Files
scadaproj/ZB.MOM.WW.LocalDb/tests/ZB.MOM.WW.LocalDb.Tests/LwwApplierTests.cs
T
Joseph Doherty 9663279594 fix(localdb): preserve the poison cause when dead-lettering itself fails; pin self-referencing cascade (0.3.3 review follow-ups)
Three review follow-ups on 122940c. Still 0.3.3 — unpublished, so no further
version bump. No behaviour change to any succeeding path.

- The per-entry poison handler's recovery work (ROLLBACK TO + the dead-letter
  INSERT) was unguarded: a wedged connection, an I/O error, or a dead-letter
  INSERT that faults would propagate the SECOND exception and silently discard
  the FIRST — the one that says why the entry was poison at all. The pair is now
  wrapped; a recovery failure throws an AggregateException whose message names
  the entry (table + seq) and the recovery fault, and whose InnerException is the
  ORIGINAL entry fault, with the recovery fault carried alongside it at
  InnerExceptions[1] with its own stack. The outcome is unchanged and still
  fail-closed: nothing commits, and disposing the batch transaction unwinds it.
  OperationCanceledException is deliberately excluded from the wrap so a
  shutdown still surfaces as a cancellation rather than as a fault. No upstream
  caller catches SqliteException from the apply path (checked), so widening the
  escaping type is safe.

  Injected cheaply after all: a RAISE(ABORT) trigger on __localdb_dead_letter,
  stacked on the existing row-version poison trigger, produces exactly the
  two-fault case with no production test seam. The test asserts both causes are
  carried AND that the batch committed nothing — the entry that applied cleanly
  before the poison one is gone and the peer watermark never moved.

- Register_SelfReferencingCascade_Throws pins the README's "or from itself"
  claim: a table that is its own cascading parent (parent_id REFERENCES
  nodes(id) ON DELETE CASCADE) is refused. The guard needed no special case —
  it reads every foreign key in the database — but the promise is now tested.

- Comment on why EnterEntryAsync sits outside the try: a SAVEPOINT that failed
  opened nothing, so a handler ROLLBACK TO would name a savepoint that does not
  exist and fault in turn.

Both new tests were run against 122940c first and fail there: the self-reference
case throws nothing, and the stacked-fault case escapes as a bare
SqliteException("dead-letter write failed") with the original cause gone.

Suite: 215/215 green, build 0 warnings / 0 errors.
2026-08-20 08:49:11 -04:00

599 lines
26 KiB
C#

using Microsoft.Data.Sqlite;
using ZB.MOM.WW.LocalDb.Internal;
using ZB.MOM.WW.LocalDb.Replication;
using ZB.MOM.WW.LocalDb.Replication.Internal;
namespace ZB.MOM.WW.LocalDb.Tests;
public sealed class LwwApplierTests : IDisposable
{
private const string Pk1 = "{\"id\":1}";
private readonly string _path = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".db");
private readonly string _path2 = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".db");
public void Dispose()
{
SqliteConnection.ClearAllPools();
if (File.Exists(_path))
File.Delete(_path);
