mirror of
https://github.com/ClickHouse/ClickHouse.git
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d36f52502e
It's still hackish and dirty, but server and client compies. Server starts, but throwes meaningless exception on any query. Client seems to be working fine. Linux compilation might (but shouldn't) be broken (not tested).
128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
#pragma once
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#include <DB/Dictionaries/IDictionary.h>
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#include <DB/Common/Exception.h>
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#include <DB/Common/setThreadName.h>
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#include <DB/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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static const auto check_period_sec = 5;
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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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{
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setThreadName("ExterDictReload");
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while (true)
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{
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if (destroy.tryWait(check_period_sec * 1000))
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return;
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reloadImpl();
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}
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}
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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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: context(context), log(&Logger::get("ExternalDictionaries"))
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{
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{
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/** During synchronous loading of external dictionaries at moment of query execution,
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* we should not use per query memory limit.
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*/
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TemporarilyDisableMemoryTracker temporarily_disable_memory_tracker;
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reloadImpl(throw_on_error);
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}
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reloading_thread = std::thread{&ExternalDictionaries::reloadPeriodically, this};
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}
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~ExternalDictionaries()
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{
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destroy.set();
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reloading_thread.join();
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}
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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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