Files
scylladb/atomic_cell.hh
Tomasz Grabiec c9d4f5a49c atomic_cell_or_collection: Introduce as_atomic_cell_ref()
Needed for setting the REVERT flag on existing cell.
2016-03-21 19:25:54 +01:00

299 lines
11 KiB
C++

/*
* Copyright (C) 2015 Cloudius Systems, Ltd.
*/
/*
* 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 "bytes.hh"
#include "timestamp.hh"
#include "tombstone.hh"
#include "gc_clock.hh"
#include "utils/managed_bytes.hh"
#include "net/byteorder.hh"
#include <cstdint>
#include <iostream>
template<typename T>
static inline
void set_field(managed_bytes& v, unsigned offset, T val) {
reinterpret_cast<net::packed<T>*>(v.begin() + offset)->raw = net::hton(val);
}
template<typename T>
static inline
T get_field(const bytes_view& v, unsigned offset) {
return net::ntoh(*reinterpret_cast<const net::packed<T>*>(v.begin() + offset));
}
class atomic_cell_or_collection;
/*
* Represents atomic cell layout. Works on serialized form.
*
* Layout:
*
* <live> := <int8_t:flags><int64_t:timestamp>(<int32_t:expiry><int32_t:ttl>)?<value>
* <dead> := <int8_t: 0><int64_t:timestamp><int32_t:deletion_time>
*/
class atomic_cell_type final {
private:
static constexpr int8_t LIVE_FLAG = 0x01;
static constexpr int8_t EXPIRY_FLAG = 0x02; // When present, expiry field is present. Set only for live cells
static constexpr int8_t REVERT_FLAG = 0x04; // transient flag used to efficiently implement ReversiblyMergeable for atomic cells.
static constexpr unsigned flags_size = 1;
static constexpr unsigned timestamp_offset = flags_size;
static constexpr unsigned timestamp_size = 8;
static constexpr unsigned expiry_offset = timestamp_offset + timestamp_size;
static constexpr unsigned expiry_size = 4;
static constexpr unsigned deletion_time_offset = timestamp_offset + timestamp_size;
static constexpr unsigned deletion_time_size = 4;
static constexpr unsigned ttl_offset = expiry_offset + expiry_size;
static constexpr unsigned ttl_size = 4;
private:
static bool is_revert_set(bytes_view cell) {
return cell[0] & REVERT_FLAG;
}
template<typename BytesContainer>
static void set_revert(BytesContainer& cell, bool revert) {
cell[0] = (cell[0] & ~REVERT_FLAG) | (revert * REVERT_FLAG);
}
static bool is_live(const bytes_view& cell) {
return cell[0] & LIVE_FLAG;
}
static bool is_live_and_has_ttl(const bytes_view& cell) {
return cell[0] & EXPIRY_FLAG;
}
static bool is_dead(const bytes_view& cell) {
return !is_live(cell);
}
// Can be called on live and dead cells
static api::timestamp_type timestamp(const bytes_view& cell) {
return get_field<api::timestamp_type>(cell, timestamp_offset);
}
// Can be called on live cells only
static bytes_view value(bytes_view cell) {
auto expiry_field_size = bool(cell[0] & EXPIRY_FLAG) * (expiry_size + ttl_size);
auto value_offset = flags_size + timestamp_size + expiry_field_size;
cell.remove_prefix(value_offset);
return cell;
}
// Can be called only when is_dead() is true.
static gc_clock::time_point deletion_time(const bytes_view& cell) {
assert(is_dead(cell));
return gc_clock::time_point(gc_clock::duration(
get_field<int32_t>(cell, deletion_time_offset)));
}
// Can be called only when is_live_and_has_ttl() is true.
static gc_clock::time_point expiry(const bytes_view& cell) {
assert(is_live_and_has_ttl(cell));
auto expiry = get_field<int32_t>(cell, expiry_offset);
return gc_clock::time_point(gc_clock::duration(expiry));
}
// Can be called only when is_live_and_has_ttl() is true.
