buffered file reading for oplog (#366)

* add BasicFileBuffer for buffered read of BasicFile
* Use BasicFileBuffer when reading oplog
* changelog

1 files changed, 23 insertions, 0 deletions

diff --git a/src/zenutil/include/zenutil/basicfile.h b/src/zenutil/include/zenutil/basicfile.h
index 1c5a31c5c..5a27befd9 100644
--- a/src/zenutil/include/zenutil/basicfile.h
+++ b/src/zenutil/include/zenutil/basicfile.h
@@ -120,6 +120,29 @@ public:
 private:
 };
 
+/** Adds a layer of buffered reading to a BasicFile
+
+This class is not intended for concurrent access, it is not thread safe.
+
+*/
+
+class BasicFileBuffer
+{
+public:
+	BasicFileBuffer(BasicFile& Base, uint64_t BufferSize);
+	~BasicFileBuffer();
+
+	void Read(void* Data, uint64_t Size, uint64_t FileOffset);
+
+private:
+	BasicFile&	   m_Base;
+	uint8_t*	   m_Buffer;
+	const uint64_t m_BufferSize;
+	uint64_t	   m_Size;
+	uint64_t	   m_BufferStart;
+	uint64_t	   m_BufferEnd;
+};
+
 ZENCORE_API void basicfile_forcelink();
 
 }  // namespace zen