EVOLUTION-MANAGER

Edit File: events_writer.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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http://www.apache.org/licenses/LICENSE-2.0

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distributed under the License is distributed on an "AS IS" BASIS,
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==============================================================================*/

#ifndef TENSORFLOW_CORE_UTIL_EVENTS_WRITER_H_
#define TENSORFLOW_CORE_UTIL_EVENTS_WRITER_H_

#include <memory>
#include <string>

#include "tensorflow/core/lib/core/status.h"
#include "tensorflow/core/lib/io/record_writer.h"
#include "tensorflow/core/platform/env.h"
#include "tensorflow/core/platform/macros.h"
#include "tensorflow/core/platform/types.h"
#include "tensorflow/core/util/event.pb.h"

namespace tensorflow {

class EventsWriter {
 public:
#ifndef SWIG
  // Prefix of version string present in the first entry of every event file.
  static constexpr const char* kVersionPrefix = "brain.Event:";
  static constexpr const int kCurrentVersion = 2;
#endif

// Events files typically have a name of the form
  //   '/some/file/path/my.file.out.events.[timestamp].[hostname][suffix]'
  // To create and EventWriter, the user should provide file_prefix =
  //   '/some/file/path/my.file'
  // The EventsWriter will append '.out.events.[timestamp].[hostname][suffix]'
  // to the ultimate filename once Init() is called.
  // Note that it is not recommended to simultaneously have two
  // EventWriters writing to the same file_prefix.
  explicit EventsWriter(const std::string& file_prefix);
  ~EventsWriter();

// Sets the event file filename and opens file for writing.  If not called by
  // user, will be invoked automatically by a call to FileName() or Write*().
  // Returns false if the file could not be opened.  Idempotent: if file exists
  // and is open this is a no-op.  If on the other hand the file was opened,
  // but has since disappeared (e.g. deleted by another process), this will open
  // a new file with a new timestamp in its filename.
  Status Init();
  Status InitWithSuffix(const std::string& suffix);

// Returns the filename for the current events file:
  // filename_ = [file_prefix_].out.events.[timestamp].[hostname][suffix]
  std::string FileName();

// Append "event" to the file.  The "tensorflow::" part is for swig happiness.
  void WriteEvent(const tensorflow::Event& event);

// Append "event_str", a serialized Event, to the file.
  // Note that this function does NOT check that de-serializing event_str
  // results in a valid Event proto.  The tensorflow:: bit makes SWIG happy.
  void WriteSerializedEvent(tensorflow::StringPiece event_str);

// EventWriter automatically flushes and closes on destruction, but
  // these two methods are provided for users who want to write to disk sooner
  // and/or check for success.
  //   Flush() pushes outstanding events to disk.  Returns false if the
  // events file could not be created, or if the file exists but could not
  // be written too.
  //   Close() calls Flush() and then closes the current events file.
  // Returns true only if both the flush and the closure were successful.
  Status Flush();
  Status Close();

private:
  Status FileStillExists();  // OK if event_file_path_ exists.
  Status InitIfNeeded();

Env* env_;
  const std::string file_prefix_;
  std::string file_suffix_;
  std::string filename_;
  std::unique_ptr<WritableFile> recordio_file_;
  std::unique_ptr<io::RecordWriter> recordio_writer_;
  int num_outstanding_events_;
  TF_DISALLOW_COPY_AND_ASSIGN(EventsWriter);
};

}  // namespace tensorflow

#endif  // TENSORFLOW_CORE_UTIL_EVENTS_WRITER_H_