Refactor detect-split-packages Gradle plugin

- Use conventional plugin naming, i.e. "detect-split-packages" instead
   of applying plugin based on fully-qualified class name

 - Rename "diagnose" => "detect" consistently throughout plugin, task
   and method names and generally refactor naming throughout to follow
   "detect split packages" phrasing

 - Add Javadoc to DetectSplitPackagesPlugin

 - Improve error reporting when split packages are detected

   Upon detecting one or more split packages, `detectSplitPackages` now
   fails idiomatically, throwing a GradleException to signal task failure
   (as opposed to the previous approach of using an assert assertion), and
   the output reads as follows:

       $ gradle detectSplitPackages
       [...]
       :buildSrc:build UP-TO-DATE
       :detectSplitPackages FAILED

       FAILURE: Build failed with an exception.

       * What went wrong:
       Execution failed for task ':detectSplitPackages'.
       > The following split package(s) have been detected:
          - org.springframework.beans (split across spring-beans and spring-orm)
          - org.springframework.core.env (split across spring-context and spring-core)

 - DetectSplitPackagesTask now automatically attaches itself to `check`
   task lifecycle if the enclosing project contains a `check` task

 - DetectSplitPackagesTask adds itself to the 'Verification' task group,
   ensuring that it shows up correctly in `gradle tasks` task listings

 - packagesToScan now defaults to all subprojects; users may then
   customize this by removing individual subprojects from the collection

Issue: SPR-9990

build.gradle

@@ -752,16 +752,16 @@ configure(rootProject) {
 
 	apply plugin: "docbook-reference"
 	apply plugin: "groovy"
+	apply plugin: "detect-split-packages"
 	apply from: "${gradleScriptDir}/jdiff.gradle"
-	apply plugin: org.springframework.build.gradle.SplitPackageDetectorPlugin
 
 	reference {
 		sourceDir = file("src/reference/docbook")
 		pdfFilename = "spring-framework-reference.pdf"
 	}
 
-	diagnoseSplitPackages {
-		projectsToScan = project.subprojects - project(":spring-instrument-tomcat") // SPR-10150
+	detectSplitPackages {
+		projectsToScan -= project(":spring-instrument-tomcat")
 	}
 
 	// don"t publish the default jar for the root project
@@ -788,8 +788,6 @@ configure(rootProject) {
 		testCompile("hsqldb:hsqldb:${hsqldbVersion}")
 	}
 
-	check.dependsOn diagnoseSplitPackages
-
 	task api(type: Javadoc) {
 		group = "Documentation"
 		description = "Generates aggregated Javadoc API documentation."

buildSrc/src/main/groovy/org/springframework/build/gradle/DetectSplitPackagesPlugin.groovy

