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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 "confighandle.h"
#include "subscriptionid.h"
#include "configsubscription.h"
#include "configsubscriptionset.h"
#include "configprovider.h"
#include "sourcespec.h"
#include <vespa/config/common/timingvalues.h>
namespace config {
/**
* A subscriber is a class capable of subscribing to one or more configs. The
* class should be used as follows:
* - subscribe for all configs you need.
* - run nextConfig or nextGeneration to fetch the next generation of configs.
*
* Once nextConfig/nextGeneration is called, the state of a ConfigSubscriber is
* FROZEN, which means that in order to change the set of subscriptions, you
* have to recreate the ConfigSubscriber.
*
* Note that this class is NOT thread safe and that you should design your
* application so that you only need to use it from one thread.
*/
class ConfigSubscriber
{
public:
typedef std::unique_ptr<ConfigSubscriber> UP;
/**
* Constructs a new ConfigSubscriber object which can be used to subscribe
* for 1 or more configs.
*
* @param spec The source spec from which to get config.
*/
ConfigSubscriber(const SourceSpec & spec = ServerSpec());
/**
* Constructs a new ConfigSubscriber object which can be used to subscribe
* for 1 or more configs. The provided context is used to share resources
* betweeen multiple config subscribers.
*
* @param context A ConfigContext shared between all subscribers.
*/
explicit ConfigSubscriber(std::shared_ptr<IConfigContext> context);
ConfigSubscriber(const ConfigSubscriber &) = delete;
ConfigSubscriber & operator= (const ConfigSubscriber &) = delete;
~ConfigSubscriber();
/**
* Checks if one or more of the configs in the set is updated or not.
*
* @param timeout The timeout.
* @return true if new configs are available, false if timeout was reached
* or subscriber has been closed.
*/
bool nextConfig(vespalib::duration timeout = DEFAULT_NEXTCONFIG_TIMEOUT);
bool nextConfigNow() { return nextConfig(vespalib::duration::zero()); }
/**
* Checks if the generation of this config set is updated.
*
* @param timeout The timeout
* @return true if a new generation are available, false if timeout was reached
* or subscriber has been closed.
*/
bool nextGeneration(vespalib::duration timeout = DEFAULT_NEXTCONFIG_TIMEOUT);
bool nextGenerationNow() { return nextGeneration(vespalib::duration::zero()); }
/**
* Subscribe to a config fetched from the default source specification.
*
* @param configId The configId to get config for.
* @param timeout An optional timeout on the subscribe call
* @return A subscription handle which can be used to
* retrieve config.
* @throws ConfigTimeoutException if subscription timed out.
* @throws ConfigRuntimeException if subscriber has been closed.
*/
template <typename ConfigType>
std::unique_ptr<ConfigHandle<ConfigType> >
subscribe(const std::string & configId, vespalib::duration timeout = DEFAULT_SUBSCRIBE_TIMEOUT);
/**
* Return the current generation number for configs.
*
* @return generation number
*/
int64_t getGeneration() const;
/**
* Closes the set, which will interrupt nextConfig() or nextGeneration(), and unsubscribe all
* configs currently subscribed for.
*/
void close();
/**
* Check if this retriever is closed.
*
* @return true if closed, false if not.
*/
bool isClosed() const;
private:
ConfigSubscriptionSet _set; // The set of subscriptions for this set.
};
} // namespace config
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