if (File.Exists(_path2))
File.Delete(_path2);
}
private async Task<SqliteLocalDb> NewOrdersDb()
{
var db = new SqliteLocalDb(new LocalDbOptions { Path = _path });
await db.ExecuteAsync("CREATE TABLE orders (id INTEGER PRIMARY KEY, sku TEXT, qty INTEGER)");
db.RegisterReplicated("orders");
return db;
}
private static async Task<long> RowVersionHlc(SqliteLocalDb db, string pkJson)
{
var r = await db.QueryAsync(
"SELECT hlc FROM __localdb_row_version WHERE table_name = 'orders' AND pk_json = @pk",
x => x.GetInt64(0), new { pk = pkJson });
return r[0];
}
private static async Task<(string? Sku, long? Qty)?> ReadOrder(SqliteLocalDb db, long id)
{
var r = await db.QueryAsync(
"SELECT sku, qty FROM orders WHERE id = @id",
x => (x.IsDBNull(0) ? null : x.GetString(0), (long?)(x.IsDBNull(1) ? null : x.GetInt64(1))),
new { id });
return r.Count == 0 ? null : r[0];
}
private static async Task<long> OplogCount(SqliteLocalDb db)
{
var r = await db.QueryAsync("SELECT COUNT(*) FROM __localdb_oplog", x => x.GetInt64(0));
return r[0];
}
private static OplogEntryRecord Entry(
long seq, string pkJson, string? rowJson, long hlc, string nodeId, bool tombstone = false) =>
new(seq, "orders", pkJson, rowJson, hlc, nodeId, tombstone);
[Fact]
public async Task Apply_NewerRemote_Wins()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(1, Pk1, "{\"id\":1,\"sku\":\"REMOTE\",\"qty\":99}", localHlc + 1000, "remote-node")], default);
Assert.Equal(1, result.Applied);
var row = await ReadOrder(db, 1);
Assert.Equal(("REMOTE", (long?)99), row);
var rv = await db.QueryAsync(
"SELECT hlc, node_id FROM __localdb_row_version WHERE pk_json = @pk",
x => (Hlc: x.GetInt64(0), Node: x.GetString(1)), new { pk = Pk1 });
Assert.Equal(localHlc + 1000, rv[0].Hlc);
Assert.Equal("remote-node", rv[0].Node);
}
[Fact]
public async Task Apply_OlderRemote_Discarded_StillCounted()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(7, Pk1, "{\"id\":1,\"sku\":\"OLD\",\"qty\":1}", localHlc - 1000, "remote-node")], default);
Assert.Equal(0, result.Applied);
Assert.Equal(1, result.Discarded);
Assert.Equal(7, result.AppliedThruSeq);
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
var peer = await db.QueryAsync(
"SELECT last_applied_remote_seq FROM __localdb_peer_state WHERE id = 1", x => x.GetInt64(0));
Assert.Equal(7, peer[0]);
}
[Fact]
public async Task Apply_EqualHlc_NodeIdTieBreak_Deterministic()
{
// Greater remote node_id wins the tie.
using (var db = await NewOrdersDb())
{
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var greater = db.NodeId + "z";
Assert.True(string.CompareOrdinal(greater, db.NodeId) > 0);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(1, Pk1, "{\"id\":1,\"sku\":\"WINS\",\"qty\":9}", localHlc, greater)], default);
Assert.Equal(1, result.Applied);
Assert.Equal(("WINS", (long?)9), await ReadOrder(db, 1));
}
SqliteConnection.ClearAllPools();
File.Delete(_path);
// Smaller remote node_id loses the tie.
using (var db = await NewOrdersDb())
{
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var smaller = "!" + db.NodeId;
