Joseph Doherty
ee314d1b9e
The QuestDB live writer waited for WAL visibility after every tag group, and the wait polled wal_tables() every 10 ms. With DrainConcurrency = 8 that was up to eight pollers at ~100 queries/s each against a database whose WAL apply was already behind. New Runtime seam IHistorianPassWriter (WriteLiveValuesInPassAsync + FlushAsync). The recorder writes every group of a pass through it and calls FlushAsync once after all groups report, before the ack, whenever any group wrote (an un-acked pass is redelivered and its insert-if-absent check must see this pass's rows). A flush failure does not fail the pass. The QuestDB writer implements it: in-pass writes only mark a flush as owed; FlushAsync waits once. The poll now backs off 10 -> 20 -> ... -> 200 ms, never past the timeout. Direct WriteLiveValuesAsync callers still wait per call. Also updates the QuestDB cancelled-write integration test to the rethrow contract from the previous commit. Rebased from the unpushed remed/lane-H2 branch (originally authored 2026-10-22 in session_01Ub9hGmYLQvn9XETzw7CMsT) onto current master. Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
42 lines
1.7 KiB
C#
42 lines
1.7 KiB
C#
using Shouldly;
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using Xunit;
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namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.Tests;
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public sealed class QuestDbWalVisibilityTests
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{
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[Fact]
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public async Task Timeout_zero_skips_the_wait_without_touching_the_database()
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{
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// Port 1 refuses connections: any attempt to query would throw, so returning true proves nothing was opened.
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var conn = new QuestDbConnection(new QuestDbHistorianOptions { ConnectionString = "Host=127.0.0.1;Port=1;Timeout=1" });
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var wal = new QuestDbWalVisibility(conn, TimeSpan.Zero);
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wal.Disabled.ShouldBeTrue();
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(await wal.WaitAsync("hist_sample", CancellationToken.None)).ShouldBeTrue();
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}
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[Fact]
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public async Task A_positive_timeout_does_touch_the_database_control()
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{
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var conn = new QuestDbConnection(new QuestDbHistorianOptions { ConnectionString = "Host=127.0.0.1;Port=1;Timeout=1" });
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var wal = new QuestDbWalVisibility(conn, TimeSpan.FromSeconds(1));
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wal.Disabled.ShouldBeFalse();
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await Should.ThrowAsync<Exception>(() => wal.WaitAsync("hist_sample", CancellationToken.None));
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}
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[Theory]
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[InlineData(5, 5, true)]
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[InlineData(6, 5, true)]
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[InlineData(4, 5, false)]
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public void Reached_is_writerTxn_at_or_beyond_the_target(long writer, long target, bool expected) =>
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QuestDbWalVisibility.Reached(writer, target).ShouldBe(expected);
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[Fact]
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public void The_poll_backs_off_exponentially_from_10_ms_to_a_200_ms_cap()
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{
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var delays = new List<TimeSpan> { QuestDbWalVisibility.FirstPollInterval };
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while (delays.Count < 8) delays.Add(QuestDbWalVisibility.NextPollInterval(delays[^1]));
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delays.Select(d => (int)d.TotalMilliseconds).ShouldBe([10, 20, 40, 80, 160, 200, 200, 200]);
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}
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}
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