Skip OIO transport from FileRegion drain-loop overshoot test

LuciferYang · LuciferYang · commit 088ebed0a2ac · 2026-05-19T18:14:17.000+08:00
OioByteStreamChannel#doWriteFileRegion drives its drain loop with a
locally-tracked bytes-written counter and passes it as the transferTo
position, never consulting region.transferred() for termination. The
OvershootDetectingFileRegion fixture advances transferred() to count()
after writing only one byte -- exactly to exercise the overshoot path
on transports that do consult transferred() -- which violates OIO's
position invariant and surfaces as a spurious IOException on the OIO
permutation in CI.

Skip the OIO client via assumeFalse(cc instanceof OioSocketChannel),
mirroring the precedent in SocketShutdownOutputBySelfTest. The check
runs alongside the existing supportsCustomFileRegion gate so the
NIO/epoll/kqueue/io_uring permutations still cover the regression.
diff --git a/testsuite/src/main/java/io/netty/testsuite/transport/socket/SocketFileRegionTest.java b/testsuite/src/main/java/io/netty/testsuite/transport/socket/SocketFileRegionTest.java
@@ -26,6 +26,7 @@
 import io.netty.channel.DefaultFileRegion;
 import io.netty.channel.FileRegion;
 import io.netty.channel.SimpleChannelInboundHandler;
+import io.netty.channel.socket.oio.OioSocketChannel;
 import io.netty.util.AbstractReferenceCounted;
 import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.PlatformDependent;
@@ -49,6 +50,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
 import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 public class SocketFileRegionTest extends AbstractSocketTest {
@@ -215,6 +217,15 @@ protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) {
         Channel sc = sb.bind().sync().channel();
         Channel cc = cb.connect(sc.localAddress()).sync().channel();
         try {
+            // OioByteStreamChannel#doWriteFileRegion drains using a locally-tracked
+            // bytes-written counter as the transferTo position (ignoring transferred()), so an
+            // ill-behaved FileRegion that advances transferred() past actual bytes written --
+            // the exact pattern this fixture uses to exercise the overshoot path -- cannot
+            // satisfy OIO's loop without violating the position invariant. The overshoot
+            // detection is meaningless on OIO for the same reason; skip the permutation.
+            assumeFalse(cc instanceof OioSocketChannel,
+                    "OIO transport does not honour transferred() for drain-loop termination");
+
             OvershootDetectingFileRegion region = new OvershootDetectingFileRegion(regionSize);
             // sync() blocks until the write future completes, by which point every
             // transferTo() call the transport is going to make has already been made --
