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.
- 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().
To perform writes in AioSocketChannel, we get a ByteBuffer view of the
outbound buffer and specify it as a parameter when we call
AsynchronousSocketChannel.write().
In most cases, the write() operation is finished immediately. However,
sometimes, it is scheduled for later execution. In such a case, there's
a chance for a user's handler to append more data to the outbound
buffer.
When more data is appended to the outbound buffer, the outbound buffer
can expand its capacity by itself. Changing the capacity of a buffer is
basically made of the following steps:
1. Allocate a larger new internal memory region.
2. Copy the current content of the buffer to the new memory region.
3. Rewire the buffer so that it refers to the new region.
4. Deallocate the old memory region.
Because the old memory region is deallocated at the step 4, the write
operation scheduled later will access the deallocated region, leading
all sort of data corruption or even segfaults.
To prevent this situation, I added suspendIntermediaryDeallocations()
and resumeIntermediaryDeallocations() to UnsafeByteBuf.
AioSocketChannel.doFlushByteBuf() now calls suspendIntermediaryDealloc()
to defer the deallocation of the old memory regions until the completion
handler is notified.
An AssertionError is triggered by a ByteBuf when beginRead() attempts to
access the buffer which has been freed already. This commit ensures the
buffer is not freed before performing an I/O operation.
To determine if the buffer has been freed, UnsafeByteBuf.isFreed() has
been added.
(See #768)
Once too long object is received, CompatibleMarshallingDecoder has to
discard all input from now on, just like MarshallingDecoder does.
Otherwise, the decoder will raise more exceptions because the decoder
has no idea anymore where the object starts.
Before this fix, SerialThreadLocalCompatibleMarshallingDecoderTest
logged many additional exceptions raised by the decoder after test is
finished.
Using DelimiterBasedFrameDecoder with Delimiters.lineDelimiter() has
quadratic performance in the size of the input buffer. Needless to
say, the performance degrades pretty quickly as the size of the buffer
increases. Larger MTUs or loopback connections can make it so bad that
it appears that the code is "busy waiting", when in fact it's spending
almost 100% of the CPU time in DelimiterBasedFrameDecoder.indexOf().
Add a new LineBasedFrameDecoder that decodes line-delimited frames
in O(n) instead of DelimiterBasedFrameDecoder's O(n^2) implementation.
In OpenTSDB's telnet-style protocol decoder this resulted in throughput
increases of an order of magnitude.
Change DelimiterBasedFrameDecoder to automatically detect when the
frames are delimited by line endings, and automatically switch to
using LineBasedFrameDecoder under the hood. This means that all Netty
applications out there that using the combo DelimiterBasedFrameDecoder
with Delimiters.lineDelimiter() will automatically benefit from the
better performance of LineBasedFrameDecoder, without requiring a code
change.
This commit introduces a new API for ByteBuf allocation which fixes
issue #643 along with refactoring of ByteBuf for simplicity and better
performance. (see #62)
A user can configure the ByteBufAllocator of a Channel via
ChannelOption.ALLOCATOR or ChannelConfig.get/setAllocator(). The
default allocator is currently UnpooledByteBufAllocator.HEAP_BY_DEFAULT.
To allocate a buffer, do not use Unpooled anymore. do the following:
ctx.alloc().buffer(...); // allocator chooses the buffer type.
ctx.alloc().heapBuffer(...);
ctx.alloc().directBuffer(...);
To deallocate a buffer, use the unsafe free() operation:
((UnsafeByteBuf) buf).free();
The following is the list of the relevant changes:
- Add ChannelInboundHandler.freeInboundBuffer() and
ChannelOutboundHandler.freeOutboundBuffer() to let a user free the
buffer he or she allocated. ChannelHandler adapter classes implement
is already, so most users won't need to call free() by themselves.
freeIn/OutboundBuffer() methods are invoked when a Channel is closed
and deregistered.
