Add MCP shutdown notification, in-flight cap, cancellation plumbing (#1567) - #2210
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…1567) The MCP JSON-RPC loop now accepts `notifications/shutdown` (and the legacy LSP-style `notifications/exit` alias) that cancels an internal shutdown token, unblocks any pending `IMcpTransport.ReadFrameAsync`, and exits the loop after the current tool call drains; frames queued behind the shutdown notification are not served. `ProcessFrame` is now wrapped in a `SemaphoreSlim` (default cap `8`, exposed as `McpServer.MaxConcurrency` and validated by the constructor) so a future parallel-dispatch transport cannot exceed the bound. The per-request `CancellationToken` is plumbed through `WithDbReader` into `DbReader` via a new `(connection, isReadOnly, cancellation)` ctor plus `DbReader.Cancellation` / `ThrowIfCancellationRequested`, so SQLite work started by a tool observes shutdown / client-disconnect cancellation instead of running to completion after the client is gone. The legacy two-argument `DbReader` ctor is preserved as a thin wrapper that passes `CancellationToken.None`, keeping existing CLI and test call sites source-compatible. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
notifications/shutdownhandler (with legacy LSP-stylenotifications/exitalias) that cancels an internal shutdown token, unblocks pendingIMcpTransport.ReadFrameAsync, drains the current tool call, and exits the loop without serving frames queued behind the shutdown notification.SemaphoreSlim(default cap8, exposed asMcpServer.MaxConcurrencyand validated by the constructor) before everyProcessFrameso any future parallel-dispatch transport cannot exceed the bound.CancellationTokenintoDbReader(new DbReader(connection, isReadOnly, cancellation)+DbReader.Cancellation/ThrowIfCancellationRequested) so SQLite work observes shutdown / client-disconnect cancellation. The legacy 2-argDbReaderctor is preserved as a thin wrapper that passesCancellationToken.None.Fixes #1567
Codex adversarial review (
codex exec review --base origin/main) reported no blocking or actionable correctness issues against the focus areas (race on_currentRequestToken, dispose order vs in-flight requests,notifications/exitalias semantics, JSON-RPC error semantics forOperationCanceledException, callers on removed ctor signatures, loop break semantics on!_running,RateLimiterenv read at construction).Test plan
dotnet test— 4894 passed, 0 failed, 3 skipped (post-rebase)McpServerTests.Notification_Shutdown_ReturnsNullAndLogsToStderrMcpServerTests.Notification_Exit_ReturnsNullAndLogsToStderrMcpServerTests.RunAsync_ShutdownNotification_DrainsAndExitsMcpServerTests.RunAsync_ShutdownNotification_PreemptsRemainingFramesMcpServerTests.MaxConcurrency_DefaultExposesIssueBoundMcpServerTests.MaxConcurrency_ExplicitOverride_TakesEffectMcpServerTests.MaxConcurrency_NonPositive_ThrowsDbReaderTests.Constructor_DefaultOverload_LeavesCancellationNoneDbReaderTests.Constructor_ExplicitToken_PropagatedThroughHelperscodex exec review --base origin/main): no blocking issuesGenerated with Claude Code