EVOLUTION-MANAGER

Edit File: buffered_inputstream.h

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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distributed under the License is distributed on an "AS IS" BASIS,
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==============================================================================*/

#ifndef TENSORFLOW_CORE_LIB_IO_BUFFERED_INPUTSTREAM_H_
#define TENSORFLOW_CORE_LIB_IO_BUFFERED_INPUTSTREAM_H_

#include "tensorflow/core/lib/io/inputstream_interface.h"
#include "tensorflow/core/platform/file_system.h"

namespace tensorflow {
namespace io {

// Provides a buffer on top of an InputStreamInterface. A single instance of
// BufferedInputStream is NOT safe for concurrent use by multiple threads.
class BufferedInputStream : public InputStreamInterface {
 public:
  // Does not take ownership of input_stream unless owns_input_stream is set
  // to true. input_stream must outlive *this then.
  // TODO(rohanj): Remove owns_input_stream once the constructor below is
  // removed.
  BufferedInputStream(InputStreamInterface* input_stream, size_t buffer_bytes,
                      bool owns_input_stream = false);

// For backwards compatibility, expose an interface that is similar to what
  // InputBuffer exposes. Does not take ownership of file. file must outlive
  // *this. This will be removed once we migrate all uses of this class to the
  // constructor above.
  BufferedInputStream(RandomAccessFile* file, size_t buffer_bytes);

~BufferedInputStream() override;

tensorflow::Status ReadNBytes(int64 bytes_to_read, tstring* result) override;

tensorflow::Status SkipNBytes(int64 bytes_to_skip) override;

int64 Tell() const override;

// Seek to this offset within the file.
  //
  // If we seek to somewhere within our pre-buffered data, we will re-use what
  // data we can.  Otherwise, Seek() throws out the current buffer and the next
  // read will trigger an underlying read.
  //
  // Note: When seeking backwards in a stream, this implementation uses
  // Reset() + SkipNBytes(), so its performance will be dependent
  // largely on the performance of SkipNBytes().
  tensorflow::Status Seek(int64 position);

// Read one text line of data into "*result" until end-of-file or a
  // \n is read.  (The \n is not included in the result.)  Overwrites
  // any existing data in *result.
  //
  // If successful, returns OK.  If we are already at the end of the
  // file, we return an OUT_OF_RANGE error.  Otherwise, we return
  // some other non-OK status.
  tensorflow::Status ReadLine(string* result);
  tensorflow::Status ReadLine(tstring* result);

// Returns one text line of data until end-of-file or a '\n' is read. The '\n'
  // is included in the result.
  // This method is a substitute for ReadLine() when called from Python which is
  // the expectation in the python File::readline() API.
  // Also, '\0's are treated like any other character within the line and given
  // no special treatment.
  string ReadLineAsString();

// Reads the entire contents of the file into *result.
  //
  // Note: the amount of memory used by this function call is unbounded, so only
  // use in ops that expect that behavior.
  template <typename T>
  tensorflow::Status ReadAll(T* result);

tensorflow::Status Reset() override;

private:
  tensorflow::Status FillBuffer();
  template <typename StringType>
  tensorflow::Status ReadLineHelper(StringType* result, bool include_eol);

InputStreamInterface* input_stream_;  // not owned.
  size_t size_;                         // buffer size.
  tstring buf_;                         // the buffer itself.
  // buf_[pos_, limit_) holds the valid "read ahead" data in the file.
  size_t pos_ = 0;    // current position in buf_.
  size_t limit_ = 0;  // just past the end of valid data in buf_.
  bool owns_input_stream_ = false;
  // When EoF is reached, file_status_ contains the status to skip unnecessary
  // buffer allocations.
  tensorflow::Status file_status_ = Status::OK();

TF_DISALLOW_COPY_AND_ASSIGN(BufferedInputStream);
};

// Explicit instantiations defined in buffered_inputstream.cc.
#ifndef SWIG
extern template tensorflow::Status BufferedInputStream::ReadAll<string>(
    string* result);
extern template tensorflow::Status BufferedInputStream::ReadAll<tstring>(
    tstring* result);
#endif  // SWIG

}  // namespace io
}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_LIB_IO_BUFFERED_INPUTSTREAM_H_