Files
scylladb/memtable.cc
Glauber Costa d41fcd45d1 memtables: make memtable inherit from region
The LSA memory pressure mechanism will let us know which region is the best
candidate for eviction when under pressure. We need to somehow then translate
region -> memtable -> column family.

The easiest way to convert from region to memtable, is having memtable inherit
from region. Despite the fact that this requires multiple inheritance, which
always raise a flag a bit, the other class we inherit from is
enable_shared_from_this, which has a very simple and well defined interface. So
I think it is worthy for us to do it.

Once we have the memtable, grabing the column family is easy provided we have a
database object. We can grab it from the schema.

Signed-off-by: Glauber Costa <glauber@scylladb.com>
2016-07-05 15:05:29 -04:00

329 lines
12 KiB
C++

/*
* Copyright (C) 2014 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/>.
*/
#include "memtable.hh"
#include "frozen_mutation.hh"
#include "sstable_mutation_readers.hh"
namespace stdx = std::experimental;
memtable::memtable(schema_ptr schema, logalloc::region_group* dirty_memory_region_group)
: logalloc::region(dirty_memory_region_group ? logalloc::region(*dirty_memory_region_group) : logalloc::region())
, _schema(std::move(schema))
, partitions(memtable_entry::compare(_schema)) {
}
memtable::~memtable() {
with_allocator(allocator(), [this] {
partitions.clear_and_dispose(current_deleter<memtable_entry>());
});
}
partition_entry&
memtable::find_or_create_partition_slow(partition_key_view key) {
assert(!reclaiming_enabled());
// FIXME: Perform lookup using std::pair<token, partition_key_view>
// to avoid unconditional copy of the partition key.
// We can't do it right now because std::map<> which holds
// partitions doesn't support heterogeneous lookup.
// We could switch to boost::intrusive_map<> similar to what we have for row keys.
auto& outer = current_allocator();
return with_allocator(standard_allocator(), [&, this] () -> partition_entry& {
auto dk = dht::global_partitioner().decorate_key(*_schema, key);
return with_allocator(outer, [&dk, this] () -> partition_entry& {
return with_linearized_managed_bytes([&] () -> partition_entry& {
return find_or_create_partition(dk);
});
});
});
}
partition_entry&
memtable::find_or_create_partition(const dht::decorated_key& key) {
assert(!reclaiming_enabled());
// call lower_bound so we have a hint for the insert, just in case.
auto i = partitions.lower_bound(key, memtable_entry::compare(_schema));
if (i == partitions.end() || !key.equal(*_schema, i->key())) {
memtable_entry* entry = current_allocator().construct<memtable_entry>(
_schema, dht::decorated_key(key), mutation_partition(_schema));
i = partitions.insert(i, *entry);
return entry->partition();
} else {
upgrade_entry(*i);
}
return i->partition();
}
boost::iterator_range<memtable::partitions_type::const_iterator>
memtable::slice(const query::partition_range& range) const {
if (query::is_single_partition(range)) {
const query::ring_position& pos = range.start()->value();
auto i = partitions.find(pos, memtable_entry::compare(_schema));
if (i != partitions.end()) {
return boost::make_iterator_range(i, std::next(i));
} else {
return boost::make_iterator_range(i, i);
}
} else {
auto cmp = memtable_entry::compare(_schema);
auto i1 = range.start()
? (range.start()->is_inclusive()
? partitions.lower_bound(range.start()->value(), cmp)
: partitions.upper_bound(range.start()->value(), cmp))
: partitions.cbegin();
auto i2 = range.end()
? (range.end()->is_inclusive()
? partitions.upper_bound(range.end()->value(), cmp)
: partitions.lower_bound(range.end()->value(), cmp))
: partitions.cend();
return boost::make_iterator_range(i1, i2);
}
}
class scanning_reader final : public mutation_reader::impl {
lw_shared_ptr<memtable> _memtable;
schema_ptr _schema;
const query::partition_range& _range;
stdx::optional<dht::decorated_key> _last;
memtable::partitions_type::iterator _i;
memtable::partitions_type::iterator _end;
uint64_t _last_reclaim_counter;
size_t _last_partition_count = 0;
stdx::optional<query::partition_range> _delegate_range;
mutation_reader _delegate;
const io_priority_class& _pc;
query::clustering_key_filtering_context _ck_filtering;
private:
memtable::partitions_type::iterator lookup_end() {
auto cmp = memtable_entry::compare(_memtable->_schema);
return _range.end()
? (_range.end()->is_inclusive()
? _memtable->partitions.upper_bound(_range.end()->value(), cmp)
: _memtable->partitions.lower_bound(_range.end()->value(), cmp))
: _memtable->partitions.end();
}
void update_iterators() {
// We must be prepared that iterators may get invalidated during compaction.
auto current_reclaim_counter = _memtable->reclaim_counter();
auto cmp = memtable_entry::compare(_memtable->_schema);
if (_last) {
if (current_reclaim_counter != _last_reclaim_counter ||
_last_partition_count != _memtable->partition_count()) {
_i = _memtable->partitions.upper_bound(*_last, cmp);
_end = lookup_end();
_last_partition_count = _memtable->partition_count();
}
} else {
// Initial lookup
_i = _range.start()
? (_range.start()->is_inclusive()
? _memtable->partitions.lower_bound(_range.start()->value(), cmp)
: _memtable->partitions.upper_bound(_range.start()->value(), cmp))