Assert.True(string.CompareOrdinal(smaller, db.NodeId) < 0);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(1, Pk1, "{\"id\":1,\"sku\":\"LOSES\",\"qty\":9}", localHlc, smaller)], default);
Assert.Equal(0, result.Applied);
Assert.Equal(1, result.Discarded);
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
}
}
[Fact]
public async Task Apply_NewRow_Inserts()
{
using var db = await NewOrdersDb();
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(3, Pk1, "{\"id\":1,\"sku\":\"NEW\",\"qty\":42}", 5_000_000, "remote-node")], default);
Assert.Equal(1, result.Applied);
Assert.Equal(("NEW", (long?)42), await ReadOrder(db, 1));
}
[Fact]
public async Task Apply_Tombstone_DeletesRow()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(4, Pk1, null, localHlc + 1000, "remote-node", tombstone: true)], default);
Assert.Equal(1, result.Applied);
Assert.Null(await ReadOrder(db, 1));
var rv = await db.QueryAsync(
"SELECT is_tombstone, hlc FROM __localdb_row_version WHERE pk_json = @pk",
x => (Tomb: x.GetInt64(0), Hlc: x.GetInt64(1)), new { pk = Pk1 });
Assert.Equal(1, rv[0].Tomb);
Assert.Equal(localHlc + 1000, rv[0].Hlc);
}
[Fact]
public async Task Apply_DoesNotFireCaptureTriggers()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var before = await OplogCount(db);
await new LwwApplier(db).ApplyBatchAsync(
[
Entry(1, Pk1, "{\"id\":1,\"sku\":\"R\",\"qty\":9}", 9_000_000, "remote-node"),
Entry(2, "{\"id\":2}", "{\"id\":2,\"sku\":\"R2\",\"qty\":7}", 9_000_001, "remote-node"),
], default);
Assert.Equal(before, await OplogCount(db));
}
[Fact]
public async Task Apply_Batch_Atomic_WatermarkSameTxn()
{
using var db = await NewOrdersDb();
var result = await new LwwApplier(db).ApplyBatchAsync(
[
Entry(10, Pk1, "{\"id\":1,\"sku\":\"A\",\"qty\":1}", 1_000_000, "remote-node"),
Entry(11, "{\"id\":2}", "{\"id\":2,\"sku\":\"B\",\"qty\":2}", 1_000_001, "remote-node"),
], default);
Assert.Equal(2, result.Applied);
Assert.Equal(11, result.AppliedThruSeq);
// Data and the watermark are both visible => they committed in one transaction.
Assert.Equal(("A", (long?)1), await ReadOrder(db, 1));
Assert.Equal(("B", (long?)2), await ReadOrder(db, 2));
var peer = await db.QueryAsync(
"SELECT last_applied_remote_seq, last_seen_hlc FROM __localdb_peer_state WHERE id = 1",
x => (Seq: x.GetInt64(0), Hlc: x.GetInt64(1)));
Assert.Equal(11, peer[0].Seq);
Assert.Equal(1_000_001, peer[0].Hlc);
}
[Fact]
public async Task Apply_UnregisteredTable_Throws_NothingApplied()
{
using var db = await NewOrdersDb();
var batch = new OplogEntryRecord[]
{
Entry(20, Pk1, "{\"id\":1,\"sku\":\"A\",\"qty\":1}", 1_000_000, "remote-node"),
new(21, "widgets", "{\"id\":9}", "{\"id\":9}", 1_000_001, "remote-node", false),
};
await Assert.ThrowsAsync<LocalDbSchemaMismatchException>(
() => new LwwApplier(db).ApplyBatchAsync(batch, default));
// The valid entry that preceded the violation must not have been applied.
Assert.Null(await ReadOrder(db, 1));
var peer = await db.QueryAsync(
"SELECT last_applied_remote_seq FROM __localdb_peer_state WHERE id = 1", x => x.GetInt64(0));
Assert.Equal(0, peer[0]);
}
[Fact]
public async Task Apply_PoisonEntry_DeadLettered_BatchContinues()
