EPOLL exception processing feedback loop
Motivation:
Commit cf171ff525
changed the way read operations were done. This change introduced a feedback loop between fireException and epollInReady.
Modifications:
- All EPOLL*Channel* classes should not call fireException and also continue to read. Instead a read operation should be executed on the eventloop (if the channel's input is not closed, and other conditions are satisfied)
Result:
Exception processing and channelRead will not be in a feedback loop.
Fixes https://github.com/netty/netty/issues/4091
This commit is contained in:
parent
559f1b110a
commit
ce6931e0e5
@ -311,6 +311,23 @@ abstract class AbstractEpollChannel extends AbstractChannel implements UnixChann
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*/
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*/
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abstract void epollInReady();
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abstract void epollInReady();
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/**
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* Will schedule a {@link #epollInReady()} call on the event loop if necessary.
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* @param edgeTriggered {@code true} if the channel is using ET mode. {@code false} otherwise.
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*/
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final void checkResetEpollIn(boolean edgeTriggered) {
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if (edgeTriggered && !isInputShutdown0()) {
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// trigger a read again as there may be something left to read and because of epoll ET we
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// will not get notified again until we read everything from the socket
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eventLoop().execute(new OneTimeTask() {
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@Override
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public void run() {
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epollInReady();
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}
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});
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}
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}
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/**
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/**
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* Called once EPOLLRDHUP event is ready to be processed
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* Called once EPOLLRDHUP event is ready to be processed
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*/
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*/
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@ -73,7 +73,7 @@ public abstract class AbstractEpollServerChannel extends AbstractEpollChannel im
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abstract Channel newChildChannel(int fd, byte[] remote, int offset, int len) throws Exception;
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abstract Channel newChildChannel(int fd, byte[] remote, int offset, int len) throws Exception;
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final class EpollServerSocketUnsafe extends AbstractEpollUnsafe {
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final class EpollServerSocketUnsafe extends AbstractEpollUnsafe {
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// Will hold the remote address after accept(...) was sucesssful.
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// Will hold the remote address after accept(...) was successful.
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// We need 24 bytes for the address as maximum + 1 byte for storing the length.
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// We need 24 bytes for the address as maximum + 1 byte for storing the length.
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// So use 26 bytes as it's a power of two.
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// So use 26 bytes as it's a power of two.
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private final byte[] acceptedAddress = new byte[26];
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private final byte[] acceptedAddress = new byte[26];
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@ -117,16 +117,8 @@ public abstract class AbstractEpollServerChannel extends AbstractEpollChannel im
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readPending = false;
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readPending = false;
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allocHandle.incMessagesRead(1);
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allocHandle.incMessagesRead(1);
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try {
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int len = acceptedAddress[0];
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int len = acceptedAddress[0];
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pipeline.fireChannelRead(newChildChannel(socketFd, acceptedAddress, 1, len));
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pipeline.fireChannelRead(newChildChannel(socketFd, acceptedAddress, 1, len));
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} catch (Throwable t) {
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if (edgeTriggered) { // We must keep reading if ET is enabled
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pipeline.fireExceptionCaught(t);
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} else {
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throw t;
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}
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}
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} while (allocHandle.continueReading());
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} while (allocHandle.continueReading());
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} catch (Throwable t) {
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} catch (Throwable t) {
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exception = t;
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exception = t;
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@ -136,6 +128,7 @@ public abstract class AbstractEpollServerChannel extends AbstractEpollChannel im
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if (exception != null) {
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if (exception != null) {
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pipeline.fireExceptionCaught(exception);
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pipeline.fireExceptionCaught(exception);
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checkResetEpollIn(edgeTriggered);
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}
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}
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} finally {
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} finally {
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// Check if there is a readPending which was not processed yet.
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// Check if there is a readPending which was not processed yet.
