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fix(localdb): adapter review fixes — deterministic pump teardown, always-hosted initiator, backoff clamp

Browse Source 
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
This commit is contained in:
Joseph Doherty
2026-07-17 23:13:02 -04:00
parent a64fc26391
commit e92cdc6d3a
6 changed files with 148 additions and 28 deletions
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ZB.MOM.WW.LocalDb/src/ZB.MOM.WW.LocalDb.Replication/SyncBackgroundService.cs
+34 -10
View File
@@ -12,7 +12,8 @@ namespace ZB.MOM.WW.LocalDb.Replication;
/// <summary>
/// The initiating (client) side of replication: a hosted service that dials the configured peer,
/// runs the symmetric <see cref="SyncSession"/> over the outbound bidirectional stream, and
/// reconnects with jittered exponential backoff whenever the session ends or faults.
/// reconnects with jittered exponential backoff whenever the session ends or faults. Always
/// registered; on a passive node (no <see cref="ReplicationOptions.PeerAddress"/>) it idles.
/// </summary>
public sealed class SyncBackgroundService : BackgroundService
{
@@ -34,10 +35,7 @@ public sealed class SyncBackgroundService : BackgroundService
public SyncBackgroundService(ILocalDb db, IOptions<ReplicationOptions> options, ILoggerFactory loggerFactory)
{
_db = db as SqliteLocalDb
?? throw new InvalidOperationException(
$"SyncBackgroundService requires the ILocalDb registered by AddZbLocalDb (a {nameof(SqliteLocalDb)}); " +
$"got {db.GetType().FullName}.");
_db = SyncSessionFactory.RequireSqlite(db, nameof(SyncBackgroundService));
_options = options.Value;
_loggerFactory = loggerFactory;
_logger = loggerFactory.CreateLogger<SyncBackgroundService>();
@@ -45,6 +43,12 @@ public sealed class SyncBackgroundService : BackgroundService
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
if (string.IsNullOrEmpty(_options.PeerAddress))
{
_logger.LogInformation("passive node — no peer configured, sync initiator idle");
return;
}
var backoff = InitialBackoff;
while (!stoppingToken.IsCancellationRequested)
{
@@ -65,12 +69,30 @@ public sealed class SyncBackgroundService : BackgroundService
headers.Add("Authorization", $"Bearer {_options.ApiKey}");
using var call = client.Sync(headers, cancellationToken: stoppingToken);
var (duplex, readerTask) = GrpcSyncDuplex.Create(call.ResponseStream, call.RequestStream, stoppingToken);
// The linked source exists so the reader pump is deterministically torn down on
// EVERY exit path — including a session fault for a local (non-transport) reason,
// where the stopping token never fires and the pump would otherwise keep reading a
// stream this iteration has abandoned.
using var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken);
var (duplex, readerTask) = GrpcSyncDuplex.Create(call.ResponseStream, call.RequestStream, linkedCts.Token);
var session = SyncSessionFactory.Create(_db, _options, _loggerFactory);
await session.RunAsync(duplex, stoppingToken);
await call.RequestStream.CompleteAsync();
await readerTask;
try
{
await session.RunAsync(duplex, linkedCts.Token);
await call.RequestStream.CompleteAsync();
}
finally
{
linkedCts.Cancel();
try
{
await readerTask;
}
catch (Exception ex)
{
_logger.LogDebug(ex, "Sync reader pump ended during teardown.");
}
}
}
catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
{
@@ -107,6 +129,8 @@ public sealed class SyncBackgroundService : BackgroundService
break;
}
// Overflow-safe without checked math: the validator caps ReconnectBackoffMax at 1 day
// and backoff never exceeds it, so doubling stays far below long.MaxValue ticks.
backoff = TimeSpan.FromTicks(Math.Min(backoff.Ticks * 2, _options.ReconnectBackoffMax.Ticks));
}
}