Files
scylladb/gc_clock.hh
Tomasz Grabiec b7ece4b884 gc_clock: Fix hashing to be backwards-compatible
Commit d0f9e00 changed the representation of the gc_clock::duration
from int32_t to int64_t.

Mutation hashing uses appending_hash<gc_clock::time_point>, which by
default feeds duration::count() into the hasher. duration::rep changed
from int32_t to int64_t, which changes the value of the hash.

This affects schema digest and query digests, resulting in mismatches
between nodes during a rolling upgrade.

Fixes #4460.

(cherry picked from commit 549d0eb2f3)
2019-05-10 12:48:46 +02:00

89 lines
2.7 KiB
C++

/*
* Copyright (C) 2015 ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include "clocks-impl.hh"
#include "hashing.hh"
#include <seastar/core/lowres_clock.hh>
#include <chrono>
#include <optional>
class gc_clock final {
public:
using base = seastar::lowres_system_clock;
using rep = int64_t;
using period = std::ratio<1, 1>; // seconds
using duration = std::chrono::duration<rep, period>;
using time_point = std::chrono::time_point<gc_clock, duration>;
static constexpr auto is_steady = base::is_steady;
static constexpr std::time_t to_time_t(time_point t) {
return std::chrono::duration_cast<std::chrono::seconds>(t.time_since_epoch()).count();
}
static constexpr time_point from_time_t(std::time_t t) {
return time_point(std::chrono::duration_cast<duration>(std::chrono::seconds(t)));
}
static time_point now() {
return time_point(std::chrono::duration_cast<duration>(base::now().time_since_epoch())) + get_clocks_offset();
}
static int32_t as_int32(duration d) {
auto count = d.count();
int32_t count_32 = static_cast<int32_t>(count);
if (count_32 != count) {
throw std::runtime_error("Duration too big");
}
return count_32;
}
static int32_t as_int32(time_point tp) {
return as_int32(tp.time_since_epoch());
}
};
using expiry_opt = std::optional<gc_clock::time_point>;
using ttl_opt = std::optional<gc_clock::duration>;
// 20 years in seconds
static constexpr gc_clock::duration max_ttl = gc_clock::duration{20 * 365 * 24 * 60 * 60};
std::ostream& operator<<(std::ostream& os, gc_clock::time_point tp);
template<>
struct appending_hash<gc_clock::time_point> {
template<typename Hasher>
void operator()(Hasher& h, gc_clock::time_point t) const {
// Remain backwards-compatible with the 32-bit duration::rep (refs #4460).
uint64_t d64 = t.time_since_epoch().count();
feed_hash(h, uint32_t(d64 & 0xffff'ffff));
uint32_t msb = d64 >> 32;
if (msb) {
feed_hash(h, msb);
}
}
};