1#pragma once
2
3#include <string>
4#include <memory>
5#include <boost/noncopyable.hpp>
6#include <pcg_random.hpp>
7#include <Core/Types.h>
8
9
10namespace Poco::Util
11{
12 class AbstractConfiguration;
13}
14
15
16namespace DB
17{
18
19/// Min and max lifetimes for a loadable object or it's entry
20struct ExternalLoadableLifetime
21{
22 UInt64 min_sec;
23 UInt64 max_sec;
24
25 ExternalLoadableLifetime(const Poco::Util::AbstractConfiguration & config, const std::string & config_prefix);
26};
27
28/// Get delay before trying to load again after error.
29UInt64 calculateDurationWithBackoff(pcg64 & rnd_engine, size_t error_count = 1);
30
31/// Basic interface for external loadable objects. Is used in ExternalLoader.
32class IExternalLoadable : public std::enable_shared_from_this<IExternalLoadable>, private boost::noncopyable
33{
34public:
35 virtual ~IExternalLoadable() = default;
36
37 virtual const ExternalLoadableLifetime & getLifetime() const = 0;
38
39 virtual const std::string & getLoadableName() const = 0;
40 /// True if object can be updated when lifetime exceeded.
41 virtual bool supportUpdates() const = 0;
42 /// If lifetime exceeded and isModified(), ExternalLoader replace current object with the result of clone().
43 virtual bool isModified() const = 0;
44 /// Returns new object with the same configuration. Is used to update modified object when lifetime exceeded.
45 virtual std::shared_ptr<const IExternalLoadable> clone() const = 0;
46};
47
48}
49