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https://github.com/ClickHouse/ClickHouse.git
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97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
#pragma once
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#include <Dictionaries/IDictionary.h>
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#include <Common/Exception.h>
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#include <Common/setThreadName.h>
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#include <Common/randomSeed.h>
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#include <common/MultiVersion.h>
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#include <common/logger_useful.h>
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#include <Poco/Event.h>
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#include <unistd.h>
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#include <time.h>
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#include <mutex>
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#include <thread>
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#include <unordered_map>
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#include <chrono>
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#include <random>
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namespace DB
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{
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class Context;
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/** Manages user-defined dictionaries.
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* Monitors configuration file and automatically reloads dictionaries in a separate thread.
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* The monitoring thread wakes up every @check_period_sec seconds and checks
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* modification time of dictionaries' configuration file. If said time is greater than
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* @config_last_modified, the dictionaries are created from scratch using configuration file,
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* possibly overriding currently existing dictionaries with the same name (previous versions of
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* overridden dictionaries will live as long as there are any users retaining them).
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*
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* Apart from checking configuration file for modifications, each non-cached dictionary
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* has a lifetime of its own and may be updated if it's source reports that it has been
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* modified. The time of next update is calculated by choosing uniformly a random number
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* distributed between lifetime.min_sec and lifetime.max_sec.
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* If either of lifetime.min_sec and lifetime.max_sec is zero, such dictionary is never updated.
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*/
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class ExternalDictionaries
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{
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private:
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friend class StorageSystemDictionaries;
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mutable std::mutex dictionaries_mutex;
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using DictionaryPtr = std::shared_ptr<MultiVersion<IDictionaryBase>>;
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struct DictionaryInfo final
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{
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DictionaryPtr dict;
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std::string origin;
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std::exception_ptr exception;
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};
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struct FailedDictionaryInfo final
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{
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std::unique_ptr<IDictionaryBase> dict;
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std::chrono::system_clock::time_point next_attempt_time;
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UInt64 error_count;
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};
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/** name -> dictionary.
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*/
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std::unordered_map<std::string, DictionaryInfo> dictionaries;
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/** Here are dictionaries, that has been never loaded sussessfully.
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* They are also in 'dictionaries', but with nullptr as 'dict'.
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*/
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std::unordered_map<std::string, FailedDictionaryInfo> failed_dictionaries;
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/** Both for dictionaries and failed_dictionaries.
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*/
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std::unordered_map<std::string, std::chrono::system_clock::time_point> update_times;
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std::mt19937_64 rnd_engine{randomSeed()};
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Context & context;
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std::thread reloading_thread;
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Poco::Event destroy;
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Logger * log;
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std::unordered_map<std::string, Poco::Timestamp> last_modification_times;
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void reloadImpl(bool throw_on_error = false);
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void reloadFromFile(const std::string & config_path, bool throw_on_error);
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void reloadPeriodically();
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public:
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/// Dictionaries will be loaded immediately and then will be updated in separate thread, each 'reload_period' seconds.
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ExternalDictionaries(Context & context, const bool throw_on_error);
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~ExternalDictionaries();
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MultiVersion<IDictionaryBase>::Version getDictionary(const std::string & name) const;
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};
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}
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