Abstract the delta handling from the resource API

Currently m2e is directly wired to the resource delta API, while this
seems good in the context of eclipse for m2e this imposes to restrictive
API as it is all noimplement/extend interfaces and offer much more than
m2e actually using.

This aims to implement a thin wrapper for further improvement of delta
detection especially when it comes to resource see for example
#1302

This will not fix anything but is an important first step to ensure
things are still working as before.

Author: laeubi

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/IIncrementalBuildFramework.java

@@ -17,7 +17,6 @@
 import java.util.Set;
 
 import org.eclipse.core.resources.IProject;
-import org.eclipse.core.resources.IResourceDelta;
 import org.eclipse.core.runtime.CoreException;
 
 
@@ -45,6 +44,14 @@ public interface BuildResultCollector {
     Set<File> getFiles();
   }
 
+  /**
+   * @experimental this interface is part of work in progress and can be changed or removed without notice.
+   * @since 2.4
+   */
+  public interface BuildDelta {
+    boolean hasDelta(File file);
+  }
+
   /**
    * @experimental this interface is part of work in progress and can be changed or removed without notice.
    * @since 1.6
@@ -53,7 +60,7 @@ public interface BuildContext {
     void release();
   }
 
-  BuildContext setupProjectBuildContext(IProject project, int kind, IResourceDelta delta,
-      BuildResultCollector results) throws CoreException;
+  BuildContext setupProjectBuildContext(IProject project, int kind, BuildDelta delta, BuildResultCollector results)
+      throws CoreException;
 
 }

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/InternalBuildParticipant.java

@@ -24,7 +24,6 @@
 
 import org.sonatype.plexus.build.incremental.BuildContext;
 
-import org.eclipse.m2e.core.internal.builder.plexusbuildapi.AbstractEclipseBuildContext;
 import org.eclipse.m2e.core.project.IMavenProjectFacade;
 
 
@@ -36,7 +35,7 @@ public abstract class InternalBuildParticipant {
 
   private MavenSession session;
 
-  private AbstractEclipseBuildContext buildContext;
+  private BuildContext buildContext;
 
   protected IMavenProjectFacade getMavenProjectFacade() {
     return facade;
@@ -71,7 +70,7 @@ public void clean(IProgressMonitor monitor) throws CoreException {
 
   public abstract boolean callOnEmptyDelta();
 
-  void setBuildContext(AbstractEclipseBuildContext buildContext) {
+  void setBuildContext(BuildContext buildContext) {
     this.buildContext = buildContext;
   }
 

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilderImpl.java

@@ -52,7 +52,9 @@
 import org.eclipse.m2e.core.internal.URLConnectionCaches;
 import org.eclipse.m2e.core.internal.builder.BuildResultCollector.Message;
 import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework.BuildContext;
+import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework.BuildDelta;
 import org.eclipse.m2e.core.internal.builder.plexusbuildapi.AbstractEclipseBuildContext;
+import org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseResourceBuildDelta;
 import org.eclipse.m2e.core.internal.builder.plexusbuildapi.PlexusBuildAPI;
 import org.eclipse.m2e.core.internal.embedder.MavenProjectMutableState;
 import org.eclipse.m2e.core.internal.markers.IMavenMarkerManager;
@@ -65,6 +67,7 @@
 
 
 public class MavenBuilderImpl {
+
   private static Logger log = LoggerFactory.getLogger(MavenBuilderImpl.class);
 
   public static final QualifiedName BUILD_CONTEXT_KEY = new QualifiedName(IMavenConstants.PLUGIN_ID, "BuildContext"); //$NON-NLS-1$
@@ -129,7 +132,10 @@ public Set<IProject> build(MavenSession session, IMavenProjectFacade projectFaca
           participant.setMavenProjectFacade(projectFacade);
           participant.setGetDeltaCallback(deltaProvider);
           participant.setSession(session);
-          participant.setBuildContext((AbstractEclipseBuildContext) incrementalContexts.get(0));
+          BuildContext buildContext = incrementalContexts.get(0);
+          if(buildContext instanceof org.sonatype.plexus.build.incremental.BuildContext incremental) {
+            participant.setBuildContext(incremental);
+          }
           if(participant instanceof InternalBuildParticipant2 participant2) {
             participant2.setArgs(args);
           }
@@ -223,8 +229,10 @@ private boolean hasRelevantDelta(IMavenProjectFacade projectFacade, IResourceDel
   private List<IIncrementalBuildFramework.BuildContext> setupProjectBuildContext(IProject project, int kind,
       IResourceDelta delta, IIncrementalBuildFramework.BuildResultCollector results) throws CoreException {
     List<IIncrementalBuildFramework.BuildContext> contexts = new ArrayList<>();
+
+    BuildDelta buildDelta = delta != null ? new EclipseResourceBuildDelta(delta) : null;
     for(IIncrementalBuildFramework framework : incrementalBuildFrameworks) {
-      contexts.add(framework.setupProjectBuildContext(project, kind, delta, results));
+      contexts.add(framework.setupProjectBuildContext(project, kind, buildDelta, results));
     }
     return contexts;
   }

