Fix #12646: project-local-repo clean race condition when root pom has parent

apache-maven/src/assembly/maven/conf/maven-user.properties

@@ -30,6 +30,16 @@
 ${includes} = ?"${maven.user.conf}/maven-user.properties", \
               ?"${maven.project.conf}/maven-user.properties"
 
+#
+# Project-Local Repository
+#
+# Location of the project-local repository used by the reactor to share artifacts between
+# modules during a build. This repository enables partial and resumable builds (e.g.
+# mvn verify -r :module) without requiring install. The path may be absolute or relative
+# to the root directory.
+#
+# maven.project.local.repo = ${maven.rootDirectory}/.mvn/target/project-local-repo
+
 #
 # Maven Cache Configuration
 #

api/maven-api-core/src/main/java/org/apache/maven/api/Constants.java

@@ -379,6 +379,21 @@ public final class Constants {
     @Config
     public static final String MAVEN_VERSION_FILTER = "maven.session.versionFilter";
 
+    /**
+     * User property for overriding the project-local repository path used by the reactor reader to share
+     * artifacts between modules during a build. This repository enables partial and resumable builds
+     * (e.g. {@code mvn verify -r :module}) without requiring {@code install}.
+     * <p>
+     * The path may be absolute or relative to the root directory. If relative, it is resolved against
+     * the root directory of the project.
+     * </p>
+     * Default value: <code>${maven.rootDirectory}/.mvn/target/project-local-repo</code>.
+     *
+     * @since 4.0.0
+     */
+    @Config(defaultValue = "${maven.rootDirectory}/.mvn/target/project-local-repo")
+    public static final String MAVEN_PROJECT_LOCAL_REPO = "maven.project.local.repo";
+
     /**
      * User property for chained LRM: the new "head" local repository to use, and "push" the existing into tail.
      * Similar to <code>maven.repo.local.tail</code>, this property may contain comma separated list of paths to be

impl/maven-core/src/main/java/org/apache/maven/ReactorReader.java

@@ -43,6 +43,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import org.apache.maven.api.Constants;
 import org.apache.maven.api.model.Model;
 import org.apache.maven.api.services.Lookup;
 import org.apache.maven.eventspy.EventSpy;
@@ -352,6 +353,13 @@ private File findInProjectLocalRepository(Artifact artifact) {
      * The mojo started event is also captured to determine the lifecycle
      * phases the project has been through.
      *
+     * <p>When a project enters its clean phase, its artifacts are cleaned from the
+     * project-local-repo (per-GAV scope). Since the project-local-repo is located
+     * under {@code .mvn/target/} (not under the project's own {@code target/}),
+     * it is not affected by maven-clean-plugin's deletion of {@code target/},
+     * eliminating the race condition between clean and install operations in
+     * parallel builds.</p>
+     *
      * @param event the execution event
      */
     private void processEvent(ExecutionEvent event) {
@@ -364,9 +372,7 @@ private void processEvent(ExecutionEvent event) {
                     if (!Objects.equals(phase, phases.peekLast())) {
                         phases.addLast(phase);
                         if ("clean".equals(phase)) {
-                            synchronized (project) {
-                                cleanProjectLocalRepository(project);
-                            }
+                            cleanProjectLocalRepository(project);
                         }
                     }
                 }
@@ -402,6 +408,13 @@ private void installIntoProjectLocalRepository(MavenProject project) {
         }
     }
 
+    /**
+     * Cleans the project-local-repo artifacts for the given project's GAV coordinates.
+     * Since the project-local-repo is under {@code .mvn/target/} and not the project's
+     * own {@code target/}, it is not affected by maven-clean-plugin's deletion of
+     * {@code target/}, so there is no race between clean and install operations
+     * in parallel builds.
+     */
     private void cleanProjectLocalRepository(MavenProject project) {
         try {
             Path artifactPath = getProjectLocalRepo()
@@ -505,17 +518,12 @@ private Path getArtifactPath(
     private Path getProjectLocalRepo() {
         if (projectLocalRepository == null) {
             Path root = session.getRequest().getRootDirectory();
-            List<MavenProject> projects = session.getProjects();
-            if (projects != null) {
-                projectLocalRepository = projects.stream()
-                        .filter(project -> Objects.equals(root.toFile(), project.getBasedir()))
-                        .findFirst()
-                        .map(project -> project.getBuild().getDirectory())
-                        .map(Paths::get)
-                        .orElseGet(() -> root.resolve("target"))
-                        .resolve(PROJECT_LOCAL_REPO);
+            String userPath = session.getRequest().getUserProperties().getProperty(Constants.MAVEN_PROJECT_LOCAL_REPO);
+            if (userPath != null && !userPath.isEmpty()) {
+                Path path = Paths.get(userPath);
+                projectLocalRepository = path.isAbsolute() ? path : root.resolve(path);
             } else {
-                return root.resolve("target").resolve(PROJECT_LOCAL_REPO);
+                projectLocalRepository = root.resolve(".mvn").resolve("target").resolve(PROJECT_LOCAL_REPO);
             }
         }
         return projectLocalRepository;

