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:
Provide a faster ThreadLocal implementation
Modification:
Add a "FastThreadLocal" which uses an EnumMap and a predefined fixed set of possible thread locals (all of the static instances created by netty) that is around 10-20% faster than standard ThreadLocal in my benchmarks (and can be seen having an effect in the direct PooledByteBufAllocator benchmark that uses the DEFAULT ByteBufAllocator which uses this FastThreadLocal, as opposed to normal instantiations that do not, and in the new RecyclableArrayList benchmark);
Result:
Improved performance
Motivation:
ChannelTrafficShapingHandler may corrupt inbound data stream by
scheduling the fireChannelRead event.
Modification:
Always call fireChannelRead(...) and only suspend reads after it
Result:
No more data corruption
Motivation:
According to TLS ALPN draft-05, a client sends the list of the supported
protocols and a server responds with the selected protocol, which is
different from NPN. Therefore, ApplicationProtocolSelector won't work
with ALPN
Modifications:
- Use Iterable<String> to list the supported protocols on the client
side, rather than using ApplicationProtocolSelector
- Remove ApplicationProtocolSelector
Result:
Future compatibility with TLS ALPN
Motivation:
- OpenSslEngine and JDK SSLEngine (+ Jetty NPN) have different APIs to
support NextProtoNego extension.
- It is impossible to configure NPN with SslContext when the provider
type is JDK.
Modification:
- Implement NextProtoNego extension by overriding the behavior of
SSLSession.getProtocol() for both OpenSSLEngine and JDK SSLEngine.
- SSLEngine.getProtocol() returns a string delimited by a colon (':')
where the first component is the transport protosol (e.g. TLSv1.2)
and the second component is the name of the application protocol
- Remove the direct reference of Jetty NPN classes from the examples
- Add SslContext.newApplicationProtocolSelector
Result:
- A user can now use both JDK SSLEngine and OpenSslEngine for NPN-based
protocols such as HTTP2 and SPDY
Motivation:
For an unknown reason, JVM of JDK8 crashes intermittently when
SslHandler feeds a direct buffer to SSLEngine.unwrap() *and* the current
cipher suite has GCM (Galois/Counter Mode) enabled.
Modifications:
Convert the inbound network buffer to a heap buffer when the current
cipher suite is using GCM.
Result:
JVM does not crash anymore.
Motivation:
JDK's SSLEngine.wrap() requires the output buffer to be always as large as MAX_ENCRYPTED_PACKET_LENGTH even if the input buffer contains small number of bytes. Our OpenSslEngine implementation does not have such wasteful behaviot.
Modifications:
If the current SSLEngine is OpenSslEngine, allocate as much as only needed.
Result:
Less peak memory usage.
Motivation:
Previous fix for the OpenSslEngine compatibility issue (#2216 and
18b0e95659) was to feed SSL records one by
one to OpenSslEngine.unwrap(). It is not optimal because it will result
in more JNI calls.
Modifications:
- Do not feed SSL records one by one.
- Feed as many records as possible up to MAX_ENCRYPTED_PACKET_LENGTH
- Deduplicate MAX_ENCRYPTED_PACKET_LENGTH definitions
Result:
- No allocation of intemediary arrays
- Reduced number of calls to SSLEngine and thus its underlying JNI calls
- A tad bit increase in throughput, probably reverting the tiny drop
caused by 18b0e95659
Motivation:
Some users already use an SSLEngine implementation in finagle-native. It
wraps OpenSSL to get higher SSL performance. However, to take advantage
of it, finagle-native must be compiled manually, and it means we cannot
pull it in as a dependency and thus we cannot test our SslHandler
against the OpenSSL-based SSLEngine. For an instance, we had #2216.
Because the construction procedures of JDK SSLEngine and OpenSslEngine
are very different from each other, we also need to provide a universal
way to enable SSL in a Netty application.
Modifications:
- Pull netty-tcnative in as an optional dependency.
http://netty.io/wiki/forked-tomcat-native.html
- Backport NativeLibraryLoader from 4.0
- Move OpenSSL-based SSLEngine implementation into our code base.
- Copied from finagle-native; originally written by @jpinner et al.
- Overall cleanup by @trustin.
- Run all SslHandler tests with both default SSLEngine and OpenSslEngine
- Add a unified API for creating an SSL context
- SslContext allows you to create a new SSLEngine or a new SslHandler
with your PKCS#8 key and X.509 certificate chain.
- Add JdkSslContext and its subclasses
- Add OpenSslServerContext
- Add ApplicationProtocolSelector to ensure the future support for NPN
(NextProtoNego) and ALPN (Application Layer Protocol Negotiation) on
the client-side.
