implementing quality on java projects
DESCRIPTION
Gives 5 hands on tips on how to improve a specific aspect of Quality on Java projectsTRANSCRIPT
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27 au 29 mars 2013
Implementing Quality on Java projects
Vincent MassolCommitter XWiki
XWiki SAS
@vmassol
Sunday, March 31, 13
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Vincent Massol
• Speaker Bio
• CTO XWiki SAS
• Your Projects
• XWiki (community-driven open source project)
• Past: Maven, Apache Cargo, Apache Cactus, Pattern Testing
• Other Credentials:
• LesCastCodeurs podcast
• Creator of OSSGTP open source group in Paris
• 3 books: JUnit in Action, Maven: A Developer’s Notebook, BBWM
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What is Quality?
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The XWiki project in summary
• 9 years old
• 28 active committers
• 7 committers do 80% of work
• 700K NCLOC
• 11 commits/day
• 16 mails/day
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Examples of Quality actions
• Coding rules (Checkstyle, ...)
• Test coverage
• Track bugs
• Don’t use Commons Lang 2.x
• Use SLF4J and don’t draw Log4J/JCL in dependencies
• Automated build
• Automated unit tests
• Stable automated functional tests
• Ensure API stability
• Code reviews
• License header checks
• Release with Java 6
• Ensure javadoc exist
• Prevent JAR hell
• Release often (every 2 weeks)
• Collaborative design
• Test on supported environments (DB & Browsers)
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27 au 29 mars 2013
Quality Tip #1
API Stability
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The Problem
Class Not Found or Method Not Found
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API Stability - Deprecations
/** * ... * @deprecated since 2.4M1 use {@link #transform( * Block, TransformationContext)} */@Deprecatedvoid transform(XDOM dom, Syntax syntax) throws TransformationException;
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API Stability - CLIRR (1/2)<plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <configuration> <ignored> <difference> <differenceType>7006</differenceType> <className>org/xwiki/.../MetaDataBlock</className> <method>org.xwiki....block.Block clone()</method> <to>org.xwiki.rendering.block.MetaDataBlock</to> <justification>XDOM#clone() doesn't clone the meta data</justification> </difference>...
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API Stability - CLIRR (2/2)
Example from XWiki 5.0M1 Release notes
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<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-javadoc-plugin <configuration> <excludePackageNames>*.internal.* </excludePackageNames>
API Stability - Internal PackageJavadoc
CLIRR<plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>clirr-maven-plugin</artifactId> <excludes> <exclude>**/internal/**</exclude> <exclude>**/test/**</exclude>
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<plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>aspectj-maven-plugin</...>... <configuration> <weaveDependencies> <weaveDependency> <groupId>org.xwiki.rendering</...> <artifactId>xwiki-rendering-api</...>...
API Stability - Legacy Module
Aspect Weaving
+ “Legacy” Profile
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API Stability - Young APIs
/** * ... * @since 5.0M1 */@Unstable(<optional explanation>)public EntityReference createEntityReference(String name,...){...}
+ max duration for keeping the annotation!
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API Stability - Next steps
• Annotation or package for SPI?
• Better define when to use the @Unstable annotation
• Not possible to add a new method to an existing Interface
• Java 8 and Virtual Extension/Defender methods
interface TestInterface { public void testMe(); public void newMethod() default { System.out.println("Default from interface"); }}
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27 au 29 mars 2013
Quality Tip #2
JAR Hell
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The Problem
Class Not Found or Method Not Found or not working feature
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No duplicate classes @ runtime
<plugin> <groupId>com.ning.maven.plugins</groupId> <artifactId>maven-duplicate-finder-plugin</artifactId> <executions> <execution> <phase>verify</phase> <goals> <goal>check</goal> </goals> <configuration> <failBuildInCaseOfConflict>true</...> <exceptions> ...
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Surprising results...
• Commons Beanutils bundles some classes from Commons Collections, apparently to avoid drawing a dependency to it...
• Xalan bundles a lot of other projects (org/apache/xml/**, org/apache/bcel/**, JLex/**, java_cup/**, org/apache/regexp/**). In addition, it even has these jars in its source tree without any indication about their versions...
• stax-api, geronimo-stax-api_1.0_spec and xml-apis all draw javax.xml.stream.* classes
• xmlbeans and xml-apis draw incompatible versions of org.w3c.dom.* classes
14 exceptions in total!Sunday, March 31, 13
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Maven: dependency version issue
<dependencies> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.4.0</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>0.9.9</version> <!-- Depends on org.slf4j:slf4j-api:1.5.0 --> </dependency></dependencies>
Will run logback 0.9.9 with slf4J-api 1.4.0 instead of 1.5.0!