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITBomConsumerPomPropertyResolutionTest.java

@@ -156,6 +156,7 @@ void testConsumerPomInProjectLocalRepo() throws Exception {
 
         // Check the consumer POM in the project-local-repo
         Path consumerPom = basedir.resolve(Path.of(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.bom-property",

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITConsumerPomBomFromSettingsRepoTest.java

@@ -75,6 +75,7 @@ void testConsumerPomWithBomFromSettingsProfileRepo() throws Exception {
 
         // Verify the consumer POM was generated
         Path consumerPom = basedir.resolve(Path.of(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.cpbom",

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITgh11162ConsumerPomScopesTest.java

@@ -49,6 +49,7 @@ void testConsumerPomFiltersScopes() throws Exception {
         verifier.verifyErrorFreeLog();
 
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.gh11162",

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITgh11456MixinsConsumerPomTest.java

@@ -71,6 +71,7 @@ void testMixinsWithFlattening() throws Exception {
 
         // Verify consumer POM was created
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.gh11456",
@@ -104,6 +105,7 @@ void testMixinsWithPreserveModelVersion() throws Exception {
 
         // Verify consumer POM was created
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.gh11456",

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITgh12646ProjectLocalRepoCleanRaceTest.java

@@ -0,0 +1,59 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.it;
+
+import java.nio.file.Path;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * This is a test set for <a href="https://github.com/apache/maven/issues/12646">GH-12646</a>.
+ *
+ * Verifies that parallel builds with {@code clean install} do not fail with a race condition
+ * when the root pom has a parent (super-pom) and other modules write to
+ * {@code target/project-local-repo} while the root project's clean phase is running.
+ *
+ * @since 4.0.0-rc-6
+ */
+class MavenITgh12646ProjectLocalRepoCleanRaceTest extends AbstractMavenIntegrationTestCase {
+
+    /**
+     * Verify that a parallel {@code clean install} succeeds when the root pom has a parent
+     * that is also part of the reactor. In this scenario:
+     * <ol>
+     *   <li>super-pom builds first (no dependencies)</li>
+     *   <li>root pom and module-a..d start in parallel (all depend on super-pom)</li>
+     *   <li>root pom's clean phase runs maven-clean-plugin which deletes target/</li>
+     *   <li>modules complete and install artifacts into target/project-local-repo</li>
+     * </ol>
+     * Without the fix, step 3 and 4 race, causing maven-clean-plugin to fail because
+     * target/project-local-repo is being written to while it tries to delete target/.
+     */
+    @Test
+    void testParallelCleanInstallWithParentPom() throws Exception {
+        Path testDir = extractResources("gh-12646-project-local-repo-clean-race");
+
+        Verifier verifier = newVerifier(testDir);
+        verifier.addCliArgument("-T");
+        verifier.addCliArgument("4");
+        verifier.addCliArguments("clean", "install");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+    }
+}

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng3043BestEffortReactorResolutionTest.java

@@ -18,7 +18,6 @@
  */
 package org.apache.maven.it;
 
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
 
@@ -44,11 +43,11 @@ public class MavenITmng3043BestEffortReactorResolutionTest extends AbstractMaven
     @Test
     public void testitTestPhase() throws Exception {
         Path testDir = extractResources("mng-3043");
-        Files.createDirectories(testDir.resolve(".mvn"));
 
         Verifier verifier = newVerifier(testDir);
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.deleteDirectory("consumer-a/target");
         verifier.deleteDirectory("consumer-b/target");
         verifier.deleteDirectory("consumer-c/target");
@@ -105,6 +104,7 @@ public void testitPackagePhase() throws Exception {
         Verifier verifier = newVerifier(testDir);
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.deleteDirectory("consumer-a/target");
         verifier.deleteDirectory("consumer-b/target");
         verifier.deleteDirectory("consumer-c/target");
@@ -165,6 +165,7 @@ public void testitPackagePhasesSlitted() throws Exception {
         Verifier verifier = newVerifier(testDir);
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.deleteDirectory("consumer-a/target");
         verifier.deleteDirectory("consumer-b/target");
         verifier.deleteDirectory("consumer-c/target");

