fix: always rebuild index from log on startup, flush index after every append

Matthias Nott

8 days ago a4f64fec47b8cafb638d6643df2b56b9e152d3d3

 lib/services/message_store.dart
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@@ -64,33 +64,18 @@
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       final logFile = File(_logPath(dir));
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       final indexFile = File(_indexPath(dir));
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-      // Try loading saved index first (fast path).
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-      if (indexFile.existsSync()) {
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-        try {
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-          final raw = indexFile.readAsStringSync();
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-          final decoded = jsonDecode(raw) as Map<String, dynamic>;
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-          for (final entry in decoded.entries) {
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-            _index[entry.key] =
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-                (entry.value as List<dynamic>).map((e) => e as int).toList();
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-          }
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-        } catch (_) {
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-          _index.clear();
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-        }
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-      }
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-
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-      // Count actual lines in log to set _lineCount.
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+      // Always rebuild index from log (the saved index.json may be stale
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+      // if the app was killed before a flush).
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       if (logFile.existsSync()) {
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         final content = logFile.readAsStringSync();
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         _lineCount = content.isEmpty
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             ? 0
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             : content.trimRight().split('\n').length;
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+        if (_lineCount > 0) {
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+          await _rebuildIndex(logFile);
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+        }
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       } else {
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         _lineCount = 0;
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-      }
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-
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-      // If the index was missing or corrupt, rebuild from log.
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-      if (_index.isEmpty && _lineCount > 0) {
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-        await _rebuildIndex(logFile);
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       }
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       TraceService.instance.addTrace(
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@@ -143,15 +128,15 @@
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       logFile.writeAsStringSync(line, mode: FileMode.append);
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       // Update in-memory index.
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-      _index.putIfAbsent(sessionId, () => []).add(_lineCount);
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+      final lineNum = _lineCount;
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+      _index.putIfAbsent(sessionId, () => []).add(lineNum);
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       _lineCount++;
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-      // Periodically flush index to disk.
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-      _appendsSinceFlush++;
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-      if (_appendsSinceFlush >= _indexFlushInterval) {
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-        _flushIndex(dir);
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-        _appendsSinceFlush = 0;
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-      }
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+      TraceService.instance.addTrace('MsgStoreV2 APPEND',
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+          '${sessionId.substring(0, 8)} line=$lineNum total=$_lineCount idx=${_index[sessionId]?.length ?? 0}');
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+
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+      // Flush index after every append to prevent data loss on app kill.
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+      _flushIndex(dir);
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     } catch (e) {
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       TraceService.instance.addTrace('MsgStoreV2 APPEND ERROR', '$e');
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     }
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@@ -173,6 +158,8 @@
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       // Read all lines at once then pick the ones we need.
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       final allLines = logFile.readAsLinesSync();
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+      TraceService.instance.addTrace('MsgStoreV2 LOAD detail',
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+          '${sessionId.substring(0, 8)}: fileLines=${allLines.length} indexEntries=${lineNumbers.length} lineCount=$_lineCount');
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       final messages = <Message>[];
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       for (final n in lineNumbers) {