rebalance_types.hpp

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#pragma once
 
/// @file userver/kafka/rebalance_types.hpp
/// @brief Kafka consumer rebalance callback types
 
#include <cstdint>
#include <functional>
#include <optional>
 
#include <userver/utils/span.hpp>
#include <userver/utils/zstring_view.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace kafka {
 
enum class RebalanceEventType { kAssigned, kRevoked };
 
/// @brief Represents the topic's partition for certain topic.
struct TopicPartitionView final {
    /// @brief Topic's name.
    utils::zstring_view topic;
 
    /// @brief Partition ID for a topic
    std::uint32_t partition_id;
 
    /// @brief Offset for current partition if it has committed offset
    std::optional<std::uint64_t> offset;
 
    TopicPartitionView(utils::zstring_view topic, std::uint32_t partition_id, std::optional<std::uint64_t> offset)
        : topic{topic},
          partition_id{partition_id},
          offset{offset}
    {}
};
 
using TopicPartitionBatchView = utils::span<const TopicPartitionView>;
 
/// @brief Callback invoked when a rebalance event occurs.
/// @warning The rebalance callback should be set before calling ConsumerScope::Start or after ConsumerScope::Stop.
/// The callback must not throw exceptions; any thrown exceptions will be caught and logged by the consumer
/// implementation.
/// @note The callback is invoked after the assign or revoke event has been successfully processed.
using ConsumerRebalanceCallback = std::function<void(TopicPartitionBatchView, RebalanceEventType)>;
 
}  // namespace kafka
 
USERVER_NAMESPACE_END