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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/documentapi/common.h>
#include <vespa/messagebus/routing/hop.h>
#include <vespa/messagebus/routing/iroutingpolicy.h>
#include <map>
#include <mutex>
namespace documentapi {
/**
* This policy implements the logic to select a subset of services that matches a slobrok pattern.
*
* @author Simon Thoresen Hult
* @version $Id$
*/
class SubsetServicePolicy : public mbus::IRoutingPolicy {
private:
struct CacheEntry {
uint32_t _offset;
uint32_t _generation;
std::vector<mbus::Hop> _recipients;
CacheEntry();
};
std::mutex _lock;
uint32_t _subsetSize;
std::map<string, CacheEntry> _cache;
/**
* Returns the appropriate recipient hop for the given routing context. This method provides synchronized access to
* the internal cache.
*
* @param ctx The routing context.
* @return The recipient hop to use.
*/
mbus::Hop getRecipient(mbus::RoutingContext &ctx);
/**
* Updates and returns the cache entry for the given routing context. This method assumes that synchronization is
* handled outside of it.
*
* @param ctx The routing context.
* @return The updated cache entry.
*/
CacheEntry &update(mbus::RoutingContext &ctx);
/**
* Returns a cache key for this instance of the policy. Because behaviour is based on the hop in which the policy
* occurs, the cache key is the hop string itself.
*
* @param ctx The routing context.
* @return The cache key.
*/
string getCacheKey(const mbus::RoutingContext &ctx) const;
public:
/**
* Creates an instance of a subset service policy. The parameter string is parsed as an integer number that is the
* number of services to include in the set to choose from.
*
* @param param The number of services to include in the set.
*/
SubsetServicePolicy(const string ¶m);
~SubsetServicePolicy();
void select(mbus::RoutingContext &context) override;
void merge(mbus::RoutingContext &context) override;
};
}
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