- Use background context for cache rebuild
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bogdan committed 4 days ago
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83 additions
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HealthProbe/Doc/04-project/Import-Optimization-Log.md
@@ -471,6 +471,27 @@ from a detached task. Automatic post-snapshot refresh should read the small |
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timeline/status data directly from SQLite; full Core Data cache rebuild should |
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remain explicit/manual until partial invalidation exists. |
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+### 2026-06-03 Core Data Cache Rebuild Crash Stack |
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+ |
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+Source: user-provided LLDB backtrace after a fast crash. The stack still pointed |
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+to an app binary that called `CoreDataArchiveCacheStore.rebuild` from |
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+`DashboardViewModel.startArchiveCacheRefresh`, which was removed in `199d2ef`. |
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+However, the stack also exposed a real cache-store bug: rebuild inserted |
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+`NSManagedObject`s through `container.viewContext` while running on a Swift |
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+utility task. |
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+ |
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+Crash location: |
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+ |
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+- `CoreDataArchiveCacheStore.insertDailyAggregateRows` |
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+- `NSEntityDescription.insertNewObject` |
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+- `NSManagedObjectContext insertObject` |
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+- Core Data `__CFBasicHashAddValue` / `EXC_BAD_ACCESS` |
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+ |
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+Conclusion: even though automatic post-snapshot rebuild has been removed, manual |
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+cache rebuild must also be safe. `CoreDataArchiveCacheStore.rebuild` and |
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+`deleteCache` should use a dedicated background context and perform all Core |
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+Data mutations on that context's queue. |
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+ |
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## Optimization Iterations |
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| Date | Commit | Change | Result / Status | |
@@ -499,6 +520,7 @@ remain explicit/manual until partial invalidation exists. |
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| 2026-06-03 | `7d52262` | Start Dashboard archive cache refresh without awaiting it after snapshot completion. | Triggered by continued app unresponsiveness after a successful 31.3s incremental snapshot. Expected signal: progress sheet/result UI remains responsive while cache rows refresh later. | |
| 500 | 521 |
| 2026-06-03 | `1229f19` | Disable legacy SwiftData detail-cache precompute completely and load Snapshots timeline from SQLite. | Triggered by overnight crash after two small detail caches were built. Expected signal: no `healthKit.detailCache.buildBegin` logs during snapshot save, no Core Data mutated-while-enumerated abort, and the new SQLite observation appears in Snapshots without waiting for cache rebuild. | |
| 501 | 522 |
| 2026-06-03 | `199d2ef` | Stop automatic Dashboard Core Data cache rebuild after snapshot; refresh latest rows from SQLite only. | Triggered by freeze after copying a successful diagnostic report. Expected signal: copying diagnostics and returning to Dashboard/Snapshots remains responsive; Core Data cache rebuild is no longer started automatically after snapshot completion. | |
| 523 |
+| 2026-06-03 | pending | Run Core Data cache rebuild/delete on a dedicated background context. | Triggered by `EXC_BAD_ACCESS` inside Core Data object insertion during cache rebuild. Expected signal: manual Settings cache rebuild no longer crashes due to `NSManagedObjectContext` queue misuse. | |
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## Current Diagnosis |
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@@ -523,6 +545,8 @@ The likely bottleneck is per-row SQLite work: |
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app starts a full rebuild immediately after the import. Even detached rebuilds |
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can overwhelm real-device I/O/CPU, so automatic post-snapshot UI refresh should |
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use SQLite summary rows only. |
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+- Core Data cache rebuild must not mutate `viewContext` from background Swift |
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+ tasks. Rebuild/delete should use a private background context. |
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## Open Issues / Observations |
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+59
-36
HealthProbe/Services/CoreDataArchiveCacheStore.swift
@@ -113,47 +113,52 @@ nonisolated final class CoreDataArchiveCacheStore {
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} |
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func rebuild(fromArchiveAt archiveURL: URL) throws -> CoreDataArchiveCacheRebuildSummary {
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- let archive = try openArchive(at: archiveURL) |
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- defer { sqlite3_close(archive) }
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- |
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- let archiveSchemaVersion = try archiveSchemaVersion(db: archive) |
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- let integrityStatus = try firstText("PRAGMA integrity_check", db: archive) ?? "missing"
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- let computedAt = Date() |
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- let context = container.viewContext |
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- |
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- try resetCache(context: context) |
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- |
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- let observationCount = try insertObservationRows(db: archive, context: context, archiveSchemaVersion: archiveSchemaVersion, computedAt: computedAt) |
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- let typeSummaryCount = try insertTypeSummaryRows(db: archive, context: context, computedAt: computedAt) |
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- let dailyAggregateCount = try insertDailyAggregateRows(db: archive, context: context, computedAt: computedAt) |
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- let diffSummaryCount = try insertDiffSummaryRows(db: archive, context: context, computedAt: computedAt) |
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- let exportManifestCount = try insertExportManifestRows(db: archive, context: context, computedAt: computedAt) |
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- try insertArchiveHealthRow( |
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- context: context, |
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- archiveSchemaVersion: archiveSchemaVersion, |
