Better handling of DB timeouts on long downloads

[jvillafanez]

Description

Try to avoid hitting the DB after a long download, which could cause a failure if the DB connection timed out

Related Issue

https://github.com/owncloud/enterprise/issues/3538

Motivation and Context

How Has This Been Tested?

Checked after setting a 10 sec DB timeout and then downloading a big file through a slow network.
The first time, we still need to hit the DB to update the checksum (currently we're logging a message and keep working), but once the checksum is there, there won't be any error.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Database schema changes (next release will require increase of minor version instead of patch)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:
• Changelog item, see TEMPLATE

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[codecov]

Codecov Report

Merging #36978 into master will decrease coverage by 0.46%.
The diff coverage is 62.5%.

@@             Coverage Diff              @@
##             master   #36978      +/-   ##
============================================
- Coverage     64.75%   64.28%   -0.47%     
- Complexity    19138    19139       +1     
============================================
  Files          1270     1270              
  Lines         74912    74879      -33     
  Branches       1329     1329              
============================================
- Hits          48507    48134     -373     
- Misses        26014    26354     +340     
  Partials        391      391

Flag	Coverage Δ	Complexity Δ
#javascript	54.17% <ø> (ø)	0 <ø> (ø)	⬇️
#phpunit	65.4% <62.5%> (-0.53%)	19139 <0> (+1)

Impacted Files	Coverage Δ	Complexity Δ
lib/private/Files/View.php	84.54% <0%> (-0.3%)	389 <0> (ø)
lib/private/Files/Storage/Wrapper/Checksum.php	97.05% <71.42%> (-2.95%)	26 <0> (+1)
lib/private/DB/MySQLMigrator.php	0% <0%> (-100%)	5% <0%> (ø)
lib/private/DB/PostgreSqlMigrator.php	0% <0%> (-100%)	4% <0%> (ø)
...ilder/ExpressionBuilder/PgSqlExpressionBuilder.php	0% <0%> (-88.89%)	3% <0%> (ø)
lib/private/Repair/Collation.php	0% <0%> (-87.5%)	12% <0%> (ø)
...ivate/Files/ObjectStore/HomeObjectStoreStorage.php	0% <0%> (-86.67%)	8% <0%> (ø)
lib/private/DB/AdapterPgSql.php	0% <0%> (-85.72%)	2% <0%> (ø)
lib/private/Repair/InnoDB.php	0% <0%> (-78.95%)	6% <0%> (ø)
...ilder/ExpressionBuilder/MySqlExpressionBuilder.php	0% <0%> (-62.5%)	3% <0%> (ø)
... and 28 more

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[jvillafanez]

I can't increase the coverage. The cache can't be mocked, so we can't force the DriverException to trigger

[IljaN]

LGTM 💃