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/plexusbuildapi/EclipseIncrementalBuildContext.java

@@ -14,41 +14,57 @@
 package org.eclipse.m2e.core.internal.builder.plexusbuildapi;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
 import java.util.List;
 import java.util.Map;
 
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.IResourceDelta;
+import org.eclipse.core.runtime.Adapters;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Path;
 
 import org.codehaus.plexus.util.DirectoryScanner;
 import org.codehaus.plexus.util.Scanner;
 
+import org.sonatype.plexus.build.incremental.BuildContext;
 import org.sonatype.plexus.build.incremental.EmptyScanner;
+import org.sonatype.plexus.build.incremental.ThreadBuildContext;
 
 import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework;
+import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework.BuildDelta;
+import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework.BuildResultCollector;
 
 
-public class EclipseIncrementalBuildContext extends AbstractEclipseBuildContext {
+public class EclipseIncrementalBuildContext implements BuildContext, IIncrementalBuildFramework.BuildContext {
 
-  private final IResourceDelta delta;
+  private final BuildDelta delta;
+
+  private BuildResultCollector results;
+
+  private Map<String, Object> context;
+
+  private File baseDir;
 
   public EclipseIncrementalBuildContext(IResourceDelta delta, Map<String, Object> context,
       IIncrementalBuildFramework.BuildResultCollector results) {
-    super(context, results);
+    this(new EclipseResourceBuildDelta(delta), context, results,
+        delta.getResource().getProject().getLocation().toFile());
+  }
+
+  public EclipseIncrementalBuildContext(BuildDelta delta, Map<String, Object> context,
+      IIncrementalBuildFramework.BuildResultCollector results, File baseDir) {
     this.delta = delta;
+    this.context = context;
+    this.results = results;
+    this.baseDir = baseDir;
   }
 
   @Override
   public boolean hasDelta(String relPath) {
-    IPath path = new Path(relPath);
-    return hasDelta(path);
-  }
-
-  protected boolean hasDelta(IPath path) {
-    return delta == null || path == null || delta.findMember(path) != null;
+    return hasDelta(new File(baseDir, relPath));
   }
 
   @Override
@@ -63,7 +79,7 @@ public boolean hasDelta(List relPaths) {
 
   @Override
   public boolean hasDelta(File file) {
-    return hasDelta(getRelativePath(file));
+    return delta.hasDelta(file);
   }
 
   @Override
@@ -77,36 +93,53 @@ public Scanner newDeleteScanner(File basedir) {
     return new ResourceDeltaScanner(reldelta, true);
   }
 
+  private IResourceDelta getDelta(File file) {
+    IResourceDelta adapt = Adapters.adapt(delta, IResourceDelta.class);
+    if(adapt == null) {
+      return null;
+    }
+    IPath relpath = getRelativePath(file);
+    if(relpath == null) {
+      return null;
+    }
+    return adapt.findMember(relpath);
+  }
+
+  private IPath getRelativePath(File file) {
+    IResource adapt = Adapters.adapt(delta, IResource.class);
+    if(adapt == null) {
+      return null;
+    }
+    IPath basepath = adapt.getLocation();
+    IPath path = Path.fromOSString(file.getAbsolutePath());
+    if(!basepath.isPrefixOf(path)) {
+      return null;
+    }
+    return path.removeFirstSegments(basepath.segmentCount());
+  }
+
   @Override
   public Scanner newScanner(File basedir) {
     return newScanner(basedir, false);
   }
 
   @Override
   public Scanner newScanner(File basedir, boolean ignoreDelta) {
-    if(!ignoreDelta) {
-      IResourceDelta reldelta = getDelta(basedir);
-
-      if(reldelta == null || !isContentChange(reldelta)) {
-        return new EmptyScanner(basedir);
-      }
-
-      return new ResourceDeltaScanner(reldelta, false);
+    DirectoryScanner ds;
+    if(ignoreDelta) {
+      ds = new DirectoryScanner();
+    } else {
+      ds = new DirectoryScanner() {
+        @Override
+        protected boolean isSelected(String name, File file) {
+          return hasDelta(file);
+        }
+      };
     }
-
-    DirectoryScanner ds = new DirectoryScanner();
     ds.setBasedir(basedir);
     return ds;
   }
 
