Motivation:
DiskFileUpload and MemoryFileUpload.equals(...) are broken.
Modifications:
Fix implementation and add unit test.
Result:
Equals method are correct now.
Motivation:
Currently, the recycler max capacity it's only enforced on the
thread-local stack which is used when the recycling happens on the
same thread that requested the object.
When the recycling happens in a different thread, then the objects
will be queued into a linked list (where each node holds N objects,
default=16). These objects are then transfered into the stack when
new objects are requested and the stack is empty.
The problem is that the queue doesn't have a max capacity and that
can lead to bad scenarios. Eg:
- Allocate 1M object from recycler
- Recycle all of them from different thread
- Recycler WeakOrderQueue will contain 1M objects
- Reference graph will be very long to traverse and GC timeseems to be negatively impacted
- Size of the queue will never shrink after this
Modifications:
Add some shared counter which is used to manage capacity limits when recycle from different thread then the allocation thread. We modify the counter whenever we allocate a new Link to reduce the overhead of increment / decrement it.
Result:
More predictable number of objects mantained in the recycler pool.
Motivation:
Because of a bug we missed to include the first PoolSubpage when collection metrics.
Modifications:
- Correctly include all subpages
- Add unit test
Result:
Correctly include all subpages
Motivation:
Today when awaiting uninterruptibly on a default promise, a race
condition can lead to a missed signal. Quite simply, the check for
whether the condition holds is not made inside a lock before
waiting. This means that the waiting thread can enter the wait after the
promise has completed and will thus not be notified, thus missing the
signal. This leads to the waiting thread to enter a timed wait that will
only trip with the timeout elapses leading to unnecessarily long waits
(imagine a connection timeout, and the waiting thread missed the signal
that the connection is ready).
Modification:
This commit fixes this missed signal by checking the condition inside a
lock. We also add a test that reliably fails without the non-racy
condition check.
Result:
Timed uninterruptible waits on default promise will not race against the
condition and possibly wait longer than necessary.
Motivation:
For some use-cases it would be useful to know the number of bytes queued in the PendingWriteQueue without the need to dequeue them.
Modifications:
Add PendingWriteQueue.bytes().
Result:
Be able to get the number of bytes queued.
Motivation:
ExecutorService.invoke*(...) methods may block by API definition. This can lead to deadlocks if called from inside the EventLoop in SingleThreadEventExecutor as it only has one Thread that does all the work.
Modifications:
Throw a RejectedExectionException if someone tries to call SingleThreadEventExecutor.invoke*(...) while in the EventLoop.
Result:
No more deadlock possible.
Motivation:
Commit 4c048d069d99891d6a83859b469c39b4ff0f4ae1 moved the logic of calling handlerAdded(...) to the channelRegistered(...) callback of the head of the DefaultChannelPipeline. Unfortunatlly this may execute the callbacks to late as a user may add handlers to the pipeline in the ChannelFutureListener attached to the registration future. This can lead to incorrect ordering.
Modifications:
Ensure we always invoke ChannelHandler.handlerAdded(...) for all handlers before the registration promise is notified.
Result:
Not possible of incorrect ordering or missed events.
Motivation:
We pinned the EventExecutor for a Channel in DefaultChannelPipeline. Which means if the user added multiple handlers with the same EventExecutorGroup to the ChannelPipeline it will use the same EventExecutor for all of these handlers. This may be unexpected and even not what the user wants. If the user want to use the same one for all of them it can be done by obtain an EventExecutor and pass the same instance to the add methods. Because of this we should allow to not pin.
Modifications:
Allow to disable pinning of EventExecutor for Channel based on EventExecutorGroup via ChannelOption.
Result:
Less confusing and more flexible usage of EventExecutorGroup when adding ChannelHandlers to the ChannelPipeline.
Motivation:
DefaultPromise has a listeners member variable which is volatile to allow for an optimization which makes notification of listeners less expensive when there are no listeners to notify. However this change makes all other operations involving the listeners member variable more costly. This optimization which requires listeners to be volatile can be removed to avoid volatile writes/reads for every access on the listeners member variable.
Modifications:
- DefaultPromise listeners is made non-volatile and the null check optimization is removed
Result:
DefaultPromise.listeners is no longer volatile.
Motivation:
DefaultChannelPipelineTest creates a channel and completes promises, but does not register this channel to an event loop. This is generally an illegal state for DefaultPromise, and the 4.1 branch correctly registers the channel in all of these cases.
Modifications:
- DefaultChannelPipelineTest should register the channel to an EventLoopGroup before completing a promise generated by that channel
Result:
DefaultChannelPipelineTest is more correct and consistent with 4.1.
