// Common DSO loading functionality: exposes callables that dlopen DSOs
// in either the runfiles directories

#ifndef TENSORFLOW_STREAM_EXECUTOR_DSO_LOADER_H_
#define TENSORFLOW_STREAM_EXECUTOR_DSO_LOADER_H_

#include "tensorflow/stream_executor/platform/port.h"
#include <vector>

#include "tensorflow/stream_executor/lib/status.h"
#include "tensorflow/stream_executor/lib/statusor.h"
#include "tensorflow/stream_executor/lib/stringpiece.h"
#include "tensorflow/stream_executor/platform.h"
#include "tensorflow/stream_executor/platform/mutex.h"
#include "tensorflow/stream_executor/platform/port.h"

namespace perftools {
namespace gputools {
namespace internal {

// Permits StreamExecutor code to dynamically load a pre-determined set of
// relevant DSOs via dlopen.
//
// Thread-safe.
class DsoLoader {
 public:
  // The following methods either load the DSO of interest and return a dlopen
  // handle or error status in the canonical namespace.

  static port::Status GetCublasDsoHandle(void** dso_handle);
  static port::Status GetCudnnDsoHandle(void** dso_handle);
  static port::Status GetCufftDsoHandle(void** dso_handle);
  static port::Status GetCurandDsoHandle(void** dso_handle);
  static port::Status GetLibcudaDsoHandle(void** dso_handle);
  static port::Status GetLibcuptiDsoHandle(void** dso_handle);

  // Registers a new binary-relative path to use as a dlopen search path.
  static void RegisterRpath(port::StringPiece path);

 private:
  // Registered rpaths (singleton vector) and a mutex that guards it.
  static std::vector<string>* GetRpaths();
  static mutex rpath_mutex_;

  // Descriptive boolean wrapper to indicate whether symbols are made available
  // to resolve in later-loaded libraries.
  enum class LoadKind { kLocal, kGlobal };

  // Loads a DSO from the given "path" (which can technically be any dlopen-able
  // name). If the load kind is global, the symbols in the loaded DSO are
  // visible to subsequent DSO loading operations.
  static port::Status GetDsoHandle(port::StringPiece path, void** dso_handle,
                                   LoadKind load_kind = LoadKind::kLocal);


  // Returns the binary directory (or binary path) associated with the currently
  // executing program. If strip_executable_name is true, the executable file is
  // stripped off of the path.
  static string GetBinaryDirectory(bool strip_executable_name);

  // Returns the location of the runfiles directory.
  // * Manual invocation gets the runfiles as a relative path to the current
  //   executable.
  static string GetRunfilesDirectory();

  // Invokes realpath on the original path; updates candidate and returns true
  // if it succeeds (i.e. a file exists at the path); otherwise, returns false.
  static bool TrySymbolicDereference(string* candidate);

  // Attempts to find a path to the DSO of interest, otherwise returns the
  // bare library name:
  // Arguments:
  //   library_name: the filename in tree; e.g. libOpenCL.so.1.0.0
  //   runfiles_relpath: where to look for the library relative to the runfiles
  //      root; e.g. third_party/gpus/cuda/lib64
  static string FindDsoPath(port::StringPiece library_name,
                            port::StringPiece runfiles_relpath);

  SE_DISALLOW_COPY_AND_ASSIGN(DsoLoader);
};

// Wrapper around the DsoLoader that prevents us from dlopen'ing any of the DSOs
// more than once.
class CachedDsoLoader {
 public:
  // Cached versions of the corresponding DsoLoader methods above.
  static port::StatusOr<void*> GetCublasDsoHandle();
  static port::StatusOr<void*> GetCudnnDsoHandle();
  static port::StatusOr<void*> GetCufftDsoHandle();
  static port::StatusOr<void*> GetCurandDsoHandle();
  static port::StatusOr<void*> GetLibcudaDsoHandle();
  static port::StatusOr<void*> GetLibcuptiDsoHandle();

 private:
  // Fetches a DSO handle via "load_dso" and returns the StatusOr form of the
  // result.
  static port::StatusOr<void*> FetchHandleResult(
      std::function<port::Status(void**)> load_dso);

  SE_DISALLOW_COPY_AND_ASSIGN(CachedDsoLoader);
};

}  // namespace internal
}  // namespace gputools
}  // namespace perftools

#endif  // TENSORFLOW_STREAM_EXECUTOR_DSO_LOADER_H_