Motivation:
bytesBefore(length, ...), bytesBefore(index, length, ...), and
indexOf(fromIndex, toIndex,...) in ReplayingDecoderBuffer are buggy.
They trigger 'REPLAY even when they don't need to.
Modification:
Implement the buggy methods properly so that REPLAYs are not triggered
unnecessarily.
Result:
Correct behvaior
Motivation:
At the moment we use a lot of unnecessary memory copies in JdkZlibEncoder. This is caused by either allocate a to small ByteBuf and expand it later or using a temporary byte array.
Beside this the memory footprint of JdkZlibEncoder is pretty high because of the byte[] used for compressing.
Modification:
- Override allocateBuffer(...) and calculate the estimatedsize in there, this reduce expanding of the ByteBuf later
- Not use byte[] in the instance itself but allocate a heap ByteBuf and write directly into the byte array
Result:
Less memory copies and smaller memory footprint
Motivation:
MessageToByteEncoder always starts with ByteBuf that use initalCapacity == 0 when preferDirect is used. This is really wasteful in terms of performance as every first write into the buffer will cause an expand of the buffer itself.
Modifications:
- Change ByteBufAllocator.ioBuffer() use the same default initialCapacity as heapBuffer() and directBuffer()
- Add new allocateBuffer method to MessageToByteEncoder that allow the user to do some smarter allocation based on the message that will be encoded.
Result:
Less expanding of buffer and more flexibilty when allocate the buffer for encoding.
Motivation:
When Netty runs in a managed environment such as web application server,
Netty needs to provide an explicit way to remove the thread-local
variables it created to prevent class loader leaks.
FastThreadLocal uses different execution paths for storing a
thread-local variable depending on the type of the current thread.
It increases the complexity of thread-local removal.
Modifications:
- Moved FastThreadLocal and FastThreadLocalThread out of the internal
package so that a user can use it.
- FastThreadLocal now keeps track of all thread local variables it has
initialized, and calling FastThreadLocal.removeAll() will remove all
thread-local variables of the caller thread.
- Added FastThreadLocal.size() for diagnostics and tests
- Introduce InternalThreadLocalMap which is a mixture of hard-wired
thread local variable fields and extensible indexed variables
- FastThreadLocal now uses InternalThreadLocalMap to implement a
thread-local variable.
- Added ThreadDeathWatcher.unwatch() so that PooledByteBufAllocator
tells it to stop watching when its thread-local cache has been freed
by FastThreadLocal.removeAll().
- Added FastThreadLocalTest to ensure that removeAll() works
- Added microbenchmark for FastThreadLocal and JDK ThreadLocal
- Upgraded to JMH 0.9
Result:
- A user can remove all thread-local variables Netty created, as long as
he or she did not exit from the current thread. (Note that there's no
way to remove a thread-local variable from outside of the thread.)
- FastThreadLocal exposes more useful operations such as isSet() because
we always implement a thread local variable via InternalThreadLocalMap
instead of falling back to JDK ThreadLocal.
- FastThreadLocalBenchmark shows that this change improves the
performance of FastThreadLocal even more.
Motivation:
JdkZlibDecoder fails to decode because the length of the output buffer is not calculated correctly.
This can cause an IndexOutOfBoundsException or data-corruption when the PooledByteBuffAllocator is used.
Modifications:
Correctly calculate the length
Result:
No more IndexOutOfBoundsException or data-corruption.
Motivation:
Allow to make use of our new FastThreadLocal whereever possible
Modification:
Make use of an array to store FastThreadLocals and so allow to also use it in PooledByteBufAllocator that is instanced by users.
The maximal size of the array is configurable per system property to allow to tune it if needed. As default we use 64 entries which should be good enough.
Result:
More flexible usage of FastThreadLocal
Motivation:
At the moment MessageToMessageEncoder uses ctx.write(msg) when have more then one message was produced. This may produce more GC pressure then necessary as when the original ChannelPromise is a VoidChannelPromise we can safely also use one when write messages.
Modifications:
Use VoidChannelPromise when the original ChannelPromise was of this type
Result:
Less object creation and GC pressure
Motivation:
At the moment we call ByteBuf.readBytes(...) in these handlers but with optimizations done as part of 25e0d9d we can just use readSlice(...).retain() and eliminate the memory copy.
Modifications:
Replace ByteBuf.readBytes(...) usage with readSlice(...).retain().
Result:
Less memory copies.
Motivation:
The problem with the current snappy implementation is that it does
not comply with framing format definition found on
https://code.google.com/p/snappy/source/browse/trunk/framing_format.txt
The document describes that chunk type of the stream identifier is defined
as 0xff. The current implentation uses 0x80.
Modifications:
This patch replaces the first byte of the chunk type of the stream identifier
with 0xff.
Result:
After this modification the snappy implementation is compliant to the
framing format described at
https://code.google.com/p/snappy/source/browse/trunk/framing_format.txt.
This results in a better compatibility with other implementations.
Motivation:
When using System.getProperty(...) and various methods to get a ClassLoader it will fail when a SecurityManager is in place.
Modifications:
Use a priveled block if needed. This work is based in the PR #2353 done by @anilsaldhana .
Result:
Code works also when SecurityManager is present
Motivation:
At the moment a user can not safetly call slice().retain() or duplicate.retain()in the ByteToMessageDecoder.decode(...) implementation without the risk to see coruption because we may call discardSomeReadBytes() to make room on the buffer once the handling is done.
Modifications:
Check for the refCnt() before call discardSomeReadBytes() and also check before call decode(...) to create a copy if needed.
Result:
The user can safetly call slice().retain() or duplicate.retain() in his/her ByteToMessageDecoder.decode(...) method.
Motivation:
Reduce memory usage in ProtobufVarint32LengthFieldPrepender.
Modifications:
Explicit set the buffer size that is needed for the header (between 1 and 5 bytes).
Result:
Less memory usage in ProtobufVarint32LengthFieldPrepender.
Motivation:
Remove the synchronization bottleneck and so speed up things
Modifications:
Introduce a ThreadLocal cache that holds mappings between classes of ChannelHandlerAdapater implementations and the result of checking if the @Sharable annotation is present.
This way we only will need to do the real check one time and server the other calls via the cache. A ThreadLocal and WeakHashMap combo is used to implement the cache
as this way we can minimize the conditions while still be sure we not leak class instances in containers.
Result:
Less conditions during adding ChannelHandlerAdapter to the ChannelPipeline
- Fixes#2014
- Add the tests that mix JDK ZLIB codec and JZlib codecs
- Fix a bug where JdkZlibEncoder does not encode the GZIP header when nothing was written to te channel
- Fix a bug where the encoders do not consider the overhead of the wrapper format when calculating the estimated compressed output size.
- Fix a bug where the decoders do not discard the received data after the compressed stream is finished