Motivation
When I override ChannelHandler methods I usually (always) refire events myself via
ChannelHandlerContext instead of relieing on calling the super method (say
`super.write(ctx, ...)`). This works great and the IDE actually auto completes/generates
the right code for it except `#fireUserEventTriggered()` and `#userEventTriggered()`
which have a mismatching argument names and I have to manually "intervene".
Modification
Rename `ChannelHandlerContext#fireUserEventTriggered()` argument from `event` to `evt`
to match its handler counterpart.
Result
The IDE's auto generated code will reference the correct variable.
Motivation:
In commit f984870ccca133d6056e8b0df0b2352f8f90b0fe I made a change which operated under invalide assumption that tasks executed by an EventExecutor will always be processed in a serial fashion. This is true for SingleThreadEventExecutor sub-classes but not part of the EventExecutor interface contract.
Because of this change implementations of EventExecutor which not strictly execute tasks in a serial fashion may miss events before handlerAdded(...) is called. This is strictly speaking not correct as there is not guarantee in this case that handlerAdded(...) will be called as first task (as there is no ordering guarentee).
Cassandra itself ships such an EventExecutor implementation which has no strict ordering to spread load across multiple threads.
Modifications:
- Add new OrderedEventExecutor interface and let SingleThreadEventExecutor / EventLoop implement / extend it.
- Only expose "restriction" of skipping events until handlerAdded(...) is called for OrderedEventExecutor implementations
- Add ThreadPoolEventExecutor implementation which executes tasks in an unordered fashion. This is used in added unit test but can also be used for protocols which not expose an strict ordering.
- Add unit test.
Result:
Resurrect the possibility to implement an EventExecutor which does not enforce serial execution of events and be able to use it with the DefaultChannelPipeline.
Motivation:
Calling flush() and writeAndFlush(...) are expensive operations in the sense as both will produce a write(...) or writev(...) system call if there are any pending writes in the ChannelOutboundBuffer. Often we can consolidate multiple flush operations into one if currently a read loop is active for a Channel, as we can just flush when channelReadComplete is triggered. Consolidating flushes can give a huge performance win depending on how often is flush is called. The only "downside" may be a bit higher latency in the case of where only one flush is triggered by the user.
Modifications:
Add a FlushConsolidationHandler which will consolidate flushes and so improve the throughput.
Result:
Better performance (throughput). This is especially true for protocols that use some sort of PIPELINING.
Motivation:
We should make it clear that each acquired Channel needs to be released in all cases.
Modifications:
More clear javadocs.
Result:
Harder for users to leak Channel.
Motivation:
The field can be read from arbitrary threads via Channel.(isWritable()|bytesBeforeWritable()|bytesBeforeUnwritable()), WriteAndFlushTask.newInstance(), PendingWriteQueue, etc.
Modifications:
Make AbstractChannel.outboundBuffer volatile.
Result:
More correct in a concurrent use case.
Motivation:
ECONNREFUSED can be a common type of exception when attempting to finish the connection process. Generating a new exception each time can be costly and quickly bloat memory usage.
Modifications:
- Expose ECONNREFUSED from JNI and cache this exception in Socket.finishConnect
Result:
ECONNREFUSED during finish connect doesn't create a new exception each time.
Motivation:
We used future in many method of ChannelDuplexHandler as argument name of ChannelPromise. We should make it more consistent and correct.
Modifications:
Replace future with promise.
Result:
More correct and consistent naming.
Motivation:
The logging statements in i.n.u.c.DefaultPromise do not emit the
caught Throwable when a Throwable is thrown while a listener is being
notified of completed or progressed operations.
Modifications:
This issue arises because the logging message has a single placeholder
but is passing two additional arguments, the second one being the
caught Throwable that is thus quietly not logged. We address this by
modifying the logging statements to ensure the caught Throwable is
logged. In this case, the preferred approach is to use the logger
override that accepts a message and a Throwable parameter since logger
implementations might have special handling for this case.
Result:
Log messages from i.n.u.c.DefaultPromise when a Throwable is thrown
while notifying a listener of completed or progressed operations will
contain the caught Throwable.
Motivation:
ReadTimeoutHandler and IdleStateHandler have duplicated code, we should share whatever possible.
Modifications:
Let ReadTimeoutHandler extend IdleStateHandler.
Result:
Remove code duplication.
Motivation:
We don't have an argument named {@code value} but have {@code set} and
{@code expected} in HttpHeaders and HttpUtil respectively.
Modifications:
I replaced {@code value} to {@code set} and {@code expected} in HttpHeaders
and HttpUtil respectively.
Result:
Now javadoc says;
If {@code set} is {@code true}, the {@code "Expect: 100-continue"} header is
set and all other previous {@code "Expect"} headers are removed. Otherwise,
all {@code "Expect"} headers are removed completely. in HttpHeaders
If {@code expected} is {@code true}, the {@code "Expect: 100-continue"} header
is set and all other previous {@code "Expect"} headers are removed. Otherwise,
all {@code "Expect"} headers are removed completely. in HttpUtil
Motivation:
A race detector found that DefaultPromise.listeners is improperly synchronized [1].
