Motivation:
SslHandler will do aggregation of writes by default in an attempt to improve goodput and reduce the number of discrete buffers which must be accumulated. However if aggregation is not possible then a CompositeByteBuf is used to accumulate multiple buffers. Using a CompositeByteBuf doesn't provide any of the benefits of better goodput and in the case of small + large writes (e.g. http/2 frame header + data) this can reduce the amount of data that can be passed to writev by about half. This has the impact of increasing latency as well as reducing goodput.
Modifications:
- SslHandler should prefer copying instead of using a CompositeByteBuf
Result:
Better goodput (and potentially improved latency) at the cost of copy operations.
Motivation:
AbstractCoalescingBufferQueue#add accounts for void promises, but AbstractCoalescingBufferQueue#addFirst does not. These methods should be consistent.
Modifications:
- AbstractCoalescingBufferQueue#addFirst should account for void promises and share code with AbstractCoalescingBufferQueue#add
Result:
More correct void promise handling in AbstractCoalescingBufferQueue.
complete
Motivation:
SslHandler removes a Buffer/Promise pair from
AbstractCoalescingBufferQueue when wrapping data. However it is possible
the SSLEngine will not consume the entire buffer. In this case
SslHandler adds the Buffer back to the queue, but doesn't add the
Promise back to the queue. This may result in the promise completing
immediately in finishFlush, and generally not correlating to the
completion of writing the corresponding Buffer
Modifications:
- AbstractCoalescingBufferQueue#addFirst should also support adding the
ChannelPromise
- In the event of a handshake timeout we should immediately fail pending
writes immediately to get a more accurate exception
Result:
Fixes https://github.com/netty/netty/issues/7378.
Motivation:
HTTP/2 allows writes of 0 length data frames. However in some cases EMPTY_BUFFER is used instead of the actual buffer that was written. This may mask writes of released buffers or otherwise invalid buffer objects. It is also possible that if the buffer is invalid AbstractCoalescingBufferQueue will not release the aggregated buffer nor fail the associated promise.
Modifications:
- DefaultHttp2FrameCodec should take care to fail the promise, even if releasing the data throws
- AbstractCoalescingBufferQueue should release any aggregated data and fail the associated promise if something goes wrong during aggregation
Result:
More correct handling of invalid buffers in HTTP/2 code.
Motivation:
A regression was introduced in 86e653e which had the effect that the writability was not updated for a Channel while queueing data in the SslHandler.
Modifications:
- Factor out code that will increment / decrement pending bytes and use it in AbstractCoalescingBufferQueue and PendingWriteQueue
- Add test-case
Result:
Channel writability changes are triggered again.
Motivation:
Each call to SSL_write may introduce about ~100 bytes of overhead. The OpenSslEngine (based upon OpenSSL) is not able to do gathering writes so this means each wrap operation will incur the ~100 byte overhead. This commit attempts to increase goodput by aggregating the plaintext in chunks of <a href="https://tools.ietf.org/html/rfc5246#section-6.2">2^14</a>. If many small chunks are written this can increase goodput, decrease the amount of calls to SSL_write, and decrease overall encryption operations.
Modifications:
- Introduce SslHandlerCoalescingBufferQueue in SslHandler which will aggregate up to 2^14 chunks of plaintext by default
- Introduce SslHandler#setWrapDataSize to control how much data should be aggregated for each write. Aggregation can be disabled by setting this value to <= 0.
Result:
Better goodput when using SslHandler and the OpenSslEngine.
