Reproducer.h

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//===-- Reproducer.h --------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLDB_UTILITY_REPRODUCER_H
#define LLDB_UTILITY_REPRODUCER_H
 
#include "lldb/Utility/FileSpec.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Support/YAMLTraits.h"
 
#include <mutex>
#include <string>
#include <utility>
#include <vector>
 
namespace lldb_private {
class UUID;
namespace repro {
 
class Reproducer;
 
enum class ReproducerMode {
  Capture,
  Off,
};
 
/// The provider defines an interface for generating files needed for
/// reproducing.
///
/// Different components will implement different providers.
class ProviderBase {
public:
  virtual ~ProviderBase() = default;
 
  const FileSpec &GetRoot() const { return m_root; }
 
  /// The Keep method is called when it is decided that we need to keep the
  /// data in order to provide a reproducer.
  virtual void Keep(){};
 
  /// The Discard method is called when it is decided that we do not need to
  /// keep any information and will not generate a reproducer.
  virtual void Discard(){};
 
  // Returns the class ID for this type.
  static const void *ClassID() { return &ID; }
 
  // Returns the class ID for the dynamic type of this Provider instance.
  virtual const void *DynamicClassID() const = 0;
 
  virtual llvm::StringRef GetName() const = 0;
  virtual llvm::StringRef GetFile() const = 0;
 
protected:
  ProviderBase(const FileSpec &root) : m_root(root) {}
 
private:
  /// Every provider knows where to dump its potential files.
  FileSpec m_root;
 
  virtual void anchor();
  static char ID;
};
 
template <typename ThisProviderT> class Provider : public ProviderBase {
public:
  static const void *ClassID() { return &ThisProviderT::ID; }
 
  const void *DynamicClassID() const override { return &ThisProviderT::ID; }
 
  llvm::StringRef GetName() const override { return ThisProviderT::Info::name; }
  llvm::StringRef GetFile() const override { return ThisProviderT::Info::file; }
 
protected:
  using ProviderBase::ProviderBase; // Inherit constructor.
};
 
/// The generator is responsible for the logic needed to generate a
/// reproducer. For doing so it relies on providers, who serialize data that
/// is necessary for reproducing  a failure.
class Generator final {
 
public:
  Generator(FileSpec root);
  ~Generator();
 
  /// Method to indicate we want to keep the reproducer. If reproducer
  /// generation is disabled, this does nothing.
  void Keep();
 
  /// Method to indicate we do not want to keep the reproducer. This is
  /// unaffected by whether or not generation reproduction is enabled, as we
  /// might need to clean up files already written to disk.
  void Discard();
 
  /// Enable or disable auto generate.
  void SetAutoGenerate(bool b);
 
  /// Return whether auto generate is enabled.
  bool IsAutoGenerate() const;
 
  /// Create and register a new provider.
  template <typename T> T *Create() {
    std::unique_ptr<ProviderBase> provider = std::make_unique<T>(m_root);
    return static_cast<T *>(Register(std::move(provider)));
  }
 
  /// Get an existing provider.
  template <typename T> T *Get() {
    auto it = m_providers.find(T::ClassID());
    if (it == m_providers.end())
      return nullptr;
    return static_cast<T *>(it->second.get());
  }
 
  /// Get a provider if it exists, otherwise create it.
  template <typename T> T &GetOrCreate() {
    auto *provider = Get<T>();
    if (provider)
      return *provider;
    return *Create<T>();
  }
 
  const FileSpec &GetRoot() const;
 
private:
  friend Reproducer;
 
  ProviderBase *Register(std::unique_ptr<ProviderBase> provider);
 
  /// Builds and index with provider info.
  void AddProvidersToIndex();
 
  /// Map of provider IDs to provider instances.
  llvm::DenseMap<const void *, std::unique_ptr<ProviderBase>> m_providers;
  std::mutex m_providers_mutex;
 
  /// The reproducer root directory.
  FileSpec m_root;
 
  /// Flag to ensure that we never call both keep and discard.
  bool m_done = false;
 
  /// Flag to auto generate a reproducer when it would otherwise be discarded.
  bool m_auto_generate = false;
};
 
class Loader final {
public:
  Loader(FileSpec root, bool passive = false);
 
  template <typename T> FileSpec GetFile() {
    if (!HasFile(T::file))
      return {};
 
    return GetRoot().CopyByAppendingPathComponent(T::file);
  }
 
  template <typename T> llvm::Expected<std::string> LoadBuffer() {
    FileSpec file = GetFile<typename T::Info>();
    llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> buffer =
        llvm::vfs::getRealFileSystem()->getBufferForFile(file.GetPath());
    if (!buffer)
      return llvm::errorCodeToError(buffer.getError());
    return (*buffer)->getBuffer().str();
  }
 
  llvm::Error LoadIndex();
 
  const FileSpec &GetRoot() const { return m_root; }
 
private:
  bool HasFile(llvm::StringRef file);
 
  FileSpec m_root;
  std::vector<std::string> m_files;
  bool m_loaded;
};
 
/// The reproducer enables clients to obtain access to the Generator and
/// Loader.
class Reproducer {
public:
  static Reproducer &Instance();
  static llvm::Error Initialize(ReproducerMode mode,
                                llvm::Optional<FileSpec> root);
  static void Initialize();
  static bool Initialized();
  static void Terminate();
 
  Reproducer() = default;
 
  Generator *GetGenerator();
  Loader *GetLoader();
 
  const Generator *GetGenerator() const;
  const Loader *GetLoader() const;
 
  FileSpec GetReproducerPath() const;
 
  bool IsCapturing() { return static_cast<bool>(m_generator); };
 
protected:
  llvm::Error SetCapture(llvm::Optional<FileSpec> root);
 
private:
  static llvm::Optional<Reproducer> &InstanceImpl();
 
  llvm::Optional<Generator> m_generator;
  llvm::Optional<Loader> m_loader;
 
  mutable std::mutex m_mutex;
};
 
struct ReplayOptions {
  bool verify = true;
  bool check_version = true;
};
 
} // namespace repro
} // namespace lldb_private
 
#endif // LLDB_UTILITY_REPRODUCER_H