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cache_flat_mutation_reader.hh
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cache_flat_mutation_reader.hh
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/*
* Copyright (C) 2017 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 <vector>
#include "row_cache.hh"
#include "mutation_reader.hh"
#include "mutation_fragment.hh"
#include "partition_version.hh"
#include "utils/logalloc.hh"
#include "query-request.hh"
#include "partition_snapshot_reader.hh"
#include "partition_snapshot_row_cursor.hh"
#include "read_context.hh"
#include "flat_mutation_reader.hh"
namespace cache {
extern logging::logger clogger;
class cache_flat_mutation_reader final : public flat_mutation_reader::impl {
enum class state {
before_static_row,
// Invariants:
// - position_range(_lower_bound, _upper_bound) covers all not yet emitted positions from current range
// - if _next_row has valid iterators:
// - _next_row points to the nearest row in cache >= _lower_bound
// - _next_row_in_range = _next.position() < _upper_bound
// - if _next_row doesn't have valid iterators, it has no meaning.
reading_from_cache,
// Starts reading from underlying reader.
// The range to read is position_range(_lower_bound, min(_next_row.position(), _upper_bound)).
// Invariants:
// - _next_row_in_range = _next.position() < _upper_bound
move_to_underlying,
// Invariants:
// - Upper bound of the read is min(_next_row.position(), _upper_bound)
// - _next_row_in_range = _next.position() < _upper_bound
// - _last_row points at a direct predecessor of the next row which is going to be read.
// Used for populating continuity.
// - _population_range_starts_before_all_rows is set accordingly
reading_from_underlying,
end_of_stream
};
partition_snapshot_ptr _snp;
position_in_partition::tri_compare _position_cmp;
query::clustering_key_filter_ranges _ck_ranges;
query::clustering_row_ranges::const_iterator _ck_ranges_curr;
query::clustering_row_ranges::const_iterator _ck_ranges_end;
lsa_manager _lsa_manager;
partition_snapshot_row_weakref _last_row;
// Holds the lower bound of a position range which hasn't been processed yet.
// Only rows with positions < _lower_bound have been emitted, and only
// range_tombstones with positions <= _lower_bound.
position_in_partition _lower_bound;
position_in_partition_view _upper_bound;
state _state = state::before_static_row;
lw_shared_ptr<read_context> _read_context;
partition_snapshot_row_cursor _next_row;
bool _next_row_in_range = false;
// True iff current population interval, since the previous clustering row, starts before all clustered rows.
// We cannot just look at _lower_bound, because emission of range tombstones changes _lower_bound and
// because we mark clustering intervals as continuous when consuming a clustering_row, it would prevent
// us from marking the interval as continuous.
// Valid when _state == reading_from_underlying.
bool _population_range_starts_before_all_rows;
// Whether _lower_bound was changed within current fill_buffer().
// If it did not then we cannot break out of it (e.g. on preemption) because
// forward progress is not guaranteed in case iterators are getting constantly invalidated.
bool _lower_bound_changed = false;
future<> do_fill_buffer(db::timeout_clock::time_point);
void copy_from_cache_to_buffer();
future<> process_static_row(db::timeout_clock::time_point);
void move_to_end();
void move_to_next_range();
void move_to_range(query::clustering_row_ranges::const_iterator);
void move_to_next_entry();
void add_to_buffer(const partition_snapshot_row_cursor&);
void add_clustering_row_to_buffer(mutation_fragment&&);
void add_to_buffer(range_tombstone&&);
void add_to_buffer(mutation_fragment&&);
future<> read_from_underlying(db::timeout_clock::time_point);
void start_reading_from_underlying();
bool after_current_range(position_in_partition_view position);
bool can_populate() const;
// Marks the range between _last_row (exclusive) and _next_row (exclusive) as continuous,
// provided that the underlying reader still matches the latest version of the partition.
void maybe_update_continuity();
// Tries to ensure that the lower bound of the current population range exists.
// Returns false if it failed and range cannot be populated.
