AppRTCDemo file logging.

webrtc/base/stream.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 400 matching lines @@
 
  protected:
   virtual void DoClose();
 
   FILE* file_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FileStream);
 };
 
+// A stream that caps the output at a certain size, dropping content from the
+// middle of the logical stream and maintaining equal parts of the start/end of
+// the logical stream.
+class CircularFileStream : public FileStream {
+ public:
+  explicit CircularFileStream(size_t max_size);
+
+  bool Open(const std::string& filename, const char* mode, int* error) override;
+  StreamResult Read(void* buffer,
+                    size_t buffer_len,
+                    size_t* read,
+                    int* error) override;
+  StreamResult Write(const void* data,
+                     size_t data_len,
+                     size_t* written,
+                     int* error) override;
+
+ private:
+  enum ReadSegment {
+    READ_MARKED,  // Read 0 .. marked_position_
+    READ_MIDDLE,  // Read position_ .. file_size
+    READ_LATEST,  // Read marked_position_ .. position_ if the buffer was
+                  // overwritten or 0 .. position_ otherwise.
+  };
+
+  size_t max_write_size_;
+  size_t position_;
+  size_t marked_position_;
+  size_t last_write_position_;
+  ReadSegment read_segment_;
+  size_t read_segment_available_;
+};
+
 ///////////////////////////////////////////////////////////////////////////////
 // MemoryStream is a simple implementation of a StreamInterface over in-memory
 // data.  Data is read and written at the current seek position.  Reads return
 // end-of-stream when they reach the end of data.  Writes actually extend the
 // end of data mark.
 ///////////////////////////////////////////////////////////////////////////////
 
 class MemoryStreamBase : public StreamInterface {
  public:
   StreamState GetState() const override;
@@ skipping 263 matching lines @@
 // as a pass in parameter, it indicates data in buffer that should move to sink
 StreamResult Flow(StreamInterface* source,
                   char* buffer, size_t buffer_len,
                   StreamInterface* sink, size_t* data_len = NULL);
 
 ///////////////////////////////////////////////////////////////////////////////
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_STREAM_H_