Motivation:
For many HTTP/2 applications (such as gRPC) it is necessary to autorefill the connection window in order to prevent application-level deadlocking.
Consider an application with 2 streams, A and B. A receives a stream of messages and the application pops off one message at a time and makes a request on stream B. However, if receiving of data on A has caused the connection window to collapse, B will not be able to receive any data and the application will deadlock. The only way (currently) to get around this is 1) use multiple connections, or 2) manually refill the connection window. Both are undesirable and could needlessly complicate the application code.
Modifications:
Add a configuration option to DefaultHttp2LocalFlowController, allowing it to autorefill the connection window.
Result:
Applications can configure HTTP/2 to avoid inter-stream deadlocking.
Motivation:
If netty used as part of application, should be a way to prefix service thread name to easy distinguish such threads (for example, used in IntelliJ Platform)
Modifications:
Introduce system property io.netty.serviceThreadPrefix
Result:
ThreadDeathWatcher thread has a readable name "Netty threadDeathWatcher-2-1" if io.netty.serviceThreadPrefix set to "Netty"
Motivation:
Changing the chache of generated names to use a cache per thread. This will remove the bottleneck when many eventloops are used and names need to generate.
Modifications:
Use a FastThreadLocal to store the cached names.
Result:
Less locking between threads.
Motivation:
PriorityStreamByteDistributor saves exception state and attempts to reset state. This could be simplified by just throwing a connection error and closing the connection. PriorityStreamByteDistributor also does not handle or detect re-entry in the distribute method.
Motivation:
- PriorityStreamByteDistributor propagate an INTERNAL_ERROR if an exception occurs during writing
- PriorityStreamByteDistributor to handle re-entry on the write method
Result:
PriorityStreamByteDistributor exception code state simplified, and re-entry is detected.
Motivation:
We should allow our custom Executor to shutdown quickly.
Modifications:
Call super constructor which correct arguments.
Result:
Custom Executor can be shutdown quickly.
Motivation:
Http2ConnectionHandler verifies if the first frame after the preface is
a SETTINGS frame. However, it does not reject the SETTING ack frame
which is not expected actually.
Modifications:
Reject a SETTINGS-ack frame as well
Result:
When the first frame is a SETTINGS-ack frame, connection does not
proceed to further frame handling. (simplicity)
Motivation:
The EPOLL module was not completly respecting the half closed state. It may have missed events, or procssed events when it should not have due to checking isOpen instead of the appropriate shutdown state.
Modifications:
- use FileDescriptor's isShutdown* methods instead of isOpen to check for processing events.
Result:
Half closed code in EPOLL module is more correct.
Motivation:
transport-native-epoll is designed to be specific to Linux. However there is native code that can be extracted out and made to work on more Unix like distributions. There are a few steps to be completely decoupled but the first step is to extract out code that can run in a more general Unix environment from the Linux specific code base.
Modifications:
- Move all non-Linux specific stuff from Native.java into the io.netty.channel.unix package.
- io.netty.channel.unix.FileDescriptor will inherit all the native methods that are specific to file descriptors.
- io_netty_channel_epoll_Native.[c|h] will only have code that is specific to Linux.
Result:
Code is decoupled and design is streamlined in FileDescriptor.
Motivation:
The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-8.1.2) indicates that header names consist of ASCII characters. We currently use ByteString to represent HTTP/2 header names. The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-10.3) also eludes to header values inheriting the same validity characteristics as HTTP/1.x. Using AsciiString for the value type of HTTP/2 headers would allow for re-use of predefined HTTP/1.x values, and make comparisons more intuitive. The Headers<T> interface could also be expanded to allow for easier use of header types which do not have the same Key and Value type.
Motivation:
- Change Headers<T> to Headers<K, V>
- Change Http2Headers<ByteString> to Http2Headers<CharSequence, CharSequence>
- Remove ByteString. Having AsciiString extend ByteString complicates equality comparisons when the hash code algorithm is no longer shared.
Result:
Http2Header types are more representative of the HTTP/2 RFC, and relationship between HTTP/2 header name/values more directly relates to HTTP/1.x header names/values.
Motivation:
When DnsNameResolverContext succeeds to get the address(es), it cancels
the promise of other queries in progress.
Unlike expectation, DnsNameResolverContext.query() attempts to retry
even when the query has failed due to cancellation.