// Assumes can_populate().
bool ensure_population_lower_bound();
void maybe_add_to_cache(const mutation_fragment& mf);
void maybe_add_to_cache(const clustering_row& cr);
void maybe_add_to_cache(const range_tombstone& rt);
void maybe_add_to_cache(const static_row& sr);
void maybe_set_static_row_continuous();
void finish_reader() {
push_mutation_fragment(partition_end());
_end_of_stream = true;
_state = state::end_of_stream;
}
void touch_partition();
public:
cache_flat_mutation_reader(schema_ptr s,
dht::decorated_key dk,
query::clustering_key_filter_ranges&& crr,
lw_shared_ptr<read_context> ctx,
partition_snapshot_ptr snp,
row_cache& cache)
: flat_mutation_reader::impl(std::move(s))
, _snp(std::move(snp))
, _position_cmp(*_schema)
, _ck_ranges(std::move(crr))
, _ck_ranges_curr(_ck_ranges.begin())
, _ck_ranges_end(_ck_ranges.end())
, _lsa_manager(cache)
, _lower_bound(position_in_partition::before_all_clustered_rows())
, _upper_bound(position_in_partition_view::before_all_clustered_rows())
, _read_context(std::move(ctx))
, _next_row(*_schema, *_snp)
{
clogger.trace("csm {}: table={}.{}", this, _schema->ks_name(), _schema->cf_name());
push_mutation_fragment(partition_start(std::move(dk), _snp->partition_tombstone()));
}
cache_flat_mutation_reader(const cache_flat_mutation_reader&) = delete;
cache_flat_mutation_reader(cache_flat_mutation_reader&&) = delete;
virtual future<> fill_buffer(db::timeout_clock::time_point timeout) override;
virtual void next_partition() override {
clear_buffer_to_next_partition();
if (is_buffer_empty()) {
_end_of_stream = true;
}
}
virtual future<> fast_forward_to(const dht::partition_range&, db::timeout_clock::time_point timeout) override {
clear_buffer();
_end_of_stream = true;
return make_ready_future<>();
}
virtual future<> fast_forward_to(position_range pr, db::timeout_clock::time_point timeout) override {
throw std::bad_function_call();
}
};
inline
future<> cache_flat_mutation_reader::process_static_row(db::timeout_clock::time_point timeout) {
if (_snp->static_row_continuous()) {
_read_context->cache().on_row_hit();
static_row sr = _lsa_manager.run_in_read_section([this] {
return _snp->static_row(_read_context->digest_requested());
});
if (!sr.empty()) {
push_mutation_fragment(mutation_fragment(std::move(sr)));
}
return make_ready_future<>();
} else {
_read_context->cache().on_row_miss();
return _read_context->get_next_fragment(timeout).then([this] (mutation_fragment_opt&& sr) {
if (sr) {
assert(sr->is_static_row());
maybe_add_to_cache(sr->as_static_row());
push_mutation_fragment(std::move(*sr));
}
maybe_set_static_row_continuous();
});
}
}
inline
void cache_flat_mutation_reader::touch_partition() {
if (_snp->at_latest_version()) {
rows_entry& last_dummy = *_snp->version()->partition().clustered_rows().rbegin();
_snp->tracker()->touch(last_dummy);
}
}
inline
future<> cache_flat_mutation_reader::fill_buffer(db::timeout_clock::time_point timeout) {
if (_state == state::before_static_row) {
auto after_static_row = [this, timeout] {
if (_ck_ranges_curr == _ck_ranges_end) {
touch_partition();
finish_reader();
return make_ready_future<>();
}
_state = state::reading_from_cache;
_lsa_manager.run_in_read_section([this] {
move_to_range(_ck_ranges_curr);
});
return fill_buffer(timeout);
};
if (_schema->has_static_columns()) {
return process_static_row(timeout).then(std::move(after_static_row));
} else {
return after_static_row();
}
}
clogger.trace("csm {}: fill_buffer(), range={}, lb={}", this, *_ck_ranges_curr, _lower_bound);
return do_until([this] { return _end_of_stream || is_buffer_full(); }, [this, timeout] {
return do_fill_buffer(timeout);
});
}
inline
future<> cache_flat_mutation_reader::do_fill_buffer(db::timeout_clock::time_point timeout) {
if (_state == state::move_to_underlying) {
_state = state::reading_from_underlying;
_population_range_starts_before_all_rows = _lower_bound.is_before_all_clustered_rows(*_schema);
auto end = _next_row_in_range ? position_in_partition(_next_row.position())
: position_in_partition(_upper_bound);
return _read_context->fast_forward_to(position_range{_lower_bound, std::move(end)}, timeout).then([this, timeout] {
return read_from_underlying(timeout);
});
}
if (_state == state::reading_from_underlying) {
return read_from_underlying(timeout);
}
// assert(_state == state::reading_from_cache)
return _lsa_manager.run_in_read_section([this] {
auto next_valid = _next_row.iterators_valid();
clogger.trace("csm {}: reading_from_cache, range=[{}, {}), next={}, valid={}", this, _lower_bound,
_upper_bound, _next_row.position(), next_valid);
// We assume that if there was eviction, and thus the range may
// no longer be continuous, the cursor was invalidated.
