Fix oversize buffer reset for multiplexing (#4101)

Fixes #4099
npgsql · Nov 5, 2021 · 0b430d6 · 0b430d6
1 parent 8ff6b9d
commit 0b430d6
Show file tree

Hide file tree

Showing 3 changed files with 49 additions and 3 deletions.
diff --git a/src/Npgsql/Internal/NpgsqlConnector.cs b/src/Npgsql/Internal/NpgsqlConnector.cs
@@ -1141,6 +1141,7 @@ async Task MultiplexingReadLoop()
                         // the connector's write lock has been released (long waiting will never occur here).
                         SpinWait.SpinUntil(() => MultiplexAsyncWritingLock == 0 || IsBroken);
 
+                        ResetReadBuffer();
                         _connectorSource.Return(this);
                     }
                 }
@@ -2161,7 +2162,7 @@ internal async Task Reset(bool async)
         /// This switches us back to the original one and returns the buffer to <see cref="ArrayPool{T}" />.
         /// </summary>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void ResetReadBuffer()
+        void ResetReadBuffer()
         {
             if (_origReadBuffer != null)
             {

diff --git a/src/Npgsql/NpgsqlDataReader.cs b/src/Npgsql/NpgsqlDataReader.cs
@@ -1033,8 +1033,6 @@ internal async Task Cleanup(bool async, bool connectionClosing = false, bool isD
                 var connector = Connector;
                 UnbindIfNecessary();
 
-                connector.ResetReadBuffer();
-
                 // TODO: Refactor... Use proper scope
                 _connection.Connector = null;
                 connector.Connection = null;

diff --git a/test/Npgsql.Tests/BugTests.cs b/test/Npgsql.Tests/BugTests.cs
@@ -9,6 +9,8 @@
 using Npgsql.Tests.Support;
 
 using static Npgsql.Tests.TestUtil;
+using Npgsql.BackendMessages;
+using Npgsql.TypeMapping;
 
 namespace Npgsql.Tests
 {
@@ -1381,5 +1383,50 @@ public async Task Bug3924()
                 Assert.DoesNotThrowAsync(cmd.ExecuteNonQueryAsync);
             }
         }
+
+        [Test]
+        [IssueLink("https://github.com/npgsql/npgsql/issues/4099")]
+        public async Task Bug4099()
+        {
+            var csb = new NpgsqlConnectionStringBuilder(ConnectionString)
+            {
+                Multiplexing = true,
+                MaxPoolSize = 1
+            };
+            await using var postmaster = PgPostmasterMock.Start(csb.ConnectionString);
+            await using var firstConn = await OpenConnectionAsync(postmaster.ConnectionString);
+            await using var secondConn = await OpenConnectionAsync(postmaster.ConnectionString);
+
+            var byteArrayLength = csb.WriteBufferSize + 100;
+            var firstQuery = firstConn.ExecuteScalarAsync("SELECT data");
+
+            var server = await postmaster.WaitForServerConnection();
+            await server.ExpectExtendedQuery();
+
+            var secondQuery = secondConn.ExecuteScalarAsync("SELECT other_data");
+            await server.ExpectExtendedQuery();
+
+            var data = new byte[10000];
+            await server
+                .WriteParseComplete()
+                .WriteBindComplete()
+                .WriteRowDescription(new FieldDescription(PostgresTypeOIDs.Bytea))
+                .WriteDataRowWithFlush(data);
+
+            var otherData = new byte[10];
+            await server
+                .WriteCommandComplete()
+                .WriteReadyForQuery()
+                .WriteParseComplete()
+                .WriteBindComplete()
+                .WriteRowDescription(new FieldDescription(PostgresTypeOIDs.Bytea))
+                .WriteDataRow(otherData)
+                .WriteCommandComplete()
+                .WriteReadyForQuery()
+                .FlushAsync();
+
+            Assert.That(data, Is.EquivalentTo((byte[])(await firstQuery)!));
+            Assert.That(otherData, Is.EquivalentTo((byte[])(await secondQuery)!));
+        }
     }
 }