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'