@@ -0,0 +1,157 @@
+/*
+ * Copyright 2002-2013 the original author or authors.
+ *
+ * Licensed 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.springframework.build.gradle
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.GradleException
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.Task
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.TaskAction
+
+/**
+ * Gradle plugin that detects identically named, non-empty packages split across multiple
+ * subprojects, e.g. "org.springframework.context.annotation" existing in both spring-core
+ * and spring-aspects. Adds a 'detectSplitPackages' task to the current project's task
+ * collection. If the project already contains a 'check' task (i.e. is a typical Gradle
+ * project with the "java" plugin applied), the 'check' task will be updated to depend on
+ * the execution of 'detectSplitPackages'.
+ *
+ * By default, all subprojects will be scanned. Use the 'projectsToScan' task property to
+ * modify this value. Example usage:
+ *
+ *     apply plugin: 'detect-split-packages // typically applied to root project
+ *
+ *     detectSplitPackages {
+ *         packagesToScan -= project(":spring-xyz") // scan every project but spring-xyz
+ *     }
+ *
+ * @author Rob Winch
+ * @author Glyn Normington
+ * @author Chris Beams
+ */
+public class DetectSplitPackagesPlugin implements Plugin<Project> {
+	public void apply(Project project) {
+		def tasks = project.tasks
+		Task detectSplitPackages = tasks.add('detectSplitPackages', DetectSplitPackagesTask.class)
+		if (tasks.asMap.containsKey('check')) {
+			tasks.getByName('check').dependsOn detectSplitPackages
+		}
+	}
+}
+
+public class DetectSplitPackagesTask extends DefaultTask {
+
+	private static final String JAVA_FILE_SUFFIX = ".java"
+	private static final String PACKAGE_SEPARATOR = "."
+	private static final String HIDDEN_DIRECTORY_PREFIX = "."
+
+	@Input
+	Set<Project> projectsToScan = project.subprojects
+
+	public DetectSplitPackagesTask() {
+		this.group = 'Verification'
+		this.description = 'Detects packages split across two or more subprojects.'
+	}
+
+	@TaskAction
+	public void detectSplitPackages() {
+		def splitPackages = doDetectSplitPackages()
+		if (!splitPackages.isEmpty()) {
+			def message = "The following split package(s) have been detected:\n"
+			splitPackages.each { pkg, mod ->
+				message += " - ${pkg} (split across ${mod[0].name} and ${mod[1].name})\n"
+			}
+			throw new GradleException(message)
+		}
+	}
+
+	private Map<String, List<Project>> doDetectSplitPackages() {
+		def splitPackages = [:]
+		def mergedProjects = findMergedProjects()
+		def packagesByProject = mapPackagesByProject()
+
+		def projects = packagesByProject.keySet().toArray()
+		def nProjects = projects.length
+
+		for (int i = 0; i < nProjects - 1; i++) {
+			for (int j = i + 1; j < nProjects - 1; j++) {
+				def prj_i = projects[i]
+				def prj_j = projects[j]
+
+				def pkgs_i = new HashSet(packagesByProject.get(prj_i))
+				def pkgs_j = packagesByProject.get(prj_j)
+				pkgs_i.retainAll(pkgs_j)
+
+				if (!pkgs_i.isEmpty()
+						&& mergedProjects.get(prj_i) != prj_j
+						&& mergedProjects.get(prj_j) != prj_i) {
+					pkgs_i.each { pkg ->
+						def readablePkg = pkg.substring(1).replaceAll(File.separator, PACKAGE_SEPARATOR)
+						splitPackages[readablePkg] = [prj_i, prj_j]
+					}
+				}
+			}
+		}
+		return splitPackages;
+	}
+
+	private Map<Project, Set<String>> mapPackagesByProject() {
+		def packagesByProject = [:]
+		this.projectsToScan.each { Project p ->
+			def packages = new HashSet<String>()
+			p.sourceSets.main.java.srcDirs.each { File dir ->
+				findPackages(packages, dir, "")
+			}
+			if (!packages.isEmpty()) {
+				packagesByProject.put(p, packages)
+			}
+		}
+		return packagesByProject;
+	}
+
+	private Map<Project, Project> findMergedProjects() {
+		def mergedProjects = [:]
+		this.projectsToScan.findAll { p ->
+			p.plugins.findPlugin(MergePlugin)
+		}.findAll { p ->
+			p.merge.into
+		}.each { p ->
+			mergedProjects.put(p, p.merge.into)
+		}
+		return mergedProjects
+	}
+
+	private static void findPackages(Set<String> packages, File dir, String packagePath) {
+		def scanDir = new File(dir, packagePath)
+		def File[] javaFiles = scanDir.listFiles({ file ->
+			!file.isDirectory() && file.name.endsWith(JAVA_FILE_SUFFIX)
+		} as FileFilter)
+
+		if (javaFiles != null && javaFiles.length != 0) {
+			packages.add(packagePath)
+		}
+
+		scanDir.listFiles({ File file ->
+			file.isDirectory() && !file.name.startsWith(HIDDEN_DIRECTORY_PREFIX)
+		} as FileFilter).each { File subDir ->
+			findPackages(packages, dir, packagePath + File.separator + subDir.name)
+		}
+	}
+}
+

buildSrc/src/main/groovy/org/springframework/build/gradle/SplitPackageDetectorPlugin.groovy