Worst case a listener will not be executed when the promise is completed.
Modifications:
Make DefaultPromise.listeners a volatile.
Result:
Hopefully, DefaultPromise is more correct under concurrent execution.
[1] https://github.com/grpc/grpc-java/issues/2015
Motivation:
Unit test for the OpenSslEngine "OpenSslEngine writePlaintextData WANT_READ with no data in BIO buffer" issue.
Modifications:
- Update SslEngine test to include renegotiation
Result:
More test coverage in OpenSslEngine.
Motivation:
Currently in the single threaded and global event executors when the scheduled task queue is drained, there is a call to hasScheduledTasks(). If there are scheduled tasks then the the code polls the queue for tasks. The poll method duplicates the exact logic of hasScheduledTasks(). This involves two calls to nanoTime when one seems sufficient.
Modifications:
Directly poll the queue for tasks and break if the task returned is null.
Result:
Should be no noticeable impact on functionality. Two calls to nanoTime have been coarsened into a single call.
Motivation:
Project Jigsaw in JDK9 has moved the direct byte buffer cleaner from
sun.misc.Cleaner to java.lang.ref.Cleaner$Cleanable. This cause the
current platform tests to throw a ClassNotFoundException, disabling the
use of direct byte buffer cleaners.
Modifications:
I use reflection to find the clean method in either sun.misc.Cleaner or
java.lang.ref.Cleaner$Cleanable.
Result:
Netty uses direct byte buffers on JDK9 as it already do on earlier JDKs.
Motivation:
In JDK9 heap byte buffers have an address field, so we have to remove
the current check as it is invalid in JDK9.
Modifications:
Removed the address field check for heap byte buffers.
Result:
Netty continues to find sun.misc.Unsafe in JDK9 as in previous JDKs.
Motivation:
Netty's platform dependent parts should know about JDK9.
Modifications:
JDK9 introduce Runtime$Version Runtime.version() which has an int major()
method that always return the major Java version. I call that method to
get the Java major version.
Result:
Netty will recognize all future JDK versions.
Motivation:
The gRPC interop tests fail due to a NPE in OpenSslEngine.
Caused by: java.lang.NullPointerException
at io.netty.handler.ssl.OpenSslEngine.setSSLParameters(OpenSslEngine.java:1473)
Modifications:
Add a null check
Result:
No more NPE exceptions :-)
Motivation:
We recently added the ResourceLeakDetectorFactory but missed to updated HashedWheelTimer to use it.
Modifications:
- Add new abstract method to ResourceLeakDetectorFactory that allows to provide also samplingInterval and maxActive args.
- Deprecate most constructors in ResourceLeakDetector and add doc explaining that people should use ResourceLeakDetectorFactory
Result:
Custom ResourceLeakDetectorFactory will also be used in HashedWheelTimer if configured.
Motivation:
Sometimes a shared HashedWheelTimer can not easily be stopped in a good place. If the worker thread is daemon this is not a big deal and we should allow to not log a leak.
Modifications:
Add another constructor which allows to disable resource leak detection if worker thread is used.
Result:
Not log resource leak when HashedWheelTimer is not stopped and the worker thread is a deamon thread.
Motivation:
Some Netty use cases may want to configure the max allowed stack depth for promise listener notification.
Modifications:
- Add a system property so that this value can be configured.
Result:
DefaultPromise's max stack depth is configurable.
Motivation:
To be able to use SslProvider.OpenSsl with existing java apps that use the JDK SSL API we need to also provide a way to use it with an existing KeyManagerFactory.
Modification:
Make use of new tcnative apis and so hook in KeyManagerFactory.
Result:
SslProvider.OpenSsl can be used with KeyManagerFactory as well.
Motivation:
Java8+ adds support set a DH key size via a System property (jdk.tls.ephemeralDHKeySize). We should respect this when using OpenSSL.
Modifications:
Respect system property.
Result:
More consistent SSL implementation.
Motivation:
We recently added support for session ticket statistics which we can expose now.
Modifications:
Expose the statistics.
Result:
Be able to obtain session ticket statistics.
Motivation:
In order to prevent a regression, add test case for a bug that caused a CompositeByteBuf to not release its components.
Modifications:
Add a test case that asserts a CompositeByteBuf's component buffers have indeed been released.
Result:
AbstractCompositeByteBuf gains a test case that will prevent future regressions.
Motivation:
It is good to have used dependencies and plugins up-to-date to fix any undiscovered bug fixed by the authors.
Modification:
Scanned dependencies and plugins and carefully updated one by one.
