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tddb/td/db/utils/StreamInterface.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/buffer.h"
+#include "td/utils/Slice.h"
+#include "td/utils/Span.h"
+#include "td/utils/port/IoSlice.h"
+
+namespace td {
+// Generic stream interface
+// Will to hide implementations details.
+// CyclicBuffer, ChainBuffer, Bounded ChainBuffer, some clever writers. They all should be interchangable
+// Most implementaions will assume that reading and writing may happen concurrently
+
+class StreamReaderInterface {
+ public:
+  virtual ~StreamReaderInterface() {
+  }
+  virtual size_t reader_size() = 0;
+  virtual Slice prepare_read() = 0;
+  virtual Span<IoSlice> prepare_readv() = 0;
+  virtual void confirm_read(size_t size) = 0;
+
+  virtual void close_reader(Status error) = 0;
+  virtual bool is_writer_closed() const = 0;
+  virtual Status &writer_status() = 0;
+};
+
+class StreamWriterInterface {
+ public:
+  virtual ~StreamWriterInterface() {
+  }
+  virtual size_t writer_size() = 0;
+  virtual MutableSlice prepare_write() = 0;
+  virtual MutableSlice prepare_write_at_least(size_t size) = 0;
+  virtual void confirm_write(size_t size) = 0;
+  virtual void append(Slice data) = 0;
+  virtual void append(BufferSlice data) {
+    append(data.as_slice());
+  }
+  virtual void append(std::string data) {
+    append(Slice(data));
+  }
+
+  virtual void close_writer(Status error) = 0;
+  virtual bool is_reader_closed() const = 0;
+  virtual Status &reader_status() = 0;
+};
+
+// Hide shared_ptr
+class StreamReader : public StreamReaderInterface {
+ public:
+  StreamReader() = default;
+  StreamReader(std::shared_ptr<StreamReaderInterface> self);
+  size_t reader_size() override;
+  Slice prepare_read() override;
+  Span<IoSlice> prepare_readv() override;
+  void confirm_read(size_t size) override;
+  void close_reader(Status error) override;
+  bool is_writer_closed() const override;
+  Status &writer_status() override;
+
+ private:
+  std::shared_ptr<StreamReaderInterface> self;
+};
+
+class StreamWriter : public StreamWriterInterface {
+ public:
+  StreamWriter() = default;
+  StreamWriter(std::shared_ptr<StreamWriterInterface> self);
+  size_t writer_size() override;
+  MutableSlice prepare_write() override;
+  MutableSlice prepare_write_at_least(size_t size) override;
+  void confirm_write(size_t size) override;
+  void append(Slice data) override;
+  void append(BufferSlice data) override;
+  void append(std::string data) override;
+  void close_writer(Status error) override;
+  bool is_reader_closed() const override;
+  Status &reader_status() override;
+
+ private:
+  std::shared_ptr<StreamWriterInterface> self;
+};
+
+}  // namespace td