.role == b.role && a.osd_num < b.osd_num;
}
inline bool operator == (const obj_piece_id_t & a, const obj_piece_id_t & b)
{
return a.oid == b.oid && a.osd_num == b.osd_num;
}
inline bool operator < (const obj_piece_id_t & a, const obj_piece_id_t & b)
{
return a.oid < b.oid || a.oid == b.oid && a.osd_num < b.osd_num;
}
namespace std
{
template<> struct hash<pg_osd_set_t>
{
inline size_t operator()(const pg_osd_set_t &s) const
{
size_t seed = 0;
for (auto e: s)
{
// Copy-pasted from spp::hash_combine()
seed ^= (e.role + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
seed ^= (e.osd_num + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
}
return seed;
}
};
template<> struct hash<obj_piece_id_t>
{
inline size_t operator()(const obj_piece_id_t &s) const
{
size_t seed = std::hash<object_id>()(s.oid);
// Copy-pasted from spp::hash_combine()
seed ^= (s.osd_num + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
return seed;
}
};
}