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@ -587,7 +587,7 @@ public abstract class AbstractEpollStreamChannel extends AbstractEpollChannel {
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}
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}
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class EpollStreamUnsafe extends AbstractEpollUnsafe {
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class EpollStreamUnsafe extends AbstractEpollUnsafe {
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private boolean handleReadException(ChannelPipeline pipeline, ByteBuf byteBuf, Throwable cause, boolean close) {
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private void handleReadException(ChannelPipeline pipeline, ByteBuf byteBuf, Throwable cause, boolean close) {
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if (byteBuf != null) {
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if (byteBuf != null) {
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if (byteBuf.isReadable()) {
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if (byteBuf.isReadable()) {
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readPending = false;
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readPending = false;
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@ -601,9 +601,7 @@ public abstract class AbstractEpollStreamChannel extends AbstractEpollChannel {
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pipeline.fireExceptionCaught(cause);
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pipeline.fireExceptionCaught(cause);
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if (close || cause instanceof IOException) {
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if (close || cause instanceof IOException) {
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shutdownInput();
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shutdownInput();
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return true;
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}
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}
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return false;
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}
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}
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@Override
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@Override
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@ -769,48 +767,35 @@ public abstract class AbstractEpollStreamChannel extends AbstractEpollChannel {
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boolean close = false;
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boolean close = false;
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try {
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try {
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do {
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do {
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try {
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SpliceInTask spliceTask = spliceQueue.peek();
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SpliceInTask spliceTask = spliceQueue.peek();
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if (spliceTask != null) {
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if (spliceTask != null) {
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if (spliceTask.spliceIn(allocHandle)) {
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if (spliceTask.spliceIn(allocHandle)) {
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// We need to check if it is still active as if not we removed all SpliceTasks in
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// We need to check if it is still active as if not we removed all SpliceTasks in
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// doClose(...)
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// doClose(...)
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if (isActive()) {
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if (isActive()) {
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spliceQueue.remove();
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spliceQueue.remove();
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}
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continue;
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} else {
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break;
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}
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}
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}
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continue;
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} else {
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// we use a direct buffer here as the native implementations only be able
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// to handle direct buffers.
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byteBuf = allocHandle.allocate(allocator);
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allocHandle.lastBytesRead(doReadBytes(byteBuf));
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if (allocHandle.lastBytesRead() <= 0) {
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// nothing was read, release the buffer.
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byteBuf.release();
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byteBuf = null;
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close = allocHandle.lastBytesRead() < 0;
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break;
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break;
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}
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}
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readPending = false;
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allocHandle.incMessagesRead(1);
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pipeline.fireChannelRead(byteBuf);
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byteBuf = null;
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} catch (Throwable t) {
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if (edgeTriggered) { // We must keep reading if ET is enabled
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if (byteBuf != null) {
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byteBuf.release();
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byteBuf = null;
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}
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pipeline.fireExceptionCaught(t);
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} else {
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// byteBuf is release in outer exception handling if necessary.
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throw t;
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}
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}
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}
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// we use a direct buffer here as the native implementations only be able
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// to handle direct buffers.
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byteBuf = allocHandle.allocate(allocator);
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allocHandle.lastBytesRead(doReadBytes(byteBuf));
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if (allocHandle.lastBytesRead() <= 0) {
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// nothing was read, release the buffer.
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byteBuf.release();
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byteBuf = null;
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close = allocHandle.lastBytesRead() < 0;
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break;
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}
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readPending = false;
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allocHandle.incMessagesRead(1);
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pipeline.fireChannelRead(byteBuf);
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byteBuf = null;
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} while (allocHandle.continueReading());
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} while (allocHandle.continueReading());
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allocHandle.readComplete();
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allocHandle.readComplete();
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@ -821,17 +806,8 @@ public abstract class AbstractEpollStreamChannel extends AbstractEpollChannel {
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close = false;
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close = false;
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}
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}
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} catch (Throwable t) {
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} catch (Throwable t) {
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boolean closed = handleReadException(pipeline, byteBuf, t, close);
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handleReadException(pipeline, byteBuf, t, close);
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if (!closed) {
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checkResetEpollIn(edgeTriggered);
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// trigger a read again as there may be something left to read and because of epoll ET we
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// will not get notified again until we read everything from the socket
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eventLoop().execute(new OneTimeTask() {
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@Override
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public void run() {
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epollInReady();
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}
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});
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}
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} finally {
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} finally {
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// Check if there is a readPending which was not processed yet.
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// Check if there is a readPending which was not processed yet.