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng5102MixinsTest.java

@@ -47,6 +47,7 @@ public void testWithPath() throws Exception {
         Verifier verifier = newVerifier(testDir);
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.deleteArtifacts("org.apache.maven.its.mng5102");
         verifier.addCliArguments("install", "-Dmaven.consumer.pom.flatten=true");
         verifier.execute();
@@ -63,9 +64,9 @@ public void testWithPath() throws Exception {
         assertEquals("true", props.getProperty("project.properties.mixin3"));
 
         verifier.verifyFilePresent(
-                "target/project-local-repo/org.apache.maven.its.mng5102/child/0.1/child-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/child/0.1/child-0.1-consumer.pom");
         List<String> lines = verifier.loadLines(
-                "target/project-local-repo/org.apache.maven.its.mng5102/child/0.1/child-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/child/0.1/child-0.1-consumer.pom");
         assertTrue(lines.stream().noneMatch(l -> l.contains("<mixin>")));
     }
 
@@ -90,6 +91,7 @@ public void testWithGav() throws Exception {
         verifier = newVerifier(testDir.resolve("project"));
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.addCliArguments("install", "-Dmaven.consumer.pom.flatten");
         verifier.execute();
         verifier.verifyErrorFreeLog();
@@ -99,9 +101,9 @@ public void testWithGav() throws Exception {
         assertEquals("true", props.getProperty("project.properties.mixin2"));
 
         verifier.verifyFilePresent(
-                "target/project-local-repo/org.apache.maven.its.mng5102/gav/0.1/gav-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/gav/0.1/gav-0.1-consumer.pom");
         List<String> lines = verifier.loadLines(
-                "target/project-local-repo/org.apache.maven.its.mng5102/gav/0.1/gav-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/gav/0.1/gav-0.1-consumer.pom");
         assertTrue(lines.stream().anyMatch(l -> l.contains("<mixin>")));
     }
 
@@ -126,6 +128,7 @@ public void testWithClassifier() throws Exception {
         verifier = newVerifier(testDir.resolve("project"));
         verifier.setAutoclean(false);
         verifier.deleteDirectory("target");
+        verifier.deleteDirectory(".mvn/target");
         verifier.addCliArguments("install", "-Dmaven.consumer.pom.flatten");
         verifier.execute();
         verifier.verifyErrorFreeLog();
@@ -135,9 +138,9 @@ public void testWithClassifier() throws Exception {
         assertEquals("true", props.getProperty("project.properties.mixin4"));
 
         verifier.verifyFilePresent(
-                "target/project-local-repo/org.apache.maven.its.mng5102/classifier/0.1/classifier-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/classifier/0.1/classifier-0.1-consumer.pom");
         List<String> lines = verifier.loadLines(
-                "target/project-local-repo/org.apache.maven.its.mng5102/classifier/0.1/classifier-0.1-consumer.pom");
+                ".mvn/target/project-local-repo/org.apache.maven.its.mng5102/classifier/0.1/classifier-0.1-consumer.pom");
         assertTrue(lines.stream().anyMatch(l -> l.contains("<mixin>")));
     }
 }

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng8414ConsumerPomWithNewFeaturesTest.java

@@ -53,6 +53,7 @@ void testNotPreserving() throws Exception {
                 "The consumer POM for org.apache.maven.its:mng-8414:jar:1.0.0-SNAPSHOT cannot be downgraded to 4.0.0.");
 
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its",
@@ -83,6 +84,7 @@ void testPreserving() throws Exception {
         verifier.verifyTextNotInLog("cannot be downgraded to 4.0.0.");
 
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its",

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng8645ConsumerPomDependencyManagementTest.java

@@ -52,6 +52,7 @@ void testIt() throws Exception {
 
         // validate consumer pom
         Path consumerPom = basedir.resolve(Paths.get(
+                ".mvn",
                 "target",
                 "project-local-repo",
                 "org.apache.maven.its.mng8645",

its/core-it-suite/src/test/resources/gh-12646-project-local-repo-clean-race/module-a/pom.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.1.0">
+  <parent>
+    <groupId>org.apache.maven.its.gh12646</groupId>
+    <artifactId>super-pom</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <relativePath>../super-pom</relativePath>
+  </parent>
+
+  <artifactId>module-a</artifactId>
+</project>

its/core-it-suite/src/test/resources/gh-12646-project-local-repo-clean-race/module-a/src/main/java/a/A.java

@@ -0,0 +1,7 @@
+package a;
+
+public class A {
+    public String greet() {
+        return "Hello from A";
+    }
+}

its/core-it-suite/src/test/resources/gh-12646-project-local-repo-clean-race/module-b/pom.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.1.0">
+  <parent>
+    <groupId>org.apache.maven.its.gh12646</groupId>
+    <artifactId>super-pom</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <relativePath>../super-pom</relativePath>
+  </parent>
+
+  <artifactId>module-b</artifactId>
+</project>