Add a few comments around buffer disposal

MihaZupan · MihaZupan · commit dba590bb8821 · 2023-01-26T20:54:23.000+01:00
diff --git a/src/libraries/Common/src/System/Net/ArrayBuffer.cs b/src/libraries/Common/src/System/Net/ArrayBuffer.cs
@@ -59,7 +59,7 @@ public void Dispose()
             byte[] array = _bytes;
             _bytes = null!;
 
-            if (array != null)
+            if (array is not null)
             {
                 ReturnBufferIfPooled(array);
             }
diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs b/src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http2Connection.cs
@@ -29,6 +29,7 @@ internal sealed partial class Http2Connection : HttpConnectionBase
         private readonly Stream _stream;
 
         // NOTE: These are mutable structs; do not make these readonly.
+        // ProcessIncomingFramesAsync and ProcessOutgoingFramesAsync are responsible for disposing/returning their respective buffers.
         private ArrayBuffer _incomingBuffer;
         private ArrayBuffer _outgoingBuffer;
 
@@ -245,6 +246,9 @@ public async ValueTask SetupAsync(CancellationToken cancellationToken)
             }
             catch (Exception e)
             {
+                // ProcessIncomingFramesAsync and ProcessOutgoingFramesAsync are responsible for disposing/returning their respective buffers.
+                // SetupAsync is the exception as it's responsible for starting the ProcessOutgoingFramesAsync loop.
+                // As we're about to throw and ProcessOutgoingFramesAsync will never be called, we must return the buffer here.
                 _outgoingBuffer.Dispose();
 
                 Dispose();
@@ -1886,6 +1890,10 @@ private void FinalTeardown()
             _connectionWindow.Dispose();
             _writeChannel.Writer.Complete();
 
+            // We're not disposing the _incomingBuffer and _outgoingBuffer here as they may still be in use by
+            // ProcessIncomingFramesAsync and ProcessOutgoingFramesAsync respectively, and those methods are
+            // responsible for returning the buffers.
+
             if (HttpTelemetry.Log.IsEnabled())
             {
                 if (Interlocked.Exchange(ref _markedByTelemetryStatus, TelemetryStatus_Closed) == TelemetryStatus_Opened)

Original file line number	Diff line number	Diff line change
`@@ -59,7 +59,7 @@ public void Dispose()`
`59`	`59`	`byte[] array = _bytes;`
`60`	`60`	`_bytes = null!;`
`61`	`61`
`62`		`- if (array != null)`
	`62`	`+ if (array is not null)`
`63`	`63`	`{`
`64`	`64`	`ReturnBufferIfPooled(array);`
`65`	`65`	`}`