-  private IResourceDelta getDelta(File file) {
-    IPath relpath = getRelativePath(file);
-    if(relpath == null) {
-      return null;
-    }
-    return delta.findMember(relpath);
-  }
-
   static boolean isContentChange(IResourceDelta delta) {
     int kind = delta.getKind();
     if(IResourceDelta.ADDED == kind) {
@@ -141,13 +174,68 @@ static boolean isRemove(IResourceDelta delta) {
   }
 
   @Override
-  protected IResource getBaseResource() {
-    return delta.getResource();
+  public boolean isIncremental() {
+    return true;
   }
 
   @Override
-  public boolean isIncremental() {
-    return true;
+  public void refresh(File file) {
+    results.refresh(file);
+  }
+
+  @Override
+  public OutputStream newFileOutputStream(File file) throws IOException {
+    return new ChangedFileOutputStream(file, this);
+  }
+
+  @Override
+  public void setValue(String key, Object value) {
+    context.put(key, value);
+  }
+
+  @Override
+  public Object getValue(String key) {
+    return context.get(key);
+  }
+
+  /**
+   * @deprecated Use addMessage instead
+   */
+  @Deprecated
+  @Override
+  public void addError(File file, int line, int column, String message, Throwable cause) {
+    addMessage(file, line, column, message, BuildContext.SEVERITY_ERROR, cause);
+  }
+
+  /**
+   * @deprecated
+   * @deprecated Use addMessage instead
+   */
+  @Deprecated
+  @Override
+  public void addWarning(File file, int line, int column, String message, Throwable cause) {
+    addMessage(file, line, column, message, BuildContext.SEVERITY_WARNING, cause);
+  }
+
+  @Override
+  public void addMessage(File file, int line, int column, String message, int severity, Throwable cause) {
+    results.addMessage(file, line, column, message, severity, cause);
+  }
+
+  @Override
+  public void removeMessages(File file) {
+    results.removeMessages(file);
+  }
+
+  @Override
+  public boolean isUptodate(File target, File source) {
+    return target != null && target.exists() && source != null && source.exists()
+        && target.lastModified() > source.lastModified();
+  }
+
+  @Override
+  public void release() {
+    ThreadBuildContext.setThreadBuildContext(null);
   }
 
 }

org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/plexusbuildapi/EclipseResourceBuildDelta.java

@@ -0,0 +1,76 @@
+/*******************************************************************************
+ * Copyright (c) 2008-2023 Sonatype, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *      Sonatype, Inc. - initial API and implementation
+ *      Christoph Läubrich - extracted and implement wrapper API
+ *******************************************************************************/
+
+package org.eclipse.m2e.core.internal.builder.plexusbuildapi;
+
+import java.io.File;
+
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IResourceDelta;
+import org.eclipse.core.runtime.IAdaptable;
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.Path;
+
+import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework;
+
+
+public final class EclipseResourceBuildDelta implements IIncrementalBuildFramework.BuildDelta, IAdaptable {
+  private final IResource resource;
+
+  private final IResourceDelta delta;
+
+  /**
+   * @param resource
+   * @param delta
+   */
+  public EclipseResourceBuildDelta(IResourceDelta delta) {
+    this.resource = delta != null ? delta.getResource() : null;
+    this.delta = delta;
+  }
+
+  @Override
+  public boolean hasDelta(File file) {
+    return hasDelta(getRelativePath(file));
+  }
+
+  private boolean hasDelta(IPath path) {
+    return path == null || this.delta.findMember(path) != null;
+  }
+
+  /**
+   * Returns path relative to delta resource location.
+   */
+  private IPath getRelativePath(File file) {
+    IPath basepath = this.resource.getLocation();
+    IPath path = Path.fromOSString(file.getAbsolutePath());
+
+    if(!basepath.isPrefixOf(path)) {
+      return null;
+    }
+
+    return path.removeFirstSegments(basepath.segmentCount());
+  }
+
+  @Override
+  public <T> T getAdapter(Class<T> adapter) {
+    if(adapter.isInstance(delta)) {
+      return adapter.cast(delta);
+    }
+    if(adapter.isInstance(resource)) {
+      return adapter.cast(resource);
+    }
+    return null;
+  }
+
+}