src/developer/forensics/crash_reports/snapshot_persistence_metadata.h

// Copyright 2022 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_DEVELOPER_FORENSICS_CRASH_REPORTS_SNAPSHOT_PERSISTENCE_METADATA_H_
#define SRC_DEVELOPER_FORENSICS_CRASH_REPORTS_SNAPSHOT_PERSISTENCE_METADATA_H_

#include <map>
#include <string>

#include "src/developer/forensics/utils/storage_size.h"

namespace forensics::crash_reports {

// In-memory metadata about the snapshot store on disk at |snapshot_store_root|.
//
// Note: Clients must use Add and Delete to keep the metadata in sync with the snapshot
// store in the filesystem. Use with caution!
class SnapshotPersistenceMetadata {
 public:
  SnapshotPersistenceMetadata(std::string snapshot_store_root, StorageSize max_size);

  // Recreates the metadata from the snapshot store at |snapshot_store_root_|.
  //
  // Returns false if the |metadata| does not accurately represent the filesystem and the underlying
  // directory can't safely be used.
  bool RecreateFromFilesystem();

  // Returns true if the directory underlying the SnapshotPersistenceMetadata can safely be used.
  bool IsDirectoryUsable() const;

  bool Contains(const std::string& uuid) const;

  StorageSize CurrentSize() const;
  StorageSize RemainingSpace() const;

  const std::string& RootDir() const;

  void Add(const std::string& uuid, StorageSize size, std::string_view archive_key);
  void Delete(const std::string& uuid);

  std::vector<std::string> SnapshotUuids() const;

  // Returns the size of the snapshot archive.
  StorageSize SnapshotSize(const std::string& uuid) const;

  // Returns the directory that contains the snapshot |uuid|.
  std::string SnapshotDirectory(const std::string& uuid) const;

  // Returns the key for the snapshot |uuid|.
  std::string SnapshotKey(const std::string& uuid) const;

 private:
  // Metadata about each snapshot including:
  //  1) Its total size.
  //  2) The directory it is stored in.
  //  3) The key for the snapshot archive.
  struct SnapshotMetadata {
    StorageSize size;
    std::string dir;
    std::string snapshot_key;
  };

  // Where the snapshot store is located in the filesystem.
  std::string snapshot_store_root_;

  StorageSize current_size_;
  StorageSize max_size_;

  bool is_directory_usable_;

  std::map<std::string, SnapshotMetadata> snapshot_metadata_;
};

}  // namespace forensics::crash_reports

#endif  // SRC_DEVELOPER_FORENSICS_CRASH_REPORTS_SNAPSHOT_PERSISTENCE_METADATA_H_