Add Error Prone and NullAway static analysis to build

.github/workflows/publish.yml

@@ -66,6 +66,23 @@ jobs:
           path: target/site/jacoco/jacoco.xml
           if-no-files-found: ignore
 
+  vmlens:
+    name: Test (vmlens interleavings)
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-java@v5
+        with: { java-version: '21', distribution: temurin, cache: maven }
+      - name: Test under vmlens
+        run: mvn --batch-mode -Pvmlens test -Dmaven.javadoc.skip=true
+      - uses: actions/upload-artifact@v7
+        if: always()
+        with:
+          name: vmlens-report
+          path: target/vmlens-report/
+          if-no-files-found: ignore
+
   report:
     name: Report
     needs: [test]

.mvn/jvm.config

@@ -0,0 +1,10 @@
+--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

.mvn/jvm.config.license

@@ -0,0 +1,3 @@
+SPDX-FileCopyrightText: 2014-2026 Bernard Ladenthin <bernard.ladenthin@gmail.com>
+
+SPDX-License-Identifier: Apache-2.0

CLAUDE.md

@@ -21,9 +21,37 @@ mvn test -Dtest=StreamBufferTest#testSimpleRoundTrip
 mvn org.pitest:pitest-maven:mutationCoverage
 ```
 
+**Run JMH benchmarks:**
+
+JMH benchmarks live in `src/test/java/net/ladenthin/streambuffer/benchmark/` (e.g. `StreamBufferThroughputBenchmark`). They are not executed by `mvn test`; invoke them directly via the `exec-maven-plugin` whose default `mainClass` is `org.openjdk.jmh.Main`:
+
+```bash
+# All benchmarks
+mvn test-compile exec:java
+
+# Filter by regex (class or method name)
+mvn test-compile exec:java -Dexec.args="StreamBufferThroughput"
+
+# Allocation profile (built-in, no extra setup)
+mvn test-compile exec:java -Dexec.args="StreamBufferThroughput -prof gc"
+
+# CPU profile via async-profiler (set ASYNC_PROFILER_LIB to libasyncProfiler.so)
+mvn test-compile exec:java \
+  -Dexec.args="StreamBufferThroughput -prof async:libPath=$ASYNC_PROFILER_LIB;output=flamegraph"
+```
+
+`-prof gc` reports `gc.alloc.rate.norm` (bytes allocated per op) — useful for spotting hidden allocations on the read/write hot paths. `-prof async` produces flamegraphs and requires async-profiler installed locally; CI does not run it.
+
 `mvn test` also runs:
 - **jqwik properties** (`StreamBufferProperties`) — picked up by Surefire as a JUnit 5 engine.
 - **jcstress** tests under `net.ladenthin.streambuffer.jcstress` — executed in a forked JVM via `exec-maven-plugin` in the `test` phase (`-m quick` mode).
+- **Lincheck** linearizability test (`StreamBufferLincheckTest`) over the non-blocking subset (`write`, `available`, `close`, `isClosed`).
+
+**Opt-in vmlens interleaving analysis:**
+```bash
+mvn -Pvmlens test
+```
+The `vmlens` profile pulls in `com.vmlens:api` and runs the `vmlens-maven-plugin` during the `test` phase. Tests using `com.vmlens.api.AllInterleavings` are then driven through every possible thread interleaving. The profile is off by default — vmlens overhead is too high for every build.
 
 ## Architecture
 

pom.xml

@@ -23,6 +23,18 @@ SPDX-License-Identifier: Apache-2.0
         <java.test.version>21</java.test.version>
         <jcstress.version>0.16</jcstress.version>
         <jqwik.version>1.9.2</jqwik.version>
+        <errorprone.version>2.49.0</errorprone.version>
+        <nullaway.version>0.13.4</nullaway.version>
+        <spotless.version>2.46.1</spotless.version>
+        <palantir-java-format.version>2.66.0</palantir-java-format.version>
+        <spotbugs.version>4.8.6.6</spotbugs.version>
+        <fb-contrib.version>7.6.4</fb-contrib.version>
+        <findsecbugs.version>1.13.0</findsecbugs.version>
+        <archunit.version>1.3.0</archunit.version>
+        <awaitility.version>4.2.2</awaitility.version>
+        <concurrentunit.version>0.4.6</concurrentunit.version>
+        <lincheck.version>2.39</lincheck.version>
+        <vmlens.version>1.2.28</vmlens.version>
         <project.build.outputTimestamp>${git.commit.time}</project.build.outputTimestamp>
     </properties>
     <inceptionYear>2014</inceptionYear>
@@ -73,6 +85,11 @@ SPDX-License-Identifier: Apache-2.0
         </snapshotRepository>
     </distributionManagement>
     <dependencies>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_annotations</artifactId>
+            <version>${errorprone.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>
@@ -109,6 +126,30 @@ SPDX-License-Identifier: Apache-2.0
             <version>${jcstress.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.tngtech.archunit</groupId>
+            <artifactId>archunit-junit5</artifactId>
