Summary:
./manifest_dump --file=/tmp/dbbench/MANIFEST-000002

Output looks like

manifest_file_number 30 next_file_number 31 last_sequence 388082 log_number 28  prev_log_number 0
--- level 0 ---
--- level 1 ---
--- level 2 ---
 5:3244155['0000000000000000' @ 1 : 1 .. '0000000000028220' @ 28221 : 1]
 7:3244177['0000000000028221' @ 28222 : 1 .. '0000000000056441' @ 56442 : 1]
 9:3244156['0000000000056442' @ 56443 : 1 .. '0000000000084662' @ 84663 : 1]
 11:3244178['0000000000084663' @ 84664 : 1 .. '0000000000112883' @ 112884 : 1]
 13:3244158['0000000000112884' @ 112885 : 1 .. '0000000000141104' @ 141105 : 1]
 15:3244176['0000000000141105' @ 141106 : 1 .. '0000000000169325' @ 169326 : 1]
 17:3244156['0000000000169326' @ 169327 : 1 .. '0000000000197546' @ 197547 : 1]
 19:3244178['0000000000197547' @ 197548 : 1 .. '0000000000225767' @ 225768 : 1]
 21:3244155['0000000000225768' @ 225769 : 1 .. '0000000000253988' @ 253989 : 1]
 23:3244179['0000000000253989' @ 253990 : 1 .. '0000000000282209' @ 282210 : 1]
 25:3244157['0000000000282210' @ 282211 : 1 .. '0000000000310430' @ 310431 : 1]
 27:3244176['0000000000310431' @ 310432 : 1 .. '0000000000338651' @ 338652 : 1]
 29:3244156['0000000000338652' @ 338653 : 1 .. '0000000000366872' @ 366873 : 1]
--- level 3 ---
--- level 4 ---
--- level 5 ---
--- level 6 ---

Test Plan: run on test directory created by dbbench

Reviewers: heyongqiang

Reviewed By: heyongqiang

CC: hustliubo

Differential Revision: https://reviews.facebook.net/D4743