initial commit

tddb/td/db/KeyValue.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+#include "td/utils/Status.h"
+#include "td/utils/logging.h"
+namespace td {
+class KeyValueReader {
+ public:
+  virtual ~KeyValueReader() = default;
+  enum class GetStatus : int32 { Ok, NotFound };
+
+  virtual Result<GetStatus> get(Slice key, std::string &value) = 0;
+  virtual Result<size_t> count(Slice prefix) = 0;
+};
+
+class PrefixedKeyValueReader : public KeyValueReader {
+ public:
+  PrefixedKeyValueReader(std::shared_ptr<KeyValueReader> reader, Slice prefix)
+      : reader_(std::move(reader)), prefix_(prefix.str()) {
+  }
+  Result<GetStatus> get(Slice key, std::string &value) override {
+    return reader_->get(PSLICE() << prefix_ << key, value);
+  }
+  Result<size_t> count(Slice prefix) override {
+    return reader_->count(PSLICE() << prefix_ << prefix);
+  }
+
+ private:
+  std::shared_ptr<KeyValueReader> reader_;
+  std::string prefix_;
+};
+
+class KeyValueUtils {
+ public:
+};
+
+class KeyValue : public KeyValueReader {
+ public:
+  virtual Status set(Slice key, Slice value) = 0;
+  virtual Status erase(Slice key) = 0;
+
+  virtual Status begin_transaction() = 0;
+  virtual Status commit_transaction() = 0;
+  virtual Status abort_transaction() = 0;
+  // Desctructor will abort transaction
+
+  virtual std::unique_ptr<KeyValueReader> snapshot() = 0;
+
+  virtual std::string stats() const {
+    return "";
+  }
+  virtual Status flush() {
+    return Status::OK();
+  }
+};
+class PrefixedKeyValue : public KeyValue {
+ public:
+  PrefixedKeyValue(std::shared_ptr<KeyValue> kv, Slice prefix) : kv_(std::move(kv)), prefix_(prefix.str()) {
+  }
+  Result<GetStatus> get(Slice key, std::string &value) override {
+    return kv_->get(PSLICE() << prefix_ << key, value);
+  }
+  Result<size_t> count(Slice prefix) override {
+    return kv_->count(PSLICE() << prefix_ << prefix);
+  }
+  Status set(Slice key, Slice value) override {
+    return kv_->set(PSLICE() << prefix_ << key, value);
+  }
+  Status erase(Slice key) override {
+    return kv_->erase(PSLICE() << prefix_ << key);
+  }
+
+  Status begin_transaction() override {
+    return kv_->begin_transaction();
+  }
+  Status commit_transaction() override {
+    return kv_->commit_transaction();
+  }
+  Status abort_transaction() override {
+    return kv_->abort_transaction();
+  }
+  // Desctructor will abort transaction
+
+  std::unique_ptr<KeyValueReader> snapshot() override {
+    return kv_->snapshot();
+  }
+
+  std::string stats() const override {
+    return kv_->stats();
+  }
+  Status flush() override {
+    return kv_->flush();
+  }
+
+ private:
+  std::shared_ptr<KeyValue> kv_;
+  std::string prefix_;
+};
+
+}  // namespace td