Summary:
1. As part of IOTracing project, Add a class IOTracer,
IOTraceReader and IOTracerWriter that writes the file operations
information in a binary file. IOTrace Record contains record information
and right now it contains access_timestamp, file_operation, file_name,
io_status, len, offset and later other options will be added when file
system APIs will be call IOTracer.
2. Add few unit test cases that verify that reading and writing to a IO
Trace file is working properly and before start trace and after ending
trace nothing is added to the binary file.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6958
Test Plan:
1. make check -j64
2. New testcases for IOTracer.
Reviewed By: anand1976
Differential Revision: D21943375
Pulled By: akankshamahajan15
fbshipit-source-id: 3532204e2a3eab0104bf411ab142e3fdd4fbce54