Result:
Dependencies and plugins are up-to-date.
Motiviation:
Sometimes it is useful to allow to specify a custom strategy to handle rejected tasks. For example if someone tries to add tasks from outside the eventloop it may make sense to try to backoff and retries and so give the executor time to recover.
Modification:
Add RejectedEventExecutor interface and implementations and allow to inject it.
Result:
More flexible handling of executor overload.
Motivation:
To restrict the memory usage of a system it is sometimes needed to adjust the number of max pending tasks in the tasks queue.
Modifications:
- Add new constructors to modify the number of allowed pending tasks.
- Add system properties to configure the default values.
Result:
More flexible configuration.
Motivation:
We need to return a correct time for SSLSession.getLastAccessedTime() so it reflect when the handshake was done when the session was reused.
Modifications:
Correctly reflect handshake time in getLastAccessedTime().
Result:
More conform SSLSession implementation.
Motivation:
Sometimes its needed to customize the SSLEngine (like setting protocols etc). For this it would be useful if the user could wrap an SslContext and do init steps on the SSLEngine.
Modifications:
Add new SslContext implementation which can wrap another one and allow to customize the SSLEngine
Result:
More flexible usage of SslContext.
Motivation:
At the moment OpenSslEngine.getSupportedCipherSuites() only return the original openssl cipher names and not the java names. We need also include the java names.
Modifications:
Correctly return the java names as well.
Result:
Correct implementation of OpenSslEngine.getSupportedCipherSuites()
Motivation:
We should merge ThrowableUtils into ThrowableUtil as this name is more consistent with the naming of utility classes in netty.
Modifications:
Merge classes.
Result:
More consistent naming
Motivation:
If a user writes an own nio based transport which uses a special SelectorProvider it is useful to be able to get the SelectorProvider that is used by a NioEventLoop. This way this can be used when implement AbstractChannel.isCompatible(...) and check that the SelectorProvider is the correct one.
Modifications:
Expose the SelectorProvider.
Result:
Be able to get the SelectorProvider used by a NioEventLoop.
Motivation:
There is no need already use synchronized when validate the args of the methods.
Modifications:
First validate arguments and then use synchronized
Result:
Less code executed in synchronized block.
Motivation:
We use pre-instantiated exceptions in various places for performance reasons. These exceptions don't include a stacktrace which makes it hard to know where the exception was thrown. This is especially true as we use the same exception type (for example ChannelClosedException) in different places. Setting some StackTraceElements will provide more context as to where these exceptions original and make debugging easier.
Modifications:
Set a generated StackTraceElement on these pre-instantiated exceptions which at least contains the origin class and method name. The filename and linenumber are specified as unkown (as stated in the javadocs of StackTraceElement).
Result:
Easier to find the origin of a pre-instantiated exception.
Motivation:
When HTTPS is used we should use https in the sec-websocket-origin / origin header
Modifications:
- Correctly generate the sec-websocket-origin / origin header
- Add unit tests.
Result:
Generate correct header.
Allow users of Netty to plug in their own leak detector for the purpose
of instrumentation.
Motivation:
We are rolling out a large Netty deployment and want to be able to
track the amount of leaks we're seeing in production via custom
instrumentation. In order to achieve this today, I had to plug in a
custom `ByteBufAllocator` into the bootstrap and have it initialize a
custom `ResourceLeakDetector`. Due to these classes mostly being marked
`final` or having private or static methods, a lot of the code had to
be copy-pasted and it's quite ugly.
Modifications:
* I've added a static loader method for the `ResourceLeakDetector` in
`AbstractByteBuf` that tries to instantiate the class passed in via the
`-Dio.netty.customResourceLeakDetector`, otherwise falling back to the
default one.
* I've modified `ResourceLeakDetector` to be non-final and to have the
reporting broken out in to methods that can be overridden.
Result:
You can instrument leaks in your application by just adding something
like the following:
```java
public class InstrumentedResourceLeakDetector<T> extends
ResourceLeakDetector<T> {
@Monitor("InstanceLeakCounter")
private final AtomicInteger instancesLeakCounter;
@Monitor("LeakCounter")
private final AtomicInteger leakCounter;
public InstrumentedResourceLeakDetector(Class<T> resource) {
super(resource);
this.instancesLeakCounter = new AtomicInteger();
this.leakCounter = new AtomicInteger();
}
@Override
protected void reportTracedLeak(String records) {
super.reportTracedLeak(records);
leakCounter.incrementAndGet();
}
@Override
protected void reportUntracedLeak() {
super.reportUntracedLeak();
leakCounter.incrementAndGet();
}
@Override
protected void reportInstancesLeak() {
super.reportInstancesLeak();
instancesLeakCounter.incrementAndGet();
}
}
```
