Repo created

libs/storage/diff_scheme/diffs_data_source.hpp

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+#pragma once
+
+#include "storage/diff_scheme/diff_types.hpp"
+#include "storage/storage_defines.hpp"
+
+#include "base/thread_checker.hpp"
+
+#include <memory>
+
+namespace storage
+{
+namespace diffs
+{
+class DiffsDataSource;
+using DiffsSourcePtr = std::shared_ptr<diffs::DiffsDataSource>;
+
+class DiffsDataSource final
+{
+public:
+  void SetDiffInfo(NameDiffInfoMap && info);
+  // If the diff is available, sets |size| to its size and returns true.
+  // Otherwise, returns false.
+  bool SizeFor(storage::CountryId const & countryId, uint64_t & size) const;
+
+  // Sets |size| to how many bytes are left for the diff to be downloaded for |countryId|
+  // or 0 if there is no diff available or it has already been downloaded.
+  // This method may overestimate because it does not account for the possibility
+  // of resuming an old download, i.e. the return value is either 0 or the diff size.
+  // Returns true iff the diff is available.
+  bool SizeToDownloadFor(storage::CountryId const & countryId, uint64_t & size) const;
+
+  bool VersionFor(storage::CountryId const & countryId, uint64_t & version) const;
+
+  // Checks whether the diff for |countryId| is available for download or
+  // has been downloaded.
+  bool HasDiffFor(storage::CountryId const & countryId) const;
+
+  void MarkAsApplied(storage::CountryId const & countryId);
+  void RemoveDiffForCountry(storage::CountryId const & countryId);
+  void AbortDiffScheme();
+
+  Status GetStatus() const;
+
+private:
+  template <typename Fn>
+  bool WithNotAppliedDiff(storage::CountryId const & countryId, Fn && fn) const
+  {
+    if (m_status != Status::Available)
+      return false;
+
+    auto const it = m_diffs.find(countryId);
+    if (it == m_diffs.cend() || it->second.m_isApplied)
+      return false;
+
+    fn(it->second);
+    return true;
+  }
+
+  ThreadChecker m_threadChecker;
+
+  Status m_status = Status::NotAvailable;
+  NameDiffInfoMap m_diffs;
+};
+}  // namespace diffs
+}  // namespace storage