- Proposed fix for #1824
UniqueName and its subtypes do not allow getting the previously registered instance. For example, let's assume that a user is running his/her application in an OSGi container with Netty bundles and his server bundle. Whenever the server bundle is reloaded, the server will try to create a new AttributeKey instance with the same name. However, Netty bundles were not reloaded at all, so AttributeKey will complain that the name is taken already (by the previously loaded bundle.)
To fix this problem:
- Replaced UniqueName with Constant, AbstractConstant, and ConstantPool. Better name and better design.
- Sctp/Udt/RxtxChannelOption is not a ChannelOption anymore. They are just constant providers and ChannelOption is final now. It's because caching anything that's from outside of netty-transport will lead to ClassCastException on reload, because ChannelOption's constant pool will keep all option objects for reuse.
- Signal implements Constant because we can't ensure its uniqueness anymore by relying on the exception raised by UniqueName's constructor.
Beside this it also helps to reduce CPU usage as nioBufferCount() is quite expensive when used on CompositeByteBuf which are
nested and contains a lot of components
This ChannelOption allows to tell the DatagramChannel implementation to be active as soon as they are registrated to their EventLoop. This can be used to make it possible to write to a not bound DatagramChannel.
The ChannelOption is marked as @deprecated as I'm looking for a better solution in master which breaks default behaviour with 4.0 branch.
The problem with the old way was that we always set the OP_WRITE when the buffer could not be written
until the write-spin-count was reached. This means that in some cases the channel was still be writable
but we just was not able to write out the data quick enough. For this cases we should better break out the
write loop and schedule a write to be picked up later in the EventLoop, when other tasks was executed.
The OP_WRITE will only be set if a write actual returned 0 which means there is no more room for writing data
and this we need to wait for the os to notify us.
This move less common method patterns to extra methods and so make the nioBuffers() method with most common pattern (backed by one ByteBuffer) small enough for inlining.
This is needed because of otherwise the JDK itself will do an extra ByteBuffer copy with it's own pool implementation. Even worth it will be done
multiple times if the ByteBuffer is always only partial written. With this change the copy is done inside of netty using it's own allocator and
only be done one time in all cases.
