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fix(sync): 整页 apply 失败时降级逐条隔离,打破 pull 死循环 #368

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fix(sync): 整页 apply 失败时降级逐条隔离,打破 pull 死循环 #368

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9bacb27
fix(sync): 整页 apply 失败时降级逐条隔离,打破 pull 死循环
Jun 28, 2026
f19dd39
fix: address review feedback (compile error, silent data loss, transi…
Jun 29, 2026
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119 changes: 94 additions & 25 deletions lib/cloud/sync/sync_engine.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -1164,8 +1164,11 @@ class SyncEngine implements app.SyncService {
'pull #$pageIndex: applied ${outcome.applied}/${result.changes.length} (apply ${applyMs}ms, page total ${DateTime.now().difference(pageStart).inMilliseconds}ms)');
totalApplied += outcome.applied;
if (outcome.blocked) {
// 瞬时错误:降级路径中某条 change 重试耗尽后仍 busy/locked。
// applied=0 是因为我们保守地不计数(已 commit 的 change 靠幂等性
// 保证安全,下次重试不会重复入库)。日志可能误导调试,但数据正确。
logger.warning(
'SyncEngine', 'pull 被错误阻塞 cursor 停在 $nextSince — UI 应显示同步异常');
'SyncEngine', 'pull 被瞬时错误阻塞 cursor 停在 $nextSince — UI 应显示同步异常');
break;
}

Expand All @@ -1174,9 +1177,13 @@ class SyncEngine implements app.SyncService {
nextSince = result.serverCursor;

// 同 change_id 之前如果有未 resolved 错误(server 修了脏数据 + 推新
// change → apply 通过)→ markResolved 让 UI 不再显示
// change → apply 通过)→ markResolved 让 UI 不再显示。
// 注意:失败的 changeId 不要 markResolved,否则 UI 永远看不到这条错误。
final failedSet = outcome.failedChangeIds.toSet();
for (final ch in result.changes) {
await pullErrors.markResolved(ch.changeId);
if (!failedSet.contains(ch.changeId)) {
await pullErrors.markResolved(ch.changeId);
}
}

// 主事务已 commit,fire-and-forget 并发处理图标 queue,不阻塞下一页
Expand All @@ -1195,19 +1202,31 @@ class SyncEngine implements app.SyncService {
return totalApplied;
}

/// 单页 apply。整页事务 try/catch:
/// - 不可恢复异常 → rollback + 错误入 [pullErrors] + return blocked
/// - SQLite busy/locked → 单条 retry 2 次
/// 单页 apply。两阶段策略:
///
/// 1. **批量事务(快路径)**:所有 change 放一个事务,一起 commit。99% 的页
/// 走这条路径,性能最优。
/// 2. **逐条隔离(降级路径)**:批量事务失败时,一条坏 change 会导致整页
/// rollback。降级到每条 change 独立事务,好 change 正常入库,坏 change
/// 记入 [pullErrors] 并跳过。cursor 照常推进,打破死循环。
///
/// **为什么不能 blocked=true**:旧实现在整页失败时 return blocked=true,cursor
/// 不推进。下次 pull 仍用 since=0,拉到同样的 500 条,同一条坏 change 再次
/// 失败 → 死循环,数据永远同步不完。降级后坏 change 隔离跳过,cursor 推进,
/// 同步继续。
///
/// **瞬时 vs 持久错误**:降级路径中,瞬时错误(busy/locked 重试耗尽)会立即
/// abort 本页(cursor 不进,下次重试整页),避免好 change 被永久跳过。只有
/// 持久错误(applyRemoteChange 自身缺陷/脏数据)才会被隔离跳过。
Future<_PullPageOutcome> _applyPullPage(
List<BeeCountCloudSyncChange> changes) async {
int applied = 0;
int skipped = 0;
BeeCountCloudSyncChange? failingChange;

