initial commit

tddb/td/db/utils/ChainBuffer.cpp

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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
+*/
+#include "ChainBuffer.h"
+
+#include "td/utils/buffer.h"
+#include "td/db/utils/StreamInterface.h"
+
+namespace td {
+namespace detail {
+class ChainBuffer : public StreamWriterInterface, public StreamReaderInterface {
+ public:
+  using Options = ::td::ChainBuffer::Options;
+
+  ChainBuffer(Options options) {
+    shared_.options_ = options;
+    reader_.io_slices_.reserve(options.max_io_slices);
+    reader_.buf_ = writer_.buf_.extract_reader();
+  }
+
+  // StreamReaderInterface
+  size_t reader_size() override {
+    reader_.buf_.sync_with_writer();
+    return reader_.buf_.size();
+  }
+
+  Slice prepare_read() override {
+    return reader_.buf_.prepare_read();
+  }
+  Span<IoSlice> prepare_readv() override {
+    reader_.io_slices_.clear();
+    auto it = reader_.buf_.clone();
+    while (!it.empty() && reader_.io_slices_.size() < reader_.io_slices_.capacity()) {
+      auto slice = it.prepare_read();
+      reader_.io_slices_.push_back(as_io_slice(slice));
+      it.confirm_read(slice.size());
+    }
+    return reader_.io_slices_;
+  }
+  void confirm_read(size_t size) override {
+    reader_.buf_.advance(size);
+  }
+
+  void close_reader(Status error) override {
+    CHECK(!reader_.is_closed_);
+    reader_.status_ = std::move(error);
+    reader_.is_closed_.store(true, std::memory_order_release);
+  }
+  bool is_writer_closed() const override {
+    return writer_.is_closed_.load(std::memory_order_acquire);
+  }
+  Status &writer_status() override {
+    CHECK(is_writer_closed());
+    return writer_.status_;
+  }
+
+  // StreamWriterInterface
+  size_t writer_size() override {
+    return writer_.size_;
+  }
+  MutableSlice prepare_write() override {
+    return writer_.buf_.prepare_append(shared_.options_.chunk_size);
+  }
+  MutableSlice prepare_write_at_least(size_t size) override {
+    return writer_.buf_.prepare_append_at_least(size);
+  }
+  void confirm_write(size_t size) override {
+    writer_.buf_.confirm_append(size);
+    writer_.size_ += size;
+  }
+  void append(Slice data) override {
+    writer_.buf_.append(data, shared_.options_.chunk_size);
+    writer_.size_ += data.size();
+  }
+  void append(BufferSlice data) override {
+    writer_.size_ += data.size();
+    writer_.buf_.append(std::move(data));
+  }
+  void append(std::string data) override {
+    append(Slice(data));
+  }
+  void close_writer(Status error) override {
+    CHECK(!writer_.is_closed_);
+    writer_.status_ = std::move(error);
+    writer_.is_closed_.store(true, std::memory_order_release);
+  }
+  bool is_reader_closed() const override {
+    return reader_.is_closed_.load(std::memory_order_acquire);
+  }
+  Status &reader_status() override {
+    CHECK(is_reader_closed());
+    return reader_.status_;
+  }
+
+ private:
+  struct SharedData {
+    Options options_;
+  } shared_;
+
+  char pad1[128];
+
+  struct ReaderData {
+    ChainBufferReader buf_;
+    std::atomic<bool> is_closed_{false};
+    Status status_;
+    std::vector<IoSlice> io_slices_;
+  } reader_;
+
+  char pad2[128];
+
+  struct WriterData {
+    ChainBufferWriter buf_;
+    std::atomic<bool> is_closed_{false};
+    Status status_;
+    size_t size_{0};
+  } writer_;
+};
+}  // namespace detail
+
+std::pair<ChainBuffer::Reader, ChainBuffer::Writer> ChainBuffer::create(Options options) {
+  auto impl = std::make_shared<detail::ChainBuffer>(options);
+  return {Reader(impl), Writer(impl)};
+}
+}  // namespace td