Summary:
- Added a new subcommand, 'ldb restore', that restores from backup
- Made backup_env_uri optional (also for 'ldb backup') because it can use db_env when backup_env isn't provided
Test Plan:
verify backup and restore commands work:
$ ./ldb backup --db=/data/users/andrewkr/rocksdb/db_bench-out/ --num_threads 1 --backup_dir=/data/users/andrewkr/rocksdb/db_bench-out/backup/
$ ./ldb restore --db=/data/users/andrewkr/rocksdb/db_bench-out/restore/ --num_threads 1 --backup_dir=/data/users/andrewkr/rocksdb/db_bench-out/backup/
Reviewers: sdong, wanning
Reviewed By: wanning
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60849
bbd6a5a184