761d62cd82
Currently, when two cells have the same write timestamp and both are alive or expiring, we compare their value first, before checking if either of them is expiring and if both are expiring, comparing their expiration time and ttl value to determine which of them will expire later or was written later. This was changed in CASSANDRA-14592 for consistency with the preference for dead cells over live cells, as expiring cells will become tombstones at a future time and then they'd win over live cells with the same timestamp, hence they should win also before expiration. In addition, comparing the cell value before expiration can lead to unintuitive corner cases where rewriting a cell using the same timestamp but different TTL may cause scylla to return the cell with null value if it expired in the meanwhile. Also, when multiple columns are written using two upserts using the same write timestamp but with different expiration, selecting cells by their value may return a mixed result where each cell is selected individually from either upsert, by picking the cells with the largest values for each column, while using the expiration time to break tie will lead to a more consistent results where a set of cell from only one of the upserts will be selected. Fixes scylladb/scylladb#14182 Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
233 lines
9.2 KiB
C++
233 lines
9.2 KiB
C++
/*
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* Copyright (C) 2018-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#include "atomic_cell.hh"
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#include "atomic_cell_or_collection.hh"
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#include "counters.hh"
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#include "types/types.hh"
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atomic_cell atomic_cell::make_dead(api::timestamp_type timestamp, gc_clock::time_point deletion_time) {
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return atomic_cell_type::make_dead(timestamp, deletion_time);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, bytes_view value, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, single_fragment_range(value));
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, managed_bytes_view value, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, fragment_range(value));
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, ser::buffer_view<bytes_ostream::fragment_iterator> value, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, value);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, const fragmented_temporary_buffer::view& value, collection_member cm)
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{
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return atomic_cell_type::make_live(timestamp, value);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, bytes_view value,
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gc_clock::time_point expiry, gc_clock::duration ttl, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, single_fragment_range(value), expiry, ttl);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, managed_bytes_view value,
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gc_clock::time_point expiry, gc_clock::duration ttl, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, fragment_range(value), expiry, ttl);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, ser::buffer_view<bytes_ostream::fragment_iterator> value,
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gc_clock::time_point expiry, gc_clock::duration ttl, atomic_cell::collection_member cm) {
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return atomic_cell_type::make_live(timestamp, value, expiry, ttl);
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}
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atomic_cell atomic_cell::make_live(const abstract_type& type, api::timestamp_type timestamp, const fragmented_temporary_buffer::view& value,
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gc_clock::time_point expiry, gc_clock::duration ttl, collection_member cm)
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{
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return atomic_cell_type::make_live(timestamp, value, expiry, ttl);
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}
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atomic_cell atomic_cell::make_live_counter_update(api::timestamp_type timestamp, int64_t value) {
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return atomic_cell_type::make_live_counter_update(timestamp, value);
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}
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atomic_cell atomic_cell::make_live_uninitialized(const abstract_type& type, api::timestamp_type timestamp, size_t size) {
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return atomic_cell_type::make_live_uninitialized(timestamp, size);
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}
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atomic_cell::atomic_cell(const abstract_type& type, atomic_cell_view other)
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: _data(other._view) {
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set_view(_data);
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}
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// Based on:
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// - org.apache.cassandra.db.AbstractCell#reconcile()
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// - org.apache.cassandra.db.BufferExpiringCell#reconcile()
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// - org.apache.cassandra.db.BufferDeletedCell#reconcile()
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std::strong_ordering
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compare_atomic_cell_for_merge(atomic_cell_view left, atomic_cell_view right) {
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if (left.timestamp() != right.timestamp()) {
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return left.timestamp() <=> right.timestamp();
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}
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if (left.is_live() != right.is_live()) {
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return left.is_live() ? std::strong_ordering::less : std::strong_ordering::greater;
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}
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if (left.is_live()) {
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if (left.is_live_and_has_ttl() != right.is_live_and_has_ttl()) {
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// prefer expiring cells.
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return left.is_live_and_has_ttl() ? std::strong_ordering::greater : std::strong_ordering::less;
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}
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if (left.is_live_and_has_ttl()) {
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if (left.expiry() != right.expiry()) {
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return left.expiry() <=> right.expiry();
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} else if (right.ttl() != left.ttl()) {
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// prefer the cell that was written later,
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// so it survives longer after it expires, until purged.
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return right.ttl() <=> left.ttl();
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}
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}
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return compare_unsigned(left.value(), right.value());
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} else {
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// Both are deleted
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// Origin compares big-endian serialized deletion time. That's because it
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// delegates to AbstractCell.reconcile() which compares values after
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// comparing timestamps, which in case of deleted cells will hold
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// serialized expiry.
