[traffxml] Add traff_storage

Signed-off-by: mvglasow <michael -at- vonglasow.com>

traffxml/CMakeLists.txt

@@ -7,6 +7,8 @@ set(SRC
   traff_model.hpp
   traff_model_xml.cpp
   traff_model_xml.hpp
+  traff_storage.cpp
+  traff_storage.hpp
 )
 
 omim_add_library(${PROJECT_NAME} ${SRC})

traffxml/traff_storage.cpp

@@ -0,0 +1,76 @@
+#include "traffxml/traff_storage.hpp"
+
+#include "platform/platform.hpp"
+
+#include "coding/internal/file_data.hpp"
+
+#include "base/logging.hpp"
+
+#include <string>
+
+namespace
+{
+std::string GetFilePath(std::string const & fileName) { return GetPlatform().WritablePathForFile(fileName); }
+}  // namespace
+
+namespace traffxml
+{
+// StorageLocal ------------------------------------------------------------------------------------
+bool LocalStorage::Save(pugi::xml_document const & doc)
+{
+  auto const filePath = GetFilePath(m_fileName);
+
+  std::lock_guard<std::mutex> guard(m_mutex);
+
+  return base::WriteToTempAndRenameToFile(filePath, [&doc](std::string const & fileName) {
+    return doc.save_file(fileName.data(), "  " /* indent */);
+  });
+}
+
+bool LocalStorage::Load(pugi::xml_document & doc)
+{
+  auto const filePath = GetFilePath(m_fileName);
+
+  std::lock_guard<std::mutex> guard(m_mutex);
+
+  auto const result = doc.load_file(filePath.c_str());
+  /*
+   * Note: status_file_not_found is ok for our use cases:
+   *  - editor: if a user has never made any edits.
+   *  - traffic: if no traffic information has ever been retrieved (first run)
+   */
+  if (result != pugi::status_ok && result != pugi::status_file_not_found)
+  {
+    LOG(LERROR, ("Can't load file from disk:", filePath));
+    return false;
+  }
+
+  return true;
+}
+
+bool LocalStorage::Reset()
+{
+  std::lock_guard<std::mutex> guard(m_mutex);
+
+  return base::DeleteFileX(GetFilePath(m_fileName));
+}
+
+// StorageMemory -----------------------------------------------------------------------------------
+bool InMemoryStorage::Save(pugi::xml_document const & doc)
+{
+  m_doc.reset(doc);
+  return true;
+}
+
+bool InMemoryStorage::Load(pugi::xml_document & doc)
+{
+  doc.reset(m_doc);
+  return true;
+}
+
+bool InMemoryStorage::Reset()
+{
+  m_doc.reset();
+  return true;
+}
+}  // namespace traffxml

traffxml/traff_storage.hpp

@@ -0,0 +1,77 @@
+#pragma once
+
+#include <mutex>
+
+#include <pugixml.hpp>
+
+/*
+ * TODO combine this header and its CPP file with editor/editor_storage.hpp and its CPP counterpart,
+ * give it an appropriate namespace and place it where both editor and traffic can use it.
+ * `traff_storage` is essentially copied from `editor_storage` with just a few modifications:
+ *  - namespace
+ *  - instead of relying on a hardcoded file name, `LocalStorage` is initialized with a file name
+ *  - log output, variable names and comments changed to be use case neutral (no API changes)
+ *  - refactoring: no global `using namespace` (no API changes)
+ * Apart from the first two points, this file can serve as a drop-in replacement for `editor_storage`.
+ * Traffic uses only `LocalStorage`, the rest has been kept to ease migration to a unified storage
+ * component.
+ */
+
+namespace traffxml
+{
+/**
+ * @brief Storage interface for XML data.
+ */
+class StorageBase
+{
+public:
+  virtual ~StorageBase() = default;
+
+  virtual bool Save(pugi::xml_document const & doc) = 0;
+  virtual bool Load(pugi::xml_document & doc) = 0;
+  virtual bool Reset() = 0;
+};
+
+/**
+ * @brief Class which saves/loads XML data to/from local file.
+ * @note this class IS thread-safe.
+ */
+class LocalStorage : public StorageBase
+{
+public:
+  /**
+   * @brief Constructs a `LocalStorage` instance.
+   * @param fileName The file name and path where the file in question will be persisted. It is
+   * interpreted relative to the platform-specific path; absolute paths are not supported as some
+   * platforms restrict applications’ access to files outside their designated path.
+   */
+  LocalStorage(std::string & fileName)
+    : m_fileName(fileName)
+  {}
+
+  // StorageBase overrides:
+  bool Save(pugi::xml_document const & doc) override;
+  bool Load(pugi::xml_document & doc) override;
+  bool Reset() override;
+
+private:
+  std::string m_fileName;
+  std::mutex m_mutex;
+};
+
+/**
+ * @brief Class which saves/loads data to/from xml_document class instance.
+ * @note this class is NOT thread-safe.
+ */
+class InMemoryStorage : public StorageBase
+{
+public:
+  // StorageBase overrides:
+  bool Save(pugi::xml_document const & doc) override;
+  bool Load(pugi::xml_document & doc) override;
+  bool Reset() override;
+
+private:
+  pugi::xml_document m_doc;
+};
+}  // namespace traffxml