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Deadlock tests
This commit is contained in:
@@ -0,0 +1,446 @@
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Linq;
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using System.Threading.Tasks;
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using Esiur.Core;
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using Esiur.Misc;
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using Esiur.Protocol;
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using Esiur.Resource;
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using Xunit.Abstractions;
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namespace Esiur.Tests.Unit.Integration;
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/// <summary>
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/// End-to-end deadlock tests for EpConnection.FetchResource over a real loopback connection.
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/// Builds a range of reference topologies (self-loop, cycles of increasing length, concurrent
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/// cross-chain cycles, diamonds, dense graphs) and asserts, for every one, that the fetch
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/// completes without deadlock (a timeout would indicate one) and that every resource delivered to
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/// the application is fully attached (the cross-chain bug delivered partially-attached resources).
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/// Per-topology statistics are collected from the protocol counters and written to a report.
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/// </summary>
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[Collection("Integration")]
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public class DeadlockIntegrationTests
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{
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readonly ITestOutputHelper _out;
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public DeadlockIntegrationTests(ITestOutputHelper output) => _out = output;
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const int Timeout = 15000;
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// ---- async + counter helpers -----------------------------------------------------------
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static Task<T> ToTask<T>(AsyncReply<T> reply)
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{
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var tcs = new TaskCompletionSource<T>();
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reply.Then(v => tcs.TrySetResult(v)).Error(ex => tcs.TrySetException((Exception)ex));
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return tcs.Task;
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}
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static async Task<T> WithTimeout<T>(Task<T> task, int ms = Timeout)
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{
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if (await Task.WhenAny(task, Task.Delay(ms)) != task)
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throw new TimeoutException("Operation timed out — possible deadlock.");
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return await task;
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}
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static long Counter(string name)
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=> Global.Counters.Contains(name) ? Global.Counters[name] : 0;
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// ---- topology model --------------------------------------------------------------------
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record Topology(string Name, int Nodes, (int From, int To)[] Edges, int[] FetchRoots, bool Concurrent);
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static IEnumerable<Topology> Topologies() => new[]
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{
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new Topology("self-loop", 1, new[]{ (0,0) }, new[]{0}, false),
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new Topology("2-cycle", 2, new[]{ (0,1),(1,0) }, new[]{0}, false),
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new Topology("3-cycle", 3, new[]{ (0,1),(1,2),(2,0) }, new[]{0}, false),
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new Topology("4-cycle", 4, new[]{ (0,1),(1,2),(2,3),(3,0) }, new[]{0}, false),
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new Topology("cross-chain x2", 2, new[]{ (0,1),(1,0) }, new[]{0,1}, true),
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new Topology("cross-chain x3", 3, new[]{ (0,1),(1,2),(2,0) }, new[]{0,1,2}, true),
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new Topology("diamond", 4, new[]{ (0,1),(0,2),(1,3),(2,3) }, new[]{0}, false),
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new Topology("figure-8", 4, new[]{ (0,1),(1,0),(1,2),(2,3),(3,1) }, new[]{0}, false),
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new Topology("complete-4", 4, AllPairs(4), new[]{0}, false),
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new Topology("complete-4 concur",4, AllPairs(4), new[]{0,1,2,3}, true),
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};
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// Topologies for the legacy-vs-new comparison. The fan-in cases have many roots referencing a
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// single shared resource whose own dependency chain is deep: while that shared resource is
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// attaching its chain, the other concurrent fetchers reach it, and the legacy resolver hands
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// each of them the not-yet-attached placeholder (the bug), whereas the new resolver waits.
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static IEnumerable<Topology> ComparisonTopologies() => new[]
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{
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new Topology("single-root 4-cycle (control)", 4, new[]{ (0,1),(1,2),(2,3),(3,0) }, new[]{0}, false),
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Cycle("cross-chain ring x3", 3),
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// Staggered shared dependency (no cycle): X reaches the shared node S immediately while Y
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// reaches it through a chain, arriving during S's own deep-chain attach window. The legacy
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// resolver hands Y the not-yet-attached placeholder S (unnecessary — there is no cycle); the
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// new resolver waits for S to finish attaching.