if (!next_valid) {
auto adjacent = _next_row.advance_to(_lower_bound);
_next_row_in_range = !after_current_range(_next_row.position());
if (!adjacent && !_next_row.continuous()) {
_last_row = nullptr; // We could insert a dummy here, but this path is unlikely.
start_reading_from_underlying();
return make_ready_future<>();
}
}
_next_row.maybe_refresh();
clogger.trace("csm {}: next={}, cont={}", this, _next_row.position(), _next_row.continuous());
_lower_bound_changed = false;
while (_state == state::reading_from_cache) {
copy_from_cache_to_buffer();
// We need to check _lower_bound_changed even if is_buffer_full() because
// we may have emitted only a range tombstone which overlapped with _lower_bound
// and thus didn't cause _lower_bound to change.
if ((need_preempt() || is_buffer_full()) && _lower_bound_changed) {
break;
}
}
return make_ready_future<>();
});
}
inline
future<> cache_flat_mutation_reader::read_from_underlying(db::timeout_clock::time_point timeout) {
return consume_mutation_fragments_until(_read_context->underlying().underlying(),
[this] { return _state != state::reading_from_underlying || is_buffer_full(); },
[this] (mutation_fragment mf) {
_read_context->cache().on_row_miss();
maybe_add_to_cache(mf);
add_to_buffer(std::move(mf));
},
[this] {
_state = state::reading_from_cache;
_lsa_manager.run_in_update_section([this] {
auto same_pos = _next_row.maybe_refresh();
if (!same_pos) {
_read_context->cache().on_mispopulate(); // FIXME: Insert dummy entry at _upper_bound.
_next_row_in_range = !after_current_range(_next_row.position());
if (!_next_row.continuous()) {
start_reading_from_underlying();
}
return;
}
if (_next_row_in_range) {
maybe_update_continuity();
_last_row = _next_row;
add_to_buffer(_next_row);
try {
move_to_next_entry();
} catch (const std::bad_alloc&) {
// We cannot reenter the section, since we may have moved to the new range, and
// because add_to_buffer() should not be repeated.
_snp->region().allocator().invalidate_references(); // Invalidates _next_row
}
} else {
if (no_clustering_row_between(*_schema, _upper_bound, _next_row.position())) {
this->maybe_update_continuity();
} else if (can_populate()) {
rows_entry::compare less(*_schema);
auto& rows = _snp->version()->partition().clustered_rows();
if (query::is_single_row(*_schema, *_ck_ranges_curr)) {
with_allocator(_snp->region().allocator(), [&] {
auto e = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(_ck_ranges_curr->start()->value()));
// Use _next_row iterator only as a hint, because there could be insertions after _upper_bound.
auto insert_result = rows.insert_check(_next_row.get_iterator_in_latest_version(), *e, less);
auto inserted = insert_result.second;
auto it = insert_result.first;
if (inserted) {
_snp->tracker()->insert(*e);
e.release();
auto next = std::next(it);
it->set_continuous(next->continuous());
clogger.trace("csm {}: inserted dummy at {}, cont={}", this, it->position(), it->continuous());
}
});
} else if (ensure_population_lower_bound()) {
with_allocator(_snp->region().allocator(), [&] {
auto e = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(*_schema, _upper_bound, is_dummy::yes, is_continuous::yes));
// Use _next_row iterator only as a hint, because there could be insertions after _upper_bound.
