Merge remote-tracking branch 'tsartarzan/JENKINS-15156' into JENKINS-…

…15156

core/src/main/java/hudson/model/AbstractProject.java

@@ -162,7 +162,7 @@
      * {@link Run#getPreviousBuild()}
      */
     @Restricted(NoExternalUse.class)
-    protected transient RunMap<R> builds = new RunMap<R>();
+    protected transient RunMap<R> builds;
 
     /**
      * The quiet period. Null to delegate to the system default.
@@ -271,6 +271,12 @@ public void onCreatedFromScratch() {
         super.onCreatedFromScratch();
         // solicit initial contributions, especially from TransientProjectActionFactory
         updateTransientActions();
+        assert builds==null;
+        builds = new RunMap<R>(getBuildDir(), new Constructor<R>() {
+            public R create(File dir) throws IOException {
+        	return loadBuild(dir);
+            }
+        });
     }
 
     @Override

core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java

@@ -203,8 +203,8 @@ protected void initBaseDir(File dir) {
     private void loadIdOnDisk() {
         String[] buildDirs = dir.list(createDirectoryFilter());
         if (buildDirs==null) {
+            // the job may just have been created
             buildDirs=EMPTY_STRING_ARRAY;
-            LOGGER.log(Level.WARNING, "failed to load list of builds from {0}", dir);
         }
         // wrap into ArrayList to enable mutation
         Arrays.sort(buildDirs);
@@ -625,6 +625,7 @@ protected R load(int n, Index editInPlace) {
 
 
     protected R load(String id, Index editInPlace) {
+        assert dir != null;
         R v = load(new File(dir, id), editInPlace);
         if (v==null && editInPlace!=null) {
             // remember the failure.

test/src/test/java/hudson/model/AbstractProjectTest.java

@@ -47,6 +47,9 @@
 import java.io.File;
 import java.util.concurrent.Future;
 import org.apache.commons.io.FileUtils;
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
 
 /**
  * @author Kohsuke Kawaguchi
@@ -280,4 +283,47 @@ public void testSymlinkForPostBuildFailure() throws Exception {
         assertSymlinkForBuild(lastSuccessful, 1);
         assertSymlinkForBuild(lastStable, 1);
     }
+
+    // Force garbage collection of ref's referent. Taken from NetBeans code.
+    public static void forceGc(final Reference<?> ref) {
+        ArrayList<byte[]> alloc = new ArrayList<byte[]>();
+        int size = 100000;
+        System.out.print("forcing garbage collection...");
+        for (int i = 0; i < 50; i++) {
+            if (ref.get() == null) {
+                System.out.println("succeeded");
+                return;
+            }
+            try {
+                System.gc();
+                System.runFinalization();
+            } catch (OutOfMemoryError error) {
+                // OK
+            }
+            try {
+                alloc.add(new byte[size]);
+                size = (int)(((double)size) * 1.3);
+            } catch (OutOfMemoryError error) {
+                size = size / 2;
+            }
+            try {
+                if (i % 3 == 0) {
+                    Thread.sleep(321);
+                }
+            } catch (InterruptedException t) {
+                // ignore
+            }
+        }
+        System.out.println("failed");
+    }
+
+    @Bug(15156)
+    public void testGetBuildAfterGc() throws Exception {
+        FreeStyleProject job = createFreeStyleProject();
+        job.scheduleBuild2(0, new Cause.UserCause()).get();
+        // If this fails to garbage-collect, the test run will not have any value, but it will
+        // at least not fail.
+        forceGc(new WeakReference(job.getLastBuild()));
+        assertTrue(job.getLastBuild() != null);
+    }
 }