{
using var db = await NewOrdersDb();
var result = await new LwwApplier(db).ApplyBatchAsync(
[
Entry(30, Pk1, "NOT VALID JSON", 1_000_000, "remote-node"),
Entry(31, "{\"id\":2}", "{\"id\":2,\"sku\":\"OK\",\"qty\":8}", 1_000_001, "remote-node"),
], default);
Assert.Equal(1, result.DeadLettered);
Assert.Equal(1, result.Applied);
Assert.Equal(("OK", (long?)8), await ReadOrder(db, 2));
Assert.Null(await ReadOrder(db, 1));
var dead = await db.QueryAsync(
"SELECT pk_json, error FROM __localdb_dead_letter",
x => (Pk: x.GetString(0), Err: x.GetString(1)));
Assert.Single(dead);
Assert.Equal(Pk1, dead[0].Pk);
Assert.NotEmpty(dead[0].Err);
}
[Fact]
public async Task Apply_IsIdempotent()
{
using var db = await NewOrdersDb();
var batch = new OplogEntryRecord[]
{
Entry(40, Pk1, "{\"id\":1,\"sku\":\"X\",\"qty\":3}", 7_000_000, "remote-node"),
new(41, "orders", "{\"id\":2}", "{\"id\":2,\"sku\":\"Y\",\"qty\":4}", 7_000_001, "remote-node", false),
};
var applier = new LwwApplier(db);
var first = await applier.ApplyBatchAsync(batch, default);
Assert.Equal(2, first.Applied);
var second = await applier.ApplyBatchAsync(batch, default);
Assert.Equal(0, second.Applied);
Assert.Equal(2, second.Discarded);
Assert.Equal(("X", (long?)3), await ReadOrder(db, 1));
Assert.Equal(("Y", (long?)4), await ReadOrder(db, 2));
var rows = await db.QueryAsync("SELECT COUNT(*) FROM orders", x => x.GetInt64(0));
Assert.Equal(2, rows[0]);
}
[Fact]
public async Task Apply_ObservesRemoteHlc()
{
using var db = await NewOrdersDb();
var maxHlc = (DateTimeOffset.UtcNow.AddDays(365).ToUnixTimeMilliseconds() << 16);
await new LwwApplier(db).ApplyBatchAsync(
[Entry(1, Pk1, "{\"id\":1,\"sku\":\"R\",\"qty\":1}", maxHlc, "remote-node")], default);
Assert.True(db.Clock.Next() > maxHlc);
}
[Fact]
public async Task Apply_AdvancesPeerState()
{
using var db = await NewOrdersDb();
await new LwwApplier(db).ApplyBatchAsync(
[
Entry(50, Pk1, "{\"id\":1,\"sku\":\"A\",\"qty\":1}", 3_000_000, "remote-node"),
Entry(52, "{\"id\":2}", "{\"id\":2,\"sku\":\"B\",\"qty\":2}", 3_000_050, "remote-node"),
], default);
var peer = await db.QueryAsync(
"SELECT last_applied_remote_seq, last_seen_hlc, last_sync_utc FROM __localdb_peer_state WHERE id = 1",
x => (Seq: x.GetInt64(0), Hlc: x.GetInt64(1), Utc: x.IsDBNull(2) ? null : x.GetString(2)));
Assert.Equal(52, peer[0].Seq);
Assert.Equal(3_000_050, peer[0].Hlc);
Assert.NotNull(peer[0].Utc);
Assert.EndsWith("Z", peer[0].Utc);
}
[Fact]
public async Task Apply_NullRowJsonNonTombstone_DeadLettered_NoPhantomRow()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(60, "{\"id\":2}", null, 9_000_000_000_000_000, "remote-node", tombstone: false)], default);
Assert.Equal(1, result.DeadLettered);
Assert.Equal(0, result.Applied);
var dead = await db.QueryAsync(
"SELECT pk_json, error FROM __localdb_dead_letter",
x => (Pk: x.GetString(0), Err: x.GetString(1)));
Assert.Single(dead);
Assert.Equal("{\"id\":2}", dead[0].Pk);
Assert.Contains("null row_json", dead[0].Err);
// No phantom auto-rowid row: the table still holds exactly the one pre-existing row.