+            <version>${archunit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>net.jodah</groupId>
+            <artifactId>concurrentunit</artifactId>
+            <version>${concurrentunit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>lincheck-jvm</artifactId>
+            <version>${lincheck.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>
@@ -147,7 +188,51 @@ SPDX-License-Identifier: Apache-2.0
                     <testSource>${java.test.version}</testSource>
                     <testTarget>${java.test.version}</testTarget>
                     <encoding>${project.build.sourceEncoding}</encoding>
+                    <showWarnings>true</showWarnings>
+                    <compilerArgs>
+                        <arg>-XDaddTypeAnnotationsToSymbol=true</arg>
+                        <arg>-XDcompilePolicy=simple</arg>
+                        <arg>--should-stop=ifError=FLOW</arg>
+                        <arg>-Xplugin:ErrorProne -Xep:NullAway:ERROR -XepOpt:NullAway:AnnotatedPackages=net.ladenthin</arg>
+                    </compilerArgs>
+                    <annotationProcessorPaths>
+                        <path>
+                            <groupId>com.google.errorprone</groupId>
+                            <artifactId>error_prone_core</artifactId>
+                            <version>${errorprone.version}</version>
+                        </path>
+                        <path>
+                            <groupId>com.uber.nullaway</groupId>
+                            <artifactId>nullaway</artifactId>
+                            <version>${nullaway.version}</version>
+                        </path>
+                    </annotationProcessorPaths>
                 </configuration>
+                <executions>
+                    <execution>
+                        <id>default-testCompile</id>
+                        <configuration>
+                            <compilerArgs>
+                                <arg>-XDaddTypeAnnotationsToSymbol=true</arg>
+                                <arg>-XDcompilePolicy=simple</arg>
+                                <arg>--should-stop=ifError=FLOW</arg>
+                                <arg>-Xplugin:ErrorProne -Xep:NullAway:OFF -Xep:GuardedBy:OFF</arg>
+                            </compilerArgs>
+                            <annotationProcessorPaths combine.children="append">
+                                <path>
+                                    <groupId>org.openjdk.jcstress</groupId>
+                                    <artifactId>jcstress-core</artifactId>
+                                    <version>${jcstress.version}</version>
+                                </path>
+                                <path>
+                                    <groupId>org.openjdk.jmh</groupId>
+                                    <artifactId>jmh-generator-annprocess</artifactId>
+                                    <version>1.37</version>
+                                </path>
+                            </annotationProcessorPaths>
+                        </configuration>
+                    </execution>
+                </executions>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
@@ -244,6 +329,7 @@ SPDX-License-Identifier: Apache-2.0
                         <phase>test</phase>
                         <goals><goal>exec</goal></goals>
                         <configuration>
+                            <skip>${skipTests}</skip>
                             <executable>${java.home}/bin/java</executable>
                             <classpathScope>test</classpathScope>
                             <arguments>
@@ -258,6 +344,67 @@ SPDX-License-Identifier: Apache-2.0
                     </execution>
                 </executions>
             </plugin>
+            <plugin>
+                <groupId>com.github.spotbugs</groupId>
+                <artifactId>spotbugs-maven-plugin</artifactId>
+                <version>${spotbugs.version}</version>
+                <configuration>
+                    <effort>Default</effort>
+                    <threshold>Default</threshold>
+                    <failOnError>true</failOnError>
+                    <includeTests>false</includeTests>
+                    <excludeFilterFile>spotbugs-exclude.xml</excludeFilterFile>
+                    <plugins>
+                        <plugin>
+                            <groupId>com.mebigfatguy.fb-contrib</groupId>
+                            <artifactId>fb-contrib</artifactId>