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Staggered("staggered shared-dep", leadDepth: 0, lagDepth: 3, sharedDepth: 3),
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Staggered("staggered shared-dep (deep)", leadDepth: 0, lagDepth: 4, sharedDepth: 4),
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};
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// An N-node ring (i -> i+1, last -> 0), every node fetched concurrently.
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static Topology Cycle(string name, int n)
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{
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var edges = new (int, int)[n];
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for (var i = 0; i < n; i++) edges[i] = (i, (i + 1) % n);
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return new Topology(name, n, edges, Enumerable.Range(0, n).ToArray(), true);
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}
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// X (root 0) and Y (root 1) both depend on a shared node S. X reaches S through a chain of
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// length `leadDepth`, Y through a chain of length `lagDepth` (make lag > lead so Y arrives at S
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// later). S itself starts a chain of length `sharedDepth`, widening the window during which S is
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// attaching and another fetcher can be handed a placeholder. No cycle exists.
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static Topology Staggered(string name, int leadDepth, int lagDepth, int sharedDepth)
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{
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var edges = new List<(int, int)>();
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var next = 2;
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int Chain(int from, int depth)
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{
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for (var d = 0; d < depth; d++) { edges.Add((from, next)); from = next; next++; }
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return from; // tail
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}
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var xTail = Chain(0, leadDepth); // X = 0
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var yTail = Chain(1, lagDepth); // Y = 1
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var shared = next++; // S
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edges.Add((xTail, shared));
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edges.Add((yTail, shared));
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Chain(shared, sharedDepth); // S -> deep chain
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return new Topology(name, next, edges.ToArray(), new[] { 0, 1 }, true);
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}
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static (int, int)[] AllPairs(int n)
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{
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var edges = new List<(int, int)>();
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for (var i = 0; i < n; i++)
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for (var j = 0; j < n; j++)
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if (i != j) edges.Add((i, j));
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return edges.ToArray();
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}
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// ---- graph attach verification ---------------------------------------------------------
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// Walks the client-side object graph reachable from the fetched roots and returns whether
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// every node is fully attached, plus the number of distinct nodes reached.
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static (bool allAttached, int reached) VerifyGraph(IEnumerable<EpResource> roots)
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{
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var seen = new HashSet<uint>();
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var queue = new Queue<EpResource>(roots);
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var allAttached = true;
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while (queue.Count > 0)
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{
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var node = queue.Dequeue();
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if (node == null || !seen.Add(node.ResourceInstanceId))
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continue;
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if (node.Status != Resource.ResourceStatus.Attached)
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{
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allAttached = false;
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continue; // do not traverse into a partially attached node
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}
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// property index 1 == Links (Id is index 0)
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if (node.TryGetPropertyValue((byte)1, out var linksObj) && linksObj is IEnumerable links)
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foreach (var child in links)
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if (child is EpResource childResource)
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queue.Enqueue(childResource);
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}
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return (allAttached, seen.Count);
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}
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// ---- per-topology run ------------------------------------------------------------------
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record StatRow(string Topology, int Nodes, int Reached, long SameChain, long CrossChain,
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long Waits, long CacheHits, double Ms, bool AllAttached, bool Deadlock);
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async Task<StatRow> RunTopology(Topology topo)
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{
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await using var cluster = await IntegrationCluster.StartAsync(async wh =>
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{
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var nodes = new Node[topo.Nodes];
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for (var i = 0; i < topo.Nodes; i++)
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{
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nodes[i] = new Node { Id = i };
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await wh.Put($"sys/n{i}", nodes[i]);
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}
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foreach (var group in topo.Edges.GroupBy(e => e.From))
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nodes[group.Key].Links = group.Select(e => nodes[e.To]).ToArray();
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});
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var c0 = (same: Counter("EpResourceDeadLockSameChain"),