var rows = await db.QueryAsync("SELECT COUNT(*) FROM orders", x => x.GetInt64(0));
Assert.Equal(1, rows[0]);
Assert.Null(await ReadOrder(db, 2));
}
[Fact]
public async Task Apply_RoundTrip_PreservesRealAndBigIntegerExactly()
{
const double real17 = 1.2345678901234567; // 17 significant digits
const long bigInt = 9_007_199_254_740_993; // 2^53 + 1: not representable as a double
using var source = new SqliteLocalDb(new LocalDbOptions { Path = _path });
await source.ExecuteAsync("CREATE TABLE meas (id INTEGER PRIMARY KEY, r REAL, big INTEGER)");
source.RegisterReplicated("meas");
await source.ExecuteAsync(
"INSERT INTO meas (id, r, big) VALUES (1, @r, @big)", new { r = real17, big = bigInt });
var captured = await source.QueryAsync(
"SELECT seq, table_name, pk_json, row_json, hlc, node_id, is_tombstone FROM __localdb_oplog",
r => new OplogEntryRecord(
r.GetInt64(0), r.GetString(1), r.GetString(2), r.IsDBNull(3) ? null : r.GetString(3),
r.GetInt64(4), r.GetString(5), r.GetInt64(6) != 0));
Assert.Single(captured);
using var target = new SqliteLocalDb(new LocalDbOptions { Path = _path2 });
await target.ExecuteAsync("CREATE TABLE meas (id INTEGER PRIMARY KEY, r REAL, big INTEGER)");
target.RegisterReplicated("meas");
var result = await new LwwApplier(target).ApplyBatchAsync(captured, default);
Assert.Equal(1, result.Applied);
var applied = await target.QueryAsync(
"SELECT r, big FROM meas WHERE id = 1", x => (R: x.GetDouble(0), Big: x.GetInt64(1)));
Assert.Equal(BitConverter.DoubleToInt64Bits(real17), BitConverter.DoubleToInt64Bits(applied[0].R));
Assert.Equal(bigInt, applied[0].Big);
}
[Fact]
public async Task Apply_GuardAlwaysLoweredAfterBatch()
{
// The abort/rollback path needs no separate coverage: applying = 1 is set INSIDE the
// transaction, so any rollback restores it to 0 by SQLite transaction semantics.
using var db = await NewOrdersDb();
await new LwwApplier(db).ApplyBatchAsync(
[Entry(1, Pk1, "{\"id\":1,\"sku\":\"R\",\"qty\":1}", 5_000_000, "remote-node")], default);
var guard = await db.QueryAsync(
"SELECT applying FROM __localdb_applying WHERE id = 1", x => x.GetInt64(0));
Assert.Equal(0, guard[0]);
// A subsequent consumer write must capture normally — proof the guard is really down.
var before = await OplogCount(db);
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (2, 'LOCAL', 2)");
Assert.Equal(before + 1, await OplogCount(db));
}
[Fact]
public async Task Apply_SameTable_TombstoneAndUpsert_OneBatch()
{
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[
Entry(70, Pk1, null, localHlc + 1000, "remote-node", tombstone: true),
Entry(71, "{\"id\":2}", "{\"id\":2,\"sku\":\"NEW\",\"qty\":7}", localHlc + 1001, "remote-node"),
], default);
Assert.Equal(2, result.Applied);
Assert.Null(await ReadOrder(db, 1));
Assert.Equal(("NEW", (long?)7), await ReadOrder(db, 2));
}
[Fact]
public async Task Apply_PreparesEachStatementOnce_NotOncePerRow()
{
// The regression this guards: the old shape went through the generic transaction façade,
// which builds a fresh SqliteCommand — and therefore re-parses the SQL — per call. Three
// statements per applied row means a 200-row batch parsed 600 statements to run 6 distinct
// ones. Statement count must track distinct SQL, not rows.
using var db = await NewOrdersDb();
await db.ExecuteAsync("CREATE TABLE widgets (id INTEGER PRIMARY KEY, name TEXT)");
db.RegisterReplicated("widgets");
var entries = new List<OplogEntryRecord>();
for (var i = 1; i <= 200; i++)
entries.Add(Entry(i, $"{{\"id\":{i}}}", $"{{\"id\":{i},\"sku\":\"S\",\"qty\":{i}}}", 1_000_000 + i, "remote"));
// A second table and a tombstone, so every statement kind in the set is exercised.
entries.Add(new OplogEntryRecord(
201, "widgets", "{\"id\":1}", "{\"id\":1,\"name\":\"W\"}", 1_000_300, "remote", false));
entries.Add(Entry(202, "{\"id\":1}", null, 1_000_400, "remote", tombstone: true));
var applier = new LwwApplier(db);
var result = await applier.ApplyBatchAsync(entries, default);
Assert.Equal(202, result.Applied);
// Six table-independent statements (applying guard, version lookup, row-version write,
// peer state, and the per-entry savepoint's enter/release), plus an upsert per table
// touched and a delete for the one table tombstoned. The savepoint's rollback statement is
// built on first use like the rest, and nothing in this batch is poison.
Assert.Equal(9, applier.LastBatchStatementCount);
// ...and the batch is still correct, statement reuse notwithstanding.
Assert.Null(await ReadOrder(db, 1));
Assert.Equal(("S", (long?)200), await ReadOrder(db, 200));
var widget = await db.QueryAsync("SELECT name FROM widgets WHERE id = 1", x => x.GetString(0));
Assert.Equal("W", widget[0]);
}
[Fact]
public async Task Apply_ReusedStatements_SurviveAPoisonRowMidBatch()
{
// A statement that faults is reset and reused for the following rows; if it were not, one
// poison row would silently corrupt every row after it in the batch.
using var db = await NewOrdersDb();
var applier = new LwwApplier(db);
var result = await applier.ApplyBatchAsync(
[
Entry(1, "{\"id\":1}", "{\"id\":1,\"sku\":\"BEFORE\",\"qty\":1}", 1_000_000, "remote"),
Entry(2, "{\"id\":2}", "NOT VALID JSON", 1_000_001, "remote"),
Entry(3, "{\"id\":3}", "{\"id\":3,\"sku\":\"AFTER\",\"qty\":3}", 1_000_002, "remote"),
Entry(4, "{\"id\":4}", "ALSO NOT JSON", 1_000_003, "remote"),
Entry(5, "{\"id\":5}", "{\"id\":5,\"sku\":\"LAST\",\"qty\":5}", 1_000_004, "remote"),
], default);
Assert.Equal(3, result.Applied);
Assert.Equal(2, result.DeadLettered);
Assert.Equal(("BEFORE", (long?)1), await ReadOrder(db, 1));
Assert.Equal(("AFTER", (long?)3), await ReadOrder(db, 3));
Assert.Equal(("LAST", (long?)5), await ReadOrder(db, 5));
}
/// <summary>
/// Arms a BEFORE INSERT trigger on the row-version ledger that aborts the write for one key —
/// a genuine statement-level SQLite fault (SQLITE_CONSTRAINT), landing exactly between an
/// entry's table write and its ledger write, with no production test seam.
/// </summary>
private static Task PoisonRowVersionWriteFor(SqliteLocalDb db, string pkJson) =>
db.ExecuteAsync(
"CREATE TRIGGER poison_rv BEFORE INSERT ON __localdb_row_version " +
$"WHEN NEW.pk_json = '{pkJson}' BEGIN SELECT RAISE(ABORT, 'ledger write failed'); END");
[Fact]
public async Task Apply_TombstoneWhoseLedgerWriteFails_LeavesRowAndLedgerUntouched()
{
// The hazard: DELETE and the ledger write are two statements, and SQLite aborts only the
// failing one. Without a per-entry savepoint the row is gone while __localdb_row_version
// still calls it live — SnapshotStreamer can then only warn and skip it, so the peer never
// learns the row died and the pair diverges. Both or neither.
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
await PoisonRowVersionWriteFor(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(90, Pk1, null, localHlc + 1000, "remote-node", tombstone: true)], default);
Assert.Equal(0, result.Applied);
Assert.Equal(1, result.DeadLettered);
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
var rv = await db.QueryAsync(
"SELECT hlc, is_tombstone FROM __localdb_row_version WHERE table_name = 'orders' AND pk_json = @pk",
x => (Hlc: x.GetInt64(0), Tomb: x.GetInt64(1)), new { pk = Pk1 });
Assert.Equal(localHlc, rv[0].Hlc);
Assert.Equal(0, rv[0].Tomb);
}
[Fact]
public async Task Apply_UpsertWhoseLedgerWriteFails_LeavesRowAndLedgerUntouched()
{
// Same split, other direction: the new row would sit in the table carrying the OLD version,
// so it would lose the very next LWW comparison it should win.
