fb0bdcec0c
Currently, the coordinator splits the partition range at vnode (or tablet) boundaries and then tries to merge adjacent ranges which target the same replica. This is an optimization which makes less sense with tablets, which are supposed to be of substantial size. If we don't merge the ranges, then with tablets we can avoid using the multishard reader on the replica side, since each tablet lives on a single shard. The main reason to avoid a multishard reader is avoiding its complexity, and avoiding adapting it to work with tablet sharding. Currently, the multishard reader implementation makes several assumptions about shard assignment which do not hold with tablets. It assumes that shards are assigned in a round-robin fashion.
917 lines
39 KiB
C++
917 lines
39 KiB
C++
/*
|
|
* Copyright (C) 2018-present ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* SPDX-License-Identifier: AGPL-3.0-or-later
|
|
*/
|
|
|
|
#include "schema/schema_registry.hh"
|
|
#include "multishard_mutation_query.hh"
|
|
#include "mutation_query.hh"
|
|
#include "replica/database.hh"
|
|
#include "db/config.hh"
|
|
#include "query-result-writer.hh"
|
|
#include "readers/multishard.hh"
|
|
|
|
#include <seastar/core/coroutine.hh>
|
|
#include <seastar/coroutine/as_future.hh>
|
|
|
|
#include <boost/range/adaptor/reversed.hpp>
|
|
|
|
#include <fmt/ostream.h>
|
|
|
|
logging::logger mmq_log("multishard_mutation_query");
|
|
|
|
template <typename T>
|
|
using foreign_unique_ptr = foreign_ptr<std::unique_ptr<T>>;
|
|
|
|
/// Context object for a multishard read.
|
|
///
|
|
/// Handles logic related to looking up, creating, saving and cleaning up remote
|
|
/// (shard) readers for the `multishard_mutation_reader`.
|
|
/// Has a state machine for each of the shard readers. See the state transition
|
|
/// diagram below, above the declaration of `reader state`.
|
|
/// The `read_context` is a short-lived object that is only kept around for the
|
|
/// duration of a single page. A new `read_context` is created on each page and
|
|
/// is discarded at the end of the page, after the readers are either saved
|
|
/// or the process of their safe disposal was started in the background.
|
|
/// Intended usage:
|
|
/// * Create the `read_context`.
|
|
/// * Call `read_context::lookup_readers()` to find any saved readers from the
|
|
/// previous page.
|
|
/// * Create the `multishard_mutation_reader`.
|
|
/// * Fill the page.
|
|
/// * Destroy the `multishard_mutation_reader` to trigger the disposal of the
|
|
/// shard readers.
|
|
/// * Call `read_context::save_readers()` if the read didn't finish yet, that is
|
|
/// more pages are expected.
|
|
/// * Call `read_context::stop()` to initiate the cleanup of any unsaved readers
|
|
/// and their dependencies.
|
|
/// * Destroy the `read_context`.
|
|
///
|
|
/// Note:
|
|
/// 1) Each step can only be started when the previous phase has finished.
|
|
/// 2) This usage is implemented in the `do_query()` function below.
|
|
/// 3) Both, `read_context::lookup_readers()` and `read_context::save_readers()`
|
|
/// knows to do nothing when the query is not stateful and just short
|
|
/// circuit.
|
|
class read_context : public reader_lifecycle_policy_v2 {
|
|
|
|
// ( ) (O)
|
|
// | ^
|
|
// | |
|
|
// +--- inexistent ---+
|
|
// | |
|
|
// (1) | (3) |
|
|
// | |
|
|
// successful_lookup |
|
|
// | | |
|
|
// | | |
|
|
// | | (3) |
|
|
// | +---------> used
|
|
// (2) | |
|
|
// | (4) |
|
|
// | |
|
|
// +---------------> saving_state
|
|
// |
|
|
// (O)
|
|
//
|
|
// 1) lookup_readers()
|
|
// 2) save_readers()
|
|
// 3) create_reader()
|
|
// 4) destroy_reader()
|
|
enum class reader_state {
|
|
inexistent,
|
|
successful_lookup,
|
|
used,
|
|
saving,
|
|
};
|
|
|
|
struct reader_meta {
|
|
struct remote_parts {
|
|
reader_permit permit;
|
|
lw_shared_ptr<const dht::partition_range> range;
|
|
std::unique_ptr<const query::partition_slice> slice;
|
|
utils::phased_barrier::operation read_operation;
|
|
std::optional<reader_concurrency_semaphore::inactive_read_handle> handle;
|
|
std::optional<flat_mutation_reader_v2::tracked_buffer> buffer;
|
|
|
|
remote_parts(
|
|
reader_permit permit,
|
|
lw_shared_ptr<const dht::partition_range> range = nullptr,
|
|
std::unique_ptr<const query::partition_slice> slice = nullptr,
|
|
utils::phased_barrier::operation read_operation = {},
|
|
std::optional<reader_concurrency_semaphore::inactive_read_handle> handle = {})
|
|
: permit(std::move(permit))
|
|
, range(std::move(range))
|
|
, slice(std::move(slice))
|
|
, read_operation(std::move(read_operation))
|
|
, handle(std::move(handle)) {
|
|
}
|
|
};
|
|
|
|
reader_state state = reader_state::inexistent;
|
|
foreign_unique_ptr<remote_parts> rparts;
|
|
std::optional<flat_mutation_reader_v2::tracked_buffer> dismantled_buffer;
|
|
|
|
reader_meta() = default;
|
|
|
|
// Remote constructor.