- All ByteBuf by contract must implement UnsafeByteBuf. To access an
unsafe operation: ((UnsafeByteBuf) buf).internalNioBuffer()
- Replace WrappedByteBuf and ByteBuf.Unsafe with UnsafeByteBuf to
simplify overall class hierarchy and to avoid unnecesary instantiation
of Unsafe instances on an unsafe operation.
- Remove buffer reference counting which is confusing
- Instantiate SwappedByteBuf lazily to avoid instantiation cost
- Rename ChannelFutureFactory to ChannelPropertyAccess and move common
methods between Channel and ChannelHandlerContext there. Also made it
package-private to hide it from a user.
- Remove unused unsafe operations such as newBuffer()
- Add DetectionUtil.canFreeDirectBuffer() so that an allocator decides
which buffer type to use safely
* Add DecodeResult that represents the result of decoding a message
* Add HttpObject which HttpMessage and HttpChunk extend.
** HttpObject has a property 'decodeResult'
o Add ByteBuf.hasNioBuffers() method
o Promote CompositeByteBuf.nioBuffers() methods to ByteBuf
o Use ByteBuf.nioBuffers() methods from AioSocketChannel
- Replace ByteBufferBackedByteBuf with DirectByteBuf
- Make DirectByteBuf and HeapByteBuf dynamic
- Remove DynamicByteBuf
- Replace Unpooled.dynamicBuffer() with Unpooled.buffer() and
directBuffer()
- Remove ByteBufFactory (will be replaced with ByteBufPool later)
- Add ByteBuf.Unsafe (might change in the future)
- Removed VoidEnum because a user can now specify Void instead
- AIO: Prefer discardReadBytes to clear
- AIO: Fixed a potential bug where notifyFlushFutures() is not called
if flush() was requested with no outbound data
- Add Channel.metadata() and remove Channel.bufferType()
- DefaultPipeline automatically redirects disconnect() request to
close() if the channel has no disconnect operation
- Remove unnecessary disconnect() implementations
- Rename ZlibEncoder/Decoder to JZlibEncoder/Decoder
- Define a new ZlibEncoder/Decoder class
- Add JdkZlibEncoder
- All JZlib* and JdkZlib* extends ZlibEncoder/Decoder
- Add ZlibCodecFactory and use it everywhere
- Removed all methods that requires ByteOrder as a parameter
from Unpooled (formerly ByteBufs/ChannelBuffers)
- Instead, a user calls order(ByteOrder) to get a little endian
version of the user's buffer
- This gives less overwhelming number of methods in Unpooled.
- ChannelInboundHandler and ChannelOutboundHandler does not have a type
parameter anymore.
- User should implement ChannelInboundMessageHandler or
ChannelOutboundMessageHandler.
- Add MessageBuf which replaces java.util.Queue
- Add ChannelBuf which is common type of ByteBuf and ChannelBuf
- ChannelBuffers was renamed to ByteBufs
- Add MessageBufs
- All these changes are going to replace ChannelBufferHolder.
- ChannelBuffer gives a perception that it's a buffer of a
channel, but channel's buffer is now a byte buffer or a message
buffer. Therefore letting it be as is is going to be confusing.
- Also prohibited a user from overriding
ChannelInbound(Byte|Message)HandlerAdapter. If a user wants to do
that, he or she should extend ChannelInboundHandlerAdapter instead.
- In computing, 'stream' means both byte stream and message stream,
which is confusing.
- Also, we were already mixing stream and byte in some places and
it's better use the terms consistently.
(e.g. inboundByteBuffer & inbound stream)
- Added EventExecutor.inEventLoop(Thread) and replaced executor identity
comparison in DefaultChannelPipeline with it - more elegant IMO
- Removed the test classes that needs rewrite or is of no use
- 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
... just like we do with byte arrays. toByteBuffer() and
toByteBuffers() had an indeterministic behavior and thus it could not
tell when the returned NIO buffer is shared or not. nioBuffer() always
returns a view buffer of the Netty buffer. The only case where
hasNioBuffer() returns false and nioBuffer() fails is the
CompositeChannelBuffer, which is not very commonly used and *slow*.
