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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "configsnapshot.h"
#include "genericconfigsubscriber.h"
#include "fixedconfigsubscriber.h"
#include <vespa/config/common/configkey.h>
#include <vespa/config/subscription/configsubscription.h>
#include <vespa/vespalib/stllike/string.h>
#include <mutex>
namespace config {
class SourceSpec;
/**
* A ConfigRetriever is a helper class for retrieving a set of dynamically
* changing and depending configs. You should use this class whenever you have a
* set of bootstrap configs, and want to subscribe to a dynamically changing set
* of configs based on those.
*
* The retriever should be used from one thread only, but close can be called
* from another thread.
*/
class ConfigRetriever
{
public:
ConfigRetriever(const ConfigKeySet & bootstrapSet,
std::shared_ptr<IConfigContext> context,
vespalib::duration subscribeTimeout = DEFAULT_SUBSCRIBE_TIMEOUT);
~ConfigRetriever();
/**
* Waits for the next generation of bootstrap configs to arrive, and returns
* them. If no new generation has arrived, return an empty snapshot.
*
* @param timeout The timeout of the nextGeneration call. Optional.
* @return a snapshot of bootstrap configs, empty if no new snapshot or
* retriever has been closed.
* @throws ConfigTimeoutException if initial subscribe timed out.
*/
ConfigSnapshot getBootstrapConfigs(vespalib::duration timeout = DEFAULT_NEXTGENERATION_TIMEOUT);
/**
* Return the configs represented by a ConfigKeySet in a snapshot, and makes
* sure that it is in sync with the bootstrap config. If it is not, an empty
* snapshot is returned.
*
* @param keySet The set of configs that should be fetched. The set may only
* change when bootstrap has been changed.
* @param timeout The timeout. Optional.
* @return a snapshot of configs corresponding to the keySet or
* an empty snapshot if
* a) retriever has been closed. The isClosed() method can be
* used to check for this condition.
* b) no new generation was found, in which case getConfigs()
* should be called again.
* c) generation is not in sync with bootstrap, in which case
* getBootstrapConfigs() must be called. The bootstrapRequired
* method can be used to check for this condition.
* @throws ConfigTimeoutException if resubscribe timed out.
*/
ConfigSnapshot getConfigs(const ConfigKeySet & keySet, vespalib::duration timeout = DEFAULT_NEXTGENERATION_TIMEOUT);
/**
* Close this retriever in order to shut down.
*/
void close();
/**
* Check if this retriever is closed.
*
* @return true if closed, false if not.
*/
bool isClosed() const;
/**
* Returns if a new bootstrap call is required.
*
* @return true if required, false if not.
*/
bool bootstrapRequired() const { return _bootstrapRequired; }
/**
* Get the current generation of the configs managed by this retriever.
*
* @return the generation
*/
int64_t getGeneration() const { return _generation; }
static const vespalib::duration DEFAULT_SUBSCRIBE_TIMEOUT;
static const vespalib::duration DEFAULT_NEXTGENERATION_TIMEOUT;
private:
FixedConfigSubscriber _bootstrapSubscriber;
std::unique_ptr<GenericConfigSubscriber> _configSubscriber;
std::mutex _lock;
std::vector<std::shared_ptr<ConfigSubscription>> _subscriptionList;
ConfigKeySet _lastKeySet;
std::shared_ptr<IConfigContext> _context;
std::unique_ptr<SourceSpec> _spec;
int64_t _generation;
vespalib::duration _subscribeTimeout;
bool _bootstrapRequired;
std::atomic<bool> _closed;
};
} // namespace config
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