As a result, the resolver sends unnecessary extra queries to a DNS
server and then tries to mark the promised that's been fulfilled
already, leading to unnecessarily verbose 'failed to notify success to a
promise' messages.
Modifications:
Do not perform an extra query when the previous query has failed due to
cancellation
Result:
DnsNameResolver does not send unnecessary extra queries and thus does
not log the 'failed to notify success to a promise' message.
Motivation:
DefaultPromise.toString() returns 'DefaultPromise(incomplete)' when it's
actually complete with non-null result.
Modifications:
Handle the case where the promise is done and its result is non-null in
toString()
Result:
The String returned by DefaultPromise.toString() is not confusing
anymore.
Motivation:
As reported in #4402, the FastThreadLocalBenchmark shows that the JDK ThreadLocal
is actually faster than Netty's custom thread local implementation.
I was looking forward to doing some deep digging, but got disappointed :(.
Modifications:
The microbenchmark was not using FastThreadLocalThreads and would thus always hit the slow path.
I updated the JMH command line flags, so that FastThreadLocalThreads would be used.
Result:
FastThreadLocalBenchmark shows FastThreadLocal to be faster than JDK's ThreadLocal implementation,
by about 56% in this particular benchmark. Run on OSX El Capitan with OpenJDK 1.8u60.
Benchmark Mode Cnt Score Error Units
FastThreadLocalBenchmark.fastThreadLocal thrpt 20 55452.027 ± 725.713 ops/s
FastThreadLocalBenchmark.jdkThreadLocalGet thrpt 20 35481.888 ± 1471.647 ops/s
Motivation:
To prove one implementation is faster as the other we should have a benchmark.
Modifications:
Add benchmark which benchmarks the unsafe and non-unsafe implementation of HeapByteBuf.
Result:
Able to compare speed of implementations easily.
Motivation:
We should only call ReferenceCountUtil.touch(...) if needed as otherwise we pay the overhead of instanceof and cast
everytime.
Modifications:
Add boolean flag which indicates if touch(...) should be called.
Result:
Less overhead when leak detection is not enabled.
Motivation:
Modulo operations are slow, we can use bitwise operation to detect if resource leak detection must be done while sampling.
Modifications:
- Ensure the interval is a power of two
- Use bitwise operation for sampling
- Add benchmark.
Result:
Faster sampling.
Motivation:
When the ImmediateEventExecutor is in use it is possible to get a StackOverFlowException if when a promise completes a new listener is added to that promise.
Modifications:
- Protect against the case where LateListeners.run() smashes the stack.
Result:
Fixes https://github.com/netty/netty/issues/4395
Motivation:
Http2ConnectionHandler.BaseBuilder is constructing objects which have 'close' methods, but is not calling these methods in the event of an exception.
Modifications:
- Objects which implement 'close' should have this method called if an exception is thrown and the build operation can not complete normally.
Result:
Objects are closed even if the build process encounters an error.
Motivation:
The build fails on OSX, due to it trying to pull in an epoll specific OSX dependency. See #4409.
Modifications:
* move netty-transport-native-epoll to linux profile
* exclude Http2FrameWriterBenchmark from compiler
* include Http2FrameWriterBenchmark back only in linux profile (please check)
Result:
Build succeeds on OSX.
Motiviation:
If a user writes from outside the EventLoop we increase the pending bytes of the outbound buffer before submitting the write request. This is done so the user can stop writing asap once the channel turns unwritable. Unfortunally this doesn't take the overhead of adding the task into the account and so it is very easy for an user to full up the task queue. Beside this we use a value of 0 for an unown message by default which is not ideal.
Modifications:
- port the message calculation we used in netty 3.x into AbstractChannelHandlerContext and so better calculate the overhead of a message that is submitted from outside the EventLoop
- change the default estimated size for an unknown message to 8.
Result:
Better behaviour when submiting writes from outside the EventLoop.
Keep RTSPRequestEncoder, RTSPRequestDecoder, RTSPResponseEncoder and
RTSPResponseDecoder for backwards compatibility but they now just extends
the generic encoder/decoder and are markes as deprecated.
Renamed the decoder test, because the decoder is now generic. Added
testcase for when ANNOUNCE request is received from server.
Created testcases for encoder.
Mark abstract base classes RTSPObjectEncoder and RTSPObjectDecoder as
deprecated, that functionality is now in RTSPEncoder and RTSPDecoder.
Added annotation in RtspHeaders to suppress warnings about deprecation, no need when
whole class is deprecated.
