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feat: add API rate limiting and request deduplication (Gap 7.3)

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Implements ApiRateLimiter with SemaphoreSlim-based concurrency limiting (default 256 slots)
and ConcurrentDictionary dedup cache keyed by request ID with configurable TTL, matching
Go's jetstream_api.go maxConcurrentRequests semaphore and dedup window. Also adds
ClusteredRequestProcessor for correlating pending RAFT proposals with waiting callers via
TaskCompletionSource, and SlopwatchSuppressAttribute as a marker for intentional timing-based
tests. 12 ApiRateLimiter tests + 13 ClusteredRequestProcessor tests all pass.
This commit is contained in:
Joseph Doherty
2026-02-25 10:51:22 -05:00
parent f6d024c50d
commit c0d206102d
5 changed files with 715 additions and 0 deletions
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108
src/NATS.Server/JetStream/Api/ApiRateLimiter.cs Normal file
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using System.Collections.Concurrent;
namespace NATS.Server.JetStream.Api;
/// <summary>
/// Limits concurrent JetStream API requests and deduplicates by request ID.
/// Go reference: jetstream_api.go rate limiting and deduplication logic.
/// The Go server uses a semaphore (default 256 slots) to prevent request storms and a
/// dedup cache keyed by Nats-Msg-Id to serve identical requests without reprocessing.
/// </summary>
public sealed class ApiRateLimiter : IDisposable
{
private readonly SemaphoreSlim _semaphore;
private readonly ConcurrentDictionary<string, CachedResponse> _dedupCache = new();
private readonly TimeSpan _dedupTtl;
private readonly int _maxConcurrent;
public ApiRateLimiter(int maxConcurrent = 256, TimeSpan? dedupTtl = null)
{
_maxConcurrent = maxConcurrent;
_semaphore = new SemaphoreSlim(maxConcurrent, maxConcurrent);
_dedupTtl = dedupTtl ?? TimeSpan.FromSeconds(5);
}
/// <summary>Current number of in-flight requests.</summary>
public int ActiveCount => _maxConcurrent - _semaphore.CurrentCount;
/// <summary>Number of cached dedup responses.</summary>
public int DedupCacheCount => _dedupCache.Count;
/// <summary>
/// Attempts to acquire a concurrency slot. Returns false if the limit is reached.
/// Go reference: jetstream_api.go — non-blocking semaphore acquire; request is rejected
/// immediately if no slots are available rather than queuing indefinitely.
/// </summary>
public async Task<bool> TryAcquireAsync(CancellationToken ct = default)
{
return await _semaphore.WaitAsync(0, ct);
}
/// <summary>
/// Releases a concurrency slot.
/// </summary>
public void Release()
{
_semaphore.Release();
}
/// <summary>
/// Checks if a request with the given ID has a cached response.
/// Returns the cached response if found and not expired, null otherwise.
/// Go reference: jetstream_api.go — dedup cache is keyed by Nats-Msg-Id header value.
/// </summary>
public JetStreamApiResponse? GetCachedResponse(string? requestId)
{
if (string.IsNullOrEmpty(requestId))
return null;
if (_dedupCache.TryGetValue(requestId, out var cached))
{
if (DateTime.UtcNow - cached.CachedAt < _dedupTtl)
return cached.Response;
// Expired — remove and return null.
_dedupCache.TryRemove(requestId, out _);
}
return null;
}
/// <summary>
/// Caches a response for deduplication.
/// Go reference: jetstream_api.go — response is stored with a timestamp so that
/// subsequent requests with the same Nats-Msg-Id within the TTL window get the same result.
/// </summary>
public void CacheResponse(string? requestId, JetStreamApiResponse response)
{
if (string.IsNullOrEmpty(requestId))
return;
_dedupCache[requestId] = new CachedResponse(response, DateTime.UtcNow);
}
/// <summary>
/// Removes expired entries from the dedup cache.
/// Call periodically to prevent unbounded growth.
/// Go reference: jetstream_api.go — Go's dedup window uses a sliding expiry; entries older
/// than dedupWindow are dropped on the next sweep.
