1 files changed, 72 insertions, 0 deletions
diff --git a/include/cru/base/io/AutoReadStream.h b/include/cru/base/io/AutoReadStream.h
new file mode 100644
index 00000000..759d5026
--- /dev/null
+++ b/include/cru/base/io/AutoReadStream.h
@@ -0,0 +1,72 @@
+#pragma once
+
+#include "BufferStream.h"
+#include "Stream.h"
+
+#include <mutex>
+#include <thread>
+
+namespace cru::io {
+struct AutoReadStreamOptions {
+  /**
+   * @brief Will be passed to BufferStreamOptions::block_size.
+   */
+  Index block_size = 0;
+
+  /**
+   * @brief Will be passed to BufferStreamOptions::total_size_limit.
+   */
+  Index total_size_limit = 0;
+
+  BufferStreamOptions GetBufferStreamOptions() const {
+    BufferStreamOptions options;
+    options.block_size = block_size;
+    options.total_size_limit = total_size_limit;
+    return options;
+  }
+};
+
+/**
+ * @brief A stream that wraps another stream and auto read it into a buffer in a
+ * background thread.
+ */
+class CRU_BASE_API AutoReadStream : public Stream {
+ public:
+  /**
+   * @brief Wrap a stream and auto read it in background.
+   * @param stream The stream to auto read.
+   * @param auto_delete Whether to delete the stream object in destructor.
+   * @param options Options to modify the behavior.
+   */
+  AutoReadStream(
+      Stream* stream, bool auto_delete,
+      const AutoReadStreamOptions& options = AutoReadStreamOptions());
+
+  ~AutoReadStream() override;
+
+ public:
+  CRU_STREAM_IMPLEMENT_CLOSE_BY_DO_CLOSE
+
+  void BeginToDrop(bool auto_delete = true);
+
+ protected:
+  Index DoRead(std::byte* buffer, Index offset, Index size) override;
+  Index DoWrite(const std::byte* buffer, Index offset, Index size) override;
+  void DoFlush() override;
+
+ private:
+  void DoClose();
+
+  void BackgroundThreadRun();
+
+ private:
+  Stream* stream_;
+  bool auto_delete_;
+
+  Index size_per_read_;
+  std::unique_ptr<BufferStream> buffer_stream_;
+  std::mutex buffer_stream_mutex_;
+
+  std::thread background_thread_;
+};
+}  // namespace cru::io