fix(ear): messages can't be displayed - WPB-24136

[David-Henner]

WPB-24136 [iOS] Messages can't be displayed due to decryption errors

Issue

Sometimes, with EAR enabled, after opening the app, some messages can't be displayed.

Cause

Messages couldn't be encrypted at rest because the database key was missing.

This happens because the app went to the background and locked the database (nullified the database key from cache) while the incremental sync was running and processing messages.

When this happens, we cancel the sync

wire-ios/wire-ios-sync-engine/Source/UserSession/ZMUserSession/ZMUserSession+LifeCycle.swift

Line 46 in 48209b1

await syncAgent?.suspend()

However, the cancellation doesn't get propagated properly from the suspend method to the inner sync task. Hence, the sync continues and tries to process messages while the database key is nil

Solution

• Propagate task cancellation properly in NonReentrantTaskManager and ExpiringActivity
• Add a Task.checkCancellation before processing individual events in the incremental sync
• Add a guard against having the database locked before processing any non-backgroundAccessible event, and handle cleaning up the processed events from the current batch

Testing

1. Log in & Enable EAR
2. Put the app in the background
3. Receive many messages (use a spambot to send 100s of messages)
4. Open the app and immediately put it in the background once the sync starts
5. Reopen the app

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Checklist

• Title contains a reference JIRA issue number like [WPB-XXX].
• Description is filled and free of optional paragraphs.
• Adds/updates automated tests.

[github-actions]

Test Results

   14 files  1 112 suites   11m 15s ⏱️
8 377 tests 8 344 ✅ 31 💤 2 ❌
8 389 runs  8 358 ✅ 31 💤 0 ❌

For more details on these failures, see this check.

Results for commit 3b9e148.

♻️ This comment has been updated with latest results.

Summary: workflow run #23488867210
Allure report (download zip): html-report-28736-fix_sync-cancellation-issues

[samwyndham]

Nice work

[sonarqubecloud]

Quality Gate failed

Failed conditions
12.8% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud