[kudu-CR] WIP KUDU-2993: don't require update dirs to fix directory inconsistencies

["Andrew Wong (Code Review)" <ge...@cloudera.org>]

Andrew Wong has uploaded a new patch set (#3). ( http://gerrit.cloudera.org:8080/14760 )

Change subject: WIP KUDU-2993: don't require update_dirs to fix directory inconsistencies
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WIP KUDU-2993: don't require update_dirs to fix directory inconsistencies

This patch removes the ENFORCE_CONSISTENCY behavior when opening the
DataDirManager. By default, the directory will be opened with the
UPDATE_ON_DISK behavior. To support this:
- We can now tolerate failures when updating the PIMFs.
- When we start up, we'll look at all the PIMFs, check if any are
  missing and create those that are, and update any that have a
  different 'all_uuids' field than what actually exists.

Since we now always rewrite the PIMFs to be consistent, the "integrity
check" is now gone. This check was previously useful to ensure that the
'all_uuids' fields matched for every PIMF, which ensured that every data
directory that was expected to exist actually existed. This was
important for a couple reasons:
- When a single missing data directory spelled failure for the entire
  node, starting up with even a single "inconsistent" directory would
  break all tablets on the tserver.
- The file block manager requires that the UUID indexes used by the
  DataDirManager are static. These indexes are defined by the ordering
  of the UUIDs in the PIMFs, so we used the integrity check to ensure
  the ordering was consistent across PIMFs.

Now that Kudu tablets can start up with missing directories, the first
reason isn't particularly enticing.

The second is trickier to work around. To work around it, I've kept the
essence of the UUID picking, though I've made the "integrity checking"
virtually non-existent. For the log block manager, I've made the UUID
indexing much simpler: rather than relying on the integrity check, we'll
now always assign a PIMF a UUID, even if we couldn't read one from disk.

WIP:
- Decide what to do about `kudu fs update_dirs`

Tests:
- Adds a test to make sure that this doesn't completely break the file
  block manager. Given we don't expect heavy usage of the FBM, I didn't
  both doing extensive testing when the PIMFs are tampered with.
- Updated a few tests that previously enforced consistency among PIMFs

Change-Id: Ic3027e7edb5c60e96ced6160fec1a380b38353a5
---
M src/kudu/fs/block_manager-test.cc
M src/kudu/fs/block_manager_util-test.cc
M src/kudu/fs/block_manager_util.cc
M src/kudu/fs/block_manager_util.h
M src/kudu/fs/data_dirs.cc
M src/kudu/fs/data_dirs.h
M src/kudu/fs/error_manager.h
M src/kudu/fs/fs.proto
M src/kudu/fs/fs_manager-test.cc
M src/kudu/fs/fs_manager.cc
M src/kudu/server/server_base.cc
11 files changed, 450 insertions(+), 623 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/60/14760/3
-- 
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ic3027e7edb5c60e96ced6160fec1a380b38353a5
Gerrit-Change-Number: 14760
Gerrit-PatchSet: 3
Gerrit-Owner: Andrew Wong <aw...@cloudera.com>