auto insert_result = rows.insert_check(_next_row.get_iterator_in_latest_version(), *e, less);
auto inserted = insert_result.second;
if (inserted) {
clogger.trace("csm {}: inserted dummy at {}", this, _upper_bound);
_snp->tracker()->insert(*e);
e.release();
} else {
clogger.trace("csm {}: mark {} as continuous", this, insert_result.first->position());
insert_result.first->set_continuous(true);
}
});
}
} else {
_read_context->cache().on_mispopulate();
}
try {
move_to_next_range();
} catch (const std::bad_alloc&) {
// We cannot reenter the section, since we may have moved to the new range
_snp->region().allocator().invalidate_references(); // Invalidates _next_row
}
}
});
return make_ready_future<>();
}, timeout);
}
inline
bool cache_flat_mutation_reader::ensure_population_lower_bound() {
if (_population_range_starts_before_all_rows) {
return true;
}
if (!_last_row.refresh(*_snp)) {
return false;
}
// Continuity flag we will later set for the upper bound extends to the previous row in the same version,
// so we need to ensure we have an entry in the latest version.
if (!_last_row.is_in_latest_version()) {
with_allocator(_snp->region().allocator(), [&] {
auto& rows = _snp->version()->partition().clustered_rows();
rows_entry::compare less(*_schema);
// FIXME: Avoid the copy by inserting an incomplete clustering row
auto e = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(*_schema, *_last_row));
e->set_continuous(false);
auto insert_result = rows.insert_check(rows.end(), *e, less);
auto inserted = insert_result.second;
if (inserted) {
clogger.trace("csm {}: inserted lower bound dummy at {}", this, e->position());
_snp->tracker()->insert(*e);
e.release();
}
});
}
return true;
}
inline
void cache_flat_mutation_reader::maybe_update_continuity() {
if (can_populate() && ensure_population_lower_bound()) {
with_allocator(_snp->region().allocator(), [&] {
rows_entry& e = _next_row.ensure_entry_in_latest().row;
e.set_continuous(true);
});
} else {
_read_context->cache().on_mispopulate();
}
}
inline
void cache_flat_mutation_reader::maybe_add_to_cache(const mutation_fragment& mf) {
if (mf.is_range_tombstone()) {
maybe_add_to_cache(mf.as_range_tombstone());
} else {
assert(mf.is_clustering_row());
const clustering_row& cr = mf.as_clustering_row();
maybe_add_to_cache(cr);
}
}
inline
void cache_flat_mutation_reader::maybe_add_to_cache(const clustering_row& cr) {
if (!can_populate()) {
_last_row = nullptr;
_population_range_starts_before_all_rows = false;
_read_context->cache().on_mispopulate();
return;
}
clogger.trace("csm {}: populate({})", this, clustering_row::printer(*_schema, cr));
_lsa_manager.run_in_update_section_with_allocator([this, &cr] {
mutation_partition& mp = _snp->version()->partition();
rows_entry::compare less(*_schema);
if (_read_context->digest_requested()) {
cr.cells().prepare_hash(*_schema, column_kind::regular_column);
}
auto new_entry = alloc_strategy_unique_ptr<rows_entry>(
current_allocator().construct<rows_entry>(*_schema, cr.key(), cr.tomb(), cr.marker(), cr.cells()));
new_entry->set_continuous(false);
auto it = _next_row.iterators_valid() ? _next_row.get_iterator_in_latest_version()
: mp.clustered_rows().lower_bound(cr.key(), less);
auto insert_result = mp.clustered_rows().insert_check(it, *new_entry, less);
if (insert_result.second) {
_snp->tracker()->insert(*new_entry);
new_entry.release();
}
it = insert_result.first;
rows_entry& e = *it;
if (ensure_population_lower_bound()) {
clogger.trace("csm {}: set_continuous({})", this, e.position());
e.set_continuous(true);
} else {
_read_context->cache().on_mispopulate();
}
with_allocator(standard_allocator(), [&] {
_last_row = partition_snapshot_row_weakref(*_snp, it, true);
});
_population_range_starts_before_all_rows = false;
});
}
inline
bool cache_flat_mutation_reader::after_current_range(position_in_partition_view p) {
return _position_cmp(p, _upper_bound) >= 0;
}
inline
void cache_flat_mutation_reader::start_reading_from_underlying() {
clogger.trace("csm {}: start_reading_from_underlying(), range=[{}, {})", this, _lower_bound, _next_row_in_range ? _next_row.position() : _upper_bound);
_state = state::move_to_underlying;
_next_row.touch();
}
inline
void cache_flat_mutation_reader::copy_from_cache_to_buffer() {
clogger.trace("csm {}: copy_from_cache, next={}, next_row_in_range={}", this, _next_row.position(), _next_row_in_range);
_next_row.touch();
position_in_partition_view next_lower_bound = _next_row.dummy() ? _next_row.position() : position_in_partition_view::after_key(_next_row.key());
for (auto &&rts : _snp->range_tombstones(_lower_bound, _next_row_in_range ? next_lower_bound : _upper_bound)) {
position_in_partition::less_compare less(*_schema);
// This guarantees that rts starts after any emitted clustering_row
// and not before any emitted range tombstone.