Motivation:
Fix a race condition that was introduced by f18990a8a5 that could lead to a NPE when allocate from the PooledByteBufAllocator concurrently by many threads.
Modifications:
Correctly synchronize on the PoolSubPage head.
Result:
No more race.
Motivation:
OpenSslServerContext should not reinitialize the provided TrustManagerFactory with the key cert chain as the user should be able to pass a fully initialized TrustManagerFactory. This is also in line with how JdkSslServerContext works.
Modifications:
Not reinitialize the provided TrustManagerFactory with the key cert chain.
Result:
Correct and consistent behavior.
Motivation:
Once a FixedChannelPool was closed we must not allow to acquire or release Channels to prevent assert errors.
Modifications:
Fail release and acquire calls when FixedChannelPool is closed.
Result:
No more assert errors.1
Motiviation:
We have a lot of duplicated code which makes it hard to maintain.
Modification:
Move shared code to UnsafeByteBufUtil and use it in the implementations.
Result:
Less duplicated code and so easier to maintain.
Motiviation:
We have a lot of duplicated code which makes it hard to maintain.
Modification:
Move shared code to HeapByteBufUtil and use it in the implementations.
Result:
Less duplicated code and so easier to maintain.
Motivation:
As MaxMessageHandle is stateful we can not share the same HandleImpl instance as otherwise we will see race conditions.
Modifications:
Create a new HandleImpl instance on each newHandle() call.
Result:
No more races.
Motivation:
sun.misc.Unsafe allows us to handle heap ByteBuf in a more efficient matter. We should use special ByteBuf implementation when sun.misc.Unsafe can be used to increase performance.
Modifications:
- Add PooledUnsafeHeapByteBuf and UnpooledUnsafeHeapByteBuf that are used when sun.misc.Unsafe is ready to use.
- Add UnsafeHeapSwappedByteBuf
Result:
Better performance when using heap buffers and sun.misc.Unsafe is ready to use.
Motivation:
We had a bug in our implemention which double "reversed" bytes on systems which not support unaligned access.
Modifications:
- Correctly only reverse bytes if needed.
- Share code between unsafe implementations.
Result:
No more data-corruption on sytems without unaligned access.
Motivation:
When moving bytes between a PooledUnsafeDirectByteBuf or an UnpooledUnsafeDirectByteBuf
and a ByteBuffer, a temp ByteBuffer is allocated and will need to be GCed. This is a
common case since a ByteBuffer is always needed when reading/writing on a file,
for example.
Modifications:
Use PlatformDependent.copyMemory() to avoid the need for the temp ByteBuffer
Result:
No temp ByteBuffer allocated and GCed.
Motivation:
SlicedByteBuf did double reference count checking for various bulk operations, which affects performance.
Modifications:
- Add package private method to AbstractByteBuf that can be used to check indexes without check the reference count
- Use this new method in the bulk operation os SlicedByteBuf as the reference count checks take place on the wrapped buffer anyway
- Fix test-case to not try to read data that is out of the bounds of the buffer.
Result:
Better performance on bulk operations when using SlicedByteBuf (and sub-classes)
Motivation:
We started the thread before store it in a field which could lead to an assert error when the thread is executed before we actually store it.
Modifications:
Store thread before start it.
Result:
No more assert error possible.
Motivation:
Some of the tests in the buffer module contained unused code. Some of the tests also used unnecessary inheritance which could be avoided to simplify code.
Modifications:
Cleanup the test cases.
Result:
Cleaner code, less cruft.
Motivation:
We need to always return a real slice even when the requested length is 0. This is needed as otherwise we not correctly share the reference count and so may leak a buffer if the user call release() on the returned slice and expect it to decrement the reference count of the "parent" buffer.
Modifications:
- Always return a real slice
- Add unit test for the bug.
Result:
No more leak possible when a user requests a slice of length 0 of a SlicedByteBuf.
Motivation:
Java_io_netty_channel_epoll_Native_getSoError incorrectly returns the value from the get socket option function.
Modifications:
- return the value from the result of the get socket option call
Result:
Java_io_netty_channel_epoll_Native_getSoError returns the correct value.
Motivation:
SlicedByteBuf can be used for any ByteBuf implementations and so can not do any optimizations that could be done
when AbstractByteBuf is sliced.
Modifications:
- Add SlicedAbstractByteBuf that can eliminate range and reference count checks for _get* and _set* methods.