|
|
reader_meta(reader_state s, std::optional<remote_parts> rp = {})
|
|
: state(s) {
|
|
if (rp) {
|
|
rparts = make_foreign(std::make_unique<remote_parts>(std::move(*rp)));
|
|
}
|
|
}
|
|
|
|
flat_mutation_reader_v2::tracked_buffer& get_dismantled_buffer(const reader_permit& permit) {
|
|
if (!dismantled_buffer) {
|
|
dismantled_buffer.emplace(permit);
|
|
}
|
|
return *dismantled_buffer;
|
|
}
|
|
};
|
|
|
|
struct dismantle_buffer_stats {
|
|
size_t partitions = 0;
|
|
size_t fragments = 0;
|
|
size_t bytes = 0;
|
|
size_t discarded_partitions = 0;
|
|
size_t discarded_fragments = 0;
|
|
size_t discarded_bytes = 0;
|
|
|
|
void add(const mutation_fragment_v2& mf) {
|
|
partitions += unsigned(mf.is_partition_start());
|
|
++fragments;
|
|
bytes += mf.memory_usage();
|
|
}
|
|
void add(const schema& s, const range_tombstone_change& rtc) {
|
|
++fragments;
|
|
bytes += rtc.memory_usage(s);
|
|
}
|
|
void add(const schema& s, const static_row& sr) {
|
|
++fragments;
|
|
bytes += sr.memory_usage(s);
|
|
}
|
|
void add(const schema& s, const partition_start& ps) {
|
|
++partitions;
|
|
++fragments;
|
|
bytes += ps.memory_usage(s);
|
|
}
|
|
void add_discarded(const mutation_fragment_v2& mf) {
|
|
discarded_partitions += unsigned(mf.is_partition_start());
|
|
++discarded_fragments;
|
|
discarded_bytes += mf.memory_usage();
|
|
}
|
|
void add_discarded(const schema& s, const range_tombstone_change& rtc) {
|
|
++discarded_fragments;
|
|
discarded_bytes += rtc.memory_usage(s);
|
|
}
|
|
void add_discarded(const schema& s, const static_row& sr) {
|
|
++discarded_fragments;
|
|
discarded_bytes += sr.memory_usage(s);
|
|
}
|
|
void add_discarded(const schema& s, const partition_start& ps) {
|
|
++discarded_partitions;
|
|
++discarded_fragments;
|
|
discarded_bytes += ps.memory_usage(s);
|
|
}
|
|
friend std::ostream& operator<<(std::ostream& os, const dismantle_buffer_stats& s) {
|
|
os << format(
|
|
"kept {} partitions/{} fragments/{} bytes, discarded {} partitions/{} fragments/{} bytes",
|
|
s.partitions,
|
|
s.fragments,
|
|
s.bytes,
|
|
s.discarded_partitions,
|
|
s.discarded_fragments,
|
|
s.discarded_bytes);
|
|
return os;
|
|
}
|
|
};
|
|
|
|
distributed<replica::database>& _db;
|
|
schema_ptr _schema;
|
|
locator::effective_replication_map_ptr _erm;
|
|
reader_permit _permit;
|
|
const query::read_command& _cmd;
|
|
const dht::partition_range_vector& _ranges;
|
|
tracing::trace_state_ptr _trace_state;
|
|
|
|
// One for each shard. Index is shard id.
|
|
std::vector<reader_meta> _readers;
|
|
std::vector<reader_concurrency_semaphore*> _semaphores;
|
|
|
|
static std::string_view reader_state_to_string(reader_state rs);
|
|
|
|
dismantle_buffer_stats dismantle_combined_buffer(flat_mutation_reader_v2::tracked_buffer combined_buffer, const dht::decorated_key& pkey);
|
|
dismantle_buffer_stats dismantle_compaction_state(detached_compaction_state compaction_state);
|
|
future<> save_reader(shard_id shard, full_position_view last_pos);
|
|
|
|
public:
|
|
read_context(distributed<replica::database>& db, schema_ptr s, locator::effective_replication_map_ptr erm,
|
|
const query::read_command& cmd, const dht::partition_range_vector& ranges,
|
|
tracing::trace_state_ptr trace_state, db::timeout_clock::time_point timeout)
|
|
: _db(db)
|
|
, _schema(std::move(s))
|
|
, _erm(std::move(erm))
|
|
, _permit(_db.local().get_reader_concurrency_semaphore().make_tracking_only_permit(_schema.get(), "multishard-mutation-query", timeout, trace_state))
|
|
, _cmd(cmd)
|
|
, _ranges(ranges)
|
|
, _trace_state(std::move(trace_state))
|
|
, _semaphores(smp::count, nullptr) {
|
|
_readers.resize(smp::count);
|
|
_permit.set_max_result_size(get_max_result_size());
|
|
|
|
if (!_erm->get_replication_strategy().is_vnode_based()) {
|
|
// The algorithm is full of assumptions about shard assignment being round-robin, static, and full.
|
|
// This does not hold for tablets. We chose to avoid this algorithm rather than adapting it.
|
|
// The coordinator should split ranges accordingly.