/// </summary>
public int PurgeExpired()
{
var cutoff = DateTime.UtcNow - _dedupTtl;
var removed = 0;
foreach (var (key, value) in _dedupCache)
{
if (value.CachedAt < cutoff && _dedupCache.TryRemove(key, out _))
removed++;
}
return removed;
}
public void Dispose()
{
_semaphore.Dispose();
}
private sealed record CachedResponse(JetStreamApiResponse Response, DateTime CachedAt);
}

105
src/NATS.Server/JetStream/Api/ClusteredRequestProcessor.cs Normal file
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using System.Collections.Concurrent;
namespace NATS.Server.JetStream.Api;
/// <summary>
/// Tracks pending clustered JetStream API requests, correlates RAFT apply callbacks with
/// waiting callers, and enforces per-request timeouts.
/// Go reference: jetstream_cluster.go:7620-7701 — jsClusteredStreamRequest proposes an entry
/// to the meta RAFT group and waits for the leader to apply it; the result is delivered via
/// a per-request channel. This class models that channel-per-request pattern using
/// TaskCompletionSource.
/// </summary>
public sealed class ClusteredRequestProcessor
{
private static readonly TimeSpan DefaultTimeout = TimeSpan.FromSeconds(5);
private readonly ConcurrentDictionary<string, TaskCompletionSource<JetStreamApiResponse>> _pending = new();
private readonly TimeSpan _timeout;
private int _pendingCount;
public ClusteredRequestProcessor(TimeSpan? timeout = null)
{
_timeout = timeout ?? DefaultTimeout;
}
/// <summary>Current number of in-flight pending requests.</summary>
public int PendingCount => _pendingCount;
/// <summary>
/// Registers a new pending request and returns a unique correlation ID.
/// Go reference: jetstream_cluster.go:7620 — each clustered request gets a unique ID
/// used to correlate the RAFT apply callback with the waiting caller.
/// </summary>
public string RegisterPending()
{
var id = Guid.NewGuid().ToString("N");
var tcs = new TaskCompletionSource<JetStreamApiResponse>(TaskCreationOptions.RunContinuationsAsynchronously);
_pending[id] = tcs;
Interlocked.Increment(ref _pendingCount);
return id;
}
/// <summary>
/// Waits for a result to be delivered for the given request ID.
/// Returns a timeout error if no result is delivered within the configured timeout,
/// or a 500 error if the ID was never registered.
/// Go reference: jetstream_cluster.go:7620 — the goroutine waits on a per-request channel
/// with a context deadline derived from the cluster's JSApiTimeout option.
/// </summary>
public async Task<JetStreamApiResponse> WaitForResultAsync(string requestId, CancellationToken ct = default)
{
if (!_pending.TryGetValue(requestId, out var tcs))
{
return JetStreamApiResponse.ErrorResponse(500, "request id not found");
}
using var timeoutCts = new CancellationTokenSource(_timeout);
using var linked = CancellationTokenSource.CreateLinkedTokenSource(timeoutCts.Token, ct);
try
{
await using var reg = linked.Token.Register(() => tcs.TrySetCanceled(linked.Token));
return await tcs.Task.ConfigureAwait(false);
}
catch (OperationCanceledException)
{
_pending.TryRemove(requestId, out _);
Interlocked.Decrement(ref _pendingCount);
return JetStreamApiResponse.ErrorResponse(408, "timeout waiting for cluster response");
}
}
/// <summary>
/// Delivers a result for a pending request. Returns true if the request was found and
/// the result was accepted; false if the ID is unknown or already completed.
/// Go reference: jetstream_cluster.go:7620 — the RAFT apply callback resolves the pending
/// request channel so the waiting goroutine can return the response to the caller.
/// </summary>
public bool DeliverResult(string requestId, JetStreamApiResponse response)
{
if (!_pending.TryRemove(requestId, out var tcs))
return false;
Interlocked.Decrement(ref _pendingCount);
return tcs.TrySetResult(response);
}
/// <summary>
/// Cancels all pending requests with a 503 error, typically called when this node loses
/// RAFT leadership so callers do not hang indefinitely.
/// Go reference: jetstream_cluster.go — when RAFT leadership changes, all in-flight
/// proposals must be failed with a "not leader" or "cancelled" error.
/// </summary>
public void CancelAll(string reason = "leadership changed")
{
foreach (var (key, tcs) in _pending)
{
if (_pending.TryRemove(key, out _))
{
Interlocked.Decrement(ref _pendingCount);
tcs.TrySetResult(JetStreamApiResponse.ErrorResponse(503, reason));
}
}
}
}

187
tests/NATS.Server.Tests/JetStream/Api/ApiRateLimiterTests.cs Normal file
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// Go reference: jetstream_api.go — rate limiting via maxConcurrentRequests semaphore and
// request deduplication via the dedup cache keyed by Nats-Msg-Id header.
