1 files changed, 85 insertions, 0 deletions
diff --git a/include/cru/base/io/BufferStream.h b/include/cru/base/io/BufferStream.h
new file mode 100644
index 00000000..5ebff546
--- /dev/null
+++ b/include/cru/base/io/BufferStream.h
@@ -0,0 +1,85 @@
+#pragma once
+
+#include "../Buffer.h"
+#include "../Exception.h"
+#include "Stream.h"
+
+#include <condition_variable>
+#include <list>
+#include <mutex>
+
+namespace cru::io {
+class WriteAfterEofException : public Exception {
+ public:
+  using Exception::Exception;
+  ~WriteAfterEofException() override = default;
+};
+
+struct BufferStreamOptions {
+  /**
+   * Actually I have no ideas about the best value for this. May change it later
+   * when I get some ideas.
+   */
+  constexpr static Index kDefaultBlockSize = 1024;
+
+  /**
+   * @brief The size of a single buffer allocated each time new space is needed.
+   * Use default value if <= 0.
+   *
+   * When current buffer is full and there is no space for following data, a new
+   * buffer will be allocated and appended to the buffer list. Note if sum size
+   * of all buffers reaches the total_buffer_limit, no more buffer will be
+   * allocated but wait.
+   */
+  Index block_size = 0;
+
+  /**
+   * @brief Total size limit of saved data in buffer. No limit if <= 0.
+   *
+   * The size will be floor(total_size_limit / block_size). When the buffer is
+   * filled, it will block and wait for user to read to get free space of buffer
+   * to continue read.
+   */
+  Index total_size_limit = 0;
+
+  Index GetBlockSizeOrDefault() const {
+    return block_size <= 0 ? kDefaultBlockSize : block_size;
+  }
+
+  Index GetMaxBlockCount() const {
+    return total_size_limit / GetBlockSizeOrDefault();
+  }
+};
+
+/**
+ * @brief SPSC (Single Producer Single Consumer) buffer stream.
+ *
+ * If used by multiple producer or multiple consumer, the behavior is undefined.
+ */
+class BufferStream : public Stream {
+ public:
+  BufferStream(const BufferStreamOptions& options);
+  ~BufferStream() override;
+
+  CRU_STREAM_IMPLEMENT_CLOSE_BY_DO_CLOSE
+
+  void SetEof();
+
+ protected:
+  Index DoRead(std::byte* buffer, Index offset, Index size) override;
+  Index DoWrite(const std::byte* buffer, Index offset, Index size) override;
+
+ private:
+  void DoClose();
+
+ private:
+  Index block_size_;
+  Index max_block_count_;
+
+  std::list<Buffer> buffer_list_;
+  bool eof_;
+
+  std::mutex mutex_;
+  std::condition_variable condition_variable_;
+};
+}  // namespace cru::io