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.
- Fixes#1282 (not perfectly, but to the extent it's possible with the current API)
- Add AddressedEnvelope and DefaultAddressedEnvelope
- Make DatagramPacket extend DefaultAddressedEnvelope<ByteBuf, InetSocketAddress>
- Rename ByteBufHolder.data() to content() so that a message can implement both AddressedEnvelope and ByteBufHolder (DatagramPacket does) without introducing two getter methods for the content
- Datagram channel implementations now understand ByteBuf and ByteBufHolder as a message with unspecified remote address.
shutdownGracefully() provides two optional parameters that give more
control over when an executor has to be shut down.
- Related issue: #1307
- Add shutdownGracefully(..) and isShuttingDown()
- Deprecate shutdown() / shutdownNow()
- Replace lastAccessTime with lastExecutionTime and update it after task
execution for accurate quiet period check
- runAllTasks() and runShutdownTasks() update it automatically.
- Add updateLastExecutionTime() so that subclasses can update it
- Add a constructor parameter that tells not to add an unncessary wakeup
task in execute() if addTask() wakes up the executor thread
automatically. Previously, execute() always called wakeup() after
addTask(), which often caused an extra dummy task in the task queue.
- Use shutdownGracefully() wherever possible / Deprecation javadoc
- Reduce the running time of SingleThreadEventLoopTest from 40s to 15s
using custom graceful shutdown parameters
- Other changes made along with this commit:
- takeTask() does not throw InterruptedException anymore.
- Returns null on interruption or wakeup
- Make sure runShutdownTasks() return true even if an exception was
raised while running the shutdown tasks
- Remove unnecessary isShutdown() checks
- Consistent use of SingleThreadEventExecutor.nanoTime()
Replace isWakeupOverridden with a constructor parameter
This change also introduce a few other changes which was needed:
* ChannelHandler.beforeAdd(...) and ChannelHandler.beforeRemove(...) were removed
* ChannelHandler.afterAdd(...) -> handlerAdded(...)
* ChannelHandler.afterRemoved(...) -> handlerRemoved(...)
* SslHandler.handshake() -> SslHandler.hanshakeFuture() as the handshake is triggered automatically after
the Channel becomes active
- Now works without the transport package
- Renamed TransferFuture to ProgressiveFuture and ChannelProgressiveFuture / same for promises
- ProgressiveFutureListener now extends GenericProgressiveFutureListener and GenericFutureListener (add/removeTransferListener*() were removed)
- Renamed DefaultEventListeners to DefaultFutureListeners and only accept GenericFutureListeners
- Various clean-up
- Fixes#1229
- Primarily written by @normanmaurer and revised by @trustin
This commit removes the notion of unfolding from the codec framework
completely. Unfolding was introduced in Netty 3.x to work around the
shortcoming of the codec framework where encode() and decode() did not
allow generating multiple messages.
Such a shortcoming can be fixed by changing the signature of encode()
and decode() instead of introducing an obscure workaround like
unfolding. Therefore, we changed the signature of them in 4.0.
The change is simple, but backward-incompatible. encode() and decode()
do not return anything. Instead, the codec framework will pass a
MessageBuf<Object> so encode() and decode() can add the generated
messages into the MessageBuf.
- Add ChannelHandlerUtil and move the core logic of ChannelInbound/OutboundMessageHandler to ChannelHandlerUtil
- Add ChannelHandlerUtil.SingleInbound/OutboundMessageHandler and make ChannelInbound/OutboundMessageHandlerAdapter implement them. This is a backward incompatible change because it forces all handler methods to be public (was protected previously)
- Fixes: #1119
- Move common methods from ByteBuf to Buf
- Rename ensureWritableBytes() to ensureWritable()
- Rename readable() to isReadable()
- Rename writable() to isWritable()
- Add isReadable(int) and isWritable(int)
- Add AbstractMessageBuf
- Rewrite DefaultMessageBuf and QueueBackedMessageBuf
- based on Josh Bloch's public domain ArrayDeque impl
* This is done because we noticed that the previous change limit the usage more then it gave us any benefit. Now it is possible
again to rewrite the url on the fly or reuse the objects when writing a proxy and so limit the GC pressure.
