sst_dump: still try to print out table properties even if failing to read the file

Summary: Even if the file is corrupted, table properties are usually available to print out. Now sst_dump would just fail without printing table properties. With this patch, table properties are still try to be printed out.

Test Plan: run sst_dump against multiple scenarios

Reviewers: igor, yhchiang, ljin, haobo

Reviewed By: haobo

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D18981
Don't compress block bigger than 2GB

Summary: This is a temporary solution to a issue that we have with compression libraries. See task #4453446.

Test Plan: make check doesn't complain :)

Reviewers: haobo, ljin, yhchiang, dhruba, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18975
Clean PlainTableReader's variables for better data locality

Summary:
Clean PlainTableReader's data structures:
(1) inline bloom_ (in order to do this, change DynamicBloom to allow lazy initialization)
(2) remove some variables only used when initialization from the class
(3) put variables not used in normal read code paths to the end of the class and reference prefix_extractor directly
(4) make Options a reference.

Test Plan: make all check

Reviewers: haobo, ljin

Reviewed By: ljin

Subscribers: igor, yhchiang, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D18891
fix forward iterator bug

Summary: obvious

Test Plan: db_test

Reviewers: sdong, haobo, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18987
collect metrics for in memory workload get/seek

Summary:
collect in-memory workload get/seek metrics so that we can alert on
regression

Test Plan: ran locally

Reviewers: igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18969