- write() now accepts a ChannelPromise and returns ChannelFuture as most
users expected. It makes the user's life much easier because it is
now much easier to get notified when a specific message has been
written.
- flush() does not create a ChannelPromise nor returns ChannelFuture.
It is now similar to what read() looks like.
I must admit MesageList was pain in the ass. Instead of forcing a
handler always loop over the list of messages, this commit splits
messageReceived(ctx, list) into two event handlers:
- messageReceived(ctx, msg)
- mmessageReceivedLast(ctx)
When Netty reads one or more messages, messageReceived(ctx, msg) event
is triggered for each message. Once the current read operation is
finished, messageReceivedLast() is triggered to tell the handler that
the last messageReceived() was the last message in the current batch.
Similarly, for outbound, write(ctx, list) has been split into two:
- write(ctx, msg)
- flush(ctx, promise)
Instead of writing a list of message with a promise, a user is now
supposed to call write(msg) multiple times and then call flush() to
actually flush the buffered messages.
Please note that write() doesn't have a promise with it. You must call
flush() to get notified on completion. (or you can use writeAndFlush())
Other changes:
- Because MessageList is completely hidden, codec framework uses
List<Object> instead of MessageList as an output parameter.
The API changes made so far turned out to increase the memory footprint
and consumption while our intention was actually decreasing them.
Memory consumption issue:
When there are many connections which does not exchange data frequently,
the old Netty 4 API spent a lot more memory than 3 because it always
allocates per-handler buffer for each connection unless otherwise
explicitly stated by a user. In a usual real world load, a client
doesn't always send requests without pausing, so the idea of having a
buffer whose life cycle if bound to the life cycle of a connection
didn't work as expected.
Memory footprint issue:
The old Netty 4 API decreased overall memory footprint by a great deal
in many cases. It was mainly because the old Netty 4 API did not
allocate a new buffer and event object for each read. Instead, it
created a new buffer for each handler in a pipeline. This works pretty
well as long as the number of handlers in a pipeline is only a few.
However, for a highly modular application with many handlers which
handles connections which lasts for relatively short period, it actually
makes the memory footprint issue much worse.
Changes:
All in all, this is about retaining all the good changes we made in 4 so
far such as better thread model and going back to the way how we dealt
with message events in 3.
To fix the memory consumption/footprint issue mentioned above, we made a
hard decision to break the backward compatibility again with the
following changes:
- Remove MessageBuf
- Merge Buf into ByteBuf
- Merge ChannelInboundByte/MessageHandler and ChannelStateHandler into ChannelInboundHandler
- Similar changes were made to the adapter classes
- Merge ChannelOutboundByte/MessageHandler and ChannelOperationHandler into ChannelOutboundHandler
- Similar changes were made to the adapter classes
- Introduce MessageList which is similar to `MessageEvent` in Netty 3
- Replace inboundBufferUpdated(ctx) with messageReceived(ctx, MessageList)
- Replace flush(ctx, promise) with write(ctx, MessageList, promise)
- Remove ByteToByteEncoder/Decoder/Codec
- Replaced by MessageToByteEncoder<ByteBuf>, ByteToMessageDecoder<ByteBuf>, and ByteMessageCodec<ByteBuf>
- Merge EmbeddedByteChannel and EmbeddedMessageChannel into EmbeddedChannel
- Add SimpleChannelInboundHandler which is sometimes more useful than
ChannelInboundHandlerAdapter
- Bring back Channel.isWritable() from Netty 3
- Add ChannelInboundHandler.channelWritabilityChanges() event
- Add RecvByteBufAllocator configuration property
- Similar to ReceiveBufferSizePredictor in Netty 3
- Some existing configuration properties such as
DatagramChannelConfig.receivePacketSize is gone now.
- Remove suspend/resumeIntermediaryDeallocation() in ByteBuf
This change would have been impossible without @normanmaurer's help. He
fixed, ported, and improved many parts of the changes.
- Rename ChannelHandlerAdapter to ChannelDuplexHandler
- Add ChannelHandlerAdapter that implements only ChannelHandler
- Rename CombinedChannelHandler to CombinedChannelDuplexHandler and
improve runtime validation
- Remove ChannelInbound/OutboundHandlerAdapter which are not useful
- Make ChannelOutboundByteHandlerAdapter similar to
ChannelInboundByteHandlerAdapter
- Make the tail and head handler of DefaultChannelPipeline accept both
bytes and messages. ChannelHandlerContext.hasNext*() were removed
because they always return true now.
- Removed various unnecessary null checks.
- Correct method/field names:
inboundBufferSuspended -> channelReadSuspended
This pull request adds two new handler methods: discardInboundReadBytes(ctx) and discardOutboundReadBytes(ctx) to ChannelInboundByteHandler and ChannelOutboundByteHandler respectively. They are called between every inboundBufferUpdated() and flush() respectively. Their default implementation is to call discardSomeReadBytes() on their buffers and a user can override this behavior easily. For example, ReplayingDecoder.discardInboundReadBytes() looks like the following:
@Override
public void discardInboundReadBytes(ChannelHandlerContext ctx) throws Exception {
ByteBuf in = ctx.inboundByteBuffer();
final int oldReaderIndex = in.readerIndex();
super.discardInboundReadBytes(ctx);
final int newReaderIndex = in.readerIndex();
checkpoint -= oldReaderIndex - newReaderIndex;
}
If a handler, which has its own buffer index variable, extends ReplayingDecoder or ByteToMessageDecoder, the handler can also override discardInboundReadBytes() and adjust its index variable accordingly.