- Add SimpleTrustManagerFactory to help a user write a
TrustManagerFactory easily, which should be useful for those who need
to write an alternative verification mechanism. For example, we can
use it to implement an unsafe TrustManagerFactory that accepts
self-signed certificates for testing purposes.
- Add InsecureTrustManagerFactory and FingerprintTrustManager for quick
and dirty testing
- Add SelfSignedCertificate class which generates a self-signed X.509
certificate very easily.
- Update all our examples to use SslContext.newClient/ServerContext()
- SslHandler now logs the chosen cipher suite when handshake is
finished.
Result:
- Cleaner unified API for configuring an SSL client and an SSL server
regardless of its internal implementation.
- When native libraries are available, OpenSSL-based SSLEngine
implementation is selected automatically to take advantage of its
performance benefit.
- Examples take advantage of this modification and thus are cleaner.
Motivation:
When writing data from a server before the ssl handshake completes may not be written at all to the remote peer
if nothing else is written after the handshake was done.
Modification:
Correctly try to write pending data after the handshake was complete
Result:
Correctly write out all pending data
Motivation:
As discussed in #2250, it will become much less complicated to implement
deregistration and reregistration of a channel once #2250 is resolved.
Therefore, there's no need to deprecate deregister() and
channelUnregistered().
Modification:
- Undeprecate deregister() and channelUnregistered()
- Remove SuppressWarnings annotations where applicable
Result:
We (including @jakobbuchgraber) are now ready to play with #2250 at
master
Motivation:
4 and 5 were diverged long time ago and we recently reverted some of the
early commits in master. We must make sure 4.1 and master are not very
different now.
Modification:
Fix found differences
Result:
4.1 and master got closer.
Motivation:
4 and 5 were diverged long time ago and we recently reverted some of the
early commits in master. We must make sure 4.1 and master are not very
different now.
Modification:
Remove ChannelHandlerInvoker.writeAndFlush(...) and the related
implementations.
Result:
4.1 and master got closer.
Motivation:
4 and 5 were diverged long time ago and we recently reverted some of the
early commits in master. We must make sure 4.1 and master are not very
different now.
Modification:
Fix found differences
Result:
4.1 and master got closer.
Motivation:
Some SSLEngine implementations violate the contract and raises an
exception when SslHandler feeds an input buffer that contains multiple
SSL records to SSLEngine.unwrap(), while the expected behavior is to
decode the first record and return.
Modification:
- Modify SslHandler.decode() to keep the lengths of each record and feed
SSLEngine.unwrap() record by record to work around the forementioned
issue.
- Rename unwrap() to unwrapMultiple() and unwrapNonApp()
- Rename unwrap0() to unwrapSingle()
Result:
SslHandler now works OpenSSLEngine from finagle-native. Performance
impact remains unnoticeable. Slightly better readability. Fixes#2116.
Motivation:
Some Android SSLEngine implementations skip FINISHED handshake status
and go straightly into NOT_HANDSHAKING. This behavior blocks SslHandler
from notifying its handshakeFuture, because we do the notification when
SSLEngine enters the FINISHED state.
Modification:
When the current handshake state is NOT_HANDSHAKING and the
handshakeFuture is not fulfilled yet, treat NOT_HANDSHAKING as FINISHED.
Result:
Better Android compatibility - fixes#1823
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:
In SslHandler.safeClose(...) we attach a ChannelFutureListener to the flushFuture and will notify the ChannelPromise which was used for close(...) in it. The problem here is that we only call ChannelHandlerContext.close(ChannelPromise) if Channel.isActive() is true and otherwise not notify it at all. We should just call ChannelHandlerContext.close(ChannelPromise) in all cases.
Modifications:
Always call ChannelHandlerContext.close(ChannelPromise) in the ChannelFutureListeiner
Result:
ChannelPromise used for close the Channel is notified in all cases
Motivation:
In ChunkedWriteHandler, there is a redundant variable that servers
no purpose. It implies that under some conditions you might not want
to flush.
Modifications:
Removed the variable and the if condition that read it. The boolean
was always true so just removing the if statement was fine.
Result:
Slightly less misleading code.
Motivation:
Currently we use System.currentTimeMillis() in our timeout handlers this is bad
for various reasons like when the clock adjusts etc.
Modifications:
Replace System.currentTimeMillis() with System.nanoTime()
Result:
More robust timeout handling
Motivation:
We don't really need to propagate an event when handling the event fails.
Modifications:
Do not use finally block in AbstractRemoteAddressFilter
Result:
AbstractRemoteaddressFilter does not forward an event in case of failure.
Motivation:
Recently merged ipfilter package has the following problems:
* AbstractIpFilterHandler could be improved to support any SocketAddress types rather than only InetSocketAddress.
