⚡ Bolt: Replace Stream with loop and O(N) HashSet lookup in HomeTimelineFragment

[dlukt]

💡 What: Replaced Java Stream operations in HomeTimelineFragment with traditional loops and a HashSet lookup.
🎯 Why: In loadNewPosts, the method checked for duplicate statuses by collecting existing IDs into a List via a Stream, then calling toAdd.removeIf(s -> existingIds.contains(s.getID())). Since List.contains is an O(N) operation inside the removeIf loop, this created a hidden O(N * M) performance bottleneck in a critical data-loading hot path. Additionally, using Streams for mapping and filtering caused unnecessary object allocations, contributing to GC pressure and jank.
📊 Impact: Reduces time complexity for duplicate checking from O(N*M) to O(N+M) and eliminates intermediate Stream/Optional object allocations.
🔬 Measurement: Verify by running loadNewPosts on heavily populated accounts or large local caching scenarios; memory profiles will show zero Stream allocations and significantly less CPU time spent on removeIf.

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PR created automatically by Jules for task 6529411776881922897 started by @dlukt

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[Copilot]

Pull request overview

Optimizes timeline loading in HomeTimelineFragment by removing Java Stream/Optional usage in hot paths and replacing duplicate checks with HashSet lookups to reduce allocations and improve asymptotic performance.

Changes:

• Replaced Stream-based filtering/mapping in loadNewPosts() with explicit loops.
• Switched duplicate detection from List.contains to HashSet.contains to avoid O(N*M) behavior.
• Documented the “Bolt” performance learning for this optimization.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
settings.gradle	Bumps Foojay toolchain resolver plugin version (appears unrelated to the PR’s stated performance change).
mastodon/src/main/java/de/icod/techidon/fragments/HomeTimelineFragment.java	Replaces Stream/Optional usage with loops and introduces HashSet-based duplicate filtering in loadNewPosts().
.jules/bolt.md	Adds an entry documenting the Stream allocation + O(N²) duplicate-check trap and the applied fix.

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[dlukt]

@jules
#settings.gradle
}
plugins {
id 'org.gradle.toolchains.foojay-resolver-convention' version '0.5.0'
id 'org.gradle.toolchains.foojay-resolver-convention' version '0.8.0'
Copilot commented 5 hours ago

Copilotbot
5 hours ago

Medium

The Gradle Foojay toolchain resolver plugin version bump is unrelated to the stated PR goal (Stream/HashSet optimization in HomeTimelineFragment). Please either justify this change in the PR description or move it to a separate PR to keep performance-focused changes isolated and easier to revert.

I prefer the former

[google-labs-jules]

@jules
#settings.gradle
}
plugins {
id 'org.gradle.toolchains.foojay-resolver-convention' version '0.5.0'
id 'org.gradle.toolchains.foojay-resolver-convention' version '0.8.0'
Copilot commented 5 hours ago

Copilotbot
5 hours ago

Medium

The Gradle Foojay toolchain resolver plugin version bump is unrelated to the stated PR goal (Stream/HashSet optimization in HomeTimelineFragment). Please either justify this change in the PR description or move it to a separate PR to keep performance-focused changes isolated and easier to revert.

I prefer the former

I have updated the PR description to include the justification for the Foojay plugin version bump. It was necessary to fix a toolchain resolution error with JDK 21 that prevented the local test and lint checks from succeeding.