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Cache Inconsistency Fix

The Problem

Your cache was showing inconsistent counts:

  • Store: 349 messages
  • Sent: 491 messages
  • Unsent: 176 messages

The math doesn't add up: 491 + 176 = 667, which is much more than the 349 messages in your SMS store.

Root Cause

The cache database had a fundamental design flaw:

  1. Duplicate Entries: The CacheEntry table used an auto-incrementing ID as the primary key, but the message hash (key) was NOT unique. This allowed multiple entries for the same message.

  2. How Duplicates Occurred:

    • When the app retries failed uploads, it creates new cache entries
    • App restarts/crashes during processing could create duplicates
    • The same message processed multiple times gets multiple cache entries

  3. Counting Issue: The sent/unsent queries counted ALL rows, including duplicates, while the store count is the actual number of unique messages.

The Fix

1. Database Schema Update

  • Changed the primary key from auto-increment ID to the message hash (key)
  • Added INSERT OR REPLACE strategy to prevent duplicates
  • Created migration to clean up existing duplicates (keeps only the latest status for each message)

2. Diagnostic Features

  • Added diagnostic logging to detect inconsistencies
  • Shows duplicate count and missing entries in the activity log
  • Helps identify when the cache gets out of sync

3. UI Improvements

  • Clear Cache dialog now offers "Fix Duplicates" option
  • Better error messages and status reporting
  • Shows warnings when inconsistencies are detected

What Happens Next

When you install the updated app:

  1. Automatic Migration: On first launch, the database will migrate to version 2, removing all duplicate entries automatically.

  2. Accurate Counts: You should see:

    • Store: 349 (actual SMS count)
    • Sent + Unsent = 349 (or less if some messages were never processed)

  3. No More Duplicates: Future operations will update existing entries instead of creating duplicates.

Recommendations

  1. After Update:

    • Check the activity log for diagnostic messages
    • The counts should now add up correctly
    • If needed, use "Clear Cache" and re-sync to start fresh

  2. Going Forward:

    • The app will maintain consistency automatically
    • Retries and restarts won't create duplicates
    • Each message will have exactly one cache entry

Technical Details

  • Database version upgraded from 1 to 2
  • Migration SQL keeps only the latest entry for each message hash
  • Uses Room's OnConflictStrategy.REPLACE for upserts
  • Added getUniqueCount() and getTotalCount() queries for diagnostics