+                            <version>${fb-contrib.version}</version>
+                        </plugin>
+                        <plugin>
+                            <groupId>com.h3xstream.findsecbugs</groupId>
+                            <artifactId>findsecbugs-plugin</artifactId>
+                            <version>${findsecbugs.version}</version>
+                        </plugin>
+                    </plugins>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>spotbugs-check</id>
+                        <phase>verify</phase>
+                        <goals>
+                            <goal>check</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>com.diffplug.spotless</groupId>
+                <artifactId>spotless-maven-plugin</artifactId>
+                <version>${spotless.version}</version>
+                <configuration>
+                    <java>
+                        <includes>
+                            <include>src/main/java/**/*.java</include>
+                            <include>src/test/java/**/*.java</include>
+                        </includes>
+                        <palantirJavaFormat>
+                            <version>${palantir-java-format.version}</version>
+                        </palantirJavaFormat>
+                        <removeUnusedImports/>
+                        <trimTrailingWhitespace/>
+                        <endWithNewline/>
+                    </java>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>spotless-check</id>
+                        <phase>verify</phase>
+                        <goals>
+                            <goal>check</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>org.pitest</groupId>
                 <artifactId>pitest-maven</artifactId>
@@ -284,6 +431,47 @@ SPDX-License-Identifier: Apache-2.0
     </build>
 
     <profiles>
+        <profile>
+            <id>vmlens</id>
+            <dependencies>
+                <dependency>
+                    <groupId>com.vmlens</groupId>
+                    <artifactId>api</artifactId>
+                    <version>${vmlens.version}</version>
+                    <scope>test</scope>
+                </dependency>
+            </dependencies>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>com.vmlens</groupId>
+                        <artifactId>vmlens-maven-plugin</artifactId>
+                        <version>${vmlens.version}</version>
+                        <configuration>
+                            <!--
+                                Lincheck generates its own TestThreadExecution class on the fly.
+                                That bytecode clashes with vmlens's load-time instrumentation
+                                (java.lang.VerifyError). Skip the Lincheck test under vmlens;
+                                the default test job still runs it.
+                                **/*$* is the plugin default - kept to preserve inner-class skip.
+                            -->
+                            <excludes>
+                                <exclude>**/*$*</exclude>
+                                <exclude>**/StreamBufferLincheckTest.java</exclude>
+                            </excludes>
+                        </configuration>
+                        <executions>
+                            <execution>
+                                <id>vmlens-test</id>
+                                <goals>
+                                    <goal>test</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
         <profile>
             <id>release</id>
             <build>

spotbugs-exclude.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+SPDX-FileCopyrightText: 2014-2026 Bernard Ladenthin <bernard.ladenthin@gmail.com>
+
+SPDX-License-Identifier: Apache-2.0
+-->
+<FindBugsFilter
+    xmlns="https://github.com/spotbugs/filter/3.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="https://github.com/spotbugs/filter/3.0.0 https://raw.githubusercontent.com/spotbugs/spotbugs/4.8.6/spotbugs/etc/findbugsfilter.xsd">
+
+    <!--
+        getOutputStream() / getInputStream() intentionally expose the
+        SBOutputStream / SBInputStream fields - those streams ARE the
+        public API of StreamBuffer.
+    -->
+    <Match>
+        <Class name="net.ladenthin.streambuffer.StreamBuffer"/>
+        <Or>
+            <Method name="getOutputStream"/>
+            <Method name="getInputStream"/>
+        </Or>
+        <Bug pattern="EI_EXPOSE_REP"/>
+    </Match>
+</FindBugsFilter>