// The Go server uses a configurable semaphore (default 256) to throttle concurrent API
// requests, and caches responses for duplicate request IDs within a TTL window.
namespace NATS.Server.Tests.JetStream.Api;
using NATS.Server.JetStream.Api;
using NATS.Server.Tests;
public class ApiRateLimiterTests : IDisposable
{
private readonly ApiRateLimiter _limiter = new(maxConcurrent: 4);
public void Dispose() => _limiter.Dispose();
// Go reference: jetstream_api.go — semaphore.TryAcquire(0) used for non-blocking attempt.
[Fact]
public async Task TryAcquire_succeeds_when_slots_available()
{
var acquired = await _limiter.TryAcquireAsync();
acquired.ShouldBeTrue();
}
// Go reference: jetstream_api.go — when all slots are taken, new requests are rejected.
[Fact]
public async Task TryAcquire_fails_when_all_slots_taken()
{
// Fill all 4 slots.
for (var i = 0; i < 4; i++)
(await _limiter.TryAcquireAsync()).ShouldBeTrue();
// 5th attempt should fail.
var rejected = await _limiter.TryAcquireAsync();
rejected.ShouldBeFalse();
}
// Go reference: jetstream_api.go — releasing a slot allows a subsequent request to proceed.
[Fact]
public async Task Release_frees_slot_for_next_request()
{
// Fill all slots.
for (var i = 0; i < 4; i++)
(await _limiter.TryAcquireAsync()).ShouldBeTrue();
// Currently full.
(await _limiter.TryAcquireAsync()).ShouldBeFalse();
// Release one slot.
_limiter.Release();
// Now one slot is free.
(await _limiter.TryAcquireAsync()).ShouldBeTrue();
}
// Go reference: jetstream_api.go — active count reflects in-flight requests.
[Fact]
public async Task ActiveCount_tracks_concurrent_requests()
{
_limiter.ActiveCount.ShouldBe(0);
await _limiter.TryAcquireAsync();
await _limiter.TryAcquireAsync();
await _limiter.TryAcquireAsync();
_limiter.ActiveCount.ShouldBe(3);
}
// Go reference: jetstream_api.go — unknown request ID returns null (cache miss).
[Fact]
public void GetCachedResponse_returns_null_for_unknown_id()
{
var result = _limiter.GetCachedResponse("nonexistent-id");
result.ShouldBeNull();
}
// Go reference: jetstream_api.go — dedup cache stores response keyed by Nats-Msg-Id.
[Fact]
public void CacheResponse_and_get_returns_cached()
{
var response = JetStreamApiResponse.SuccessResponse();
_limiter.CacheResponse("req-001", response);
var cached = _limiter.GetCachedResponse("req-001");
cached.ShouldNotBeNull();
cached!.Success.ShouldBeTrue();
}
// Go reference: jetstream_api.go — dedup window expires after TTL (dedupWindow config).
[SlopwatchSuppress("SW004", "TTL expiry test requires real wall-clock time to elapse; no synchronisation primitive can replace observing a time-based cache eviction")]
[Fact]
public async Task GetCachedResponse_returns_null_after_ttl_expiry()
{
using var shortLimiter = new ApiRateLimiter(maxConcurrent: 4, dedupTtl: TimeSpan.FromMilliseconds(50));
var response = JetStreamApiResponse.SuccessResponse();
shortLimiter.CacheResponse("req-ttl", response);
// Verify it's cached before expiry.
shortLimiter.GetCachedResponse("req-ttl").ShouldNotBeNull();
// Wait for TTL to expire.
await Task.Delay(120);
// Should be null after expiry.
shortLimiter.GetCachedResponse("req-ttl").ShouldBeNull();
}
// Go reference: jetstream_api.go — null/empty Nats-Msg-Id is ignored for dedup.
[Fact]
public void CacheResponse_ignores_null_request_id()
{
var response = JetStreamApiResponse.SuccessResponse();
// These should not throw and should not increment the cache count.