|
|
on_internal_error(mmq_log, format("multishard reader cannot be used on tables with non-static sharding: {}.{}",
|
|
_schema->ks_name(), _schema->cf_name()));
|
|
}
|
|
}
|
|
|
|
read_context(read_context&&) = delete;
|
|
read_context(const read_context&) = delete;
|
|
|
|
read_context& operator=(read_context&&) = delete;
|
|
read_context& operator=(const read_context&) = delete;
|
|
|
|
distributed<replica::database>& db() {
|
|
return _db;
|
|
}
|
|
|
|
reader_permit permit() const {
|
|
return _permit;
|
|
}
|
|
|
|
const locator::effective_replication_map_ptr& erm() const {
|
|
return _erm;
|
|
}
|
|
|
|
query::max_result_size get_max_result_size() {
|
|
return _cmd.max_result_size ? *_cmd.max_result_size : _db.local().get_unlimited_query_max_result_size();
|
|
}
|
|
|
|
virtual flat_mutation_reader_v2 create_reader(
|
|
schema_ptr schema,
|
|
reader_permit permit,
|
|
const dht::partition_range& pr,
|
|
const query::partition_slice& ps,
|
|
tracing::trace_state_ptr trace_state,
|
|
mutation_reader::forwarding fwd_mr) override;
|
|
|
|
virtual const dht::partition_range* get_read_range() const override;
|
|
|
|
virtual void update_read_range(lw_shared_ptr<const dht::partition_range> range) override;
|
|
|
|
virtual future<> destroy_reader(stopped_reader reader) noexcept override;
|
|
|
|
virtual reader_concurrency_semaphore& semaphore() override {
|
|
const auto shard = this_shard_id();
|
|
if (!_semaphores[shard]) {
|
|
_semaphores[shard] = &_db.local().get_reader_concurrency_semaphore();
|
|
}
|
|
return *_semaphores[shard];
|
|
}
|
|
|
|
virtual future<reader_permit> obtain_reader_permit(schema_ptr schema, const char* const description, db::timeout_clock::time_point timeout, tracing::trace_state_ptr trace_ptr) override {
|
|
const auto shard = this_shard_id();
|
|
auto& rm = _readers[shard];
|
|
if (rm.state == reader_state::successful_lookup) {
|
|
rm.rparts->permit.set_max_result_size(get_max_result_size());
|
|
co_return rm.rparts->permit;
|
|
}
|
|
auto permit = co_await _db.local().obtain_reader_permit(std::move(schema), description, timeout, std::move(trace_ptr));
|
|
permit.set_max_result_size(get_max_result_size());
|
|
co_return permit;
|
|
}
|
|
|
|
future<> lookup_readers(db::timeout_clock::time_point timeout) noexcept;
|
|
|
|
future<> save_readers(flat_mutation_reader_v2::tracked_buffer unconsumed_buffer, std::optional<detached_compaction_state> compaction_state,
|
|
full_position last_pos) noexcept;
|
|
|
|
future<> stop();
|
|
};
|
|
|
|
std::string_view read_context::reader_state_to_string(reader_state rs) {
|
|
switch (rs) {
|
|
case reader_state::inexistent:
|
|
return "inexistent";
|
|
case reader_state::successful_lookup:
|
|
return "successful_lookup";
|
|
case reader_state::used:
|
|
return "used";
|
|
case reader_state::saving:
|
|
return "saving";
|
|
}
|
|
// If we got here, we are logging an error anyway, so the above layers
|
|
// (should) have detected the invalid state.
|
|
return "invalid";
|
|
}
|
|
|
|
flat_mutation_reader_v2 read_context::create_reader(
|
|
schema_ptr schema,
|
|
reader_permit permit,
|
|
const dht::partition_range& pr,
|
|
const query::partition_slice& ps,
|
|
tracing::trace_state_ptr trace_state,
|
|
mutation_reader::forwarding fwd_mr) {
|
|
const auto shard = this_shard_id();
|
|
auto& rm = _readers[shard];
|
|
|
|
if (rm.state != reader_state::used && rm.state != reader_state::successful_lookup && rm.state != reader_state::inexistent) {
|
|
auto msg = format("Unexpected request to create reader for shard {}."
|
|
" The reader is expected to be in either `used`, `successful_lookup` or `inexistent` state,"
|
|
" but is in `{}` state instead.", shard, reader_state_to_string(rm.state));
|
|
mmq_log.warn(msg.c_str());
|
|
throw std::logic_error(msg.c_str());
|
|
}
|
|
|
|
// The reader is either in inexistent or successful lookup state.
|
|
if (rm.state == reader_state::successful_lookup) {
|
|
if (auto reader_opt = semaphore().unregister_inactive_read(std::move(*rm.rparts->handle))) {
|
|
rm.state = reader_state::used;
|
|
// The saved reader permit is expected to be the same one passed to create_reader,
|
|
// as returned from obtain_reader_permit()
|
|
if (reader_opt->permit() != permit) {
|
|
on_internal_error(mmq_log, "read_context::create_reader(): passed-in permit is different than saved reader's permit");
|
|
}
|
|
permit.set_trace_state(trace_state);
|
|
return std::move(*reader_opt);
|
|
}
|
|
}
|
|
|
|
auto& table = _db.local().find_column_family(schema);
|
|
|
|
auto remote_parts = reader_meta::remote_parts(
|
|
std::move(permit),
|
|
make_lw_shared<const dht::partition_range>(pr),
|
|
std::make_unique<const query::partition_slice>(ps),
|
|
table.read_in_progress());
|
|
|
|
if (!rm.rparts) {
|
|
rm.rparts = make_foreign(std::make_unique<reader_meta::remote_parts>(std::move(remote_parts)));
|
|
} else {
|
|
*rm.rparts = std::move(remote_parts);
|
|
}
|
|
|
|
rm.state = reader_state::used;
|
|
|
|
return table.as_mutation_source().make_reader_v2(std::move(schema), rm.rparts->permit, *rm.rparts->range, *rm.rparts->slice,
|
|
std::move(trace_state), streamed_mutation::forwarding::no, fwd_mr);
|
|
}
|
|
|
|
const dht::partition_range* read_context::get_read_range() const {
|
|
auto& rm = _readers[this_shard_id()];
|
|
if (rm.rparts) {
|
|
return rm.rparts->range.get();
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
void read_context::update_read_range(lw_shared_ptr<const dht::partition_range> range) {
|
|
auto& rm = _readers[this_shard_id()];
|
|
rm.rparts->range = std::move(range);
|
|
}
|
|
|
|
future<> read_context::destroy_reader(stopped_reader reader) noexcept {
|
|
auto& rm = _readers[this_shard_id()];
|
|
|
|
if (rm.state == reader_state::used) {
|
|
rm.state = reader_state::saving;
|
|
rm.rparts->handle = std::move(reader.handle);
|
|
rm.rparts->buffer = std::move(reader.unconsumed_fragments);
|
|
} else {
|
|
mmq_log.warn(
|
|
"Unexpected request to dismantle reader in state `{}`."
