Partial and memory-backed storage

1 files changed, 86 insertions, 9 deletions

diff --git a/src/storage.h b/src/storage.h
index 68002fa..cdb8984 100644
--- a/src/storage.h
+++ b/src/storage.h
@@ -3,35 +3,112 @@
 #include "erebos/storage.h"
 
 #include <future>
+#include <unordered_map>
 #include <unordered_set>
 
 namespace fs = std::filesystem;
 
 using std::optional;
 using std::shared_future;
+using std::shared_ptr;
+using std::unique_ptr;
+using std::unordered_map;
 using std::unordered_set;
+using std::variant;
 using std::vector;
 
 namespace erebos {
 
-struct Storage::Priv
+class StorageBackend
 {
-	static constexpr size_t CHUNK = 16384;
+public:
+	StorageBackend() = default;
+	virtual ~StorageBackend() = default;
 
-	fs::path root;
+	virtual bool contains(const Digest &) const = 0;
+
+	virtual optional<vector<uint8_t>> loadBytes(const Digest &) const = 0;
+	virtual void storeBytes(const Digest &, const vector<uint8_t> &) = 0;
+
+	virtual optional<vector<uint8_t>> loadKey(const Digest &) const = 0;
+	virtual void storeKey(const Digest &, const vector<uint8_t> &) = 0;
+};
+
+class FilesystemStorage : public StorageBackend
+{
+public:
+	FilesystemStorage(const fs::path &);
+	virtual ~FilesystemStorage() = default;
+
+	virtual bool contains(const Digest &) const override;
+
+	virtual optional<vector<uint8_t>> loadBytes(const Digest &) const override;
+	virtual void storeBytes(const Digest &, const vector<uint8_t> &) override;
+
+	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
+	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;
+
+private:
+	static constexpr size_t CHUNK = 16384;
 
 	fs::path objectPath(const Digest &) const;
 	fs::path keyPath(const Digest &) const;
-	optional<vector<uint8_t>> loadBytes(const Digest &) const;
-	void storeBytes(const Digest &, const vector<uint8_t> &) const;
+
+	fs::path root;
 };
 
-struct Ref::Priv
+class MemoryStorage : public StorageBackend
 {
-	Storage storage;
-	Digest digest;
+public:
+	MemoryStorage() = default;
+	virtual ~MemoryStorage() = default;
+
+	virtual bool contains(const Digest &) const override;
+
+	virtual optional<vector<uint8_t>> loadBytes(const Digest &) const override;
+	virtual void storeBytes(const Digest &, const vector<uint8_t> &) override;
 
-	shared_future<Object> object;
+	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
+	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;
+
+private:
+	unordered_map<Digest, vector<uint8_t>> storage;
+	unordered_map<Digest, vector<uint8_t>> keys;
+};
+
+class ChainStorage : public StorageBackend
+{
+public:
+	ChainStorage(shared_ptr<StorageBackend> storage):
+		ChainStorage(std::move(storage), nullptr) {}
+	ChainStorage(shared_ptr<StorageBackend> storage, unique_ptr<ChainStorage> parent):
+		storage(std::move(storage)), parent(std::move(parent)) {}
+	virtual ~ChainStorage() = default;
+
+	virtual bool contains(const Digest &) const override;
+
+	virtual optional<vector<uint8_t>> loadBytes(const Digest &) const override;
+	virtual void storeBytes(const Digest &, const vector<uint8_t> &) override;
+
+	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
+	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;
+
+private:
+	shared_ptr<StorageBackend> storage;
+	unique_ptr<ChainStorage> parent;
+};
+
+struct Storage::Priv
+{
+	shared_ptr<StorageBackend> backend;
+
+	optional<vector<uint8_t>> loadBytes(const Digest & digest) const;
+};
+
+struct Ref::Priv
+{
+	const unique_ptr<PartialStorage> storage;
+	const Digest digest;
 };
 
 vector<Stored<Object>> collectStoredObjects(const Stored<Object> &);