@@ -1,131 +0,0 @@
-/*
- * Copyright 2013 the original author or authors.
- *
- * Licensed 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.springframework.build.gradle
-
-import org.gradle.api.DefaultTask
-import org.gradle.api.Plugin
-import org.gradle.api.Project
-import org.gradle.api.Task
-import org.gradle.api.artifacts.Configuration
-import org.gradle.api.artifacts.ProjectDependency
-import org.gradle.api.artifacts.maven.Conf2ScopeMapping
-import org.gradle.api.plugins.MavenPlugin
-import org.gradle.api.tasks.Input
-import org.gradle.api.tasks.TaskAction
-import org.gradle.plugins.ide.eclipse.EclipsePlugin
-import org.gradle.plugins.ide.eclipse.model.EclipseClasspath
-import org.gradle.plugins.ide.idea.IdeaPlugin
-
-class SplitPackageDetectorPlugin implements Plugin<Project> {
-	public void apply(Project project) {
-		Task diagnoseSplitPackages = project.tasks.add('diagnoseSplitPackages', SplitPackageDetectorTask.class)
-		diagnoseSplitPackages.setDescription('Detects packages which will be split across JARs')
-	}
-}
-
-public class SplitPackageDetectorTask extends DefaultTask {
-	@Input
-	Set<Project> projectsToScan
-
-	@TaskAction
-	public final void diagnoseSplitPackages() {
-		def Map<Project, Project> mergeMap = [:]
-		def projects = projectsToScan.findAll { it.plugins.findPlugin(org.springframework.build.gradle.MergePlugin) }.findAll { it.merge.into }
-		projects.each { p ->
-			mergeMap.put(p, p.merge.into)
-		}
-		def splitFound = new org.springframework.build.gradle.SplitPackageDetector(projectsToScan, mergeMap, project.logger).diagnoseSplitPackages();
-		assert !splitFound // see error log messages for details of split packages
-	}
-}
-
-class SplitPackageDetector {
-
-	private static final String HIDDEN_DIRECTORY_PREFIX = "."
-
-	private static final String JAVA_FILE_SUFFIX = ".java"
-
-	private static final String SRC_MAIN_JAVA = "src" + File.separator + "main" + File.separator + "java"
-
-	private static final String PACKAGE_SEPARATOR = "."
-
-	private final Map<Project, Project> mergeMap
-
-	private final Map<Project, Set<String>> pkgMap = [:]
-
-	private final logger
-
-	SplitPackageDetector(projectsToScan, mergeMap, logger) {
-		this.mergeMap = mergeMap
-		this.logger = logger
-		projectsToScan.each { Project p ->
-			def dir = p.projectDir
-			def packages = getPackagesInDirectory(dir)
-			if (!packages.isEmpty()) {
-				pkgMap.put(p, packages)
-			}
-		}
-	}
-
-	private File[] dirList(String dir) {
-		dirList(new File(dir))
-	}
-
-	private File[] dirList(File dir) {
-		dir.listFiles({ file -> file.isDirectory() && !file.getName().startsWith(HIDDEN_DIRECTORY_PREFIX) } as FileFilter)
-	}
-
-	private Set<String> getPackagesInDirectory(File dir) {
-		def pkgs = new HashSet<String>()
-		addPackagesInDirectory(pkgs, new File(dir, SRC_MAIN_JAVA), "")
-		return pkgs;
-	}
-
-	boolean diagnoseSplitPackages() {
-		def splitFound = false;
-		def projs = pkgMap.keySet().toArray()
-		def numProjects = projs.length
-		for (int i = 0; i < numProjects - 1; i++) {
-			for (int j = i + 1; j < numProjects - 1; j++) {
-				def pi = projs[i]
-				def pkgi = new HashSet(pkgMap.get(pi))
-				def pj = projs[j]
-				def pkgj = pkgMap.get(pj)
-				pkgi.retainAll(pkgj)
-				if (!pkgi.isEmpty() && mergeMap.get(pi) != pj && mergeMap.get(pj) != pi) {
-					pkgi.each { pkg ->
-						def readablePkg = pkg.substring(1).replaceAll(File.separator, PACKAGE_SEPARATOR)
-						logger.error("Package '$readablePkg' is split between $pi and $pj")
-					}
-					splitFound = true
-				}
-			}
-		}
-		return splitFound
-	}
-
-	private void addPackagesInDirectory(HashSet<String> packages, File dir, String pkg) {
-		def scanDir = new File(dir, pkg)
-		def File[] javaFiles = scanDir.listFiles({ file -> !file.isDirectory() && file.getName().endsWith(JAVA_FILE_SUFFIX) } as FileFilter)
-		if (javaFiles != null && javaFiles.length != 0) {
-			packages.add(pkg)
-		}
-		dirList(scanDir).each { File subDir ->
-			addPackagesInDirectory(packages, dir, pkg + File.separator + subDir.getName())
-		}
-	}
-}

buildSrc/src/main/resources/META-INF/gradle-plugins/detect-split-packages.properties

@@ -0,0 +1 @@
+implementation-class=org.springframework.build.gradle.DetectSplitPackagesPlugin