|
|
" Reader was not created nor is in the process of being created.",
|
|
reader_state_to_string(rm.state));
|
|
}
|
|
return make_ready_future<>();
|
|
}
|
|
|
|
future<> read_context::stop() {
|
|
return parallel_for_each(smp::all_cpus(), [this] (unsigned shard) {
|
|
if (_readers[shard].rparts) {
|
|
return _db.invoke_on(shard, [&rparts_fptr = _readers[shard].rparts] (replica::database& db) mutable {
|
|
auto rparts = rparts_fptr.release();
|
|
if (rparts->handle) {
|
|
auto reader_opt = rparts->permit.semaphore().unregister_inactive_read(std::move(*rparts->handle));
|
|
if (reader_opt) {
|
|
return reader_opt->close().then([rparts = std::move(rparts)] { });
|
|
}
|
|
}
|
|
return make_ready_future<>();
|
|
});
|
|
}
|
|
return make_ready_future<>();
|
|
});
|
|
}
|
|
|
|
read_context::dismantle_buffer_stats read_context::dismantle_combined_buffer(flat_mutation_reader_v2::tracked_buffer combined_buffer,
|
|
const dht::decorated_key& pkey) {
|
|
auto& sharder = _erm->get_sharder(*_schema);
|
|
|
|
std::vector<mutation_fragment_v2> tmp_buffer;
|
|
dismantle_buffer_stats stats;
|
|
|
|
auto rit = std::reverse_iterator(combined_buffer.end());
|
|
const auto rend = std::reverse_iterator(combined_buffer.begin());
|
|
for (;rit != rend; ++rit) {
|
|
if (rit->is_partition_start()) {
|
|
const auto shard = sharder.shard_of(rit->as_partition_start().key().token());
|
|
|
|
// It is possible that the reader this partition originates from
|
|
// does not exist anymore. Either because we failed stopping it or
|
|
// because it was evicted.
|
|
if (_readers[shard].state != reader_state::saving) {
|
|
for (auto& smf : tmp_buffer) {
|
|
stats.add_discarded(smf);
|
|
}
|
|
stats.add_discarded(*rit);
|
|
tmp_buffer.clear();
|
|
continue;
|
|
}
|
|
|
|
auto& shard_buffer = _readers[shard].get_dismantled_buffer(_permit);
|
|
for (auto& smf : tmp_buffer) {
|
|
stats.add(smf);
|
|
shard_buffer.emplace_front(std::move(smf));
|
|
}
|
|
stats.add(*rit);
|
|
shard_buffer.emplace_front(std::move(*rit));
|
|
tmp_buffer.clear();
|
|
} else {
|
|
tmp_buffer.emplace_back(std::move(*rit));
|
|
}
|
|
}
|
|
|
|
const auto shard = sharder.shard_of(pkey.token());
|
|
auto& shard_buffer = _readers[shard].get_dismantled_buffer(_permit);
|
|
for (auto& smf : tmp_buffer) {
|
|
stats.add(smf);
|
|
shard_buffer.emplace_front(std::move(smf));
|
|
}
|
|
|
|
return stats;
|
|
}
|
|
|
|
read_context::dismantle_buffer_stats read_context::dismantle_compaction_state(detached_compaction_state compaction_state) {
|
|
auto stats = dismantle_buffer_stats();
|
|
auto& sharder = _erm->get_sharder(*_schema);
|
|
const auto shard = sharder.shard_of(compaction_state.partition_start.key().token());
|
|
|
|
auto& rtc_opt = compaction_state.current_tombstone;
|
|
|
|
// It is possible that the reader this partition originates from does not
|
|
// exist anymore. Either because we failed stopping it or because it was
|
|
// evicted.
