4856f4acca
Extend the `system.dicts` helper for querying and modifying `system.dicts` with an ability to use names other than "general". We will use that in later commits to publish dictionaries for SSTable compression.
70 lines
2.6 KiB
C++
70 lines
2.6 KiB
C++
#include "locator/host_id.hh"
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#include "utils/enum_option.hh"
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#include "utils/updateable_value.hh"
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#include "utils/dict_trainer.hh"
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#include <any>
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namespace db {
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class system_keyspace;
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} // namespace db
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namespace utils {
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class alien_worker;
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} // namespace utils
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namespace service {
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class raft_group0_client;
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class raft_group0;
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} // namespace service
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namespace gms {
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class feature_service;
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} // namespace gms
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// A bag of code responsible for starting, stopping, pausing and unpausing RPC compression
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// dictionary training, and for publishing its results to system.dicts (via Raft group 0).
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//
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// It starts the training when the relevant cluster feature is enabled,
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// pauses and unpauses the training appropriately whenever relevant config or leadership status are updated,
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// and publishes new dictionaries whenever the training fiber produces them.
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class dictionary_service {
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db::system_keyspace& _sys_ks;
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locator::host_id _our_host_id;
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utils::updateable_value<enum_option<utils::dict_training_loop::when>> _rpc_dict_training_when;
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service::raft_group0_client& _raft_group0_client;
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abort_source& _as;
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utils::dict_training_loop _training_fiber;
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future<> _training_fiber_future;
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bool _is_leader = false;
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utils::observer<bool> _leadership_observer;
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utils::observer<enum_option<utils::dict_training_loop::when>> _when_observer;
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std::optional<std::any> _feature_observer;
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void maybe_toggle_dict_training();
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future<> publish_dict(utils::dict_sampler::dict_type);
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public:
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constexpr static std::string_view rpc_compression_dict_name = "general";
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// This template trick forces the user of `config` to initialize all fields explicitly.
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template <typename Uninitialized = void>
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struct config {
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locator::host_id our_host_id = Uninitialized();
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utils::updateable_value<uint32_t> rpc_dict_training_min_time_seconds = Uninitialized();
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utils::updateable_value<uint64_t> rpc_dict_training_min_bytes = Uninitialized();
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utils::updateable_value<enum_option<utils::dict_training_loop::when>> rpc_dict_training_when = Uninitialized();
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};
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// Note: the training fiber will start as soon as the relevant cluster feature is enabled.
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dictionary_service(
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utils::dict_sampler&,
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db::system_keyspace&,
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utils::alien_worker&,
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service::raft_group0_client&,
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service::raft_group0&,
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abort_source& stop_signal,
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gms::feature_service&,
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config<>
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);
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// For clean shutdown, this must be called and awaited before destruction.
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future<> stop();
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};
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