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Ensure channelReadComplete() is called only when necessary

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Motivation:

Even if a handler called ctx.fireChannelReadComplete(), the next handler
should not get its channelReadComplete() invoked if fireChannelRead()
was not invoked before.

Modifications:

- Ensure channelReadComplete() is invoked only when the handler of the
  current context actually produced a message, because otherwise there's
  no point of triggering channelReadComplete().
  i.e. channelReadComplete() must follow channelRead().
- Fix a bug where ctx.read() was not called if the handler of the
  current context did not produce any message, making the connection
  stall. Read the new comment for more information.

Result:

- channelReadComplete() is invoked only when it makes sense.
- No stale connection
This commit is contained in:
Trustin Lee 2015-02-07 15:54:42 +09:00
parent 270e0785fd
commit 27a25e29f7
4 changed files with 366 additions and 10 deletions
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8
codec/src/main/java/io/netty/handler/codec/ByteToMessageDecoder.java
View File

@ -133,7 +133,6 @@ public abstract class ByteToMessageDecoder extends ChannelInboundHandlerAdapter
ByteBuf cumulation;
private Cumulator cumulator = MERGE_CUMULATOR;
private boolean singleDecode;
private boolean decodeWasNull;
private boolean first;
protected ByteToMessageDecoder() {
@ -238,7 +237,6 @@ public abstract class ByteToMessageDecoder extends ChannelInboundHandlerAdapter
cumulation = null;
}
int size = out.size();
decodeWasNull = size == 0;
for (int i = 0; i < size; i ++) {
ctx.fireChannelRead(out.get(i));
@ -262,12 +260,6 @@ public abstract class ByteToMessageDecoder extends ChannelInboundHandlerAdapter
// - https://github.com/netty/netty/issues/1764
cumulation.discardSomeReadBytes();
}
if (decodeWasNull) {
decodeWasNull = false;
if (!ctx.channel().config().isAutoRead()) {
ctx.read();
}
}
ctx.fireChannelReadComplete();
}

59
codec/src/test/java/io/netty/handler/codec/ByteToMessageDecoderTest.java
View File

@ -20,6 +20,7 @@ import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.util.CharsetUtil;
import io.netty.util.ReferenceCountUtil;
import org.junit.Assert;
import org.junit.Test;
@ -27,6 +28,7 @@ import org.junit.Test;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.atomic.AtomicInteger;
public class ByteToMessageDecoderTest {
@ -160,4 +162,61 @@ public class ByteToMessageDecoderTest {
Assert.assertEquals(3, (int) queue.take());
Assert.assertTrue(queue.isEmpty());
}
// See https://github.com/netty/netty/pull/3263
@Test
public void testFireChannelReadCompleteOnlyWhenDecoded() {
final AtomicInteger readComplete = new AtomicInteger();
EmbeddedChannel ch = new EmbeddedChannel(new ByteToMessageDecoder() {
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
// Do nothing
}
}, new ChannelInboundHandlerAdapter() {
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
readComplete.incrementAndGet();
}
});
Assert.assertFalse(ch.writeInbound(Unpooled.copiedBuffer("test", CharsetUtil.US_ASCII)));
Assert.assertFalse(ch.finish());
Assert.assertEquals(0, readComplete.get());
}
// See https://github.com/netty/netty/pull/3263
@Test
public void testFireChannelReadCompleteWhenDecodeOnce() {
final AtomicInteger readComplete = new AtomicInteger();
EmbeddedChannel ch = new EmbeddedChannel(new ChannelInboundHandlerAdapter() {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
ctx.fireChannelRead(msg);
ctx.fireChannelRead(Unpooled.EMPTY_BUFFER);
}
}, new ByteToMessageDecoder() {
private boolean first = true;
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
if (first) {
first = false;
out.add(in.readSlice(in.readableBytes()).retain());
}
}
}, new ChannelInboundHandlerAdapter() {
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
readComplete.incrementAndGet();
}
});
Assert.assertTrue(ch.writeInbound(Unpooled.copiedBuffer("test", CharsetUtil.US_ASCII)));
Assert.assertTrue(ch.finish());
Assert.assertEquals(1, readComplete.get());
for (;;) {
ByteBuf buf = ch.readInbound();
if (buf == null) {
break;
}
buf.release();
}
}
}

62
transport/src/main/java/io/netty/channel/AbstractChannelHandlerContext.java
View File