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- integrityStatus: integrityStatus, |
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- computedAt: computedAt |
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- ) |
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+ let context = makeBackgroundContext() |
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+ |
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+ return try performAndWait(in: context) {
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+ let archive = try openArchive(at: archiveURL) |
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+ defer { sqlite3_close(archive) }
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+ |
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+ let archiveSchemaVersion = try archiveSchemaVersion(db: archive) |
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+ let integrityStatus = try firstText("PRAGMA integrity_check", db: archive) ?? "missing"
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+ let computedAt = Date() |
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+ |
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+ try resetCache(context: context) |
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+ |
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+ let observationCount = try insertObservationRows(db: archive, context: context, archiveSchemaVersion: archiveSchemaVersion, computedAt: computedAt) |
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+ let typeSummaryCount = try insertTypeSummaryRows(db: archive, context: context, computedAt: computedAt) |
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+ let dailyAggregateCount = try insertDailyAggregateRows(db: archive, context: context, computedAt: computedAt) |
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+ let diffSummaryCount = try insertDiffSummaryRows(db: archive, context: context, computedAt: computedAt) |
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+ let exportManifestCount = try insertExportManifestRows(db: archive, context: context, computedAt: computedAt) |
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+ try insertArchiveHealthRow( |
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+ context: context, |
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+ archiveSchemaVersion: archiveSchemaVersion, |
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+ integrityStatus: integrityStatus, |
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+ computedAt: computedAt |
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+ ) |
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- if context.hasChanges {
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- try context.save() |
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- } |
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+ if context.hasChanges {
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+ try context.save() |
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+ } |
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- return CoreDataArchiveCacheRebuildSummary( |
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- observationRows: observationCount, |
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- typeSummaryRows: typeSummaryCount, |
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- dailyAggregateRows: dailyAggregateCount, |
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- diffSummaryRows: diffSummaryCount, |
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- exportManifestRows: exportManifestCount, |
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- archiveHealthRows: 1 |
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- ) |
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+ return CoreDataArchiveCacheRebuildSummary( |
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+ observationRows: observationCount, |
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+ typeSummaryRows: typeSummaryCount, |
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+ dailyAggregateRows: dailyAggregateCount, |
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+ diffSummaryRows: diffSummaryCount, |
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+ exportManifestRows: exportManifestCount, |
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+ archiveHealthRows: 1 |
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+ ) |
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+ } |
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} |
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func deleteCache() throws {
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- let context = container.viewContext |
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- try resetCache(context: context) |
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- if context.hasChanges {
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- try context.save() |
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+ let context = makeBackgroundContext() |
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+ try performAndWait(in: context) {
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+ try resetCache(context: context) |
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+ if context.hasChanges {
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+ try context.save() |
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+ } |
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} |
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} |
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@@ -217,6 +222,24 @@ nonisolated final class CoreDataArchiveCacheStore {
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return try container.viewContext.fetch(request).first.map(Self.archiveHealthStatus) |
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} |
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+ private func makeBackgroundContext() -> NSManagedObjectContext {
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+ let context = container.newBackgroundContext() |
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+ context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy |
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+ context.undoManager = nil |
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+ return context |
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+ } |
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+ |
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+ private func performAndWait<T>( |
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+ in context: NSManagedObjectContext, |
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+ _ body: () throws -> T |
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+ ) throws -> T {
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+ var result: Result<T, Error>? |
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+ context.performAndWait {
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+ result = Result { try body() }
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+ } |
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+ return try result!.get() |
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+ } |
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+ |
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private func resetCache(context: NSManagedObjectContext) throws {
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for entityName in Self.cacheEntityNames {
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let request = NSFetchRequest<NSManagedObject>(entityName: entityName) |