Backups broken in develop

[wolfgangmm]

What is the problem

Restoring a backup created with current develop will result in all binary files missing. It doesn't matter if you restore into a remote or local instance.

The __contents__.xml descriptors inside the backup are missing entries for all binary files.

Backup/restore was tested extensively not long ago, so this bug must have been introduced very recently.

Describe how to reproduce or add a test

A backup is attached. On a fresh database, install a package which is not contained by default, e.g. the demo app. Create a backup via the dashboard and check the __contents__.xml files contained inside. They should be missing entries for all binary resources. Restoring the backup will thus miss all binary resources.

Context information

Please always add the following information

• eXist-db 96993a5
• Java version 1.8.0_181
• Operating system (MacOs)

full20190530-1459.zip

[adamretter]

@wolfgangmm Okay so the backup process from the Java Admin Client works just fine. It seems to be just the backup process triggered from the Dashboard. I have no idea how the Dashboard works, I will try and figure it and let you know...

[adamretter]

@wolfgangmm After a bit of a search, I have found that the Dashboard uses the ConsistencyCheckTask which itself uses the SystemExport as opposed to the backup classes used by the Java Admin Client and elsewhere.

As far as I can see, this can't have ever worked in 5.x.x. The reason being that the SystemExport will attempt to work with transactions, but because it is a system task (via ConsistencyCheckTask) it is triggered from TransactionManager#doCommitTransaction it is not possible to start a new transaction, as the current transaction is being finished. I am not quite sure how we can fix this yet...

[adamretter]

I would also add that these transaction errors are logged, but it seems that files that are skipped by the backup are never reported back to the Dashboard. This seems like a bit of a failing on behalf of the Dashboard as it gives the user the idea that everything worked fine, when in fact there are serious issues they need to attend to.