HDDS-2777. Add bytes read statistics to Ozone FileSystem implementation

[fapifta]

NOTE: please forgive me and be aware the fact that I have created the branch with the wrong JIRA ID in the name, and the commit also contains a wrong JIRA ID, please fix it when commiting or if needed let me know and I recreate the PR...

What changes were proposed in this pull request?

The main aim is to account the number of bytes read FileSystem statistics.
Besides that the PR adds tests around the number of bytes read and number of bytes write, the number of read operations, and the number of write operations statistics.
Also there is a fix for the BasicOzoneFileSystem#open call which was accounted as a write operation before the patch.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-2777

How was this patch tested?

See added JUnit tests.

[adoroszlai]

Thanks @fapifta for this improvement. Really great test coverage.

Note that OzoneFSInputStream implements ByteBufferReadable, so there is a read(ByteBuffer) method, which is still not collecting stats. It can be fixed simply by changing it to call read instead of inputStream.read:

https://github.com/apache/hadoop-ozone/blob/b834fa48afef4ee4c73577c7af564e1e97cb9d5b/hadoop-ozone/ozonefs/src/main/java/org/apache/hadoop/fs/ozone/OzoneFSInputStream.java#L96

[fapifta]

Hi Attila,

thank you for the review, somehow I did not went down in the file enough and haven't noticed that method... However I tried to review all the implementations, I missed this one.

I have pushed the discussed modifications to the PR. And also added two new tests to cover the method as well.

[adoroszlai]

Thanks @fapifta for updating the patch. Confirmed unit test passes locally (since it's excluded by CI).

[bharatviswa504]

+1 LGTM.
Nice test coverage for the Stats code.

[bharatviswa504]

Thank You @fapifta for the contribution and @adoroszlai for the review.