* AbstractIpFilterHandler can be removed immediately after decision is made rather than keeping the outcome of the decision as an attribute.
* AbstractIpFilterHandler doesn't have a hook for the accepted addresses.
* The hook method (reject()) needs to be named in line with other handler methods (i.e. channelRejected())
* IpFilterRuleHandler should allow accepting zero rules - it's particularly useful for machine-configured setup (i.e. specifying zero rules disables ipfilter).
* IpFilterRuleType.ALLOW/DENY should be ACCEPT/REJECT for consistency.
Modifications:
* AbstractIpFilterHandler has been renamed to AbstractRemoteAddressFilter and now uses type parameter.
* Added channelAccepted() and renamed reject() to channelRejected()
* Added ChannelHandlerContext as a parameter of accept() so that accept() can add a listener to the closeFuture() of the channel. This way, UniqueIpFilter continue working even if we remove the filtering handler early.
* Various renames
* IpFilterRuleHandler -> RuleBasedIpFilter
* UniqueIpFilterHandler -> UniqueIpFilter
Result:
* Much cleaner API with more extensibility
Motivation:
ChunkedWriteHandler can sometimes fail to write the last chunk of a ChunkedInput due to an I/O error. Subsequently, the ChunkedInput's associated promise is marked as failure and the connection is closed. When the connection is closed, ChunkedWriteHandler attempts to clean up its message queue and to mark their promises as success or failure. However, because the promise of the ChunkedInput, which was consumed completely yet failed to be written, is already marked as failure, the attempt to mark it as success fails, leading a WARN level log.
Modification:
Use trySuccess() instead of setSuccess() so that the attempt to mark a ChunkedInput as success does not raise an exception even if the promise is already done.
Result:
Fixes#2249
- Use ': ' instead of '(...)' for simpler string concatenation and prettier presentation
- Optimize the overall performance of format*() methods
- All format*() methods are now expected to encode the channel information by themselves so that StringBuilder instances are created less often.
- Use a look-up table for generating per-row prefixes
- Hid formatByteBuf(), formatByteBufHolder(), and formatNonByteBuf() from user because a user can always override format(ctx, eventName, arg). For example, to disable hexdump:
protected void format(ChannelHandlerContext ctx, String eventName, Object arg) {
if (arg instanceof ByteBuf) {
super.format(ctx, eventName, arg.toString());
} else {
super.format(ctx, eventName, arg);
}
}
- Fixes#1905
- Call ctx.flush() only when necessary
- Improve the estimation of application and packet buffer sizes
- decode() method now tries to call unwrap() with as many SSL records as
possible to reduce the number of events triggered
The old implementation was broken and could lead to pending message never be picked up again until the user either explicit called flush or
resumeTransfer().
Fix for first issue from #1652 on computation of time to wait in AbstractTrafficShapingHandler for Netty 4, using the same formula than in Netty 3 (wrong place for parenthese).
Was:
(bytes * 1000 / limit - interval / 10) * 10;
Becomes:
(bytes * 1000 / limit - interval) / 10 * 10;
- Fix a bug in DefaultProgressivePromise.tryProgress() where the notification is dropped
- Fix a bug in AbstractChannel.calculateMessageSize() where FileRegion is not counted
- HttpStaticFileServer example now uses zero copy file transfer if possible.
- 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.
- Remove channelReadSuspended because it's actually same with messageReceivedLast
- Rename messageReceived to channelRead
- Rename messageReceivedLast to channelReadComplete
We renamed messageReceivedLast to channelReadComplete because it
reflects what it really is for. Also, we renamed messageReceived to
channelRead for consistency in method names.
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.
- Fixes#1366: No elegant way to free non-in/outbound buffers held by a handler
- handlerRemoved() is now also invoked when a channel is deregistered, as well as when a handler is removed from a pipeline.
- A little bit of clean-up for readability
- Fix a bug in forwardBufferContentAndRemove() where the handler buffers are not freed (mainly because we were relying on channel.isRegistered() to determine if the handler has been removed from inside the handler.
- ChunkedWriteHandler.handlerRemoved() is unnecessary anymore because ChannelPipeline now always forwards the content of the buffer.
- Fixes#1308
freeInboundBuffer() and freeOutboundBuffer() were introduced in the early days of the new API when we did not have reference counting mechanism in the buffer. A user did not want Netty to free the handler buffers had to override these methods.
However, now that we have reference counting mechanism built into the buffer, a user who wants to retain the buffers beyond handler's life cycle can simply return the buffer whose reference count is greater than 1 in newInbound/OutboundBuffer().
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
- 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
- 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 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.
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().
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
- 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)