static gc_clock::duration ttl(const bytes_view& cell) {
assert(is_live_and_has_ttl(cell));
return gc_clock::duration(get_field<int32_t>(cell, ttl_offset));
}
static managed_bytes make_dead(api::timestamp_type timestamp, gc_clock::time_point deletion_time) {
managed_bytes b(managed_bytes::initialized_later(), flags_size + timestamp_size + deletion_time_size);
b[0] = 0;
set_field(b, timestamp_offset, timestamp);
set_field(b, deletion_time_offset, deletion_time.time_since_epoch().count());
return b;
}
static managed_bytes make_live(api::timestamp_type timestamp, bytes_view value) {
auto value_offset = flags_size + timestamp_size;
managed_bytes b(managed_bytes::initialized_later(), value_offset + value.size());
b[0] = LIVE_FLAG;
set_field(b, timestamp_offset, timestamp);
std::copy_n(value.begin(), value.size(), b.begin() + value_offset);
return b;
}
static managed_bytes make_live(api::timestamp_type timestamp, bytes_view value, gc_clock::time_point expiry, gc_clock::duration ttl) {
auto value_offset = flags_size + timestamp_size + expiry_size + ttl_size;
managed_bytes b(managed_bytes::initialized_later(), value_offset + value.size());
b[0] = EXPIRY_FLAG | LIVE_FLAG;
set_field(b, timestamp_offset, timestamp);
set_field(b, expiry_offset, expiry.time_since_epoch().count());
set_field(b, ttl_offset, ttl.count());
std::copy_n(value.begin(), value.size(), b.begin() + value_offset);
return b;
}
template<typename ByteContainer>
friend class atomic_cell_base;
friend class atomic_cell;
};
template<typename ByteContainer>
class atomic_cell_base {
protected:
ByteContainer _data;
protected:
atomic_cell_base(ByteContainer&& data) : _data(std::forward<ByteContainer>(data)) { }
friend class atomic_cell_or_collection;
public:
bool is_revert_set() const {
return atomic_cell_type::is_revert_set(_data);
}
bool is_live() const {
return atomic_cell_type::is_live(_data);
}
bool is_live(tombstone t) const {
return is_live() && !is_covered_by(t);
}
bool is_live(tombstone t, gc_clock::time_point now) const {
return is_live() && !is_covered_by(t) && !has_expired(now);
}
bool is_live_and_has_ttl() const {
return atomic_cell_type::is_live_and_has_ttl(_data);
}
bool is_dead(gc_clock::time_point now) const {
return atomic_cell_type::is_dead(_data) || has_expired(now);
}
bool is_covered_by(tombstone t) const {
return timestamp() <= t.timestamp;
}
// Can be called on live and dead cells
api::timestamp_type timestamp() const {
return atomic_cell_type::timestamp(_data);
}
// Can be called on live cells only
bytes_view value() const {
return atomic_cell_type::value(_data);
}
// Can be called only when is_dead(gc_clock::time_point)
gc_clock::time_point deletion_time() const {
return !is_live() ? atomic_cell_type::deletion_time(_data) : expiry() - ttl();
}
// Can be called only when is_live_and_has_ttl()
gc_clock::time_point expiry() const {
return atomic_cell_type::expiry(_data);
}
// Can be called only when is_live_and_has_ttl()
gc_clock::duration ttl() const {
return atomic_cell_type::ttl(_data);
}
// Can be called on live and dead cells
bool has_expired(gc_clock::time_point now) const {
return is_live_and_has_ttl() && expiry() < now;
}
bytes_view serialize() const {
return _data;
}
void set_revert(bool revert) {
atomic_cell_type::set_revert(_data, revert);
}
};
class atomic_cell_view final : public atomic_cell_base<bytes_view> {
atomic_cell_view(bytes_view data) : atomic_cell_base(std::move(data)) {}
public:
static atomic_cell_view from_bytes(bytes_view data) { return atomic_cell_view(data); }
friend class atomic_cell;
friend std::ostream& operator<<(std::ostream& os, const atomic_cell_view& acv);
};
class atomic_cell_ref final : public atomic_cell_base<managed_bytes&> {
public:
atomic_cell_ref(managed_bytes& buf) : atomic_cell_base(buf) {}
};
class atomic_cell final : public atomic_cell_base<managed_bytes> {
atomic_cell(managed_bytes b) : atomic_cell_base(std::move(b)) {}
public:
atomic_cell(const atomic_cell&) = default;
atomic_cell(atomic_cell&&) = default;
atomic_cell& operator=(const atomic_cell&) = default;
atomic_cell& operator=(atomic_cell&&) = default;
static atomic_cell from_bytes(managed_bytes b) {
return atomic_cell(std::move(b));
}
atomic_cell(atomic_cell_view other) : atomic_cell_base(managed_bytes{other._data}) {}
operator atomic_cell_view() const {
return atomic_cell_view(_data);
}
static atomic_cell make_dead(api::timestamp_type timestamp, gc_clock::time_point deletion_time) {
return atomic_cell_type::make_dead(timestamp, deletion_time);
}
static atomic_cell make_live(api::timestamp_type timestamp, bytes_view value) {
return atomic_cell_type::make_live(timestamp, value);
}
static atomic_cell make_live(api::timestamp_type timestamp, bytes_view value,
gc_clock::time_point expiry, gc_clock::duration ttl)
{
return atomic_cell_type::make_live(timestamp, value, expiry, ttl);
}
static atomic_cell make_live(api::timestamp_type timestamp, bytes_view value, ttl_opt ttl) {
if (!ttl) {
return atomic_cell_type::make_live(timestamp, value);
} else {
return atomic_cell_type::make_live(timestamp, value, gc_clock::now() + *ttl, *ttl);
}
}
friend class atomic_cell_or_collection;
friend std::ostream& operator<<(std::ostream& os, const atomic_cell& ac);
};
class collection_mutation_view;
// Represents a mutation of a collection. Actual format is determined by collection type,
// and is:
// set: list of atomic_cell
// map: list of pair<atomic_cell, bytes> (for key/value)
// list: tbd, probably ugly
class collection_mutation {
public:
managed_bytes data;
collection_mutation() {}
collection_mutation(managed_bytes b) : data(std::move(b)) {}
collection_mutation(collection_mutation_view v);
operator collection_mutation_view() const;
};
class collection_mutation_view {
public:
bytes_view data;
bytes_view serialize() const { return data; }
static collection_mutation_view from_bytes(bytes_view v) { return { v }; }
};
inline
collection_mutation::collection_mutation(collection_mutation_view v)
: data(v.data) {
}
inline
collection_mutation::operator collection_mutation_view() const {
return { data };
}
namespace db {
template<typename T>
class serializer;
}
class column_definition;
int compare_atomic_cell_for_merge(atomic_cell_view left, atomic_cell_view right);
void merge_column(const column_definition& def,
atomic_cell_or_collection& old,
const atomic_cell_or_collection& neww);