if (!less(_lower_bound, rts.position())) {
rts.set_start(*_schema, _lower_bound);
} else {
_lower_bound = position_in_partition(rts.position());
_lower_bound_changed = true;
if (is_buffer_full()) {
return;
}
}
push_mutation_fragment(std::move(rts));
}
// We add the row to the buffer even when it's full.
// This simplifies the code. For more info see #3139.
if (_next_row_in_range) {
_last_row = _next_row;
add_to_buffer(_next_row);
move_to_next_entry();
} else {
move_to_next_range();
}
}
inline
void cache_flat_mutation_reader::move_to_end() {
finish_reader();
clogger.trace("csm {}: eos", this);
}
inline
void cache_flat_mutation_reader::move_to_next_range() {
auto next_it = std::next(_ck_ranges_curr);
if (next_it == _ck_ranges_end) {
move_to_end();
_ck_ranges_curr = next_it;
} else {
move_to_range(next_it);
}
}
inline
void cache_flat_mutation_reader::move_to_range(query::clustering_row_ranges::const_iterator next_it) {
auto lb = position_in_partition::for_range_start(*next_it);
auto ub = position_in_partition_view::for_range_end(*next_it);
_last_row = nullptr;
_lower_bound = std::move(lb);
_upper_bound = std::move(ub);
_lower_bound_changed = true;
_ck_ranges_curr = next_it;
auto adjacent = _next_row.advance_to(_lower_bound);
_next_row_in_range = !after_current_range(_next_row.position());
clogger.trace("csm {}: move_to_range(), range={}, lb={}, ub={}, next={}", this, *_ck_ranges_curr, _lower_bound, _upper_bound, _next_row.position());
if (!adjacent && !_next_row.continuous()) {
// FIXME: We don't insert a dummy for singular range to avoid allocating 3 entries
// for a hit (before, at and after). If we supported the concept of an incomplete row,
// we could insert such a row for the lower bound if it's full instead, for both singular and
// non-singular ranges.
if (_ck_ranges_curr->start() && !query::is_single_row(*_schema, *_ck_ranges_curr)) {
// Insert dummy for lower bound
if (can_populate()) {
// FIXME: _lower_bound could be adjacent to the previous row, in which case we could skip this
clogger.trace("csm {}: insert dummy at {}", this, _lower_bound);
auto it = with_allocator(_lsa_manager.region().allocator(), [&] {
auto& rows = _snp->version()->partition().clustered_rows();
auto new_entry = current_allocator().construct<rows_entry>(*_schema, _lower_bound, is_dummy::yes, is_continuous::no);
return rows.insert_before(_next_row.get_iterator_in_latest_version(), *new_entry);
});
_snp->tracker()->insert(*it);
_last_row = partition_snapshot_row_weakref(*_snp, it, true);
} else {
_read_context->cache().on_mispopulate();
}
}
start_reading_from_underlying();
}
}
// _next_row must be inside the range.
