BackendFactory.h

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// SPDX-FileCopyrightText: Deutsches Elektronen-Synchrotron DESY, MSK, ChimeraTK Project <chimeratk-support@desy.de>
// SPDX-License-Identifier: LGPL-3.0-or-later
#pragma once
 
#include "DeviceAccessVersion.h"
#include "DeviceInfoMap.h"
#include "ForwardDeclarations.h"
 
#include <boost/function.hpp>
 
#include <map>
#include <mutex>
 
/* For test purposes; if a dummies.dmap file is found in the folder from where
 * the program is being executed it would be used as dmap file. The default dmap
 * file would be DMAP_FILE_PATH.
 */
#define TEST_DMAP_FILE_PATH "./dummies.dmap" // FIXME remove
#define ENV_VAR_DMAP_FILE "DMAP_PATH_ENV"    // FIXME remove
 
namespace ChimeraTK {
 
  class BackendFactory {
   public:
    void setDMapFilePath(std::string dMapFilePath);
 
    std::string getDMapFilePath();
 
    void registerBackendType(const std::string& backendType,
        boost::shared_ptr<DeviceBackend> (*creatorFunction)(
            std::string address, std::map<std::string, std::string> parameters),
        const std::vector<std::string>& sdmParameterNames = {},
        const std::string& deviceAccessVersion = CHIMERATK_DEVICEACCESS_VERSION);
 
    [[deprecated]] void registerBackendType(const std::string& interface, const std::string& protocol,
        boost::shared_ptr<DeviceBackend> (*creatorFunction)(
            std::string host, std::string instance, std::list<std::string> parameters, std::string mapFileName),
        const std::string& version);
 
    boost::shared_ptr<DeviceBackend> createBackend(const std::string& aliasOrUri);
 
    static BackendFactory& getInstance();
 
    void loadPluginLibrary(const std::string& soFile);
 
   protected:
    std::string _dMapFile; 
 
    std::map<std::string,
        boost::function<boost::shared_ptr<DeviceBackend>(
            std::string address, std::map<std::string, std::string> parameters)>>
        creatorMap;
 
    std::map<std::pair<std::string, std::string>,
        boost::function<boost::shared_ptr<DeviceBackend>(
            std::string host, std::string instance, std::list<std::string> parameters, std::string mapFileName)>>
        creatorMap_compat;
 
    std::string aliasLookUp(std::string aliasName, std::string dmapFilePath);
 
    boost::shared_ptr<DeviceBackend> createBackendInternal(const DeviceInfoMap::DeviceInfo& deviceInfo);
 
    std::map<std::string, boost::weak_ptr<DeviceBackend>> _existingBackends;
 
    std::mutex _mutex;
 
    // A function which has the signature of a creator function, plus one string
    // 'exception_what'. If a plugins fails to register, this function is bound to
    // an error string and stored in the creatorMap. It later it is tried to open
    // the backend, an exception with this error message is thrown.
    static boost::shared_ptr<DeviceBackend> failedRegistrationThrowerFunction(std::string host, std::string instance,
        std::list<std::string> parameters, std::string mapFileName, std::string exception_what);
 
    void loadAllPluginsFromDMapFile();
 
    bool called_registerBackendType{false};
 
   private:
    // These functions are not to be inherited. As also the constructor is
    // private, you cannot derrive from this class.
    BackendFactory();
 
    BackendFactory(BackendFactory const&);           
    BackendFactory(BackendFactory const&&) noexcept; 
    void operator=(BackendFactory const&);           
  };
 
} // namespace ChimeraTK