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cross: Counter("EpResourceDeadLockCrossChain"),
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wait: Counter("EpResourcePendingCacheHit"),
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hit: Counter("EpResourceAttachedCacheHit"));
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var sw = Stopwatch.StartNew();
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var deadlock = false;
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var reached = 0;
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var allAttached = false;
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try
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{
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var fetchTasks = topo.FetchRoots
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.Select(r => ToTask(cluster.Connection.Get($"sys/n{r}")))
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.ToArray();
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if (!topo.Concurrent)
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{
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// sequential roots (usually a single root)
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foreach (var t in fetchTasks)
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await WithTimeout(t);
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}
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var results = await WithTimeout(Task.WhenAll(fetchTasks));
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sw.Stop();
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(allAttached, reached) = VerifyGraph(results.Cast<EpResource>());
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}
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catch (TimeoutException)
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{
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sw.Stop();
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deadlock = true;
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}
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return new StatRow(topo.Name, topo.Nodes, reached,
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Counter("EpResourceDeadLockSameChain") - c0.same,
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Counter("EpResourceDeadLockCrossChain") - c0.cross,
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Counter("EpResourcePendingCacheHit") - c0.wait,
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Counter("EpResourceAttachedCacheHit") - c0.hit,
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sw.Elapsed.TotalMilliseconds, allAttached, deadlock);
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}
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// ---- tests -----------------------------------------------------------------------------
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[Fact]
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public async Task DeadlockMatrix_AllTopologies()
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{
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var rows = new List<StatRow>();
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foreach (var topo in Topologies())
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{
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var row = await RunTopology(topo);
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rows.Add(row);
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Assert.False(row.Deadlock, $"{topo.Name}: fetch deadlocked (timed out)");
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Assert.True(row.AllAttached, $"{topo.Name}: a partially-attached resource reached the application");
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Assert.True(row.Reached >= topo.Nodes, $"{topo.Name}: expected to reach {topo.Nodes} nodes, reached {row.Reached}");
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}
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EmitReport(rows);
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}
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[Theory]
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[InlineData(1)]
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[InlineData(2)]
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[InlineData(4)]
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[InlineData(8)]
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[InlineData(16)]
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public async Task Concurrency_Sweep_CyclicGraph(int concurrency)
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{
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// A 4-node cycle fetched by N concurrent application requests for all four roots. Stresses
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// the wait-for/cycle-break paths under contention; all requests must complete and attach.
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await using var cluster = await IntegrationCluster.StartAsync(async wh =>
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{
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var nodes = new Node[4];
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for (var i = 0; i < 4; i++)
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{
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nodes[i] = new Node { Id = i };
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await wh.Put($"sys/n{i}", nodes[i]);
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}
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for (var i = 0; i < 4; i++)
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nodes[i].Links = new[] { nodes[(i + 1) % 4] };
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});
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var sw = Stopwatch.StartNew();
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var tasks = Enumerable.Range(0, concurrency)
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.SelectMany(_ => Enumerable.Range(0, 4).Select(r => ToTask(cluster.Connection.Get($"sys/n{r}"))))
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.ToArray();
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var results = await WithTimeout(Task.WhenAll(tasks), 30000);
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sw.Stop();
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var (allAttached, _) = VerifyGraph(results.Cast<EpResource>());
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Assert.True(allAttached, $"concurrency {concurrency}: a partially-attached resource was delivered");
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_out.WriteLine($"concurrency={concurrency,2} requests={tasks.Length,3} time={sw.Elapsed.TotalMilliseconds,8:F1} ms " +
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$"throughput={tasks.Length / sw.Elapsed.TotalSeconds,7:F0} req/s");
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}
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// ---- legacy vs new comparison ----------------------------------------------------------
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// Counts resources reachable from the delivered roots that are NOT published — i.e. handed to
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// the application while their own dependency graph is not fully attached.