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// This could be for two reasons:
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// This could be for two reasons:
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@ -535,9 +535,9 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
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Throwable exception = null;
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Throwable exception = null;
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try {
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try {
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do {
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ByteBuf data = null;
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ByteBuf data = null;
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try {
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try {
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do {
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data = allocHandle.allocate(allocator);
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data = allocHandle.allocate(allocator);
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allocHandle.attemptedBytesRead(data.writableBytes());
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allocHandle.attemptedBytesRead(data.writableBytes());
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final DatagramSocketAddress remoteAddress;
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final DatagramSocketAddress remoteAddress;
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@ -564,21 +564,14 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
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readBuf.add(new DatagramPacket(data, (InetSocketAddress) localAddress(), remoteAddress));
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readBuf.add(new DatagramPacket(data, (InetSocketAddress) localAddress(), remoteAddress));
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data = null;
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data = null;
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} catch (Throwable t) {
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} while (allocHandle.continueReading());
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if (data != null) {
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} catch (Throwable t) {
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data.release();
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if (data != null) {
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data = null;
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data.release();
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}
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data = null;
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if (edgeTriggered) {
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// We do not break from the loop here and remember the last exception,
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// because we need to consume everything from the socket used with epoll ET.
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pipeline.fireExceptionCaught(t);
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} else {
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exception = t;
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break;
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}
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}
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}
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} while (allocHandle.continueReading());
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exception = t;
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}
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int size = readBuf.size();
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int size = readBuf.size();
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for (int i = 0; i < size; i ++) {
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for (int i = 0; i < size; i ++) {
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@ -590,6 +583,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
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if (exception != null) {
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if (exception != null) {
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pipeline.fireExceptionCaught(exception);
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pipeline.fireExceptionCaught(exception);
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checkResetEpollIn(edgeTriggered);
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}
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}
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} finally {
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} finally {
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// Check if there is a readPending which was not processed yet.
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// Check if there is a readPending which was not processed yet.
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@ -157,16 +157,7 @@ public final class EpollDomainSocketChannel extends AbstractEpollStreamChannel i
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readPending = false;
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readPending = false;
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allocHandle.incMessagesRead(1);
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allocHandle.incMessagesRead(1);
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try {
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pipeline.fireChannelRead(new FileDescriptor(socketFd));
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pipeline.fireChannelRead(new FileDescriptor(socketFd));
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} catch (Throwable t) {
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// If ET is enabled we need to consume everything from the socket
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if (edgeTriggered) {
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pipeline.fireExceptionCaught(t);
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} else {
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throw t;
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}
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}
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} while (allocHandle.continueReading());
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} while (allocHandle.continueReading());
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allocHandle.readComplete();
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allocHandle.readComplete();
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@ -175,14 +166,7 @@ public final class EpollDomainSocketChannel extends AbstractEpollStreamChannel i
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allocHandle.readComplete();
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allocHandle.readComplete();
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pipeline.fireChannelReadComplete();
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pipeline.fireChannelReadComplete();
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pipeline.fireExceptionCaught(t);
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pipeline.fireExceptionCaught(t);
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// trigger a read again as there may be something left to read and because of epoll ET we
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checkResetEpollIn(edgeTriggered);
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// will not get notified again until we read everything from the socket
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eventLoop().execute(new OneTimeTask() {
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@Override
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public void run() {
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epollInReady();
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}
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});
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} finally {
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} finally {
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// Check if there is a readPending which was not processed yet.
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// Check if there is a readPending which was not processed yet.
