Allow flushing of NpgsqlReadBuffer.Stream (#4122)

aromaa · web-flow · commit dcaf1c31101c · 2021-11-13T11:28:36.000+03:00
Fixes #4123
diff --git a/src/Npgsql/Internal/NpgsqlReadBuffer.Stream.cs b/src/Npgsql/Internal/NpgsqlReadBuffer.Stream.cs
@@ -112,10 +112,14 @@ public override long Seek(long offset, SeekOrigin origin)
             }
 
             public override void Flush()
-                => throw new NotSupportedException();
+                => CheckDisposed();
 
             public override Task FlushAsync(CancellationToken cancellationToken)
-                => throw new NotSupportedException();
+            {
+                CheckDisposed();
+                return cancellationToken.IsCancellationRequested
+                    ? Task.FromCanceled(cancellationToken) : Task.CompletedTask;
+            }
 
             public override int Read(byte[] buffer, int offset, int count)
             {
diff --git a/test/Npgsql.Tests/BugTests.cs b/test/Npgsql.Tests/BugTests.cs
@@ -1428,5 +1428,20 @@ await server
             Assert.That(data, Is.EquivalentTo((byte[])(await firstQuery)!));
             Assert.That(otherData, Is.EquivalentTo((byte[])(await secondQuery)!));
         }
+
+        [Test]
+        [IssueLink("https://github.com/npgsql/npgsql/issues/4123")]
+        public async Task Bug4123()
+        {
+            using var conn = OpenConnection();
+            using var cmd = new NpgsqlCommand("SELECT 1", conn);
+            using var rdr = await cmd.ExecuteReaderAsync();
+
+            await rdr.ReadAsync();
+            using var stream = await rdr.GetStreamAsync(0);
+
+            Assert.DoesNotThrowAsync(stream.FlushAsync);
+            Assert.DoesNotThrow(stream.Flush);
+        }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -112,10 +112,14 @@ public override long Seek(long offset, SeekOrigin origin)`
`112`	`112`	`}`
`113`	`113`
`114`	`114`	`public override void Flush()`
`115`		`- => throw new NotSupportedException();`
	`115`	`+ => CheckDisposed();`
`116`	`116`
`117`	`117`	`public override Task FlushAsync(CancellationToken cancellationToken)`
`118`		`- => throw new NotSupportedException();`
	`118`	`+ {`
	`119`	`+ CheckDisposed();`
	`120`	`+ return cancellationToken.IsCancellationRequested`
	`121`	`+ ? Task.FromCanceled(cancellationToken) : Task.CompletedTask;`
	`122`	`+ }`
`119`	`123`
`120`	`124`	`public override int Read(byte[] buffer, int offset, int count)`
`121`	`125`	`{`