crypto: In sqlite, use the SQL column value for backed_up everywhere

[andybalaam]

Most times we pulled an InboundGroupSession from the sqlite DB, we were overriding whatever value for backed_up was stored inside the pickled value, and using the value stored in the SQL column.

But when we pulled a single InboundGroupSession from the DB by ID, we did not override it.

I am fairly sure this was an accidental oversight, so this change corrects it, and unifies the code with other places we create these objects.

Part of #3544
Applies on top of #3862

[richvdh]

Hrm. I support the principle of being consistent, but (other than the comment asserting as much) why do we consider the sql column to be the primary source of truth?

• It's not what the indexeddb impl does? I think?
• It requires additional work to SELECT the column and overwrite the value we have in the pickle
• I think the column was added later, so there is probably some migration code that reads from the pickle and populates the column. At the very least, that makes the runtime code inconsistent with the migration code.

[andybalaam]

Hrm. I support the principle of being consistent, but (other than the comment asserting as much) why do we consider the sql column to be the primary source of truth?

When we mark the sessions as backed up, we only update the SQL column, not the pickled value.

• It's not what the indexeddb impl does

Yeah, it modifies the serialized values.

• It requires additional work to SELECT the column and overwrite the value we have in the pickle

A very tiny amount of work, yes.

• I think the column was added later, so there is probably some migration code that reads from the pickle and populates the column. At the very least, that makes the runtime code inconsistent with the migration code.

This is a one-time operation though, right? Then as soon as the column exists, it is the source of truth.

[richvdh]

(in other words, I'd change

When we mark the sessions as backed up, we only update the SQL column, not the pickled value.

Right. This is the clincher. Sorry, I'd forgotten that.

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.10%. Comparing base (668a267) to head (dec768c).
Report is 2 commits behind head on main.

Files	Patch %	Lines
crates/matrix-sdk-sqlite/src/crypto_store.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3863      +/-   ##
==========================================
+ Coverage   84.09%   84.10%   +0.01%     
==========================================
  Files         261      261              
  Lines       27629    27628       -1     
==========================================
+ Hits        23235    23237       +2     
+ Misses       4394     4391       -3     

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