- Fixes#826
Unsafe.isFreed(), free(), suspend/resumeIntermediaryAllocations() are not that dangerous. internalNioBuffer() and internalNioBuffers() are dangerous but it seems like nobody is using it even inside Netty. Removing those two methods also removes the necessity to keep Unsafe interface at all.
* UnsafeByteBuf is gone. I added ByteBuf.unsafe() back.
* To avoid extra instantiation, all ByteBuf implementations implement the ByteBuf.Unsafe interface.
* To hide this implementation detail, all ByteBuf implementations are package-private.
* AbstractByteBuf and SwappedByteBuf are public and they do not implement ByteBuf.Unsafe because they don't need to.
* unwrap() is not an unsafe operation anymore.
* ChannelBuf also has unsafe() and Unsafe. ByteBuf.Unsafe extends ChannelBuf.unsafe(). ChannelBuf.unsafe() provides free() operation so that a user does not need to down-cast the buffer in freeInbound/OutboundBuffer().
- ChannelInboundHandler and ChannelOutboundHandler does not have a type
parameter anymore.
- User should implement ChannelInboundMessageHandler or
ChannelOutboundMessageHandler.
- Also prohibited a user from overriding
ChannelInbound(Byte|Message)HandlerAdapter. If a user wants to do
that, he or she should extend ChannelInboundHandlerAdapter instead.
- LoggingHandler now only logs state and operations
- StreamLoggingHandler and MessageLoggingHandler log the buffer content
- Added ChannelOperationHandlerAdapter
- Used by WriteTimeoutHandler
- Extracted some handler methods from ChannelInboundHandler into
ChannelStateHandler
- Extracted some handler methods from ChannelOutboundHandler into
ChannelOperationHandler
- Moved exceptionCaught and userEventTriggered are now in
ChannelHandler
- Channel(Inbound|Outbound)HandlerContext is merged into
ChannelHandlerContext
- ChannelHandlerContext adds direct access methods for inboud and
outbound buffers
- The use of ChannelBufferHolder is minimal now.
- Before: inbound().byteBuffer()
- After: inboundByteBuffer()
- Simpler and better performance
- Bypass buffer types were removed because it just does not work at all
with the thread model.
- All handlers that uses a bypass buffer are broken. Will fix soon.
- CombinedHandlerAdapter does not make sense anymore either because
there are four handler interfaces to consider and often the two
handlers will implement the same handler interface such as
ChannelStateHandler. Thinking of better ways to provide this feature
- Add ChannelHandlerContext.eventLoop() for convenience
- Bootstrap and ServerBootstrap handles channel initialization failure
better
- More strict checks for missing @Sharable annotation
- A handler without @Sharable annotation cannot be added more than
once now.
- Previous API did not support the pipeline which contains multiple
MessageToStreamEncoders because there was no way to find the closest
outbound byte buffer. Now you always get the correct buffer even if
the handler that provides the buffer is placed distantly.
For example:
Channel -> MsgAEncoder -> MsgBEncoder -> MsgCEncoder
Msg(A|B|C)Encoder will all have access to the channel's outbound
byte buffer. Previously, it was simply impossible.
- Improved ChannelBufferHolder.toString()
- Added ChannelBufferHolders.(inbound|outbound)BypassBuffer()
- The holder returned by these methods returns the next handler's
buffer. When a handler's new(Inbound|Outbound)Buffer returns
a bypass holder, your inboundBufferUpdated() and flush()
implementation should check if the buffer is a bypass and should not
modify the content of the buffer.
- Channel(Inbound|Outbound)?HandlerAdapter is now abstract.
- A user has to specify the exact inbound/outbound buffer type
- It's because there's no way to determine the best buffer type
- Implemented LoggingHandler using the new API.
- It doesn't dump received or sent messages yet.
- Fixed a bug where DefaultUnsafe.close() does not trigger deregister()
- Fixed a bug where NioSocketChannel.isActive() does not return false
when closed
- Optimized AbstractChannelBuffer.discardReadBytes()
- Split ChannelHandlerInvoker into ChannelInboundInvoker and
ChannelOutboundInvoker
- Channel implements ChannelOutboundInvoker
- ChannelOutboundInvoker.nextOut() is now out()
- ChannelOutboundHandlerContext.out() is now prevOut()
- Added the outbound operations without future
parameter to ChannelOutboundInvoker for user convenience
- All async operations which requires a ChannelFuture as a parameter
now returns ChannelFuture for user convenience
- Added ChannelFutureFactory.newVoidFuture() to allow a user specify
a dummy future that is of no use
- I'm unsure if it is actually a good idea to introduce it. It might
go away later.
- Made the contract of AbstractChannel.doXXX() much simpler and moved
all common code up to AbstractChannel.DefaultUnsafe
- Added Channel.isOpen()
- Fixed a bug where MultithreadEventLoop always shut down its child
event loops on construction
- Maybe more changes I don't remember :-)
- Channel now creates a ChannelPipeline by itself
I find no reason to allow a user to use one's own pipeline
implementation since I saw nobody does except for the cases where a
user wants to add a user attribute to a channel, which is now covered
by AttributeMap.
- Removed ChannelEvent and its subtypes because they are replaced by
direct method invocation.
- Replaced ChannelSink with Channel.unsafe()
- Various getter renaming (e.g. Channel.getId() -> Channel.id())
- Added ChannelHandlerInvoker interface
- Implemented AbstractChannel and AbstractServerChannel
- Some other changes I don't remember
- Rename ChannelReader to ChannelInboundHandler
- Rename ChannelWriter to ChannelOutboundHandler
- Introduce ChannelBufferHolder instead of adding the common super type
of message buffers and byte buffers
- This is more type-safe and natural.
- Remove the notification methods for buffer closure (might add back
later when revisiting half-closed connection support)
