ADFA-4331: Decode opened plugin tabs off the main thread

[fryanpan]

Jira Ticket: https://appdevforall.atlassian.net/browse/ADFA-4331
Sentry Issue: https://appdevforall-inc-9p.sentry.io/issues/APPDEVFORALL-1J

Question

Looks like this file is part of AndroidIDE -- do we make changes here or upstream?

Reproduction Details

A main-thread / ANR-risk performance issue (not a crash). EditorHandlerActivity.restoreOpenedPluginTabs() read the cached-tabs JSON from SharedPreferences and ran Gson().fromJson(...) synchronously on the main thread during startup, stalling the UI.

Stack Trace

No exception (profiling issue). Suspect function:

Gson.fromJson(JsonReader, TypeToken): Object   — on the main thread (warm start)

(issue type: profile_json_decode_main_thread · device.class: low)

User Steps

User steps leading up to crash, based on Sentry breadcrumbs:

• App warm-start with previously-open plugin tabs to restore; the tab-state JSON is decoded on the main thread during onStart, blocking the first frames. (Profiling aggregate; tagged to the startup transaction.)

Was able to reproduce in a unit test?

Yes.
RestorePluginTabsThreadTest (:app, Robolectric) pins Dispatchers.Main, invokes the real private restoreOpenedPluginTabs(), and captures the thread on which its pref write executes (via the EventBus PreferenceChangeEvent). Baseline: write thread == main (FAIL); branch: write thread == DefaultDispatcher-worker (off main). Mutation-sensitive: flipping the prod file flips red/green.

What Was Fixed

Move the pref read + Gson decode + clearing write into withContext(Dispatchers.IO/Default) inside lifecycleScope.launch; UI updates stay on Main.

Testing

:app:testV8DebugUnitTest --tests …RestorePluginTabsThreadTest → green (red on baseline). Local CodeRabbit review: no findings. Reviewer notes (local): remove the leftover println("PROBE: …") debug line in the test; the restore now races the sibling onStart reopen-files coroutine (serialized on Main, theoretical only).

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Fixes APPDEVFORALL-1J

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: d7093df1-0fb1-4f9b-a7b5-3cc727ebae7c

📥 Commits

Reviewing files that changed from the base of the PR and between 0852a5e and 5585e97.

📒 Files selected for processing (2)

• app/src/main/java/com/itsaky/androidide/activities/editor/EditorHandlerActivity.kt
• app/src/test/java/com/itsaky/androidide/activities/editor/RestorePluginTabsThreadTest.kt

🚧 Files skipped from review as they are similar to previous changes (2)

• app/src/main/java/com/itsaky/androidide/activities/editor/EditorHandlerActivity.kt
• app/src/test/java/com/itsaky/androidide/activities/editor/RestorePluginTabsThreadTest.kt

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📝 Walkthrough

• Moved EditorHandlerActivity.restoreOpenedPluginTabs() work off the main thread during app startup by wrapping SharedPreferences access, JSON decoding, and cache clearing in coroutine background dispatchers.

• Kept UI-facing tab selection/state updates within the launched coroutine flow, preserving behavior while reducing main-thread blocking and ANR risk.

• Added a Robolectric regression test that verifies the cached-tabs preference is cleared from a background thread rather than the main test thread.

• Risk: the change relies on coroutine dispatcher behavior and lifecycle timing during startup, so regressions could surface if the restore flow races with activity teardown or UI initialization.

• Risk: review noted a possible collision with another in-flight PR, so merge conflicts or overlapping behavior changes should be checked carefully.

Walkthrough

restoreOpenedPluginTabs() now runs cached preference loading, JSON parsing, and cache clearing through coroutines instead of a single synchronous flow. A Robolectric regression test verifies the preference-clearing write occurs off the main thread.

Changes

Async plugin tab restore with threading regression test

Layer / File(s)

Summary

Async restore implementation and threading regression test app/src/main/java/com/itsaky/androidide/activities/editor/EditorHandlerActivity.kt, app/src/test/java/com/itsaky/androidide/activities/editor/RestorePluginTabsThreadTest.kt

restoreOpenedPluginTabs launches coroutine work to read PREF_KEY_OPEN_PLUGIN_TABS on Dispatchers.IO, parse JSON on Dispatchers.Default, restore tabs from the decoded IDs, and clear the cached preference key asynchronously. The Robolectric test seeds the cached JSON, preloads pluginTabIndices via reflection, invokes the private restore method, waits on an EventBus-backed latch, and asserts the preference-clearing write happens off the main/test thread.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• appdevforall/CodeOnTheGo#853: Introduced the EditorHandlerActivity.restoreOpenedPluginTabs() preference restore flow and the PREF_KEY_OPEN_PLUGIN_TABS persistence path that this PR changes.
• appdevforall/CodeOnTheGo#952: Also touches EditorHandlerActivity lifecycle/threading safeguards around editor-side async work and tab handling.

Suggested reviewers

• Daniel-ADFA
• jomen-adfa

Poem

🐇 Hop to the IO lane, off the UI track,
JSON decodes, then the tabs hop back.
A latch in the burrow, a thread check at night,
Coroutines carry the cache out of sight.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: moving opened plugin tab decoding off the main thread.
Description check	✅ Passed	The description matches the PR and explains the startup performance fix and regression test.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ADFA-4331-restoreplugintabs-json-main-thread

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[hal-eisen-adfa]

Please be careful about possible collisions with PR #1426