overlord/snapstate/backend: some copydata improvements #3611
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The state machinery needs that every handler either succeeds or fails
entirely. Currently copy-snap-data has a few half-failure modes; this
addresses that.
In particular, copying data has multiple steps that can fail
independently. This makes it so that when one of them fails, the
previous ones are cleaned up (undone), and anything that had been
trashed in the same operation is brought back from the trash.
This is easy to check, currently: simply
snap refresh <some snap> --revision=<the current revision it's on>
and you'll see the operation fail, but also you'll notice that if the
snap had data dirs they're gone, moved to .old. This PR also enables
this operation to succeed, by explicitly checking for it in both
directions.
Codecov Report
@@ Coverage Diff @@
## master #3611 +/- ##
==========================================
+ Coverage 74.9% 74.99% +0.08%
==========================================
Files 380 383 +3
Lines 32952 33237 +285
==========================================
+ Hits 24682 24925 +243
- Misses 6477 6504 +27
- Partials 1793 1808 +15
Continue to review full report at Codecov.
|
zyga
approved these changes
Jul 20, 2017
| if err := os.RemoveAll(newDir); err != nil { | ||
| logger.Noticef("while undoing creation of new data directory %q: %v", newDir, err) | ||
| } | ||
| if err := untrash(newDir); err != nil { |
| // try to fix that; hope for the best | ||
| if e := untrash(newPath); e != nil { | ||
| // oh noes | ||
| msg += fmt.Sprintf("; and when trying to restore the old data directory: %v", e) |
There was a problem hiding this comment.
// TODO: issue a warning to the user that data was lost
pedronis
approved these changes
Jul 24, 2017
| @@ -40,13 +40,20 @@ func (b Backend) CopySnapData(newSnap, oldSnap *snap.Info, meter progress.Meter) | |||
|
|
|||
| if oldSnap == nil { | |||
| return os.MkdirAll(newSnap.DataDir(), 0755) | |||
| } else if oldSnap.Revision == newSnap.Revision { | |||
There was a problem hiding this comment.
should we turn this into a NOP much higher ?
There was a problem hiding this comment.
Probably, but that doesn't make this wrong?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The state machinery needs that every handler either succeeds or fails
entirely. Currently copy-snap-data has a few half-failure modes; this
addresses that.
In particular, copying data has multiple steps that can fail
independently. This makes it so that when one of them fails, the
previous ones are cleaned up (undone), and anything that had been
trashed in the same operation is brought back from the trash.
This is easy to check, currently: simply
and you'll see the operation fail, but also you'll notice that if the
snap had data dirs they're gone, moved to .old. This PR also enables
this operation to succeed, by explicitly checking for it in both
directions.