[#2572] Correctly calculate length of output buffer before inflate to fix IndexOutOfBoundException

Motivation:

JdkZlibDecoder fails to decode because the length of the output buffer is not calculated correctly.
This can cause an IndexOutOfBoundsException or data-corruption when the PooledByteBuffAllocator is used.

Modifications:

Correctly calculate the length

Result:

No more IndexOutOfBoundsException or data-corruption.
[#2573] UnpooledUnsafeDirectByteBuf.setBytes(int,ByteBuf,int,int) fails to use fast-path when src has array

Motivation:

UnpooledUnsafeDirectByteBuf.setBytes(int,ByteBuf,int,int) fails to use fast-path when src uses an array as backing storage. This is because the if else uses the wrong ByteBuf for its check.

Modifications:

- Use correct ByteBuf when check for array as backing storage
- Also eliminate unecessary check in UnpooledDirectByteBuf which always fails anyway

Result:

Faster setBytes(...) when src ByteBuf is backed by an array.

No more IndexOutOfBoundsException or data-corruption.
Fix incorrect method signature of awaitInactivity()

- Related: #2084
[#2577] ChannelOutboundBuffer.addFlush() unnecessary loop through all entries on multiple calls

Motivation:

If ChannelOutboundBuffer.addFlush() is called multiple times and flushed != unflushed it will still loop through all entries that are not flushed yet even if it is not needed anymore as these were marked uncancellable before.

Modifications:

Check if new messages were added since addFlush() was called and only if this was the case loop through all entries and try to mark the uncancellable.

Result:

Less overhead when ChannelOuboundBuffer.addFlush() is called multiple times without new messages been added.
Make use of AtomicLongFieldUpdater.addAndGet(...) for cleaner code

Motivation:

The code in ChannelOutboundBuffer can be simplified by using AtomicLongFieldUpdater.addAndGet(...)

Modification:

Replace our manual looping with AtomicLongFieldUpdater.addAndGet(...)

Result:

Cleaner code
Small improvement in SimpleChannelInboundHandlerAdapter javadoc
Refactor FastThreadLocal to simplify TLV management

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.
[#2586] Use correct EventLoop to notify delayed successful registration

Motivation:

At the moment AbstractBoostrap.bind(...) will always use the GlobalEventExecutor to notify the returned ChannelFuture if the registration is not done yet. This should only be done if the registration fails later. If it completes successful we should just notify with the EventLoop of the Channel.

Modification:

Use EventLoop of the Channel if possible to use the correct Thread to notify and so guaranteer the right order of events.

Result:

Use the correct EventLoop for notification
[#2580] [#2587] Fix buffer corruption regression when ByteBuf.order(LITTLE_ENDIAN) is used

Motivation:

To improve the speed of ByteBuf with order LITTLE_ENDIAN and where the native order is also LITTLE_ENDIAN (intel) we introduces a new special SwappedByteBuf before in commit 4ad3984c8b725ef59856d174d09d1209d65933fc. Unfortunally the commit has a flaw which does not handle correctly the case when a ByteBuf expands. This was caused because the memoryAddress was cached and never changed again even if the underlying buffer expanded. This can lead to corrupt data or even to SEGFAULT the JVM if you are lucky enough.

Modification:

Always lookup the actual memoryAddress of the wrapped ByteBuf.

Result:

No more data-corruption for ByteBuf with order LITTLE_ENDIAN and no JVM crashes.
Remove System.out.println(...) debug messages
[#2589] LocalServerChannel.doClose() throws NPE when localAddress == null

Motivation:

LocalServerChannel.doClose() calls LocalChannelRegistry.unregister(localAddress); without check if localAddress is null and so produce a NPE when pass null the used ConcurrentHashMapV8

Modification:
Check for localAddress != null before try to remove it from Map. Also added a unit test which showed the stacktrace of the error.

Result:

No more NPE during doClose().
Improve the allocation algorithm in PoolChunk

Motivation:

Depth-first search is not always efficient for buddy allocation.

Modification:

Employ a new faster search algorithm with different memoryMap layout.

Result:

With thread-local cache disabled, we see a lot of performance
improvment, especially when the size of the allocation is as small as
the page size, which had the largest search space previously:

-- master head --
Benchmark                (size) Mode    Score  Error Units
pooledDirectAllocAndFree  8192 thrpt  215.392  1.565 ops/ms
pooledDirectAllocAndFree 16384 thrpt  594.625  2.154 ops/ms
pooledDirectAllocAndFree 65536 thrpt 1221.520 18.965 ops/ms
pooledHeapAllocAndFree    8192 thrpt  217.175  1.653 ops/ms
pooledHeapAllocAndFree   16384 thrpt  587.250 14.827 ops/ms
pooledHeapAllocAndFree   65536 thrpt 1217.023 44.963 ops/ms

-- changes --
Benchmark                (size) Mode    Score  Error Units
pooledDirectAllocAndFree  8192 thrpt 3656.744 94.093 ops/ms
pooledDirectAllocAndFree 16384 thrpt 4087.152 22.921 ops/ms
pooledDirectAllocAndFree 65536 thrpt 4058.814 29.276 ops/ms
pooledHeapAllocAndFree    8192 thrpt 3640.355 44.418 ops/ms
pooledHeapAllocAndFree   16384 thrpt 4030.206 24.365 ops/ms
pooledHeapAllocAndFree   65536 thrpt 4103.991 70.991 ops/ms
Fix the inconsistencies between performance tests in ByteBufAllocatorBenchmark

Motivation:

default*() tests are performing a test in a different way, and they must be same with other tests.

Modification:

Make sure default*() tests are same with the others

Result:

Easier to compare default and non-default allocators
Adding int-to-object map implementation.

Motivation:

Maps with integer keys are used in several places (HTTP/2 code, for
example). To reduce the memory footprint of these structures, we need a
specialized map class that uses ints as keys.

Modifications:

Added IntObjectHashMap, which is uses open addressing and double hashing
for collision resolution.

Result:

A new int-based map class that can be shared across Netty.
Fix false sharing between head and tail reference in MpscLinkedQueue

Motivation:

The tail node reference writes (by producer threads) are very likely to
invalidate the cache line holding the headRef which is read by the
consumer threads in order to access the padded reference to the head
node. This is because the resulting layout for the object is:

- header
- Object AtomicReference.value -> Tail node
- Object MpscLinkedQueue.headRef -> PaddedRef -> Head node

This is 'passive' false sharing where one thread reads and the other
writes.  The current implementation suffers from further passive false
sharing potential from any and all neighbours to the queue object as no
pre/post padding is provided for the class fields.

Modifications:

Fix the memory layout by adding pre-post padding for the head node and
putting the tail node reference in the same object.

Result:

Fixed false sharing
Checkstyle / Overall clean-up / Fix serialization
Add missing last padding / Comment
Remove padding utility classes

- It's not used anywhere
Make sure OpenSslEngine is tested against transport-native-epoll
Revert "Improve the allocation algorithm in PoolChunk"

This reverts commit 36305d7dcee60bac9d353ba12e044c260435da57, which
seems to cause an assertion failure on our CI machine.