HeightRequestProcessor.h

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#pragma once
#include "catapult/io/BlockStorageCache.h"
#include "catapult/ionet/PacketHandlers.h"
 
namespace catapult { namespace handlers {
 
    template<typename TRequest>
    struct HeightRequestInfo {
    public:
        constexpr HeightRequestInfo() : pRequest(nullptr)
        {}
 
    public:
        Height ChainHeight;
 
        Height NormalizedRequestHeight;
 
        const TRequest* pRequest;
 
    public:
        uint32_t numAvailableBlocks() const {
            return static_cast<uint32_t>((ChainHeight - NormalizedRequestHeight).unwrap() + 1);
        }
    };
 
    template<typename TRequest>
    class HeightRequestProcessor {
    private:
        static auto CreateResponsePacket(uint32_t payloadSize) {
            auto pPacket = ionet::CreateSharedPacket<ionet::Packet>(payloadSize);
            pPacket->Type = TRequest::Packet_Type;
            return pPacket;
        }
 
    public:
        static HeightRequestInfo<TRequest> Process(
                const io::BlockStorageView& storage,
                const ionet::Packet& packet,
                ionet::ServerPacketHandlerContext& context,
                bool shouldAllowZeroHeight) {
            const auto* pRequest = ionet::CoercePacket<TRequest>(&packet);
            if (!pRequest)
                return HeightRequestInfo<TRequest>();
 
            HeightRequestInfo<TRequest> info;
            info.ChainHeight = storage.chainHeight();
            CATAPULT_LOG(trace) << "local height = " << info.ChainHeight << ", request height = " << pRequest->Height;
            if (info.ChainHeight < pRequest->Height || (!shouldAllowZeroHeight && Height(0) == pRequest->Height)) {
                context.response(ionet::PacketPayload(CreateResponsePacket(0)));
                return HeightRequestInfo<TRequest>();
            }
 
            info.NormalizedRequestHeight = Height(0) == pRequest->Height ? info.ChainHeight : pRequest->Height;
            info.pRequest = pRequest;
            return info;
        }
    };
}}