: _memtable->partitions.begin();
_end = lookup_end();
_last_partition_count = _memtable->partition_count();
}
_last_reclaim_counter = current_reclaim_counter;
}
public:
scanning_reader(schema_ptr s,
lw_shared_ptr<memtable> m,
const query::partition_range& range,
const query::clustering_key_filtering_context& ck_filtering,
const io_priority_class& pc)
: _memtable(std::move(m))
, _schema(std::move(s))
, _range(range)
, _pc(pc)
, _ck_filtering(ck_filtering)
{ }
virtual future<streamed_mutation_opt> operator()() override {
if (_delegate_range) {
return _delegate();
}
// We cannot run concurrently with row_cache::update().
if (_memtable->is_flushed()) {
// FIXME: Use cache. See column_family::make_reader().
_delegate_range = _last ? _range.split_after(*_last, dht::ring_position_comparator(*_memtable->_schema)) : _range;
_delegate = make_mutation_reader<sstable_range_wrapping_reader>(
_memtable->_sstable, _schema, *_delegate_range, _ck_filtering, _pc);
_memtable = {};
_last = {};
return _delegate();
}
logalloc::reclaim_lock _(*_memtable);
managed_bytes::linearization_context_guard lcg;
update_iterators();
if (_i == _end) {
return make_ready_future<streamed_mutation_opt>(stdx::nullopt);
}
memtable_entry& e = *_i;
++_i;
_last = e.key();
_memtable->upgrade_entry(e);
return make_ready_future<streamed_mutation_opt>(e.read(_memtable, _schema, _ck_filtering));
}
};
mutation_reader
memtable::make_reader(schema_ptr s,
const query::partition_range& range,
const query::clustering_key_filtering_context& ck_filtering,
const io_priority_class& pc) {
if (query::is_wrap_around(range, *s)) {
fail(unimplemented::cause::WRAP_AROUND);
}
if (query::is_single_partition(range)) {
const query::ring_position& pos = range.start()->value();
return _read_section(*this, [&] {
managed_bytes::linearization_context_guard lcg;
auto i = partitions.find(pos, memtable_entry::compare(_schema));
if (i != partitions.end()) {
upgrade_entry(*i);
return make_reader_returning(i->read(shared_from_this(), s, ck_filtering));
} else {
return make_empty_reader();
}
});
} else {
return make_mutation_reader<scanning_reader>(std::move(s), shared_from_this(), range, ck_filtering, pc);
}
}
void
memtable::update(const db::replay_position& rp) {
if (_replay_position < rp) {
_replay_position = rp;
}
}
future<>
memtable::apply(memtable& mt) {
return do_with(mt.make_reader(_schema), [this] (auto&& rd) mutable {
return consume(rd, [self = this->shared_from_this(), &rd] (mutation&& m) {
self->apply(m);
return stop_iteration::no;
});
});
}
void
memtable::apply(const mutation& m, const db::replay_position& rp) {
with_allocator(allocator(), [this, &m] {
_allocating_section(*this, [&, this] {
with_linearized_managed_bytes([&] {
auto& p = find_or_create_partition(m.decorated_key());
p.apply(*_schema, m.partition(), *m.schema());
});
});
});
update(rp);
}
void
memtable::apply(const frozen_mutation& m, const schema_ptr& m_schema, const db::replay_position& rp) {
with_allocator(allocator(), [this, &m, &m_schema] {
_allocating_section(*this, [&, this] {
with_linearized_managed_bytes([&] {
auto& p = find_or_create_partition_slow(m.key(*_schema));
p.apply(*_schema, m.partition(), *m_schema);
});
});
});
update(rp);
}
logalloc::occupancy_stats memtable::occupancy() const {
return logalloc::region::occupancy();
}
mutation_source memtable::as_data_source() {
return mutation_source([mt = shared_from_this()] (schema_ptr s, const query::partition_range& range) {
return mt->make_reader(std::move(s), range);
});
}
key_source memtable::as_key_source() {
return key_source([mt = shared_from_this()] (const query::partition_range& range) {
return make_key_from_mutation_reader(mt->make_reader(mt->_schema, range));
});
}
size_t memtable::partition_count() const {
return partitions.size();
}
memtable_entry::memtable_entry(memtable_entry&& o) noexcept
: _link()
, _schema(std::move(o._schema))
, _key(std::move(o._key))
, _pe(std::move(o._pe))
{
using container_type = memtable::partitions_type;
container_type::node_algorithms::replace_node(o._link.this_ptr(), _link.this_ptr());
container_type::node_algorithms::init(o._link.this_ptr());
}
void memtable::mark_flushed(lw_shared_ptr<sstables::sstable> sst) {
_sstable = std::move(sst);
}
bool memtable::is_flushed() const {
return bool(_sstable);
}
streamed_mutation
memtable_entry::read(lw_shared_ptr<memtable> mtbl, const schema_ptr& target_schema, const query::clustering_key_filtering_context& ck_filtering) {
if (_schema->version() != target_schema->version()) {
auto mp = mutation_partition(_pe.squashed(_schema, target_schema), *target_schema, ck_filtering.get_ranges(_key.key()));
mutation m = mutation(target_schema, _key, std::move(mp));
return streamed_mutation_from_mutation(std::move(m));
}
auto& cr = ck_filtering.get_ranges(_key.key());
auto snp = _pe.read(_schema);
return make_partition_snapshot_reader(_schema, _key, ck_filtering, cr, snp, *mtbl, mtbl->_read_section, mtbl);
}
void memtable::upgrade_entry(memtable_entry& e) {
if (e._schema != _schema) {
assert(!reclaiming_enabled());
with_allocator(allocator(), [this, &e] {
with_linearized_managed_bytes([&] {
e.partition().upgrade(e._schema, _schema);
e._schema = _schema;
});
});
}
}
void memtable::set_schema(schema_ptr new_schema) noexcept {
_schema = std::move(new_schema);
}