inline
void cache_flat_mutation_reader::move_to_next_entry() {
clogger.trace("csm {}: move_to_next_entry(), curr={}", this, _next_row.position());
if (no_clustering_row_between(*_schema, _next_row.position(), _upper_bound)) {
move_to_next_range();
} else {
if (!_next_row.next()) {
move_to_end();
return;
}
_next_row_in_range = !after_current_range(_next_row.position());
clogger.trace("csm {}: next={}, cont={}, in_range={}", this, _next_row.position(), _next_row.continuous(), _next_row_in_range);
if (!_next_row.continuous()) {
start_reading_from_underlying();
}
}
}
inline
void cache_flat_mutation_reader::add_to_buffer(mutation_fragment&& mf) {
clogger.trace("csm {}: add_to_buffer({})", this, mutation_fragment::printer(*_schema, mf));
if (mf.is_clustering_row()) {
add_clustering_row_to_buffer(std::move(mf));
} else {
assert(mf.is_range_tombstone());
add_to_buffer(std::move(mf).as_range_tombstone());
}
}
inline
void cache_flat_mutation_reader::add_to_buffer(const partition_snapshot_row_cursor& row) {
if (!row.dummy()) {
_read_context->cache().on_row_hit();
add_clustering_row_to_buffer(row.row(_read_context->digest_requested()));
}
}
// Maintains the following invariants, also in case of exception:
// (1) no fragment with position >= _lower_bound was pushed yet
// (2) If _lower_bound > mf.position(), mf was emitted
inline
void cache_flat_mutation_reader::add_clustering_row_to_buffer(mutation_fragment&& mf) {
clogger.trace("csm {}: add_clustering_row_to_buffer({})", this, mutation_fragment::printer(*_schema, mf));
auto& row = mf.as_clustering_row();
auto new_lower_bound = position_in_partition::after_key(row.key());
push_mutation_fragment(std::move(mf));
_lower_bound = std::move(new_lower_bound);
_lower_bound_changed = true;
}
inline
void cache_flat_mutation_reader::add_to_buffer(range_tombstone&& rt) {
clogger.trace("csm {}: add_to_buffer({})", this, rt);
// This guarantees that rt starts after any emitted clustering_row
// and not before any emitted range tombstone.
position_in_partition::less_compare less(*_schema);
if (!less(_lower_bound, rt.end_position())) {
return;
}
if (!less(_lower_bound, rt.position())) {
rt.set_start(*_schema, _lower_bound);
} else {
_lower_bound = position_in_partition(rt.position());
_lower_bound_changed = true;
}
push_mutation_fragment(std::move(rt));
}
inline
void cache_flat_mutation_reader::maybe_add_to_cache(const range_tombstone& rt) {
if (can_populate()) {
clogger.trace("csm {}: maybe_add_to_cache({})", this, rt);
_lsa_manager.run_in_update_section_with_allocator([&] {
_snp->version()->partition().row_tombstones().apply_monotonically(*_schema, rt);
});
} else {
_read_context->cache().on_mispopulate();
}
}
inline
void cache_flat_mutation_reader::maybe_add_to_cache(const static_row& sr) {
if (can_populate()) {
clogger.trace("csm {}: populate({})", this, static_row::printer(*_schema, sr));
_read_context->cache().on_static_row_insert();
_lsa_manager.run_in_update_section_with_allocator([&] {
if (_read_context->digest_requested()) {
sr.cells().prepare_hash(*_schema, column_kind::static_column);
}
_snp->version()->partition().static_row().apply(*_schema, column_kind::static_column, sr.cells());
});
} else {
_read_context->cache().on_mispopulate();
}
}
inline
void cache_flat_mutation_reader::maybe_set_static_row_continuous() {
if (can_populate()) {
clogger.trace("csm {}: set static row continuous", this);
_snp->version()->partition().set_static_row_continuous(true);
} else {
_read_context->cache().on_mispopulate();
}
}
inline
bool cache_flat_mutation_reader::can_populate() const {
return _snp->at_latest_version() && _read_context->cache().phase_of(_read_context->key()) == _read_context->phase();
}
} // namespace cache
inline flat_mutation_reader make_cache_flat_mutation_reader(schema_ptr s,
dht::decorated_key dk,
query::clustering_key_filter_ranges crr,
row_cache& cache,
lw_shared_ptr<cache::read_context> ctx,
partition_snapshot_ptr snp)
{
return make_flat_mutation_reader<cache::cache_flat_mutation_reader>(
std::move(s), std::move(dk), std::move(crr), std::move(ctx), std::move(snp), cache);
}