Add FileSystem wrapper classes for IO tracing. (#7002)

Summary:
1. Add the wrapper classes FileSystemTracingWrapper, FSSequentialFileTracingWrapper, FSRandomAccessFileTracingWrapper, FSWritableFileTracingWrapper, FSRandomRWFileTracingWrapper that forward the calls to underlying storage system and then pass the file operation information to IOTracer. IOTracer dumps the record in binary format for tracing.
2. Add the wrapper classes FileSystemPtr, FSSequentialFilePtr, FSRandomAccessFilePtr, FSWritableFilePtr and FSRandomRWFilePtr that overload operator-> and return ptr to underlying storage system or Tracing wrapper class based on enabling/disabling of IO tracing. These classes are added to bypass Tracing Wrapper classes when we disable tracing.
3. Add enums in trace.h that distinguish which options need to be added for different file operations(Read, close, write etc) as part of tracing record.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7002

Test Plan: make check -j64

Reviewed By: anand1976

Differential Revision: D22127897

Pulled By: akankshamahajan15

fbshipit-source-id: 74cff58ce5661c9a3832dfaa52483f3b2d8565e0

1 files changed, 1 insertions, 0 deletions

diff --git a/src.mk b/src.mk
index 2e438f9df..a8592ff3a 100644
--- a/src.mk
+++ b/src.mk
@@ -78,6 +78,7 @@ LIB_SOURCES =                                                   \
   env/env_posix.cc                                              \
   env/file_system.cc                                            \
   env/fs_posix.cc                                               \
+  env/file_system_tracer.cc                                     \
   env/io_posix.cc                                               \
   env/mock_env.cc                                               \
   file/delete_scheduler.cc                                      \