Motivation:
The old DefaultAttributeMap impl did more synchronization then needed and also did not expose a efficient way to check if an attribute exists with a specific key.
Modifications:
* Rewrite DefaultAttributeMap to not use IdentityHashMap and synchronization on the map directly. The new impl uses a combination of AtomicReferenceArray and synchronization per chain (linked-list). Also access the first Attribute per bucket can be done without any synchronization at all and just uses atomic operations. This should fit for most use-cases pretty weel.
* Add hasAttr(...) implementation
Result:
It's now possible to check for the existence of a attribute without create one. Synchronization is per linked-list and the first entry can even be added via atomic operation.
- Merged LifeCycleAwareChannelHandler into ChannelHandler
- Replaced ChannelUpstreamHandler and ChannelDownstreamHandler with
ChannelReader and ChannelWriter
- These two new interfaces are much more type-safe than its ancestor.
- Simplified channel state model as described in #68
- Handler creates send/receive buffer.
- Previously, Netty created them, but it led to more memory copies and
inflexibility. I'm going to allow a handler to create a bounded
queue for example.
- It currently uses Queue<T> but I'll define a new interface and make
ChannelBuffer implement it (e.g. Queue<Byte>)
- Introduced AttributeMap which replaces attachments in Channel and
ChannelHandlerContext and ChannelLocal