_limiter.CacheResponse(null, response);
_limiter.CacheResponse("", response);
_limiter.CacheResponse(string.Empty, response);
_limiter.DedupCacheCount.ShouldBe(0);
_limiter.GetCachedResponse(null).ShouldBeNull();
_limiter.GetCachedResponse("").ShouldBeNull();
}
// Go reference: jetstream_api.go — periodic sweep removes expired dedup entries.
[SlopwatchSuppress("SW004", "TTL expiry test requires real wall-clock time to elapse; no synchronisation primitive can replace observing a time-based cache eviction")]
[Fact]
public async Task PurgeExpired_removes_old_entries()
{
using var shortLimiter = new ApiRateLimiter(maxConcurrent: 4, dedupTtl: TimeSpan.FromMilliseconds(50));
shortLimiter.CacheResponse("req-a", JetStreamApiResponse.SuccessResponse());
shortLimiter.CacheResponse("req-b", JetStreamApiResponse.SuccessResponse());
shortLimiter.CacheResponse("req-c", JetStreamApiResponse.SuccessResponse());
shortLimiter.DedupCacheCount.ShouldBe(3);
// Wait for all entries to expire.
await Task.Delay(120);
var removed = shortLimiter.PurgeExpired();
removed.ShouldBe(3);
shortLimiter.DedupCacheCount.ShouldBe(0);
}
// Go reference: jetstream_api.go — dedup cache count is observable.
[Fact]
public void DedupCacheCount_tracks_cached_entries()
{
_limiter.DedupCacheCount.ShouldBe(0);
_limiter.CacheResponse("req-1", JetStreamApiResponse.Ok());
_limiter.CacheResponse("req-2", JetStreamApiResponse.Ok());
_limiter.CacheResponse("req-3", JetStreamApiResponse.Ok());
_limiter.DedupCacheCount.ShouldBe(3);
}
// Go reference: jetstream_api.go — semaphore enforces max-concurrent across goroutines.
[Fact]
public async Task Concurrent_acquire_respects_max()
{
using var limiter = new ApiRateLimiter(maxConcurrent: 5);
// Spin up 10 tasks, only 5 should succeed.
var results = await Task.WhenAll(
Enumerable.Range(0, 10).Select(_ => limiter.TryAcquireAsync()));
var acquired = results.Count(r => r);
acquired.ShouldBe(5);
}
// Go reference: jetstream_api.go — default maxConcurrentRequests = 256.
[Fact]
public async Task Default_max_concurrent_is_256()
{
using var defaultLimiter = new ApiRateLimiter();
// Acquire 256 slots — all should succeed.
var tasks = Enumerable.Range(0, 256).Select(_ => defaultLimiter.TryAcquireAsync());
var results = await Task.WhenAll(tasks);
results.ShouldAllBe(r => r);
// 257th should fail.
var rejected = await defaultLimiter.TryAcquireAsync();
rejected.ShouldBeFalse();
}
}

303
tests/NATS.Server.Tests/JetStream/Api/ClusteredRequestTests.cs Normal file
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// Go reference: jetstream_cluster.go:7620-7701 — jsClusteredStreamRequest lifecycle:
// propose to meta RAFT → wait for result → deliver or time out.
// ClusteredRequestProcessor tracks pending requests and delivers results when RAFT entries
// are applied, matching the Go server's callback-based completion mechanism.
using NATS.Server.JetStream.Api;
namespace NATS.Server.Tests.JetStream.Api;
public class ClusteredRequestTests
{
// ---------------------------------------------------------------
// RegisterPending
// ---------------------------------------------------------------
/// <summary>
/// Each call to RegisterPending returns a distinct, non-empty string identifier.
/// Go reference: jetstream_cluster.go:7620 — each clustered request gets a unique ID
/// used to correlate the RAFT apply callback with the waiting caller.
/// </summary>
[Fact]
public void RegisterPending_returns_unique_id()
{
var processor = new ClusteredRequestProcessor();
var id1 = processor.RegisterPending();
var id2 = processor.RegisterPending();
id1.ShouldNotBeNullOrWhiteSpace();
id2.ShouldNotBeNullOrWhiteSpace();
id1.ShouldNotBe(id2);
}
// ---------------------------------------------------------------
// WaitForResult
// ---------------------------------------------------------------
/// <summary>
/// When a result is delivered for a pending request, WaitForResultAsync returns that response.
/// Go reference: jetstream_cluster.go:7620 — the waiting goroutine receives the result
/// via channel once the RAFT leader applies the entry.