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
await PoisonRowVersionWriteFor(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(91, Pk1, "{\"id\":1,\"sku\":\"REMOTE\",\"qty\":99}", localHlc + 1000, "remote-node")], default);
Assert.Equal(0, result.Applied);
Assert.Equal(1, result.DeadLettered);
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
Assert.Equal(localHlc, await RowVersionHlc(db, Pk1));
}
[Fact]
public async Task Apply_LedgerWriteFailureMidBatch_DoesNotUndoTheRestOfTheBatch()
{
// The savepoint must rewind ONE entry, not the batch: entries either side of the poison
// still apply, and the batch still commits.
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
await PoisonRowVersionWriteFor(db, Pk1);
var result = await new LwwApplier(db).ApplyBatchAsync(
[
Entry(92, "{\"id\":2}", "{\"id\":2,\"sku\":\"BEFORE\",\"qty\":2}", localHlc + 1000, "remote-node"),
Entry(93, Pk1, null, localHlc + 1001, "remote-node", tombstone: true),
Entry(94, "{\"id\":3}", "{\"id\":3,\"sku\":\"AFTER\",\"qty\":3}", localHlc + 1002, "remote-node"),
], default);
Assert.Equal(2, result.Applied);
Assert.Equal(1, result.DeadLettered);
Assert.Equal(94, result.AppliedThruSeq);
Assert.Equal(("BEFORE", (long?)2), await ReadOrder(db, 2));
Assert.Equal(("AFTER", (long?)3), await ReadOrder(db, 3));
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
}
[Fact]
public async Task Apply_DeadLetterFailure_ReportsBothCausesAndCommitsNothing()
{
// Two faults stacked: the entry is poison (its ledger write aborts) AND recovering from it
// fails (the dead-letter INSERT aborts too). Reporting only the second would discard the
// one that says WHY the entry was poison, leaving an operator with "dead-letter failed"
// and no cause.
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
await PoisonRowVersionWriteFor(db, Pk1);
await db.ExecuteAsync(
"CREATE TRIGGER poison_dl BEFORE INSERT ON __localdb_dead_letter " +
"BEGIN SELECT RAISE(ABORT, 'dead-letter write failed'); END");
var ex = await Assert.ThrowsAsync<AggregateException>(() => new LwwApplier(db).ApplyBatchAsync(
[
Entry(95, "{\"id\":2}", "{\"id\":2,\"sku\":\"BEFORE\",\"qty\":2}", localHlc + 1000, "remote-node"),
Entry(96, Pk1, null, localHlc + 1001, "remote-node", tombstone: true),
], default));
// The entry's own fault first (InnerException), the recovery fault carried alongside it.
Assert.Contains("ledger write failed", ex.InnerException!.Message);
Assert.Contains("dead-letter write failed", ex.InnerExceptions[1].Message);
Assert.Contains("orders", ex.Message);
Assert.Contains("96", ex.Message);
// Fail-closed: the batch never commits, so even the entry that applied cleanly is gone.
Assert.Null(await ReadOrder(db, 2));
Assert.Equal(("LOCAL", (long?)5), await ReadOrder(db, 1));
var watermark = await db.QueryAsync(
"SELECT last_applied_remote_seq FROM __localdb_peer_state WHERE id = 1", x => x.GetInt64(0));
Assert.Equal(0, watermark[0]);
}
[Fact]
public async Task Apply_ReplaceExistingRow_DoesNotFireCaptureTriggers()
{
// INSERT OR REPLACE over an existing row also exercises the delete side of REPLACE;
// neither half may reach the capture triggers.
using var db = await NewOrdersDb();
await db.ExecuteAsync("INSERT INTO orders (id, sku, qty) VALUES (1, 'LOCAL', 5)");
var localHlc = await RowVersionHlc(db, Pk1);
var before = await OplogCount(db);
var result = await new LwwApplier(db).ApplyBatchAsync(
[Entry(80, Pk1, "{\"id\":1,\"sku\":\"REPL\",\"qty\":6}", localHlc + 1000, "remote-node")], default);
Assert.Equal(1, result.Applied);
Assert.Equal(("REPL", (long?)6), await ReadOrder(db, 1));
Assert.Equal(before, await OplogCount(db));
}
}