Motivation:
https in xmlns URIs does not work and will let the maven release plugin fail:
```
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.779 s
[INFO] Finished at: 2020-11-10T07:45:21Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare (default-cli) on project netty-parent: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare failed: The namespace xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" could not be added as a namespace to "project": The namespace prefix "xsi" collides with an additional namespace declared by the element -> [Help 1]
[ERROR]
```
See also https://issues.apache.org/jira/browse/HBASE-24014.
Modifications:
Use http for xmlns
Result:
Be able to use maven release plugin
Motivation:
Subscription ID property of the PUBLISH message may be repeated multiple times, which wasn't taken into account when developing `MqttProperties` API.
Modification:
Store Subscription ID properties separately from others - in `MqttProperties.subscriptionIds`.
Add `MqttProperties.getProperties` method to retrieve properties that may be repeated.
Change internal representation of User Properties for uniformity with Subscription ID - now they're stored in `MqttProperties.userProperties` rather than the common hash map.
Result:
Multiple Subscription ID properties can be set or retrieved.
Motivation:
HTTP is a plaintext protocol which means that someone may be able
to eavesdrop the data. To prevent this, HTTPS should be used whenever
possible. However, maintaining using https:// in all URLs may be
difficult. The nohttp tool can help here. The tool scans all the files
in a repository and reports where http:// is used.
Modifications:
- Added nohttp (via checkstyle) into the build process.
- Suppressed findings for the websites
that don't support HTTPS or that are not reachable
Result:
- Prevent using HTTP in the future.
- Encourage users to use HTTPS when they follow the links they found in
the code.
Motivation:
LGTM reports multiple issues. They need to be triaged,
and real ones should be fixed.
Modifications:
- Fixed multiple issues reported by LGTM, such as redundant conditions,
resource leaks, typos, possible integer overflows.
- Suppressed false-positives.
- Added a few testcases.
Result:
Fixed several possible issues, get rid of false alarms in the LGTM report.
Motivation:
Reason code for MQTT SUBACK messages is truncated, thus not allowing to get new codes supported by MQTT v.5
Modification:
Changed `MqttCodecTest.testUnsubAckMessageForMqtt5` to catch it then, removed truncation in `MqttDecoder.decodeSubackPayload` to make it pass.
Result:
Codec users can get all reason codes supported by MQTT5 now.
Motivation:
There was no way to read MQTT properties outside of `io.netty.handler.codec.mqtt` package
Modification:
Expose `MqttProperties.MqttProperty` fields `value` and `propertyId` via public methods
Result:
It's possible to read MQTT properties now
Recent changes for MQTT5 may cause NPE if UNSUBACK message is created with `MqttMessageFactory`
and client code isn't up-to-date.
Modifications:
Added default body in `MqttUnsubAckMessage` constructor if null body is passed,
added null checks in `encodeUnsubAckMessage`
Result:
`MqttUnsubAckMessage` created with `MqttMessageFactory` doesn't cause NPE
even if null body is supplied.
Motivation:
Impossible to specify retained messages handling policy because the corresponding enum
isn't public (https://github.com/netty/netty/issues/10562)
Modification:
Made `RetainedHandlingPolicy` public
Result:
Fixes#10562.
Reduce garbage on MQTT encoding
Motivation:
MQTT encoding and decoding is doing unnecessary object allocation in a number of places:
- MqttEncoder create many byte[] to encode Strings into UTF-8 bytes
- MqttProperties uses Integer keys instead of int
- Some enums valueOf create unnecessary arrays on the hot paths
- MqttDecoder was using unecessary Result<T>
Modification:
- ByteBufUtil::utf8Bytes and ByteBufUtil::reserveAndWriteUtf8 allows to perform the same operation GC-free
- MqttProperties uses a primitive key map
- Implemented GC free const table lookup/switch valueOf
- Use some bit-tricks to pack 2 ints into a single primitive long to store both result and numberOfBytesConsumed and use byte[].length to compute numberOfByteConsumed on fly. These changes allowed to save creating Result<T>.
Result:
Significantly less garbage produced in MQTT encoding/decoding
Motivation:
MQTT Specification version 5 was released over a year ago,
netty-codec-mqtt should be changed to support it.
Modifications:
Added more message and header types in `io.netty.handler.codec.mqtt`
package in `netty-coded-mqtt` subproject,
changed `MqttEncoder` and `MqttDecoder` to handle them properly,
added attribute `NETTY_CODEC_MQTT_VERSION` to track protocol version
Result:
`netty-codec-mqtt` supports both MQTT5 and MQTT3 now.
Motivation
ByteBuf has an isAccessible method which was introduced as part of ref
counting optimizations but there are some places still doing
accessibility checks by accessing the volatile refCnt() directly.
Modifications
- Have PooledNonRetained(Duplicate|Sliced)ByteBuf#isAccessible() use
their refcount delegate's isAccessible() method
- Add static isAccessible(buf) and ensureAccessible(buf) methods to
ByteBufUtil
(since ByteBuf#isAccessible() is package-private)
- Adjust DefaultByteBufHolder and similar classes to use these methods
rather than access refCnt() directly
Result
- More efficient accessibility checks in more places
Motivation:
Mqtt procotol defines packetId instead of messageId, replace deprecated method to match protocol definition
Modification:
Replace messageId() to packetId() in MqttEncoder
Result:
Match mqtt protocol definition and improve readability.
Motivation:
Currently, the only way to create fixed-header only messages PINGREQ,
PINGRESP and DISCONNECT is to explicitly instantiate a `MqttFixedHeader` like:
```
MqttFixedHeader disconnectFixedHeader = new MqttFixedHeader(MqttMessageType.DISCONNECT,
false, MqttQoS.AT_MOST_ONCE, false, 0);
MqttMessage disconnectMessage = new MqttMessage(disconnectFixedHeader);
```
According to the MQTT spec
(http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718077),
the fixed-header flags for these messages are reserved and must be set to zero, otherwise
the receiver must close the connection. It's easy to mess this up when
you're creating the header explicitly, for e.g by setting the QoS bit to
`AT_LEAST_ONCE`.
As such, provide static constants for PINGREQ, PINGRESP and
DISCONNECT messages that will set the flags correctly for the developer.
Modification:
Add static constants to MqttMessage class to construct PINGREQ, PINGRESP and
DISCONNECT messages that will set the fixed-header flags correctly to 0.
Result:
Easier usage.