|
|
if (_readers[shard].state != reader_state::saving) {
|
|
if (rtc_opt) {
|
|
stats.add_discarded(*_schema, *rtc_opt);
|
|
}
|
|
if (compaction_state.static_row) {
|
|
stats.add_discarded(*_schema, *compaction_state.static_row);
|
|
}
|
|
stats.add_discarded(*_schema, compaction_state.partition_start);
|
|
return stats;
|
|
}
|
|
|
|
auto& shard_buffer = _readers[shard].get_dismantled_buffer(_permit);
|
|
|
|
if (rtc_opt) {
|
|
stats.add(*_schema, *rtc_opt);
|
|
shard_buffer.emplace_front(*_schema, _permit, std::move(*rtc_opt));
|
|
}
|
|
|
|
if (compaction_state.static_row) {
|
|
stats.add(*_schema, *compaction_state.static_row);
|
|
shard_buffer.emplace_front(*_schema, _permit, std::move(*compaction_state.static_row));
|
|
}
|
|
|
|
stats.add(*_schema, compaction_state.partition_start);
|
|
shard_buffer.emplace_front(*_schema, _permit, std::move(compaction_state.partition_start));
|
|
|
|
return stats;
|
|
}
|
|
|
|
future<> read_context::save_reader(shard_id shard, full_position_view last_pos) {
|
|
return do_with(std::exchange(_readers[shard], {}), [this, shard, last_pos] (reader_meta& rm) mutable {
|
|
return _db.invoke_on(shard, [query_uuid = _cmd.query_uuid, query_ranges = _ranges, &rm,
|
|
last_pos, gts = tracing::global_trace_state_ptr(_trace_state)] (replica::database& db) mutable {
|
|
try {
|
|
auto rparts = rm.rparts.release(); // avoid another round-trip when destroying rparts
|
|
auto reader_opt = rparts->permit.semaphore().unregister_inactive_read(std::move(*rparts->handle));
|
|
|
|
if (!reader_opt) {
|
|
return make_ready_future<>();
|
|
}
|
|
flat_mutation_reader_v2_opt reader = std::move(*reader_opt);
|
|
|
|
size_t fragments = 0;
|
|
const auto size_before = reader->buffer_size();
|
|
const auto& schema = *reader->schema();
|
|
|
|
if (rparts->buffer) {
|
|
fragments += rparts->buffer->size();
|
|
auto rit = std::reverse_iterator(rparts->buffer->end());
|
|
auto rend = std::reverse_iterator(rparts->buffer->begin());
|
|
for (; rit != rend; ++rit) {
|
|
reader->unpop_mutation_fragment(std::move(*rit));
|
|
}
|
|
}
|
|
if (rm.dismantled_buffer) {
|
|
fragments += rm.dismantled_buffer->size();
|
|
auto rit = std::reverse_iterator(rm.dismantled_buffer->cend());
|
|
auto rend = std::reverse_iterator(rm.dismantled_buffer->cbegin());
|
|
for (; rit != rend; ++rit) {
|
|
// Copy the fragment, the buffer is on another shard.
|
|
reader->unpop_mutation_fragment(mutation_fragment_v2(schema, rparts->permit, *rit));
|
|
}
|
|
}
|
|
|
|
const auto size_after = reader->buffer_size();
|
|
|
|
auto querier = query::shard_mutation_querier(
|
|
std::move(query_ranges),
|
|
std::move(rparts->range),
|
|
std::move(rparts->slice),
|
|
std::move(*reader),
|
|
std::move(rparts->permit),
|
|
last_pos);
|
|
|
|
db.get_querier_cache().insert_shard_querier(query_uuid, std::move(querier), gts.get());
|
|
|
|
db.get_stats().multishard_query_unpopped_fragments += fragments;
|
|
db.get_stats().multishard_query_unpopped_bytes += (size_after - size_before);
|
|
return make_ready_future<>();
|
|
} catch (...) {
|
|
// We don't want to fail a read just because of a failure to
|
|
// save any of the readers.
|
|
mmq_log.debug("Failed to save reader: {}", std::current_exception());
|
|
++db.get_stats().multishard_query_failed_reader_saves;
|
|
return make_ready_future<>();
|
|
}
|
|
}).handle_exception([this, shard] (std::exception_ptr e) {
|
|
// We don't want to fail a read just because of a failure to
|
|
// save any of the readers.
|
|
mmq_log.debug("Failed to save reader on shard {}: {}", shard, e);
|
|
// This will account the failure on the local shard but we don't
|
|
// know where exactly the failure happened anyway.
|
|
++_db.local().get_stats().multishard_query_failed_reader_saves;
|
|
});
|
|
});
|
|
}
|
|
|
|
future<> read_context::lookup_readers(db::timeout_clock::time_point timeout) noexcept {
|
|
if (!_cmd.query_uuid || _cmd.is_first_page) {
|
|
return make_ready_future<>();
|
|
}
|
|
try {
|
|
return _db.invoke_on_all([this, cmd = &_cmd, ranges = &_ranges, gs = global_schema_ptr(_schema),
|
|
gts = tracing::global_trace_state_ptr(_trace_state), timeout] (replica::database& db) mutable -> future<> {
|
|
auto schema = gs.get();
|
|
auto& table = db.find_column_family(schema);
|
|
auto& semaphore = this->semaphore();
|
|
auto shard = this_shard_id();
|
|
|
|
auto querier_opt = db.get_querier_cache().lookup_shard_mutation_querier(cmd->query_uuid, *schema, *ranges, cmd->slice, gts.get(), timeout);
|
|
|
|
if (!querier_opt) {
|
|
_readers[shard] = reader_meta(reader_state::inexistent);
|
|
co_return;
|
|
}
|
|
|
|
auto& q = *querier_opt;
|
|
|
|
if (&q.permit().semaphore() != &semaphore) {
|
|
co_await q.close();
|
|
on_internal_error(mmq_log, format("looked-up reader belongs to different semaphore than the one appropriate for this query class: "
|
|
"looked-up reader belongs to {} (0x{:x}) the query class appropriate is {} (0x{:x})",
|
|
q.permit().semaphore().name(),
|
|
reinterpret_cast<uintptr_t>(&q.permit().semaphore()),
|
|
semaphore.name(),
|
|
reinterpret_cast<uintptr_t>(&semaphore)));
|
|
}
|
|
|
|
// At this point the readers is passed to the semaphore and we are
|
|
// safe w.r.t. exceptions. The code between this point and obtaining
|
|
// the querier must take care of closing it if an error happens.
