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50 lines
1.4 KiB
C++
50 lines
1.4 KiB
C++
#pragma once
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#include <string>
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#include <memory>
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#include <boost/noncopyable.hpp>
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#include <pcg_random.hpp>
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#include <base/types.h>
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namespace Poco::Util
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{
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class AbstractConfiguration;
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}
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namespace DB
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{
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/// Min and max lifetimes for a loadable object or it's entry
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struct ExternalLoadableLifetime
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{
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UInt64 min_sec = 0;
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UInt64 max_sec = 0;
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ExternalLoadableLifetime(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix);
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ExternalLoadableLifetime() {}
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};
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/// Get delay before trying to load again after error.
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UInt64 calculateDurationWithBackoff(pcg64 & rnd_engine, size_t error_count = 1);
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/// Basic interface for external loadable objects. Is used in ExternalLoader.
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class IExternalLoadable : public std::enable_shared_from_this<IExternalLoadable>, private boost::noncopyable
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{
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public:
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virtual ~IExternalLoadable() = default;
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virtual const ExternalLoadableLifetime & getLifetime() const = 0;
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virtual const std::string & getLoadableName() const = 0;
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/// True if object can be updated when lifetime exceeded.
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virtual bool supportUpdates() const = 0;
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/// If lifetime exceeded and isModified(), ExternalLoader replace current object with the result of clone().
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virtual bool isModified() const = 0;
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/// Returns new object with the same configuration. Is used to update modified object when lifetime exceeded.
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virtual std::shared_ptr<const IExternalLoadable> clone() const = 0;
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};
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}
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