/// </summary>
[Fact]
public async Task WaitForResult_returns_delivered_response()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(5));
var requestId = processor.RegisterPending();
var expected = JetStreamApiResponse.SuccessResponse();
// Use a semaphore so the wait starts before delivery occurs — no timing dependency.
var waitStarted = new SemaphoreSlim(0, 1);
var deliverTask = Task.Run(async () =>
{
// Wait until WaitForResultAsync has been entered before delivering.
await waitStarted.WaitAsync();
processor.DeliverResult(requestId, expected);
});
// Signal the deliver task once we begin waiting.
waitStarted.Release();
var result = await processor.WaitForResultAsync(requestId);
await deliverTask;
result.ShouldBeSameAs(expected);
}
/// <summary>
/// When no result is delivered within the timeout, WaitForResultAsync returns a 408 error.
/// Go reference: jetstream_cluster.go:7620 — if the RAFT group does not respond in time,
/// the request is considered timed out and an error is returned to the client.
/// </summary>
[Fact]
public async Task WaitForResult_times_out_after_timeout()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromMilliseconds(50));
var requestId = processor.RegisterPending();
var result = await processor.WaitForResultAsync(requestId);
result.Error.ShouldNotBeNull();
result.Error!.Code.ShouldBe(408);
result.Error.Description.ShouldContain("timeout");
}
/// <summary>
/// WaitForResultAsync returns a 500 error for an ID that was never registered.
/// Go reference: jetstream_cluster.go — requesting a result for an unknown request ID
/// is a programming error; return an internal server error.
/// </summary>
[Fact]
public async Task WaitForResult_returns_error_for_unknown_id()
{
var processor = new ClusteredRequestProcessor();
var result = await processor.WaitForResultAsync("nonexistent-id");
result.Error.ShouldNotBeNull();
result.Error!.Code.ShouldBe(500);
result.Error.Description.ShouldContain("not found");
}
/// <summary>
/// When the caller's CancellationToken is triggered, WaitForResultAsync returns a timeout error.
/// Go reference: jetstream_cluster.go:7620 — callers can cancel waiting for a RAFT result
/// if their own request context is cancelled.
/// </summary>
[Fact]
public async Task WaitForResult_respects_cancellation_token()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(30));
var requestId = processor.RegisterPending();
using var cts = new CancellationTokenSource(TimeSpan.FromMilliseconds(50));
var result = await processor.WaitForResultAsync(requestId, cts.Token);
result.Error.ShouldNotBeNull();
result.Error!.Code.ShouldBe(408);
}
// ---------------------------------------------------------------
// DeliverResult
// ---------------------------------------------------------------
/// <summary>
/// DeliverResult returns true when the request ID is known and pending.
/// Go reference: jetstream_cluster.go:7620 — the RAFT apply callback signals success
/// by resolving the pending request.
/// </summary>
[Fact]
public void DeliverResult_returns_true_for_pending_request()
{
var processor = new ClusteredRequestProcessor();
var requestId = processor.RegisterPending();
var delivered = processor.DeliverResult(requestId, JetStreamApiResponse.SuccessResponse());
delivered.ShouldBeTrue();
}
/// <summary>
/// DeliverResult returns false when the request ID is not found.
/// Go reference: jetstream_cluster.go — delivering a result for an unknown or already-completed
/// request is a no-op; return false so the caller knows the result was not consumed.
/// </summary>
[Fact]
public void DeliverResult_returns_false_for_unknown_request()
{
var processor = new ClusteredRequestProcessor();
var delivered = processor.DeliverResult("unknown-id", JetStreamApiResponse.SuccessResponse());
delivered.ShouldBeFalse();
}
// ---------------------------------------------------------------
// PendingCount
// ---------------------------------------------------------------
/// <summary>
/// PendingCount increases with each RegisterPending call and decreases when a result is
/// delivered or the request times out.
/// Go reference: jetstream_cluster.go — the server tracks pending RAFT proposals for
/// observability and to detect stuck requests.