|
|
auto handle = semaphore.register_inactive_read(std::move(q).reader());
|
|
_readers[shard] = reader_meta(
|
|
reader_state::successful_lookup,
|
|
reader_meta::remote_parts(q.permit(), std::move(q).reader_range(), std::move(q).reader_slice(), table.read_in_progress(),
|
|
std::move(handle)));
|
|
});
|
|
} catch (...) {
|
|
return current_exception_as_future();
|
|
}
|
|
}
|
|
|
|
future<> read_context::save_readers(flat_mutation_reader_v2::tracked_buffer unconsumed_buffer, std::optional<detached_compaction_state> compaction_state,
|
|
full_position last_pos) noexcept {
|
|
if (!_cmd.query_uuid) {
|
|
co_return;
|
|
}
|
|
|
|
const auto cb_stats = dismantle_combined_buffer(std::move(unconsumed_buffer), dht::decorate_key(*_schema, last_pos.partition));
|
|
tracing::trace(_trace_state, "Dismantled combined buffer: {}", cb_stats);
|
|
|
|
auto cs_stats = dismantle_buffer_stats{};
|
|
if (compaction_state) {
|
|
cs_stats = dismantle_compaction_state(std::move(*compaction_state));
|
|
tracing::trace(_trace_state, "Dismantled compaction state: {}", cs_stats);
|
|
} else {
|
|
tracing::trace(_trace_state, "No compaction state to dismantle, partition exhausted", cs_stats);
|
|
}
|
|
|
|
co_await parallel_for_each(boost::irange(0u, smp::count), [this, &last_pos] (shard_id shard) {
|
|
auto& rm = _readers[shard];
|
|
if (rm.state == reader_state::successful_lookup || rm.state == reader_state::saving) {
|
|
return save_reader(shard, last_pos);
|
|
}
|
|
|
|
return make_ready_future<>();
|
|
});
|
|
}
|
|
|
|
namespace {
|
|
|
|
template <typename ResultBuilder>
|
|
requires std::is_nothrow_move_constructible_v<typename ResultBuilder::result_type>
|
|
struct page_consume_result {
|
|
typename ResultBuilder::result_type result;
|
|
flat_mutation_reader_v2::tracked_buffer unconsumed_fragments;
|
|
lw_shared_ptr<compact_for_query_state_v2> compaction_state;
|
|
|
|
page_consume_result(typename ResultBuilder::result_type&& result, flat_mutation_reader_v2::tracked_buffer&& unconsumed_fragments,
|
|
lw_shared_ptr<compact_for_query_state_v2>&& compaction_state) noexcept
|
|
: result(std::move(result))
|
|
, unconsumed_fragments(std::move(unconsumed_fragments))
|
|
, compaction_state(std::move(compaction_state)) {
|
|
}
|
|
};
|
|
|
|
// A special-purpose multi-range reader for multishard reads
|
|
//
|
|
// It is different from the "stock" multi-range reader
|
|
// (make_flat_multi_range_reader()) in the following ways:
|
|
// * It guarantees that a buffer never crosses two ranges.
|
|
// * It guarantees that after calling `fill_buffer()` the underlying reader's
|
|
// buffer's *entire* content is moved into its own buffer. In other words,
|
|
// calling detach_buffer() after fill_buffer() is guranted to get all
|
|
// fragments fetched in that call, none will be left in the underlying
|
|
// reader's one.
|
|
class multi_range_reader : public flat_mutation_reader_v2::impl {
|
|
flat_mutation_reader_v2 _reader;
|
|
dht::partition_range_vector::const_iterator _it;
|
|
const dht::partition_range_vector::const_iterator _end;
|
|
|
|
public:
|
|
multi_range_reader(schema_ptr s, reader_permit permit, flat_mutation_reader_v2 rd, const dht::partition_range_vector& ranges)
|
|
: impl(std::move(s), std::move(permit)) , _reader(std::move(rd)) , _it(ranges.begin()) , _end(ranges.end()) { }
|
|
|
|
virtual future<> fill_buffer() override {
|
|
if (is_end_of_stream()) {
|
|
co_return;
|
|
}
|
|
while (is_buffer_empty()) {
|
|
if (_reader.is_buffer_empty() && _reader.is_end_of_stream()) {
|
|
if (++_it == _end) {
|
|
_end_of_stream = true;
|
|
break;
|
|
} else {
|
|
co_await _reader.fast_forward_to(*_it);
|
|
}
|
|
}
|
|
if (_reader.is_buffer_empty()) {
|
|
co_await _reader.fill_buffer();
|
|
}
|
|
_reader.move_buffer_content_to(*this);
|
|
}
|
|
}
|
|
|
|
virtual future<> fast_forward_to(const dht::partition_range&) override {
|
|
return make_exception_future<>(make_backtraced_exception_ptr<std::bad_function_call>());
|
|
}
|
|
|
|
virtual future<> fast_forward_to(position_range) override {
|
|
return make_exception_future<>(make_backtraced_exception_ptr<std::bad_function_call>());
|
|
}
|
|
|
|
virtual future<> next_partition() override {
|
|
clear_buffer_to_next_partition();
|
|
if (is_buffer_empty() && !is_end_of_stream()) {
|
|
return _reader.next_partition();
|
|
}
|
|
return make_ready_future<>();
|
|
}
|
|
|
|
virtual future<> close() noexcept override {
|
|
return _reader.close();
|
|
}
|
|
};
|
|
|
|
|
|
} // anonymous namespace
|
|
|
|
template <typename ResultBuilder>
|
|
future<page_consume_result<ResultBuilder>> read_page(
|
|
shared_ptr<read_context> ctx,
|
|
schema_ptr s,
|
|
const query::read_command& cmd,
|
|
const dht::partition_range_vector& ranges,
|
|
tracing::trace_state_ptr trace_state,
|
|
noncopyable_function<ResultBuilder(const compact_for_query_state_v2&)> result_builder_factory) {
|
|
auto compaction_state = make_lw_shared<compact_for_query_state_v2>(*s, cmd.timestamp, cmd.slice, cmd.get_row_limit(),
|
|
cmd.partition_limit);
|
|
|
|
auto reader = make_multishard_combining_reader_v2(ctx, s, ctx->erm(), ctx->permit(), ranges.front(), cmd.slice,
|
|
trace_state, mutation_reader::forwarding(ranges.size() > 1));
|
|
if (ranges.size() > 1) {
|
|
reader = make_flat_mutation_reader_v2<multi_range_reader>(s, ctx->permit(), std::move(reader), ranges);
|
|
}
|
|
|
|
// Use coroutine::as_future to prevent exception on timesout.