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static int CountUnpublished(IEnumerable<EpResource> roots)
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{
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var seen = new HashSet<uint>();
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var queue = new Queue<EpResource>(roots);
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var unpublished = 0;
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while (queue.Count > 0)
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{
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var node = queue.Dequeue();
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if (node == null || !seen.Add(node.ResourceInstanceId))
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continue;
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if (node.Status != ResourceStatus.Published)
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unpublished++;
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if ((node.Status == ResourceStatus.Attached) && node.TryGetPropertyValue((byte)1, out var linksObj) && linksObj is IEnumerable links)
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foreach (var child in links)
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if (child is EpResource childResource)
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queue.Enqueue(childResource);
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}
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return unpublished;
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}
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async Task<(bool deadlock, int unnecessaryPlaceholders)> RunForCompare(Topology topo, bool legacy)
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{
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await using var cluster = await IntegrationCluster.StartAsync(async wh =>
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{
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var nodes = new Node[topo.Nodes];
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for (var i = 0; i < topo.Nodes; i++)
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{
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nodes[i] = new Node { Id = i };
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await wh.Put($"sys/n{i}", nodes[i]);
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}
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foreach (var group in topo.Edges.GroupBy(e => e.From))
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nodes[group.Key].Links = group.Select(e => nodes[e.To]).ToArray();
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});
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cluster.Connection.DeadlockResolution = legacy
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? DeadlockResolutionMode.LegacyCrossChainPlaceholder
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: DeadlockResolutionMode.WaitWithCycleDetection;
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var completions = new List<Task<bool>>();
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try
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{
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foreach (var r in topo.FetchRoots)
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{
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var tcs = new TaskCompletionSource<bool>();
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cluster.Connection.Get($"sys/n{r}")
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.Then(_ => tcs.TrySetResult(true))
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.Error(ex => tcs.TrySetException((Exception)ex));
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completions.Add(tcs.Task);
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}
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await WithTimeout(Task.WhenAll(completions));
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// Per-connection counter (fresh connection starts at 0), free of cross-connection noise.
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return (false, (int)cluster.Connection.UnnecessaryPlaceholderCount);
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}
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catch (TimeoutException)
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{
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return (true, -1);
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}
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}
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record CompareRow(string Topology, int Iterations,
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int LegacyDeadlocks, int LegacyBugRuns, double LegacyAvgUnnecessary,
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int NewDeadlocks, int NewBugRuns, double NewAvgUnnecessary);
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[Fact]
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public async Task LegacyVsNew_UnnecessaryPlaceholderComparison()
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{
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const int iterations = 20;
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var rows = new List<CompareRow>();
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foreach (var topo in ComparisonTopologies())
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{
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int legDead = 0, legBug = 0, legUnnec = 0;
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int newDead = 0, newBug = 0, newUnnec = 0;
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for (var i = 0; i < iterations; i++)
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{
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var (ld, lu) = await RunForCompare(topo, legacy: true);
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if (ld) legDead++; else { if (lu > 0) legBug++; legUnnec += Math.Max(0, lu); }
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var (nd, nu) = await RunForCompare(topo, legacy: false);
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if (nd) newDead++; else { if (nu > 0) newBug++; newUnnec += Math.Max(0, nu); }
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}
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rows.Add(new CompareRow(topo.Name, iterations,
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legDead, legBug, (double)legUnnec / iterations,
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newDead, newBug, (double)newUnnec / iterations));
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}
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EmitComparison(rows, iterations);
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// The new resolver must never deadlock and must never hand out an unnecessary placeholder
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// (it only breaks genuine wait-for cycles) — both deterministic invariants.
