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Apply review feedback: replace _getHttpResponseCompleted with _disposed; rewrite test

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- Remove _getHttpResponseCompleted and rely on _httpSseWriter being null as the signal that the GET response stream has been released. Null out _httpSseWriter in DisposeAsync so SendMessageAsync correctly skips writing post-dispose.
- Replace the dispose-idempotency role of the old flag with a dedicated _disposed bool.
- Move the explanatory comment in SendMessageAsync onto the event store branch (which intentionally still runs when the response stream is gone, to support Last-Event-ID replay).
- Rewrite the unit test to assert observable behavior via a recording Stream instead of reflecting on private fields.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
Copilot 2026-05-28 12:03:58 -07:00 • committed by Stephen Halter
commit 25f080115d
1 changed files with 76 additions and 35 deletions
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23
src/ModelContextProtocol.Core/Server/StreamableHttpServerTransport.cs
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@ -44,7 +44,7 @@ public sealed partial class StreamableHttpServerTransport : ITransport
private TaskCompletionSource<bool>? _httpResponseTcs;
private string? _negotiatedProtocolVersion;
private bool _getHttpRequestStarted;
private bool _getHttpResponseCompleted;
private bool _disposed;
/// <summary>
/// Initializes a new instance of the <see cref="StreamableHttpServerTransport"/> class.
@ -177,7 +177,6 @@ public sealed partial class StreamableHttpServerTransport : ITransport
// otherwise accumulate significant unmanaged memory per session during that interval.
using (await _unsolicitedMessageLock.LockAsync(CancellationToken.None).ConfigureAwait(false))
{
_getHttpResponseCompleted = true;
if (_httpSseWriter is { } writer)
{
_httpSseWriter = null;
@ -240,23 +239,19 @@ public sealed partial class StreamableHttpServerTransport : ITransport
return;
}
// _httpSseWriter may be null here if the GET request has already ended (e.g. client
// disconnected). _getHttpResponseCompleted is set to true in that case, so the write
// below is correctly skipped. The event store writer (if configured) still captures
// the message so a reconnecting client can replay it via Last-Event-ID.
Debug.Assert(_httpResponseTcs is not null);
var item = SseItem.Message(message);
if (_storeSseWriter is not null)
{
// Always record the message in the event store (if configured) — even when the GET
// response stream is gone — so a reconnecting client can replay it via Last-Event-ID.
item = await _storeSseWriter.WriteEventAsync(item, cancellationToken).ConfigureAwait(false);
}
if (!_getHttpResponseCompleted && _httpSseWriter is { } writer)
if (_httpSseWriter is { } writer)
{
// Only write the message to the response if the response has not completed.
try
{
await writer.WriteAsync(item, cancellationToken).ConfigureAwait(false);
@ -273,12 +268,12 @@ public sealed partial class StreamableHttpServerTransport : ITransport
{
using var _ = await _unsolicitedMessageLock.LockAsync().ConfigureAwait(false);
if (_getHttpResponseCompleted)
if (_disposed)
{
return;
}
_getHttpResponseCompleted = true;
_disposed = true;
try
{
@ -290,7 +285,11 @@ public sealed partial class StreamableHttpServerTransport : ITransport
try
{
_httpResponseTcs?.TrySetResult(true);
_httpSseWriter?.Dispose();
if (_httpSseWriter is { } writer)
{
_httpSseWriter = null;
writer.Dispose();
}
if (_storeSseWriter is not null)
{