* Fixes also #979
This changes the behavior of the ChannelPipeline.remove(..) and ChannelPipeline.replace(..) methods in that way
that after invocation it is not possible anymore to access any data in the inbound or outbound buffer. This is
because it empty it now to prevent side-effects. If a user want to preserve the content and forward it to the
next handler in the pipeline it is adviced to use one of the new methods which where introduced.
- ChannelPipeline.removeAndForward(..)
- ChannelPipeline.replaceAndForward(..)
- Rename message types for clarity
- HttpMessage -> FullHttpMessage
- HttpHeader -> HttpMessage
- HttpRequest -> FullHttpRequest
- HttpResponse -> FulllHttpResponse
- HttpRequestHeader -> HttpRequest
- HttpResponseHeader -> HttpResponse
- HttpContent now extends ByteBufHolder; no more content() method
- Make HttpHeaders abstract, make its header access methods public, and
add DefaultHttpHeaders
- Header accessor methods in HttpMessage and LastHttpContent are
replaced with HttpMessage.headers() and
LastHttpContent.trailingHeaders(). Both methods return HttpHeaders.
- Remove setters wherever possible and remove 'get' prefix
- Instead of calling setContent(), a user can either specify the content
when constructing a message or write content into the buffer.
(e.g. m.content().writeBytes(...))
- Overall cleanup & fixes
This commit tries to simplify the handling of Http easier and more consistent. This has a effect of many channges. Including:
- HttpMessage was renamed to HttpHeader and the setContent and getContent methods were removed
- HttpChunk was renamed to HttpContent
- HttpChunkTrailer was renamed to LastHttpContent
- HttpCodecUtil was merged into HttpHeaders
Now a "complete" Http message (request or response) contains of the following parts:
- HttpHeader (HttpRequestHeader or HttpResponseHeader)
- 0 - n HttpContent objects which contains parts of the content of the message
- 1 LastHttpContent which marks the end of the message and contains the remaining data of the content
I also changed the sematic of HttpResponse and HttpRequest, these now represent a "complete" message which contains the HttpHeader and the HttpLastContent, and so can be used to eeasily send requests. The HttpMessageAggregator was renamed to HttpObjectAggregator and produce HttpResponse / HttpRequest message.
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.
use single static initialization of available metrics monitor registries
* This changes the original implementation to work in a similar way to
how slf4j selects and loads an implementation.
* Uses a single static instance so intialization is done only once.
* Doesn't throw IllegalStateException if multiple implementations are
found on the classpath. It instead selects and uses the first
implementation returned by iterator()
* Class left as an iterable to keep the API the same
add yammer metrics to examples to allow them to publish metrics
publish the number of threads used in an EventLoopGroup see issue #718
* seems like the better place to put this because it sets the default
thread count if the MultithreadEventLoopGroup uses super(0,...)
* It also happens to be the common parent class amongst all the
MultiThreadedEventLoopGroup implementations
* Count is reported for
io.netty.channel.{*,.local,.socket.aio,.socket.nio}
fix cosmetic issues pointed out in pull request and updated notice.txt
see https://github.com/netty/netty/pull/780
count # of channels registered in single threaded event loop
measure how many times Selector.select return before SELECT_TIME
This pull request introduces a new operation called read() that replaces the existing inbound traffic control method. EventLoop now performs socket reads only when the read() operation has been issued. Once the requested read() operation is actually performed, EventLoop triggers an inboundBufferSuspended event that tells the handlers that the requested read() operation has been performed and the inbound traffic has been suspended again. A handler can decide to continue reading or not.
Unlike other outbound operations, read() does not use ChannelFuture at all to avoid GC cost. If there's a good reason to create a new future per read at the GC cost, I'll change this.
This pull request consequently removes the readable property in ChannelHandlerContext, which means how the traffic control works changed significantly.
This pull request also adds a new configuration property ChannelOption.AUTO_READ whose default value is true. If true, Netty will call ctx.read() for you. If you need a close control over when read() is called, you can set it to false.
Another interesting fact is that non-terminal handlers do not really need to call read() at all. Only the last inbound handler will have to call it, and that's just enough. Actually, you don't even need to call it at the last handler in most cases because of the ChannelOption.AUTO_READ mentioned above.
There's no serious backward compatibility issue. If the compiler complains your handler does not implement the read() method, add the following:
public void read(ChannelHandlerContext ctx) throws Exception {
ctx.read();
}
Note that this pull request certainly makes bounded inbound buffer support very easy, but itself does not add the bounded inbound buffer support.