@ -35,6 +35,26 @@ abstract class AbstractChannelHandlerContext implements ChannelHandlerContext, R
private final AbstractChannel channel;
private final DefaultChannelPipeline pipeline;
private final String name;
/**
* Set when a user calls {@link #fireChannelRead(Object)} on this context.
* Cleared when a user calls {@link #fireChannelReadComplete()} on this context.
*
* See {@link #fireChannelReadComplete()} to understand how this flag is used.
*/
private volatile boolean firedChannelRead;
/**
* Set when a user calls {@link #read()} on this context.
* Cleared when a user calls {@link #fireChannelReadComplete()} on this context.
*
* See {@link #fireChannelReadComplete()} to understand how this flag is used.
*/
private volatile boolean invokedRead;
/**
* {@code true} if and only if this context has been removed from the pipeline.
*/
private boolean removed;
final ChannelHandlerInvoker invoker;
@ -154,14 +174,51 @@ abstract class AbstractChannelHandlerContext implements ChannelHandlerContext, R
public ChannelHandlerContext fireChannelRead(Object msg) {
AbstractChannelHandlerContext next = findContextInbound();
ReferenceCountUtil.touch(msg, next);
firedChannelRead = true;
next.invoker().invokeChannelRead(next, msg);
return this;
}
@Override
public ChannelHandlerContext fireChannelReadComplete() {
AbstractChannelHandlerContext next = findContextInbound();
next.invoker().invokeChannelReadComplete(next);
/**
* If the handler of this context did not produce any messages via {@link #fireChannelRead(Object)},
* there's no reason to trigger {@code channelReadComplete()} even if the handler called this method.
*
* This is pretty common for the handlers that transform multiple messages into one message,
* such as byte-to-message decoder and message aggregators.
*/
if (firedChannelRead) {
// The handler of this context produced a message, so we are OK to trigger this event.
firedChannelRead = false;
invokedRead = false;
AbstractChannelHandlerContext next = findContextInbound();
next.invoker().invokeChannelReadComplete(next);
return this;
}
/**
* At this point, we are sure the handler of this context did not produce anything and
* we suppressed the {@code channelReadComplete()} event.
*
* If the next handler invoked {@link #read()} to read something but nothing was produced
* by the handler of this context, someone has to issue another {@link #read()} operation
* until the handler of this context produces something.
*
* Why? Because otherwise the next handler will not receive {@code channelRead()} nor
* {@code channelReadComplete()} event at all for the {@link #read()} operation it issued.
*/
if (invokedRead && !channel().config().isAutoRead()) {
/**
* The next (or upstream) handler invoked {@link #read()}, but it didn't get any
* {@code channelRead()} event. We should read once more, so that the handler of the current
* context have a chance to produce something.
*/
read();
} else {
invokedRead = false;
}
return this;
}
@ -249,6 +306,7 @@ abstract class AbstractChannelHandlerContext implements ChannelHandlerContext, R
@Override
public ChannelHandlerContext read() {
AbstractChannelHandlerContext next = findContextOutbound();
invokedRead = true;
next.invoker().invokeRead(next);
return this;
}

247
transport/src/test/java/io/netty/channel/DefaultChannelPipelineTest.java
View File