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Assert.All(rows, r => Assert.Equal(0, r.NewDeadlocks));
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Assert.All(rows, r => Assert.Equal(0, r.NewBugRuns));
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}
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void EmitComparison(List<CompareRow> rows, int iterations)
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{
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var sb = new System.Text.StringBuilder();
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sb.AppendLine("# Esiur FetchResource — legacy vs new cross-chain resolution");
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sb.AppendLine();
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sb.AppendLine($"Generated: {DateTime.UtcNow:yyyy-MM-dd HH:mm} UTC | iterations per cell: {iterations}");
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sb.AppendLine();
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sb.AppendLine("Metric: 'unnecessary placeholder' = a not-yet-attached resource handed to a requester");
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sb.AppendLine("where NO genuine wait-for cycle exists — a partial delivery that the new resolver avoids");
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sb.AppendLine("by waiting for full attachment. Genuine cycles are excluded (both resolvers must break those).");
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sb.AppendLine();
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sb.AppendLine("| Topology | Legacy deadlocks | Legacy buggy runs | Legacy avg unnecessary | New deadlocks | New buggy runs | New avg unnecessary |");
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sb.AppendLine("|----------|-----------------:|------------------:|-----------------------:|--------------:|---------------:|--------------------:|");
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foreach (var r in rows)
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sb.AppendLine($"| {r.Topology} | {r.LegacyDeadlocks} | {r.LegacyBugRuns}/{r.Iterations} | {r.LegacyAvgUnnecessary:F2} | " +
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$"{r.NewDeadlocks} | {r.NewBugRuns}/{r.Iterations} | {r.NewAvgUnnecessary:F2} |");
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sb.AppendLine();
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sb.AppendLine($"Legacy: {rows.Sum(r => r.LegacyBugRuns)} runs with an unnecessary placeholder, " +
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$"{rows.Sum(r => r.LegacyDeadlocks)} deadlocks across {rows.Count * iterations} runs.");
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sb.AppendLine($"New: {rows.Sum(r => r.NewBugRuns)} runs with an unnecessary placeholder, " +
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$"{rows.Sum(r => r.NewDeadlocks)} deadlocks across {rows.Count * iterations} runs.");
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var report = sb.ToString();
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_out.WriteLine(report);
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var path = Path.Combine(AppContext.BaseDirectory, "deadlock-comparison.md");
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File.WriteAllText(path, report);
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_out.WriteLine($"Comparison written to: {path}");
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}
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// ---- report ----------------------------------------------------------------------------
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void EmitReport(List<StatRow> rows)
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{
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var sb = new System.Text.StringBuilder();
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sb.AppendLine("# Esiur FetchResource deadlock test results");
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sb.AppendLine();
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sb.AppendLine($"Generated: {DateTime.UtcNow:yyyy-MM-dd HH:mm} UTC");
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sb.AppendLine();
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sb.AppendLine("| Topology | Nodes | Reached | Same-chain breaks | Cross-chain breaks | Waits | Cache hits | Time (ms) | All attached | Deadlock |");
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sb.AppendLine("|----------|------:|--------:|------------------:|-------------------:|------:|-----------:|----------:|:------------:|:--------:|");
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||||
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foreach (var r in rows)
|
||||
sb.AppendLine($"| {r.Topology} | {r.Nodes} | {r.Reached} | {r.SameChain} | {r.CrossChain} | " +
|
||||
$"{r.Waits} | {r.CacheHits} | {r.Ms:F1} | {(r.AllAttached ? "yes" : "**NO**")} | {(r.Deadlock ? "**YES**" : "no")} |");
|
||||
|
||||
sb.AppendLine();
|
||||
sb.AppendLine($"Topologies: {rows.Count} | Deadlocks: {rows.Count(r => r.Deadlock)} | " +
|
||||
$"Fully attached: {rows.Count(r => r.AllAttached)}/{rows.Count} | " +
|
||||
$"Total cycle breaks: same-chain {rows.Sum(r => r.SameChain)}, cross-chain {rows.Sum(r => r.CrossChain)} | " +
|
||||
$"Total waits: {rows.Sum(r => r.Waits)}");
|
||||
|
||||
var report = sb.ToString();
|
||||
_out.WriteLine(report);
|
||||
|
||||
var path = Path.Combine(AppContext.BaseDirectory, "deadlock-stats.md");
|
||||
File.WriteAllText(path, report);
|
||||
_out.WriteLine($"Report written to: {path}");
|
||||
}
|
||||
}
|
||||
|
||||
[CollectionDefinition("Integration", DisableParallelization = true)]
|
||||
public class IntegrationCollection { }
|
||||
Reference in New Issue
Block a user