Add an implementation of a stream wrapper that limits reading rate, to

control bandwidth usage.

1 files changed, 71 insertions, 0 deletions

diff --git a/lib/common/RateLimitingStream.h b/lib/common/RateLimitingStream.h
new file mode 100644
index 00000000..a322b99b
--- /dev/null
+++ b/lib/common/RateLimitingStream.h
@@ -0,0 +1,71 @@
+// --------------------------------------------------------------------------
+//
+// File
+//		Name:    RateLimitingStream.h
+//		Purpose: Rate-limiting write-only wrapper around IOStreams
+//		Created: 2011/01/11
+//
+// --------------------------------------------------------------------------
+
+#ifndef RATELIMITINGSTREAM__H
+#define RATELIMITINGSTREAM__H
+
+#include "BoxTime.h"
+#include "IOStream.h"
+
+class RateLimitingStream : public IOStream
+{
+private:
+	IOStream& mrSink;
+	box_time_t mStartTime;
+	uint64_t mTotalBytesRead;
+	size_t mTargetBytesPerSecond;
+
+public:
+	RateLimitingStream(IOStream& rSink, size_t targetBytesPerSecond);
+	virtual ~RateLimitingStream() { }
+
+	// This is the only magic
+	virtual int Read(void *pBuffer, int NBytes,
+		int Timeout = IOStream::TimeOutInfinite);
+
+	// Everything else is delegated to the sink
+	virtual void Write(const void *pBuffer, int NBytes)
+	{
+		Write(pBuffer, NBytes);
+	}
+	virtual pos_type BytesLeftToRead()
+	{
+		return mrSink.BytesLeftToRead();
+	}
+	virtual pos_type GetPosition() const
+	{
+		return mrSink.GetPosition();
+	}
+	virtual void Seek(IOStream::pos_type Offset, int SeekType)
+	{
+		mrSink.Seek(Offset, SeekType);
+	}
+	virtual void Flush(int Timeout = IOStream::TimeOutInfinite)
+	{
+		mrSink.Flush(Timeout);
+	}
+	virtual void Close()
+	{
+		mrSink.Close();
+	}
+	virtual bool StreamDataLeft()
+	{
+		return mrSink.StreamDataLeft();
+	}
+	virtual bool StreamClosed()
+	{
+		return mrSink.StreamClosed();
+	}
+
+private:
+	RateLimitingStream(const RateLimitingStream &rToCopy) 
+	: mrSink(rToCopy.mrSink) { /* do not call */ }
+};
+
+#endif // RATELIMITINGSTREAM__H