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#ifndef TENSORFLOW_FRAMEWORK_READER_INTERFACE_H_
#define TENSORFLOW_FRAMEWORK_READER_INTERFACE_H_
#include <memory>
#include <string>
#include <vector>
#include "tensorflow/core/framework/op_kernel.h"
#include "tensorflow/core/framework/resource_mgr.h"
#include "tensorflow/core/platform/port.h"
#include "tensorflow/core/public/status.h"
#include "tensorflow/core/public/tensor.h"
namespace tensorflow {
class QueueInterface;
class ReaderInterface;
// Readers are the mechanism for reading records from files in
// TensorFlow graphs. Each supported file format has a corresponding
// ReaderInterface descendant and a corresponding Op & OpKernel
// (implemented using ReaderOpKernel from reader_op_kernel.h).
//
// To use a Reader, you first encode "work" (some string, typically a
// filename) in the Reader's "work queue". It then processes the
// "work" (reading records from the file), to produce key/value
// strings. The methods of this class are called by ReaderFoo ops,
// so see ../ops/io_ops.cc for detailed descriptions.
//
// All descendants of this class must be thread-safe.
//
// See the design document here:
// https://docs.google.com/document/d/1UAgZOoeehYr20TdzW2CoZ30V-aqQphU4SwKXsW7eJv4/edit#
// TODO(josh11b): Switch this to Async.
class ReaderInterface : public ResourceBase {
public:
// Read a single record into *key / *value. May get more work from
// *queue if the current work is complete. Sets the status on
// *context with an OutOfRange Status if the the current work is
// complete and the queue is done (closed and empty).
// This method may block.
virtual void Read(QueueInterface* queue, string* key, string* value,
OpKernelContext* context) = 0;
// Restore this reader to its newly-constructed state.
virtual Status Reset() = 0;
// Accessors
virtual int64 NumRecordsProduced() = 0;
virtual int64 NumWorkUnitsCompleted() = 0;
// -- Serialization/Restoration support --
// Not all readers will support saving and restoring state.
virtual Status SerializeState(string* state) = 0;
// Note: Must Reset on error.
virtual Status RestoreState(const string& state) = 0;
string DebugString() override { return "a reader"; }
protected:
virtual ~ReaderInterface() {}
};
} // namespace tensorflow
#endif // TENSORFLOW_FRAMEWORK_READER_INTERFACE_H_
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