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clio/src/cluster/Backend.hpp
2026-03-24 15:25:32 +00:00

134 lines
4.1 KiB
C++

#pragma once
#include "cluster/ClioNode.hpp"
#include "cluster/impl/RepeatedTask.hpp"
#include "data/BackendInterface.hpp"
#include "data/LedgerCacheLoadingState.hpp"
#include "etl/WriterState.hpp"
#include "util/log/Logger.hpp"
#include <boost/asio/any_io_executor.hpp>
#include <boost/asio/cancellation_signal.hpp>
#include <boost/asio/execution_context.hpp>
#include <boost/asio/executor.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/asio/strand.hpp>
#include <boost/asio/thread_pool.hpp>
#include <boost/signals2/connection.hpp>
#include <boost/signals2/signal.hpp>
#include <boost/signals2/variadic_signal.hpp>
#include <boost/uuid/uuid.hpp>
#include <chrono>
#include <concepts>
#include <memory>
#include <string>
#include <vector>
namespace cluster {
/**
* @brief Backend communication handler for cluster state synchronization.
*
* This class manages reading and writing cluster state information to/from the backend database.
* It periodically reads the state of other nodes in the cluster and writes the current node's
* state, enabling cluster-wide coordination and awareness.
*/
class Backend {
public:
/** @brief Type representing cluster data result - either a vector of nodes or an error message
*/
using ClusterData = std::expected<std::vector<ClioNode>, std::string>;
private:
util::Logger log_{"ClusterCommunication"};
std::shared_ptr<data::BackendInterface> backend_;
std::unique_ptr<etl::WriterStateInterface const> writerState_;
std::unique_ptr<data::LedgerCacheLoadingStateInterface const> cacheLoadingState_;
impl::RepeatedTask<boost::asio::thread_pool> readerTask_;
impl::RepeatedTask<boost::asio::thread_pool> writerTask_;
ClioNode::Uuid selfUuid_;
boost::signals2::signal<void(ClioNode::CUuid, std::shared_ptr<ClusterData const>)> onNewState_;
public:
/**
* @brief Construct a Backend communication handler.
*
* @param ctx The execution context for asynchronous operations
* @param backend Interface to the backend database
* @param writerState State indicating whether this node is writing to the database
* @param cacheLoadingState State controlling whether this node is allowed to load the cache
* @param readInterval How often to read cluster state from the backend
* @param writeInterval How often to write this node's state to the backend
*/
Backend(
boost::asio::thread_pool& ctx,
std::shared_ptr<data::BackendInterface> backend,
std::unique_ptr<etl::WriterStateInterface const> writerState,
std::unique_ptr<data::LedgerCacheLoadingStateInterface const> cacheLoadingState,
std::chrono::steady_clock::duration readInterval,
std::chrono::steady_clock::duration writeInterval
);
~Backend();
Backend(Backend&&) = delete;
Backend&
operator=(Backend&&) = delete;
Backend(Backend const&) = delete;
Backend&
operator=(Backend const&) = delete;
/**
* @brief Start the backend read and write tasks.
*
* Begins periodic reading of cluster state from the backend and writing of this node's state.
*/
void
run();
/**
* @brief Stop the backend read and write tasks.
*
* Stops all periodic tasks and waits for them to complete.
*/
void
stop();
/**
* @brief Subscribe to new cluster state notifications.
*
* @tparam S Callable type accepting (ClioNode::cUUID, ClusterData)
* @param s Subscriber callback to be invoked when new cluster state is available
* @return A connection object that can be used to unsubscribe
*/
template <typename S>
requires std::invocable<S, ClioNode::CUuid, std::shared_ptr<ClusterData const>>
boost::signals2::connection
subscribeToNewState(S&& s)
{
return onNewState_.connect(s);
}
/**
* @brief Get the UUID of this node in the cluster.
*
* @return The UUID of this node.
*/
ClioNode::CUuid
selfId() const;
private:
ClusterData
doRead(boost::asio::yield_context yield);
void
doWrite();
};
} // namespace cluster