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Respect ctx.read() calls while processing reads for the child channels when using the Http2MultiplexCodec. (#8617) 

Motivation:

We did not correct respect ctx.read() calls while processing a read for a child Channel. This could lead to read stales when auto read is disabled and no other read was requested.

Modifications:

- Keep track of extra read() calls while processing reads
- Add unit tests that verify that read() is respected when triggered either in channelRead(...) or channelReadComplete(...)

Result:

Fixes https://github.com/netty/netty/issues/8209.
This commit is contained in:
Norman Maurer 2018-12-05 15:29:33 +01:00 committed by GitHub
parent d0d30f1fbe
commit 9f9aa1ae01
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2 changed files with 102 additions and 13 deletions
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61
codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodec.java
View File

@ -446,6 +446,26 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
return !isStreamIdValid(stream.id()) || isWritable(stream);
}
/**
* The current status of the read-processing for a {@link Http2StreamChannel}.
*/
private enum ReadStatus {
/**
* No read in progress and no read was requested (yet)
*/
IDLE,
/**
* Reading in progress
*/
IN_PROGRESS,
/**
* A read operation was requested.
*/
REQUESTED
}
// TODO: Handle writability changes due writing from outside the eventloop.
private final class DefaultHttp2StreamChannel extends DefaultAttributeMap implements Http2StreamChannel {
private final Http2StreamChannelConfig config = new Http2StreamChannelConfig(this);
@ -461,13 +481,15 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
private volatile boolean writable;
private boolean outboundClosed;
/**
* This variable represents if a read is in progress for the current channel. Note that depending upon the
* {@link RecvByteBufAllocator} behavior a read may extend beyond the {@link Http2ChannelUnsafe#beginRead()}
* method scope. The {@link Http2ChannelUnsafe#beginRead()} loop may drain all pending data, and then if the
* parent channel is reading this channel may still accept frames.
* This variable represents if a read is in progress for the current channel or was requested.
* Note that depending upon the {@link RecvByteBufAllocator} behavior a read may extend beyond the
* {@link Http2ChannelUnsafe#beginRead()} method scope. The {@link Http2ChannelUnsafe#beginRead()} loop may
* drain all pending data, and then if the parent channel is reading this channel may still accept frames.
*/
private boolean readInProgress;
private ReadStatus readStatus = ReadStatus.IDLE;
private Queue<Object> inboundBuffer;
/** {@code true} after the first HEADERS frame has been written **/
@ -757,9 +779,9 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
assert eventLoop().inEventLoop();
if (!isActive()) {
ReferenceCountUtil.release(frame);
} else if (readInProgress) {
// If readInProgress there cannot be anything in the queue, otherwise we would have drained it from the
// queue and processed it during the read cycle.
} else if (readStatus != ReadStatus.IDLE) {
// If a read is in progress or has been requested, there cannot be anything in the queue,
// otherwise we would have drained it from the queue and processed it during the read cycle.
assert inboundBuffer == null || inboundBuffer.isEmpty();
final Handle allocHandle = unsafe.recvBufAllocHandle();
unsafe.doRead0(frame, allocHandle);
@ -783,7 +805,7 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
void fireChildReadComplete() {
assert eventLoop().inEventLoop();
assert readInProgress;
assert readStatus == ReadStatus.IN_PROGRESS;
unsafe.notifyReadComplete(unsafe.recvBufAllocHandle());
}
@ -985,11 +1007,20 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
@Override
public void beginRead() {
if (readInProgress || !isActive()) {
if (!isActive()) {
return;
}
readInProgress = true;
doBeginRead();
switch (readStatus) {
case IDLE:
readStatus = ReadStatus.IN_PROGRESS;
doBeginRead();
break;
case IN_PROGRESS:
readStatus = ReadStatus.REQUESTED;
break;
default:
break;
}
}
void doBeginRead() {
@ -1026,7 +1057,11 @@ public class Http2MultiplexCodec extends Http2FrameCodec {
void notifyReadComplete(Handle allocHandle) {
assert next == null && previous == null;
readInProgress = false;
if (readStatus == ReadStatus.REQUESTED) {
readStatus = ReadStatus.IN_PROGRESS;
} else {
readStatus = ReadStatus.IDLE;
}
allocHandle.readComplete();
pipeline().fireChannelReadComplete();
// Reading data may result in frames being written (e.g. WINDOW_UPDATE, RST, etc..). If the parent

54
codec-http2/src/test/java/io/netty/handler/codec/http2/Http2MultiplexCodecTest.java
View File

@ -260,6 +260,60 @@ public class Http2MultiplexCodecTest {
verifyFramesMultiplexedToCorrectChannel(inboundStream, inboundHandler, 2);
}
@Test
public void readInChannelReadWithoutAutoRead() {
useReadWithoutAutoRead(false);
}
@Test
public void readInChannelReadCompleteWithoutAutoRead() {
useReadWithoutAutoRead(true);
}
private void useReadWithoutAutoRead(final boolean readComplete) {
LastInboundHandler inboundHandler = streamActiveAndWriteHeaders(inboundStream);
Channel childChannel = inboundHandler.channel();
assertTrue(childChannel.config().isAutoRead());
childChannel.config().setAutoRead(false);
assertFalse(childChannel.config().isAutoRead());
Http2HeadersFrame headersFrame = inboundHandler.readInbound();
assertNotNull(headersFrame);
// Add a handler which will request reads.
childChannel.pipeline().addFirst(new ChannelInboundHandlerAdapter() {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ctx.fireChannelRead(msg);
if (!readComplete) {
ctx.read();
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.fireChannelReadComplete();
if (readComplete) {
ctx.read();
}
}
});
codec.onHttp2Frame(
new DefaultHttp2DataFrame(bb("hello world"), false).stream(inboundStream));
codec.onHttp2Frame(new DefaultHttp2DataFrame(bb("foo"), false).stream(inboundStream));
codec.onHttp2Frame(new DefaultHttp2DataFrame(bb("bar"), true).stream(inboundStream));
codec.onChannelReadComplete();
codec.onHttp2Frame(
new DefaultHttp2DataFrame(bb("hello world"), false).stream(inboundStream));
codec.onHttp2Frame(new DefaultHttp2DataFrame(bb("foo"), false).stream(inboundStream));
codec.onHttp2Frame(new DefaultHttp2DataFrame(bb("bar"), true).stream(inboundStream));
codec.onChannelReadComplete();
verifyFramesMultiplexedToCorrectChannel(inboundStream, inboundHandler, 6);
}
private Http2StreamChannel newOutboundStream() {
return new Http2StreamChannelBootstrap(parentChannel).handler(childChannelInitializer)
.open().syncUninterruptibly().getNow();