@ -21,12 +21,15 @@ import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.channel.local.LocalAddress;
import io.netty.channel.local.LocalChannel;
import io.netty.channel.local.LocalServerChannel;
import io.netty.util.AbstractReferenceCounted;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.ReferenceCounted;
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import io.netty.util.concurrent.EventExecutorGroup;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Test;
@ -38,6 +41,7 @@ import java.util.List;
import java.util.Queue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import static org.junit.Assert.*;
@ -548,6 +552,249 @@ public class DefaultChannelPipelineTest {
assertNull(pipeline.last());
}
@Test
public void testSupressChannelReadComplete() throws Exception {
testSupressChannelReadComplete0(false);
}
@Test
public void testSupressChannelReadCompleteDifferentExecutors() throws Exception {
testSupressChannelReadComplete0(true);
}
// See:
// https://github.com/netty/netty/pull/3263
// https://github.com/netty/netty/pull/3272
private static void testSupressChannelReadComplete0(boolean executors) throws Exception {
final AtomicInteger read1 = new AtomicInteger();
final AtomicInteger read2 = new AtomicInteger();
final AtomicInteger readComplete1 = new AtomicInteger();
final AtomicInteger readComplete2 = new AtomicInteger();
final CountDownLatch latch = new CountDownLatch(1);
final EventExecutorGroup group = executors ? new DefaultEventExecutorGroup(2) : null;
EmbeddedChannel ch = new EmbeddedChannel(new ChannelInitializer<Channel>() {
@Override
protected void initChannel(Channel ch) throws Exception {
ch.pipeline().addLast(group, new ChannelInboundHandlerAdapter() {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (read1.incrementAndGet() == 1) {
return;
}
ctx.fireChannelRead(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
readComplete1.incrementAndGet();
ctx.fireChannelReadComplete();
}
});
ch.pipeline().addLast(group, new ChannelInboundHandlerAdapter() {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
read2.incrementAndGet();
ctx.fireChannelRead(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
readComplete2.incrementAndGet();
ctx.fireChannelReadComplete();
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
latch.countDown();
}
});
}
});
ch.writeInbound(1);
ch.writeInbound(2);
ch.writeInbound(3);
ch.finish();
latch.await();
assertEquals(3, read1.get());
assertEquals(3, readComplete1.get());
assertEquals(2, read2.get());
assertEquals(2, readComplete2.get());
assertEquals(2, ch.readInbound());
assertEquals(3, ch.readInbound());
assertNull(ch.readInbound());
if (group != null) {
group.shutdownGracefully();
}
}
@Test
public void testChannelReadTriggered() {
final AtomicInteger read1 = new AtomicInteger();
final AtomicInteger channelRead1 = new AtomicInteger();
final AtomicInteger channelReadComplete1 = new AtomicInteger();
final AtomicInteger read2 = new AtomicInteger();
final AtomicInteger channelRead2 = new AtomicInteger();
final AtomicInteger channelReadComplete2 = new AtomicInteger();
final AtomicInteger read3 = new AtomicInteger();
final AtomicInteger channelRead3 = new AtomicInteger();
final AtomicInteger channelReadComplete3 = new AtomicInteger();
EmbeddedChannel ch = new EmbeddedChannel(new ChannelDuplexHandler() {
@Override
public void read(ChannelHandlerContext ctx) throws Exception {
read1.incrementAndGet();
ctx.read();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
channelRead1.incrementAndGet();
ctx.fireChannelRead(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
channelReadComplete1.incrementAndGet();
ctx.fireChannelReadComplete();
}
}, new ChannelDuplexHandler() {
@Override
public void read(ChannelHandlerContext ctx) throws Exception {
read2.incrementAndGet();
ctx.read();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// Consume
channelRead2.incrementAndGet();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
channelReadComplete2.incrementAndGet();
ctx.fireChannelReadComplete();
}
}, new ChannelDuplexHandler() {
@Override
public void read(ChannelHandlerContext ctx) throws Exception {
read3.incrementAndGet();
ctx.read();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
channelRead3.incrementAndGet();
ctx.fireChannelRead(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
channelReadComplete3.incrementAndGet();
ctx.fireChannelReadComplete();
}
});
ch.config().setAutoRead(false);
ch.writeInbound(1);
ch.writeInbound(2);
ch.writeInbound(3);
ch.finish();
assertEquals(4, read1.get());
assertEquals(3, channelRead1.get());
assertEquals(3, channelReadComplete1.get());
assertEquals(1, read2.get());
assertEquals(3, channelRead2.get());
assertEquals(3, channelReadComplete1.get());
assertEquals(1, read3.get());
assertEquals(0, channelRead3.get());
assertEquals(0, channelReadComplete3.get());
assertNull(ch.readInbound());
}
@Test
public void testChannelReadNotTriggeredWhenLast() throws Exception {
final AtomicInteger read1 = new AtomicInteger();
final AtomicInteger channelRead1 = new AtomicInteger();
final AtomicInteger channelReadComplete1 = new AtomicInteger();
final AtomicInteger read2 = new AtomicInteger();
final AtomicInteger channelRead2 = new AtomicInteger();
final AtomicInteger channelReadComplete2 = new AtomicInteger();
EmbeddedChannel ch = new EmbeddedChannel(new ChannelInboundHandlerAdapter());
// Ensure pipeline is really empty
ChannelPipeline pipeline = ch.pipeline();
while (pipeline.first() != null) {
pipeline.removeFirst();
}
pipeline.addLast(new ChannelDuplexHandler() {
@Override
public void read(ChannelHandlerContext ctx) throws Exception {
read1.incrementAndGet();
ctx.read();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
channelRead1.incrementAndGet();
ctx.fireChannelRead(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
channelReadComplete1.incrementAndGet();
ctx.fireChannelReadComplete();
}
}, new ChannelDuplexHandler() {
@Override
public void read(ChannelHandlerContext ctx) throws Exception {
read2.incrementAndGet();
ctx.read();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// Consume
channelRead2.incrementAndGet();
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
channelReadComplete2.incrementAndGet();
ctx.fireChannelReadComplete();
}
});
ch.config().setAutoRead(false);
ch.writeInbound(1);
ch.writeInbound(2);
ch.writeInbound(3);
ch.finish();
assertEquals(0, read1.get());
assertEquals(3, channelRead1.get());
assertEquals(3, channelReadComplete1.get());
assertEquals(0, read2.get());
assertEquals(3, channelRead2.get());
assertEquals(3, channelReadComplete1.get());
assertNull(ch.readInbound());
}
private static int next(AbstractChannelHandlerContext ctx) {
AbstractChannelHandlerContext next = ctx.next;
if (next == null) {