perf: don't refresh project facade during full build

Changed maven builder to refresh facade when project pom.xml has
changed or facade is not available or facade is stale. Use cached
facade instance in all other cases. This improves performance in
common case when project configuration update and clean build
are performed as one user operations.

May cause stale facade cache when full build is invoked right after
out-of-workspace pom.xml change. This is (and always was) an edge
case, if this happens, the workaround is to manually invoke project
configuration update.

Signed-off-by: Igor Fedorenko <igor@ifedorenko.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilder.java b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilder.java
index 9faf9596..6562d046 100644
--- a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilder.java
+++ b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilder.java
@@ -197,11 +197,22 @@ public class MavenBuilder extends IncrementalProjectBuilder implements DeltaProv
 
   /*package*/IMavenProjectFacade getProjectFacade(final IFile pomResource, final IProject project,
       final IProgressMonitor monitor) throws CoreException {
+
+    // facade refresh should be forced whenever pom.xml has changed
+    // there is no delta info for full builds
+    // but these are usually forced from Project/Clean
+    // so assume pom did not change
+    boolean force = false;
+
     IResourceDelta delta = getDelta(project);
+    if(delta != null) {
+      delta = delta.findMember(pomResource.getFullPath());
+      force = delta != null && delta.getKind() == IResourceDelta.CHANGED;
+    }
 
     IMavenProjectFacade projectFacade = projectManager.create(getProject(), monitor);
 
-    if(delta == null || projectFacade == null || projectFacade.isStale()) {
+    if(force || projectFacade == null || projectFacade.isStale()) {
       projectManager.refresh(Collections.singleton(pomResource), monitor);
       projectFacade = projectManager.create(project, monitor);
       if(projectFacade == null) {