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.venv/Lib/site-packages/pyarrow/include/arrow/io/buffered.h

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+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// Buffered stream implementations
+
+#pragma once
+
+#include <cstdint>
+#include <memory>
+
+#include "arrow/io/concurrency.h"
+#include "arrow/io/interfaces.h"
+#include "arrow/util/string_view.h"
+#include "arrow/util/visibility.h"
+
+namespace arrow {
+
+class Buffer;
+class MemoryPool;
+class Status;
+
+namespace io {
+
+class ARROW_EXPORT BufferedOutputStream : public OutputStream {
+ public:
+  ~BufferedOutputStream() override;
+
+  /// \brief Create a buffered output stream wrapping the given output stream.
+  /// \param[in] buffer_size the size of the temporary write buffer
+  /// \param[in] pool a MemoryPool to use for allocations
+  /// \param[in] raw another OutputStream
+  /// \return the created BufferedOutputStream
+  static Result<std::shared_ptr<BufferedOutputStream>> Create(
+      int64_t buffer_size, MemoryPool* pool, std::shared_ptr<OutputStream> raw);
+
+  /// \brief Resize internal buffer
+  /// \param[in] new_buffer_size the new buffer size
+  /// \return Status
+  Status SetBufferSize(int64_t new_buffer_size);
+
+  /// \brief Return the current size of the internal buffer
+  int64_t buffer_size() const;
+
+  /// \brief Return the number of remaining bytes that have not been flushed to
+  /// the raw OutputStream
+  int64_t bytes_buffered() const;
+
+  /// \brief Flush any buffered writes and release the raw
+  /// OutputStream. Further operations on this object are invalid
+  /// \return the underlying OutputStream
+  Result<std::shared_ptr<OutputStream>> Detach();
+
+  // OutputStream interface
+
+  /// \brief Close the buffered output stream.  This implicitly closes the
+  /// underlying raw output stream.
+  Status Close() override;
+  Status Abort() override;
+  bool closed() const override;
+
+  Result<int64_t> Tell() const override;
+  // Write bytes to the stream. Thread-safe
+  Status Write(const void* data, int64_t nbytes) override;
+  Status Write(const std::shared_ptr<Buffer>& data) override;
+
+  Status Flush() override;
+
+  /// \brief Return the underlying raw output stream.
+  std::shared_ptr<OutputStream> raw() const;
+
+ private:
+  explicit BufferedOutputStream(std::shared_ptr<OutputStream> raw, MemoryPool* pool);
+
+  class ARROW_NO_EXPORT Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+/// \class BufferedInputStream
+/// \brief An InputStream that performs buffered reads from an unbuffered
+/// InputStream, which can mitigate the overhead of many small reads in some
+/// cases
+class ARROW_EXPORT BufferedInputStream
+    : public internal::InputStreamConcurrencyWrapper<BufferedInputStream> {
+ public:
+  ~BufferedInputStream() override;
+
+  /// \brief Create a BufferedInputStream from a raw InputStream
+  /// \param[in] buffer_size the size of the temporary read buffer
+  /// \param[in] pool a MemoryPool to use for allocations
+  /// \param[in] raw a raw InputStream
+  /// \param[in] raw_read_bound a bound on the maximum number of bytes
+  /// to read from the raw input stream. The default -1 indicates that
+  /// it is unbounded
+  /// \return the created BufferedInputStream
+  static Result<std::shared_ptr<BufferedInputStream>> Create(
+      int64_t buffer_size, MemoryPool* pool, std::shared_ptr<InputStream> raw,
+      int64_t raw_read_bound = -1);
+
+  /// \brief Resize internal read buffer; calls to Read(...) will read at least
+  /// \param[in] new_buffer_size the new read buffer size
+  /// \return Status
+  Status SetBufferSize(int64_t new_buffer_size);
+
+  /// \brief Return the number of remaining bytes in the read buffer
+  int64_t bytes_buffered() const;
+
+  /// \brief Return the current size of the internal buffer
+  int64_t buffer_size() const;
+
+  /// \brief Release the raw InputStream. Any data buffered will be
+  /// discarded. Further operations on this object are invalid
+  /// \return raw the underlying InputStream
+  std::shared_ptr<InputStream> Detach();
+
+  /// \brief Return the unbuffered InputStream
+  std::shared_ptr<InputStream> raw() const;
+
+  // InputStream APIs
+
+  bool closed() const override;
+  Result<std::shared_ptr<const KeyValueMetadata>> ReadMetadata() override;
+  Future<std::shared_ptr<const KeyValueMetadata>> ReadMetadataAsync(
+      const IOContext& io_context) override;
+
+ private:
+  friend InputStreamConcurrencyWrapper<BufferedInputStream>;
+
+  explicit BufferedInputStream(std::shared_ptr<InputStream> raw, MemoryPool* pool,
+                               int64_t raw_total_bytes_bound);
+
+  Status DoClose();
+  Status DoAbort() override;
+
+  /// \brief Returns the position of the buffered stream, though the position
+  /// of the unbuffered stream may be further advanced.
+  Result<int64_t> DoTell() const;
+
+  Result<int64_t> DoRead(int64_t nbytes, void* out);
+
+  /// \brief Read into buffer.
+  Result<std::shared_ptr<Buffer>> DoRead(int64_t nbytes);
+
+  /// \brief Return a zero-copy string view referencing buffered data,
+  /// but do not advance the position of the stream. Buffers data and
+  /// expands the buffer size if necessary
+  Result<util::string_view> DoPeek(int64_t nbytes) override;
+
+  class ARROW_NO_EXPORT Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+}  // namespace io
+}  // namespace arrow