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return (uint64_t) left.deletion_time().time_since_epoch().count()
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<=> (uint64_t) right.deletion_time().time_since_epoch().count();
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}
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return std::strong_ordering::equal;
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}
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atomic_cell_or_collection atomic_cell_or_collection::copy(const abstract_type& type) const {
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if (_data.empty()) {
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return atomic_cell_or_collection();
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}
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return atomic_cell_or_collection(managed_bytes(_data));
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}
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atomic_cell_or_collection::atomic_cell_or_collection(const abstract_type& type, atomic_cell_view acv)
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: _data(acv._view)
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{
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}
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bool atomic_cell_or_collection::equals(const abstract_type& type, const atomic_cell_or_collection& other) const
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{
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if (_data.empty() || other._data.empty()) {
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return _data.empty() && other._data.empty();
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}
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if (type.is_atomic()) {
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auto a = atomic_cell_view::from_bytes(type, _data);
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auto b = atomic_cell_view::from_bytes(type, other._data);
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if (a.timestamp() != b.timestamp()) {
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return false;
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}
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if (a.is_live() != b.is_live()) {
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return false;
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}
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if (a.is_live()) {
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if (a.is_counter_update() != b.is_counter_update()) {
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return false;
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}
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if (a.is_counter_update()) {
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return a.counter_update_value() == b.counter_update_value();
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}
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if (a.is_live_and_has_ttl() != b.is_live_and_has_ttl()) {
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return false;
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}
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if (a.is_live_and_has_ttl()) {
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if (a.ttl() != b.ttl() || a.expiry() != b.expiry()) {
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return false;
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}
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}
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return a.value() == b.value();
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}
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return a.deletion_time() == b.deletion_time();
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} else {
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return as_collection_mutation().data == other.as_collection_mutation().data;
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}
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}
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size_t atomic_cell_or_collection::external_memory_usage(const abstract_type& t) const
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{
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return _data.external_memory_usage();
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}
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std::ostream&
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operator<<(std::ostream& os, const atomic_cell_view& acv) {
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if (acv.is_live()) {
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fmt::print(os, "atomic_cell{{{},ts={:d},expiry={:d},ttl={:d}}}",
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acv.is_counter_update()
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? "counter_update_value=" + to_sstring(acv.counter_update_value())
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: to_hex(to_bytes(acv.value())),
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acv.timestamp(),
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acv.is_live_and_has_ttl() ? acv.expiry().time_since_epoch().count() : -1,
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acv.is_live_and_has_ttl() ? acv.ttl().count() : 0);
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} else {
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fmt::print(os, "atomic_cell{{DEAD,ts={:d},deletion_time={:d}}}",
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acv.timestamp(), acv.deletion_time().time_since_epoch().count());
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}
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return os;
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}
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std::ostream&
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operator<<(std::ostream& os, const atomic_cell& ac) {
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return os << atomic_cell_view(ac);
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}
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std::ostream&
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operator<<(std::ostream& os, const atomic_cell_view::printer& acvp) {
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auto& type = acvp._type;
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auto& acv = acvp._cell;
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if (acv.is_live()) {
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std::ostringstream cell_value_string_builder;
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if (type.is_counter()) {
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if (acv.is_counter_update()) {
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fmt::print(cell_value_string_builder, "counter_update_value={}", acv.counter_update_value());
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} else {
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auto ccv = counter_cell_view(acv);
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fmt::print(cell_value_string_builder, "shards: {}", fmt::join(ccv.shards(), ", "));
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}
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} else {
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fmt::print(cell_value_string_builder, "{}", type.to_string(to_bytes(acv.value())));
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}
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fmt::print(os, "atomic_cell{{{},ts={:d},expiry={:d},ttl={:d}}}",
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cell_value_string_builder.str(),
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acv.timestamp(),
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acv.is_live_and_has_ttl() ? acv.expiry().time_since_epoch().count() : -1,
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acv.is_live_and_has_ttl() ? acv.ttl().count() : 0);
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} else {
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fmt::print(os, "atomic_cell{{DEAD,ts={:d},deletion_time={:d}}}",
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acv.timestamp(), acv.deletion_time().time_since_epoch().count());
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}
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return os;
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}
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std::ostream&
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operator<<(std::ostream& os, const atomic_cell::printer& acp) {
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return operator<<(os, static_cast<const atomic_cell_view::printer&>(acp));
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}
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std::ostream& operator<<(std::ostream& os, const atomic_cell_or_collection::printer& p) {
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if (p._cell._data.empty()) {
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return os << "{ null atomic_cell_or_collection }";
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}
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os << "{ ";
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if (p._cdef.type->is_multi_cell()) {
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os << "collection ";
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auto cmv = p._cell.as_collection_mutation();
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os << collection_mutation_view::printer(*p._cdef.type, cmv);
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} else {
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os << atomic_cell_view::printer(*p._cdef.type, p._cell.as_atomic_cell(p._cdef));
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}
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return os << " }";
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}
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