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#pragma once
#include <memory>
#include <Storages/MergeTree/RequestResponse.h>
namespace DB
{
/// The main class to spread mark ranges across replicas dynamically
/// The reason why it uses pimpl - this header file is included in
/// multiple other files like Context or RemoteQueryExecutor
class ParallelReplicasReadingCoordinator
{
public:
class ImplInterface;
explicit ParallelReplicasReadingCoordinator(size_t replicas_count_);
~ParallelReplicasReadingCoordinator();
void handleInitialAllRangesAnnouncement(InitialAllRangesAnnouncement);
ParallelReadResponse handleRequest(ParallelReadRequest request);
/// Called when some replica is unavailable and we skipped it.
/// This is needed to "finalize" reading state e.g. spread all the marks using
/// consistent hashing, because otherwise coordinator will continue working in
/// "pending" state waiting for the unavailable replica to send the announcement.
void markReplicaAsUnavailable(size_t replica_number);
private:
void initialize();
std::mutex mutex;
size_t replicas_count{0};
CoordinationMode mode{CoordinationMode::Default};
std::atomic<bool> initialized{false};
std::unique_ptr<ImplInterface> pimpl;
};
using ParallelReplicasReadingCoordinatorPtr = std::shared_ptr<ParallelReplicasReadingCoordinator>;
}
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