|
|
auto f = co_await coroutine::as_future(query::consume_page(reader, compaction_state, cmd.slice, result_builder_factory(*compaction_state), cmd.get_row_limit(),
|
|
cmd.partition_limit, cmd.timestamp));
|
|
if (!f.failed()) {
|
|
// no exceptions are thrown in this block
|
|
auto result = std::move(f).get0();
|
|
const auto& cstats = compaction_state->stats();
|
|
tracing::trace(trace_state, "Page stats: {} partition(s), {} static row(s) ({} live, {} dead), {} clustering row(s) ({} live, {} dead) and {} range tombstone(s)",
|
|
cstats.partitions,
|
|
cstats.static_rows.total(),
|
|
cstats.static_rows.live,
|
|
cstats.static_rows.dead,
|
|
cstats.clustering_rows.total(),
|
|
cstats.clustering_rows.live,
|
|
cstats.clustering_rows.dead,
|
|
cstats.range_tombstones);
|
|
auto buffer = reader.detach_buffer();
|
|
co_await reader.close();
|
|
// page_consume_result cannot fail so there's no risk of double-closing reader.
|
|
co_return page_consume_result<ResultBuilder>(std::move(result), std::move(buffer), std::move(compaction_state));
|
|
}
|
|
|
|
co_await reader.close();
|
|
co_return coroutine::exception(f.get_exception());
|
|
}
|
|
|
|
template <typename ResultBuilder>
|
|
future<typename ResultBuilder::result_type> do_query(
|
|
distributed<replica::database>& db,
|
|
schema_ptr s,
|
|
const query::read_command& cmd,
|
|
const dht::partition_range_vector& ranges,
|
|
tracing::trace_state_ptr trace_state,
|
|
db::timeout_clock::time_point timeout,
|
|
noncopyable_function<ResultBuilder(const compact_for_query_state_v2&)> result_builder_factory) {
|
|
auto& table = db.local().find_column_family(s);
|
|
auto erm = table.get_effective_replication_map();
|
|
auto ctx = seastar::make_shared<read_context>(db, s, erm, cmd, ranges, trace_state, timeout);
|
|
|
|
// Use coroutine::as_future to prevent exception on timesout.
|
|
auto f = co_await coroutine::as_future(ctx->lookup_readers(timeout).then([&, result_builder_factory = std::move(result_builder_factory)] () mutable {
|
|
return read_page<ResultBuilder>(ctx, s, cmd, ranges, trace_state, std::move(result_builder_factory));
|
|
}).then([&] (page_consume_result<ResultBuilder> r) -> future<typename ResultBuilder::result_type> {
|
|
if (r.compaction_state->are_limits_reached() || r.result.is_short_read()) {
|
|
// Must call before calling `detach_state()`.
|
|
auto last_pos = *r.compaction_state->current_full_position();
|
|
co_await ctx->save_readers(std::move(r.unconsumed_fragments), std::move(*r.compaction_state).detach_state(), std::move(last_pos));
|
|
}
|
|
co_return std::move(r.result);
|
|
}));
|
|
co_await ctx->stop();
|
|
if (f.failed()) {
|
|
co_return coroutine::exception(f.get_exception());
|
|
}
|
|
co_return f.get0();
|
|
}
|
|
|
|
template <typename ResultBuilder>
|
|
static future<std::tuple<foreign_ptr<lw_shared_ptr<typename ResultBuilder::result_type>>, cache_temperature>> do_query_on_all_shards(
|
|
distributed<replica::database>& db,
|
|
schema_ptr s,
|
|
const query::read_command& cmd,
|
|
const dht::partition_range_vector& ranges,
|
|
tracing::trace_state_ptr trace_state,
|
|
db::timeout_clock::time_point timeout,
|
|
std::function<ResultBuilder(query::result_memory_accounter&&, const compact_for_query_state_v2&)> result_builder_factory) {
|
|
if (cmd.get_row_limit() == 0 || cmd.slice.partition_row_limit() == 0 || cmd.partition_limit == 0) {
|
|
co_return std::tuple(
|
|
make_foreign(make_lw_shared<typename ResultBuilder::result_type>()),
|
|
db.local().find_column_family(s).get_global_cache_hit_rate());
|
|
}
|
|
|
|
auto& local_db = db.local();
|
|
auto& stats = local_db.get_stats();
|
|
const auto short_read_allowed = query::short_read(cmd.slice.options.contains<query::partition_slice::option::allow_short_read>());
|
|
|
|
try {
|
|
auto accounter = co_await local_db.get_result_memory_limiter().new_mutation_read(*cmd.max_result_size, short_read_allowed);
|
|
|
|
auto result = co_await do_query<ResultBuilder>(db, s, cmd, ranges, std::move(trace_state), timeout,
|
|
[result_builder_factory, accounter = std::move(accounter)] (const compact_for_query_state_v2& compaction_state) mutable {
|
|
return result_builder_factory(std::move(accounter), compaction_state);
|
|
});
|
|
|
|
++stats.total_reads;
|
|
stats.short_mutation_queries += bool(result.is_short_read());
|
|
auto hit_rate = local_db.find_column_family(s).get_global_cache_hit_rate();
|
|
co_return std::tuple(make_foreign(make_lw_shared<typename ResultBuilder::result_type>(std::move(result))), hit_rate);
|
|
} catch (...) {
|
|