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// This could be for two reasons:
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// This could be for two reasons:
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@ -16,12 +16,27 @@
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package io.netty.channel.epoll;
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package io.netty.channel.epoll;
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import io.netty.bootstrap.Bootstrap;
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import io.netty.bootstrap.Bootstrap;
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import io.netty.bootstrap.ServerBootstrap;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.Channel;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelInboundHandlerAdapter;
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import io.netty.channel.ChannelInboundHandlerAdapter;
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import io.netty.channel.ChannelInitializer;
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import io.netty.channel.ChannelOption;
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import io.netty.channel.ChannelPipeline;
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import io.netty.channel.EventLoopGroup;
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import io.netty.channel.EventLoopGroup;
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import io.netty.channel.ServerChannel;
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import org.junit.Assert;
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import org.junit.Assert;
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import org.junit.Test;
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import org.junit.Test;
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import java.net.InetSocketAddress;
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import java.net.InetSocketAddress;
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import java.net.SocketAddress;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicLong;
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import static org.junit.Assert.assertFalse;
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import static org.junit.Assert.assertTrue;
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public class EpollSocketChannelTest {
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public class EpollSocketChannelTest {
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@ -98,4 +113,97 @@ public class EpollSocketChannelTest {
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Assert.assertTrue(info.rcvSpace() >= 0);
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Assert.assertTrue(info.rcvSpace() >= 0);
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Assert.assertTrue(info.totalRetrans() >= 0);
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Assert.assertTrue(info.totalRetrans() >= 0);
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}
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}
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@Test
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public void testExceptionHandlingDoesNotInfiniteLoop() throws InterruptedException {
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EventLoopGroup group = new EpollEventLoopGroup();
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try {
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runExceptionHandleFeedbackLoop(group, EpollServerSocketChannel.class, EpollSocketChannel.class,
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new InetSocketAddress(0));
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runExceptionHandleFeedbackLoop(group, EpollServerDomainSocketChannel.class, EpollDomainSocketChannel.class,
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EpollSocketTestPermutation.newSocketAddress());
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} finally {
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group.shutdownGracefully();
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}
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}
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private void runExceptionHandleFeedbackLoop(EventLoopGroup group, Class<? extends ServerChannel> serverChannelClass,
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Class<? extends Channel> channelClass, SocketAddress bindAddr) throws InterruptedException {
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Channel serverChannel = null;
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Channel clientChannel = null;
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try {
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MyInitializer serverInitializer = new MyInitializer();
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ServerBootstrap sb = new ServerBootstrap();
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sb.option(ChannelOption.SO_BACKLOG, 1024);
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sb.group(group)
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.channel(serverChannelClass)
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.childHandler(serverInitializer);
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serverChannel = sb.bind(bindAddr).syncUninterruptibly().channel();
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Bootstrap b = new Bootstrap();
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b.group(group);
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b.channel(channelClass);
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b.option(ChannelOption.SO_KEEPALIVE, true);
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b.remoteAddress(serverChannel.localAddress());
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b.handler(new MyInitializer());
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clientChannel = b.connect().syncUninterruptibly().channel();
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clientChannel.writeAndFlush(Unpooled.wrappedBuffer(new byte[1024]));
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// We expect to get 2 exceptions (1 from BuggyChannelHandler and 1 from ExceptionHandler).
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assertTrue(serverInitializer.exceptionHandler.latch1.await(2, TimeUnit.SECONDS));
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// After we get the first exception, we should get no more, this is expected to timeout.
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assertFalse("Encountered " + serverInitializer.exceptionHandler.count.get() +
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" exceptions when 1 was expected",
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serverInitializer.exceptionHandler.latch2.await(2, TimeUnit.SECONDS));
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} finally {
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if (serverChannel != null) {
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serverChannel.close().syncUninterruptibly();
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}
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if (clientChannel != null) {
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clientChannel.close().syncUninterruptibly();
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}
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}
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}
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private static class MyInitializer extends ChannelInitializer<Channel> {
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final ExceptionHandler exceptionHandler = new ExceptionHandler();
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@Override
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protected void initChannel(Channel ch) throws Exception {
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ChannelPipeline pipeline = ch.pipeline();
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pipeline.addLast(new BuggyChannelHandler());
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pipeline.addLast(exceptionHandler);
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}
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}
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private static class BuggyChannelHandler extends ChannelInboundHandlerAdapter {
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@Override
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||||||
|
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
|
||||||
|
throw new NullPointerException("I am a bug!");
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
private static class ExceptionHandler extends ChannelInboundHandlerAdapter {
|
||||||
|
final AtomicLong count = new AtomicLong();
|
||||||
|
/**
|
||||||
|
* We expect to get 2 calls to {@link #exceptionCaught(ChannelHandlerContext, Throwable)}.
|
||||||
|
* 1 call from BuggyChannelHandler and 1 from closing the channel in this class.
|
||||||
|
*/
|
||||||
|
final CountDownLatch latch1 = new CountDownLatch(2);
|
||||||
|
final CountDownLatch latch2 = new CountDownLatch(1);
|
||||||
|
|
||||||
|
@Override
|
||||||
|
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
|
||||||
|
if (count.incrementAndGet() <= 2) {
|
||||||
|
latch1.countDown();
|
||||||
|
} else {
|
||||||
|
latch2.countDown();
|
||||||
|
}
|
||||||
|
// This is expected to throw an exception!
|
||||||
|
ctx.close();
|
||||||
|
}
|
||||||
|
}
|
||||||
}
|
}
|
||||||
|
Loading…
Reference in New Issue
Block a user