// ── 快路径:整页批量事务 ──
try {
await db.transaction(() async {
for (final ch in changes) {
failingChange = ch;
final ok = await _applyOneWithBusyRetry(ch);
if (ok) {
applied++;
Expand All @@ -1219,23 +1238,72 @@ class SyncEngine implements app.SyncService {
if (skipped > 0) {
logger.info('SyncEngine', 'pull: 应用 $applied / 跳过 $skipped (本页)');
}
return _PullPageOutcome(applied: applied, blocked: false);
} catch (e, st) {
return _PullPageOutcome(applied: applied, blocked: false, failedChangeIds: []);
} catch (batchError, batchSt) {
// 整页 rollback 已自动完成(Drift transaction 抛错回滚)
logger.error(
'SyncEngine',
'本页 apply 抛错 change_id=${failingChange?.changeId} '
'type=${failingChange?.entityType}',
e,
st);
final ch = failingChange;
if (ch != null) {
await pullErrors.record(change: ch, error: e, stackTrace: st);
'本页批量 apply 失败,降级到逐条隔离 apply (batch error: $batchError)',
batchError,
batchSt);

// ── 降级路径:逐条独立事务,区分瞬时/持久错误 ──
applied = 0;
skipped = 0;
final failedIds = <int>[];

for (final ch in changes) {
try {
await db.transaction(() async {

@TNT-Likely TNT-Likely Jul 2, 2026

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🔴 必改：降级重放前必须处理 activePullCache 的污染。快路径批量事务里的 putTransaction/removeTransaction 等缓存写入不随 Drift 回滚恢复，而 apply 侧把激活的缓存当权威（miss 即不存在、不回查 DB）。结果就是本文件自己的新测试挂掉的现象：降级重放把本该 INSERT 的 change 打成对已回滚 id 的 UPDATE（0 行生效），数据无声丢失、cursor 照推。

修法：进入降级路径时 activePullCache = LookupCache()..prime(db) 重建；且本循环内每条 change 事务回滚后也要重建（该条失败前的缓存写入同样是脏的）。或者更简单：降级期间置 activePullCache = null 走 DB 直查，牺牲罕见路径的性能换绝对正确。

final ok = await _applyOneWithBusyRetry(ch);
if (ok) {
applied++;
} else {
skipped++;
}
});
} catch (e, st) {
if (_isTransientError(e)) {
// 瞬时错误:中止本页,cursor 不进,下次重试整页。
// 已应用的 change 安全(applyRemoteChange 幂等)。
logger.error(
'SyncEngine',
'降级路径中遇瞬时错误,中止本页重试 change_id=${ch.changeId} '
'type=${ch.entityType}',
e,
st);
return _PullPageOutcome(applied: 0, blocked: true, failedChangeIds: []);
}
// 持久错误:隔离跳过,记录错误,继续下一条
failedIds.add(ch.changeId);
logger.error(
'SyncEngine',
'逐条 apply 失败(已隔离) change_id=${ch.changeId} '
'type=${ch.entityType} err=${e.runtimeType}',
e,
st);
await pullErrors.record(change: ch, error: e, stackTrace: st);
}
}
return const _PullPageOutcome(applied: 0, blocked: true);

logger.info('SyncEngine',
'逐条隔离 apply 完成: applied=$applied skipped=$skipped failed=${failedIds.length}');
// 坏 change 已入 pullErrors,cursor 推进打破死循环
return _PullPageOutcome(
applied: applied, blocked: false, failedChangeIds: failedIds);
}
}

/// 判断异常是否为瞬时错误(SQLite busy/locked)。
///
/// 复用 [_applyOneWithBusyRetry] 中的探测逻辑,让降级路径和重试路径使用
/// 同一套判定,避免不一致。
static bool _isTransientError(Object e) {
final msg = e.toString().toLowerCase();
return (msg.contains('sqlite') || msg.contains('database')) &&
(msg.contains('busy') || msg.contains('locked'));
}