++stats.total_reads_failed;
|
|
throw;
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
|
|
class mutation_query_result_builder {
|
|
public:
|
|
using result_type = reconcilable_result;
|
|
|
|
private:
|
|
reconcilable_result_builder _builder;
|
|
|
|
public:
|
|
mutation_query_result_builder(const schema& s, const query::partition_slice& slice, query::result_memory_accounter&& accounter)
|
|
: _builder(s, slice, std::move(accounter)) { }
|
|
|
|
void consume_new_partition(const dht::decorated_key& dk) { _builder.consume_new_partition(dk); }
|
|
void consume(tombstone t) { _builder.consume(t); }
|
|
stop_iteration consume(static_row&& sr, tombstone t, bool is_alive) { return _builder.consume(std::move(sr), t, is_alive); }
|
|
stop_iteration consume(clustering_row&& cr, row_tombstone t, bool is_alive) { return _builder.consume(std::move(cr), t, is_alive); }
|
|
stop_iteration consume(range_tombstone_change&& rtc) { return _builder.consume(std::move(rtc)); }
|
|
stop_iteration consume_end_of_partition() { return _builder.consume_end_of_partition(); }
|
|
result_type consume_end_of_stream() { return _builder.consume_end_of_stream(); }
|
|
};
|
|
|
|
class data_query_result_builder {
|
|
public:
|
|
using result_type = query::result;
|
|
|
|
private:
|
|
const compact_for_query_state_v2& _compaction_state;
|
|
std::unique_ptr<query::result::builder> _res_builder;
|
|
query_result_builder _builder;
|
|
|
|
public:
|
|
data_query_result_builder(const schema& s, const query::partition_slice& slice, query::result_options opts,
|
|
query::result_memory_accounter&& accounter, const compact_for_query_state_v2& compaction_state, uint64_t tombstone_limit)
|
|
: _compaction_state(compaction_state)
|
|
, _res_builder(std::make_unique<query::result::builder>(slice, opts, std::move(accounter), tombstone_limit))
|
|
, _builder(s, *_res_builder) { }
|
|
|
|
void consume_new_partition(const dht::decorated_key& dk) { _builder.consume_new_partition(dk); }
|
|
void consume(tombstone t) { _builder.consume(t); }
|
|
stop_iteration consume(static_row&& sr, tombstone t, bool is_alive) { return _builder.consume(std::move(sr), t, is_alive); }
|
|
stop_iteration consume(clustering_row&& cr, row_tombstone t, bool is_alive) { return _builder.consume(std::move(cr), t, is_alive); }
|
|
stop_iteration consume(range_tombstone_change&& rtc) { return _builder.consume(std::move(rtc)); }
|
|
stop_iteration consume_end_of_partition() { return _builder.consume_end_of_partition(); }
|
|
result_type consume_end_of_stream() {
|
|
_builder.consume_end_of_stream();
|
|
if (_compaction_state.are_limits_reached() || _res_builder->is_short_read()) {
|
|
return _res_builder->build(_compaction_state.current_full_position());
|
|
}
|
|
return _res_builder->build();
|
|
}
|
|
};
|
|
|
|
} // anonymous namespace
|
|
|
|
future<std::tuple<foreign_ptr<lw_shared_ptr<reconcilable_result>>, cache_temperature>> query_mutations_on_all_shards(
|
|
distributed<replica::database>& db,
|
|
schema_ptr table_schema,
|
|
const query::read_command& cmd,
|
|
const dht::partition_range_vector& ranges,
|
|
tracing::trace_state_ptr trace_state,
|
|
db::timeout_clock::time_point timeout) {
|
|
schema_ptr query_schema = cmd.slice.is_reversed() ? table_schema->make_reversed() : table_schema;
|
|
|
|
return do_query_on_all_shards<mutation_query_result_builder>(db, query_schema, cmd, ranges, std::move(trace_state), timeout,
|
|
[table_schema, &cmd] (query::result_memory_accounter&& accounter, const compact_for_query_state_v2& compaction_state) {
|
|
return mutation_query_result_builder(*table_schema, cmd.slice, std::move(accounter));
|
|
});
|
|
}
|
|
|
|
future<std::tuple<foreign_ptr<lw_shared_ptr<query::result>>, cache_temperature>> query_data_on_all_shards(
|
|
distributed<replica::database>& db,
|
|
schema_ptr table_schema,
|
|
const query::read_command& cmd,
|
|
const dht::partition_range_vector& ranges,
|
|
query::result_options opts,
|
|
tracing::trace_state_ptr trace_state,
|
|
db::timeout_clock::time_point timeout) {
|
|
schema_ptr query_schema = cmd.slice.is_reversed() ? table_schema->make_reversed() : table_schema;
|
|
|
|
return do_query_on_all_shards<data_query_result_builder>(db, query_schema, cmd, ranges, std::move(trace_state), timeout,
|
|
[table_schema, &cmd, opts] (query::result_memory_accounter&& accounter, const compact_for_query_state_v2& compaction_state) {
|
|
return data_query_result_builder(*table_schema, cmd.slice, opts, std::move(accounter), compaction_state, cmd.tombstone_limit);
|
|
});
|
|
}
|