ceph/src/tools/ceph-dencoder/denc_plugin.h

   1 #include <dlfcn.h>
   2 #include <filesystem>
   3 #include <vector>
   4
   5 #include "denc_registry.h"
   6
   7 namespace fs = std::filesystem;
   8
   9 class DencoderPlugin {
  10   using dencoders_t = std::vector<std::pair<std::string, Dencoder*>>;
  11 public:
  12   DencoderPlugin(const fs::path& path) {
  13     mod = dlopen(path.c_str(), RTLD_NOW);
  14     if (mod == nullptr) {
  15       std::cerr << "failed to dlopen(" << path << "): " << dlerror() << std::endl;
  16     }
  17   }
  18   DencoderPlugin(DencoderPlugin&& other)
  19     : mod{other.mod},
  20       dencoders{std::move(other.dencoders)}
  21   {
  22     other.mod = nullptr;
  23     other.dencoders.clear();
  24   }
  25   ~DencoderPlugin() {
  26 #if !defined(__FreeBSD__)
  27     if (mod) {
  28       dlclose(mod);
  29     }
  30 #endif
  31   }
  32   const dencoders_t& register_dencoders() {
  33     static constexpr std::string_view REGISTER_DENCODERS_FUNCTION = "register_dencoders\0";
  34
  35     assert(mod);
  36     using register_dencoders_t = void (*)(DencoderPlugin*);
  37     const auto do_register =
  38       reinterpret_cast<register_dencoders_t>(dlsym(mod, REGISTER_DENCODERS_FUNCTION.data()));
  39     if (do_register == nullptr) {
  40       std::cerr << "failed to dlsym(" << REGISTER_DENCODERS_FUNCTION << "): "
  41                 << dlerror() << std::endl;
  42       return dencoders;
  43     }
  44     do_register(this);
  45     return dencoders;
  46   }
  47
  48   bool good() const {
  49     return mod != nullptr;
  50   }
  51
  52   void unregister_dencoders() {
  53     while (!dencoders.empty()) {
  54       delete dencoders.back().second;
  55       dencoders.pop_back();
  56     }
  57   }
  58   template<typename DencoderT, typename...Args>
  59   void emplace(const char* name, Args&&...args) {
  60     dencoders.emplace_back(name, new DencoderT(std::forward<Args>(args)...));
  61   }
  62
  63 private:
  64   void *mod = nullptr;
  65   dencoders_t dencoders;
  66 };
  67
  68 #define TYPE(t) plugin->emplace<DencoderImplNoFeature<t>>(#t, false, false);
  69 #define TYPE_STRAYDATA(t) plugin->emplace<DencoderImplNoFeature<t>>(#t, true, false);
  70 #define TYPE_NONDETERMINISTIC(t) plugin->emplace<DencoderImplNoFeature<t>>(#t, false, true);
  71 #define TYPE_FEATUREFUL(t) plugin->emplace<DencoderImplFeatureful<t>>(#t, false, false);
  72 #define TYPE_FEATUREFUL_STRAYDATA(t) plugin->emplace<DencoderImplFeatureful<t>>(#t, true, false);
  73 #define TYPE_FEATUREFUL_NONDETERMINISTIC(t) plugin->emplace<DencoderImplFeatureful<t>>(#t, false, true);
  74 #define TYPE_FEATUREFUL_NOCOPY(t) plugin->emplace<DencoderImplFeaturefulNoCopy<t>>(#t, false, false);
  75 #define TYPE_NOCOPY(t) plugin->emplace<DencoderImplNoFeatureNoCopy<t>>(#t, false, false);
  76 #define MESSAGE(t) plugin->emplace<MessageDencoderImpl<t>>(#t);
  77
  78 #define DENC_API extern "C" [[gnu::visibility("default")]]