prototype for issue2570

[beiwei30]

…pring framework is absent

What is the purpose of the change

a prototype for issue #2570

Brief changelog

dubbo-config/dubbo-config-spring/src/main/java/org/apache/dubbo/config/spring/initializer/DubboContextListener.java
dubbo-config/dubbo-config-spring/src/main/resources/META-INF/web-fragment.xml

Verifying this change

XXXXX

Follow this checklist to help us incorporate your contribution quickly and easily:

• Make sure there is a GITHUB_issue filed for the change (usually before you start working on it). Trivial changes like typos do not require a GITHUB issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [Dubbo-XXX] Fix UnknownException when host config not exist #XXX. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add integration-test in test module.
• Run mvn clean install -DskipTests & mvn clean test-compile failsafe:integration-test to make sure unit-test and integration-test pass.
• If this contribution is large, please follow the Software Donation Guide.

[ralf0131]

Hi,

This will solve the specific problem, but will break on another scenario. If user already specified org.springframework.web.context.ContextLoaderListener in web.xml, this code will add another Listener, which will result in failure.

[beiwei30]

if user explicitly specify spring relevant listener, then it's user's responsibility to add spring dependency.

[codecov-io]

Codecov Report

Merging #2640 into master will increase coverage by 8.31%.
The diff coverage is 77.77%.

@@             Coverage Diff              @@
##             master    #2640      +/-   ##
============================================
+ Coverage     54.95%   63.27%   +8.31%     
============================================
  Files           571      574       +3     
  Lines         25510    25609      +99     
  Branches       4532     4524       -8     
============================================
+ Hits          14019    16203    +2184     
+ Misses         9393     7260    -2133     
- Partials       2098     2146      +48

Impacted Files	Coverage Δ	Complexity Δ
...onfig/spring/initializer/DubboContextListener.java	77.77% <77.77%> (ø)	0 <0> (?)
...apache/dubbo/rpc/protocol/dubbo/FutureAdapter.java	58.06% <0%> (-6.46%)	0% <0%> (-3%)
...org/apache/dubbo/rpc/filter/ActiveLimitFilter.java	83.33% <0%> (-5.56%)	0% <0%> (-7%)
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-4.17%)	0% <0%> (-3%)
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.2% <0%> (-1.48%)	0% <0%> (-29%)
...n/java/org/apache/dubbo/config/ConsumerConfig.java	92.3% <0%> (ø)	0% <0%> (-15%)	⬇️
...n/java/org/apache/dubbo/metrics/MetricManager.java
.../java/org/apache/dubbo/metrics/MetricRegistry.java
...ain/java/org/apache/dubbo/metrics/MetricLevel.java
...main/java/org/apache/dubbo/metrics/MetricName.java
... and 170 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 45b3ab4...ea9fa5a. Read the comment docs.

[diecui1202]

what is "executed" used for?

[beiwei30]

it is a flag for contextDestroyed, this is necessary because there are probably multiple org.springframework.web.context.ContextLoaderListener registered, one from web.xml, explicitly configured by user, the other is org.apache.dubbo.config.spring.initializer.DubboContextListener, automatically wried in from web-fragment.xml

[diecui1202]

What's the initial order about DubboContextListener and spring ContextLoaderListener? ContextLoaderListener initializes first?

[diecui1202]

sorry for closing it by mistake.

[beiwei30]

according to servlet spec, the listeners configured in web.xml will be registered first, then other listeners from web-fragment.xml will be registered. In this case, if a spring context listener is explicitly configured in web.xml, and at the same time, metadata-complete attribute is false, then, this spring context listener will be registered first, then the dubbo context listener from web-fragment,xml will be registered.

[diecui1202]

It looks good to me.

[carryxyh]

@beiwei30 @diecui1202
private boolean executed = false;
I have a question. Is volatile needed for this field like:
private volatile boolean executed = false;

[beiwei30]

I don't think it's necessary. Servlet container will guarantee the code will only be executed once and only once.