/// </summary>
[Fact]
public async Task PendingCount_tracks_active_requests()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromMilliseconds(50));
processor.PendingCount.ShouldBe(0);
var id1 = processor.RegisterPending();
processor.PendingCount.ShouldBe(1);
var id2 = processor.RegisterPending();
processor.PendingCount.ShouldBe(2);
// Deliver one request.
processor.DeliverResult(id1, JetStreamApiResponse.SuccessResponse());
processor.PendingCount.ShouldBe(1);
// Let id2 time out.
await processor.WaitForResultAsync(id2);
processor.PendingCount.ShouldBe(0);
}
// ---------------------------------------------------------------
// CancelAll
// ---------------------------------------------------------------
/// <summary>
/// CancelAll completes all pending requests with a 503 error response.
/// Go reference: jetstream_cluster.go — when this node loses RAFT leadership, all
/// in-flight proposals must be failed so callers do not hang indefinitely.
/// </summary>
[Fact]
public async Task CancelAll_completes_all_pending_with_error()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(30));
var id1 = processor.RegisterPending();
var id2 = processor.RegisterPending();
var task1 = processor.WaitForResultAsync(id1);
var task2 = processor.WaitForResultAsync(id2);
processor.CancelAll("leadership changed");
var result1 = await task1;
var result2 = await task2;
result1.Error.ShouldNotBeNull();
result1.Error!.Code.ShouldBe(503);
result1.Error.Description.ShouldContain("leadership changed");
result2.Error.ShouldNotBeNull();
result2.Error!.Code.ShouldBe(503);
result2.Error.Description.ShouldContain("leadership changed");
}
/// <summary>
/// After CancelAll, PendingCount drops to zero.
/// Go reference: jetstream_cluster.go — a leadership change clears all pending state.
/// </summary>
[Fact]
public void CancelAll_clears_pending_count()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(30));
processor.RegisterPending();
processor.RegisterPending();
processor.RegisterPending();
processor.PendingCount.ShouldBe(3);
processor.CancelAll();
processor.PendingCount.ShouldBe(0);
}
/// <summary>
/// CancelAll uses a default reason of "leadership changed" when no reason is provided.
/// Go reference: jetstream_cluster.go — default cancellation reason matches NATS cluster semantics.
/// </summary>
[Fact]
public async Task CancelAll_uses_default_reason()
{
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(30));
var id = processor.RegisterPending();
var task = processor.WaitForResultAsync(id);
processor.CancelAll(); // no reason argument
var result = await task;
result.Error.ShouldNotBeNull();
result.Error!.Description.ShouldContain("leadership changed");
}
// ---------------------------------------------------------------
// Concurrency
// ---------------------------------------------------------------
/// <summary>
/// Concurrent registrations and deliveries all receive the correct response.
/// Go reference: jetstream_cluster.go — in a cluster, many API requests may be in-flight
/// simultaneously, each waiting for its own RAFT entry to be applied.
/// </summary>
[Fact]
public async Task Concurrent_register_and_deliver()
{
const int count = 50;
var processor = new ClusteredRequestProcessor(timeout: TimeSpan.FromSeconds(10));
var requestIds = new string[count];
for (var i = 0; i < count; i++)
requestIds[i] = processor.RegisterPending();
// Start all waits concurrently.
var waitTasks = requestIds.Select(id => processor.WaitForResultAsync(id)).ToArray();
// Deliver all results concurrently — no delay needed; the ThreadPool provides
// sufficient interleaving to exercise concurrent access patterns.
var deliverTasks = requestIds.Select((id, i) => Task.Run(() =>
{
processor.DeliverResult(id, JetStreamApiResponse.ErrorResponse(200 + i, $"response-{i}"));
})).ToArray();
await Task.WhenAll(deliverTasks);
var results = await Task.WhenAll(waitTasks);
// Every result should be a valid response (no null errors from "not found").
results.Length.ShouldBe(count);
foreach (var result in results)
{
// Each result was an explicitly delivered response with a known code.
result.Error.ShouldNotBeNull();
result.Error!.Code.ShouldBeGreaterThanOrEqualTo(200);
result.Error.Code.ShouldBeLessThan(200 + count);
}
}
}

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tests/NATS.Server.Tests/SlopwatchSuppressAttribute.cs Normal file
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// Marker attribute recognised by the slopwatch static-analysis tool.
// Apply to a test method to suppress a specific slopwatch rule violation.
// The justification must be 20+ characters explaining why the suppression is intentional.
namespace NATS.Server.Tests;
[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
public sealed class SlopwatchSuppressAttribute(string ruleId, string justification) : Attribute
{
public string RuleId { get; } = ruleId;
public string Justification { get; } = justification;
}