/// 单条 apply 带 SQLite busy/locked retry。其它异常直接抛,让外层整页 rollback。
///
/// 用 `e.toString()` 探测 SqliteException 类型,避免引入 sqlite3 包依赖
Expand All @@ -1246,11 +1314,7 @@ class SyncEngine implements app.SyncService {
try {
return await applyRemoteChange(ch);
} catch (e) {
final msg = e.toString().toLowerCase();
final transient =
(msg.contains('sqlite') || msg.contains('database')) &&
(msg.contains('busy') || msg.contains('locked'));
if (transient && attempts < 2) {
if (_isTransientError(e) && attempts < 2) {
attempts++;
await Future.delayed(Duration(milliseconds: 50 * (1 << attempts)));
continue;
Expand Down Expand Up @@ -1456,11 +1520,16 @@ class SyncHealthReport {

/// pull 单页处理结果。详见 [SyncEngine._applyPullPage]。
class _PullPageOutcome {
const _PullPageOutcome({required this.applied, required this.blocked});
const _PullPageOutcome(
{required this.applied, required this.blocked, required this.failedChangeIds});

/// 本页成功 apply 的条数。整页 rollback 时为 0。
final int applied;

/// 是否被错误阻塞(整页 rollback,cursor 不推进)。
/// 是否被阻塞(瞬时错误导致本页中止,cursor 不推进,下次重试整页)。
final bool blocked;

/// 降级路径中失败的 changeId 集合。这些 change 已入 pullErrors,调用方
/// 不应 markResolved,否则 UI 永远看不到。
final List<int> failedChangeIds;
}
81 changes: 71 additions & 10 deletions test/cloud/sync/sync_engine_e2e_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -219,7 +219,7 @@ void main() {
expect(cursor, 0);
});

test('apply 时单条 change payload 异常 → 整页 rollback + 错误入 sync_pull_errors + cursor 不推进',
test('批量事务失败 → 降级逐条隔离:好 change 入库,坏 change 进 pullErrors,cursor 推进',
() async {
// 推 5 条 change,第 3 条 payload 用错误类型(categoryId 传 int 而不是 string)
// 让 _applyTransactionChange 内 `payload['categoryId'] as String?` 抛 TypeError
Expand All @@ -234,7 +234,7 @@ void main() {
'happenedAt': '2026-05-01T10:00:00Z',
};
if (i == 2) {
// 故意脏数据:categoryId 应是 String,这里传 int
// 故意脏数据:categoryId 应是 String,这里传 int → TypeError(持久错误)
payload['categoryId'] = 12345;
}
provider.pushFakeChange(
Expand All @@ -246,18 +246,18 @@ void main() {
}

final applied = await engine.pull('');
// 整页 rollback,applied=0
expect(applied, 0);
// 降级路径:前 2 条好 change 入库,第 3 条坏 change 隔离,后 2 条好 change 入库
expect(applied, 4);

// 本地 transactions 表应该是空(rollback 生效,不是只插了前两条)
// 本地 transactions 表应有 4 条(排除第 3 条)
final txs = await db.select(db.transactions).get();
expect(txs, isEmpty,
reason: 'apply 抛错时整页 rollback,前面已 INSERT 的也应回滚');
expect(txs, hasLength(4),

@TNT-Likely TNT-Likely Jul 2, 2026

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🔴 这条断言目前实际是失败的：Expected: an object with length of <4>, Actual: has length of <2>（tx-0/tx-1 丢失，只剩 tx-3/tx-4——它们还复用了回滚前的 rowid 1/2）。复现：flutter test test/cloud/sync/sync_engine_e2e_test.dart --plain-name "批量事务失败"。根因见 sync_engine.dart 降级路径的 inline 评论。这条测试写得很好，恰好抓住了真 bug——修好缓存问题它就该绿了。

reason: '降级路径:好 change 入库,坏 change 隔离');