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Maven: ensure correct version<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <executions> <execution> <id>enforce-version-compatibility</id> <phase>verify</phase> <goals> <goal>enforce</goal> </goals> <configuration> <rules> <requireUpperBoundDeps/> </rules>
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27 au 29 mars 2013
Quality Tip #3
Test Coverage
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The Problem
More bugs reported, overall quality goes down and harder to debug
software
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Use Jacoco to fail the build<plugin> <groupId>org.jacoco</groupId> <artifactId>jacoco-maven-plugin</artifactId> <executions> <execution><id>jacoco-prepare</id> <goals><goal>prepare-agent</goal></goals> </execution> <execution><id>jacoco-check</id> <goals><goal>check</goal></goals> </execution> </executions> <configuration> <check> <instructionRatio>${xwiki.jacoco.instructionRatio}</...> </check>}
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Strategy
• When devs add code (and thus tests), increase the TPC percentage
• Put the Jacoco check in “Quality” Maven Profile
• Have a CI job to execute that profile regularly
• About 15% overhead compared to build without checks
• “Cheat mode”: Add easier-to-write test
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Quizz Time!
[INFO] --- jacoco-maven-plugin:0.6.2.201302030002:check (jacoco-check)[INFO] All coverage checks have been met.
[INFO] --- jacoco-maven-plugin:0.6.2.201302030002:check (jacoco-check) [WARNING] Insufficient code coverage for INSTRUCTION: 75.52% < 75.53%
Step 1: Building on my local machine gives the following:
Step 2: Building on the CI machine gave:
Non determinism! Why?
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Quizz Answer
private Map componentEntries = new ConcurrentHashMap();...for (Map.Entry entry : componentEntries.entrySet()){ if (entry.getValue().instance == component) { key = entry.getKey(); oldDescriptor = entry.getValue().descriptor; break; }}
... because the JVM is non deterministic!
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27 au 29 mars 2013
Quality Tip #4
Functional Testing Stability (with Jenkins)
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The Problem
Too many false positives leading to developers not paying attention to CI
emails anymore... leading to failing software
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False positives examples
• The JVM has crashed
• VNC is down (we run Selenium tests)
• Browser crash (we run Selenium tests)
• Git connection issue
• Machine slowness (if XWiki cannot start under 2 minutes then it means the machine has some problems)
• Nexus is down (we deploy our artifacts to a Nexus repository)
• Connection issue (Read time out)
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Step 1: Groovy PostBuild Plugin (1/2)def messages = [ [".*A fatal error has been detected by the Java Runtime Environment.*", "JVM Crash", "A JVM crash happened!"], [".*Error: cannot open display: :1.0.*", "VNC not running", "VNC connection issue!"], ...]def shouldSendEmail = truemessages.each { message -> if (manager.logContains(message.get(0))) { manager.addWarningBadge(message.get(1)) manager.createSummary("warning.gif").appendText(...) manager.buildUnstable() shouldSendEmail = false }}
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Step 1: Groovy PostBuild Plugin (2/2)
... continued from previous slide...
if (!shouldSendEmail) { def pa = new ParametersAction([ new BooleanParameterValue("noEmail", true) ]) manager.build.addAction(pa)}
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Step 2: Mail Ext Plugin
import hudson.model.*
build.actions.each { action -> if (action instanceof ParametersAction) { if (action.getParameter("noEmail")) { cancel = true } }}
Pre-send Script
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Results
+ use the Scriptler plugin to automate configuration for all jobs
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27 au 29 mars 2013
Quality Tip #5
Bug Fixing Day
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The Problem
Bugs increasing, even simple to fixones, devs focusing too much on new
features (i.e. scope creep) vs fixing what exists
Bugs created vs closed
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Bug Fixing Day
• Every Thursday
• Goal is to close the max number of bugs
• Triaging: Can be closed with Won’t fix, Duplicate, Cannot Reproduce, etc
• Close low hanging fruits in priority
• Started with last 365 days then with last 547 days and currently with last 730 days (we need to catch up with 40 bugs!)
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Results
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27 au 29 mars 2013
Conclusion
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Parting words
• Slowly add new quality check over time
• Everyone must be on board
• Favor Active Quality (i.e. make the build fail) over Passive checks
• Be ready to adapt/remove checks if found not useful enough
• Quality brings some risks:
• Potentially less committers for your project (especially open source)
• Project seen as “less fun”
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Be proud of your Quality!
“I have offended God and mankind because my work didn't reach the quality it should have.”
Leonardo da Vinci, on his death bed
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