Simplified distributed block storage with strong consistency, like in Ceph
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71 lines
2.0 KiB

// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.0 or GNU GPL-2.0+ (see README.md for details)
#pragma once
#include <stdint.h>
#include <functional>
// 16 bytes per object/stripe id
// stripe = (start of the parity stripe + peer role)
// i.e. for example (256KB + one of 0,1,2)
struct __attribute__((__packed__)) object_id
{
uint64_t inode;
uint64_t stripe;
};
inline bool operator == (const object_id & a, const object_id & b)
{
return a.inode == b.inode && a.stripe == b.stripe;
}
inline bool operator != (const object_id & a, const object_id & b)
{
return a.inode != b.inode || a.stripe != b.stripe;
}
inline bool operator < (const object_id & a, const object_id & b)
{
return a.inode < b.inode || a.inode == b.inode && a.stripe < b.stripe;
}
// 56 = 24 + 32 bytes per dirty entry in memory (obj_ver_id => dirty_entry)
struct __attribute__((__packed__)) obj_ver_id
{
object_id oid;
uint64_t version;
};
inline bool operator < (const obj_ver_id & a, const obj_ver_id & b)
{
return a.oid < b.oid || a.oid == b.oid && a.version < b.version;
}
namespace std
{
template<> struct hash<object_id>
{
inline size_t operator()(const object_id &s) const
{
size_t seed = 0;
// Copy-pasted from spp::hash_combine()
seed ^= (s.inode + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
seed ^= (s.stripe + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
return seed;
}
};
template<> struct hash<obj_ver_id>
{
inline size_t operator()(const obj_ver_id &s) const
{
size_t seed = 0;
// Copy-pasted from spp::hash_combine()
seed ^= (s.oid.inode + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
seed ^= (s.oid.stripe + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
seed ^= (s.version + 0xc6a4a7935bd1e995 + (seed << 6) + (seed >> 2));
return seed;
}
};
}