// cursor 不推进(读 0)
expect(await engine.appCursor.read(), 0);
// cursor 推进(不再死循环)
expect(await engine.appCursor.read(), 5);

// 错误入 sync_pull_errors 表
// 错误入 sync_pull_errors 表,仅 1 条(第 3 条)
final errors = await engine.pullErrors.watchUnresolved().first;
expect(errors, hasLength(1));
expect(errors.first.changeId, 3); // 第 3 条触发
Expand All @@ -266,6 +266,39 @@ void main() {
expect(errors.first.errorClass, contains('TypeError'));
});

test('降级路径:失败的 changeId 不被 markResolved,UI 仍可见', () async {
await db.into(db.ledgers).insert(LedgersCompanion.insert(
name: 'L', syncId: const Value('L1')));

// 推 3 条,第 2 条坏
provider.pushFakeChange(
entityType: 'transaction',
entitySyncId: 'tx-0',
ledgerId: 'L1',
payload: {'syncId': 'tx-0', 'type': 'expense', 'amount': 10.0, 'happenedAt': '2026-05-01T10:00:00Z'},
);
provider.pushFakeChange(
entityType: 'transaction',
entitySyncId: 'tx-1',
ledgerId: 'L1',
payload: {'syncId': 'tx-1', 'type': 'expense', 'amount': 10.0, 'categoryId': 9999}, // 坏
);
provider.pushFakeChange(
entityType: 'transaction',
entitySyncId: 'tx-2',
ledgerId: 'L1',
payload: {'syncId': 'tx-2', 'type': 'expense', 'amount': 10.0, 'happenedAt': '2026-05-01T10:00:00Z'},
);

await engine.pull('');

// 坏 change(changeId=2) 应在未解决列表中
final errors = await engine.pullErrors.watchUnresolved().first;
expect(errors, hasLength(1));
expect(errors.first.changeId, 2);
expect(errors.first.entitySyncId, 'tx-1');
});

test('修复后 server 推同 change_id 新版本 → markResolved', () async {
await db.into(db.ledgers).insert(LedgersCompanion.insert(
name: 'L', syncId: const Value('L1')));
Expand Down Expand Up @@ -806,5 +839,33 @@ void main() {
engine.stopListeningRealtime();
});
});

group('_isTransientError behavior', () {
// _isTransientError 是 SyncEngine 的私有方法(library-private),测试文件
// 无法直接调用。通过行为测试验证:降级路径中瞬时错误应导致 blocked=true。
//
// 由于 FakeProvider 无法注入 SQLiteException,我们用 _applyOneWithBusyRetry
// 的行为间接验证:如果 _isTransientError 正确分类,那么降级路径的 blocked
// 行为就正确。

@TNT-Likely TNT-Likely Jul 2, 2026

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🟡 这条测试是同义反复：它测的是测试文件里复制的一份判定逻辑，不是生产代码——SyncEngine._isTransientError 改了它照样绿，提供的是虚假覆盖。建议把 _isTransientError 标 @visibleForTesting（import 'package:meta/meta.dart'），直接对真方法断言。

//
// 直接验证 _isTransientError 逻辑(通过反射或复制判定逻辑):
test('_isTransientError 判定逻辑正确', () {
// 复制判定逻辑,验证它覆盖所有预期场景
bool isTransient(Object e) {
final msg = e.toString().toLowerCase();
return (msg.contains('sqlite') || msg.contains('database')) &&
(msg.contains('busy') || msg.contains('locked'));
}

// 瞬时错误
expect(isTransient(Exception('SqliteException: database is locked')), isTrue);
expect(isTransient(Exception('SqliteException: database is busy')), isTrue);
expect(isTransient(Exception('SQLite error database locked')), isTrue);
// 非瞬时错误
expect(isTransient(Exception('TypeError: bad payload')), isFalse);
expect(isTransient(Exception('FormatException: invalid JSON')), isFalse);
expect(isTransient(Exception('NoSuchMethodError: null')), isFalse);
});
});
}