Result:
Faster SlicedByteBuf implementations for AbstractByteBuf sub-classes.
Motivation:
DuplicatedByteBuf can be used for any ByteBuf implementations and so can not do any optimizations that could be done
when AbstractByteBuf is duplicated.
Modifications:
- Add DuplicatedAbstractByteBuf that can eliminate range and reference count checks for _get* and _set* methods.
Result:
Faster DuplicatedByteBuf implementations for AbstractByteBuf sub-classes.
Motivation:
Calling AbstractByteBuf.toString(..., Charset) is used quite frequently by users but produce a lot of GC.
Modification:
- Use a FastThreadLocal to store the CharBuffer that are needed for decoding.
- Use internalNioBuffer(...) when possible
Result:
Less object creation / Less GC
Motivation:
The SSLSession allows to invalidate a SSLSession and so disallow resume of a session. We should support this for OpenSSLEngine as well.
Modifications:
- Correctly implement SSLSession.isValid() and invalidate() in OpenSSLEngine
- Add unit test.
Result:
Invalidate of SSL sessions is supported when using OpenSSL now.
Motivation:
As part of recent efforts to rectify performance and make 4.1 headers more similar to 5.0 some methods were deprecated. Some of these methods were deprecated because they used String instead of CharSequence in the signature, which may require casting at the user level. Some of the deprecated methods have no direct alternatives and were done to inform a user the method will go away in future releases.
Modifications:
- Remove the deprecated qualifier from methods where no direct replacement exists
Result:
Less warnings in user code.
Motiviation:
Checking reference count on every access on a ByteBuf can have some big performance overhead depending on how the access pattern is. If the user is sure that there are no reference count errors on his side it should be possible to disable the check and so gain the max performance.
Modification:
- Add io.netty.buffer.bytebuf.checkAccessible system property which allows to disable the checks. Enabled by default.
- Add microbenchmark
Result:
Increased performance for operations on the ByteBuf.
Motivation:
We should minimize and optimize bound checks as much as possible to get the most out of performance.
Modifications:
- Use bitwise operations to remove branching
- Remove branches when possible
Result:
Better performance for various operations.
Motivation:
Remove encoderMaxConcurrentStreams(...) and use the default settings. Also throw an exception if server mode is used.
Modifications:
- Remove encoderMaxConcurrentStreams(...) method
- Throw exception if server mode is used and trying to enforce conncurrent streams.
Result:
Correctly support settings stuff via builder
Motivation:
The proxy example contains some code that is not needed. This can confuse the reader.
Modifications:
Remove the not needed ctx.write(...).
Result:
Less confusing code.
Motivation:
EmbeddedChannelId#hashCode() and equals() do not behave correctly if an
instance is serialized and then deserialized. Additionally,
EmbeddedChannel does not allow use of any other type of ChannelId, and
EmbeddedChannelId is (mostly) a singleton instance. This creates a
problem for unit tests that construct multiple EmbeddedChannels and
expect each channel to have a unique ID.
Modifications:
EmbeddedChannelId is modified so equals() will return true and
hashCode() will return the same value for any instance of the class.
EmbeddedChannel is modified to allow a ChannelId to be specified when
the channel is constructed. Tests added for both changes.
Result:
EmbeddedChannelId now behaves correctly when deserialized, and
EmbeddedChannels can now have unique IDs.
Motivation:
ByteBufUtil.writeUtf8(...) / writeUsAscii(...) can use a fast-path when writing into AbstractByteBuf. We should try to unwrap WrappedByteBuf implementations so
we are able to do the same on wrapped AbstractByteBuf instances.
Modifications:
- Try to unwrap WrappedByteBuf to use the fast-path
Result:
Faster writing of utf8 and usascii for WrappedByteBuf instances.
Motivation:
As relaying on external DNS Server can result to test-failures we should better use a mock DNS Server for the dns tests.
Modifications:
- Refactor the DnsNameResolverTest to use a mock DNS Server which is using apacheds.
- Allow to disable adding an opt resources as some servers not support it.
Result:
More stable testsuite.
Motivation:
As toString() is often used while logging we need to ensure this produces no exception.
Modifications:
Ensure we never throw an IllegalReferenceCountException.
Result:
Be able to log without produce exceptions.
Motivation:
PendingWriteQueueTest needs some cleanup.
Modifications:
- Cleanup code to remove deprecation warnings
- use static imports
Result:
No more warnings
