Merge pull request #928 from olivierdagenais/FixRandomHttp404

[FIXED JENKINS-19418] Fix random HTTP 404 when viewing build details

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

@@ -498,6 +498,13 @@ public abstract class AbstractLazyLoadRunMap<R> extends AbstractMap<Integer,R> i
             }
             return getById(idOnDisk.get(lo-1));
         case EXACT:
+            if (hi<=0)                 return null;
+            R r = load(idOnDisk.get(hi-1), null);
+            if (r==null)               return null;
+
+            int found = getNumberOf(r);
+            if (found==n)
+                return r;   // exact match
             return null;
         default:
             throw new AssertionError();

core/src/test/java/jenkins/model/lazy/AbstractLazyLoadRunMapTest.java

@@ -57,6 +57,21 @@ public class AbstractLazyLoadRunMapTest extends Assert {
     @Rule
     public FakeMapBuilder localBuilder = new FakeMapBuilder();
 
+    @Rule
+    public FakeMapBuilder localExpiredBuilder = new FakeMapBuilder() {
+        @Override
+        public FakeMap make() {
+            assert getDir()!=null;
+            return new FakeMap(getDir()) {
+                @Override
+                protected BuildReference<Build> createReference(Build r) {
+                    return new BuildReference<Build>(getIdOf(r), /* pretend referent expired */ null);
+                }
+            };
+        }
+    };
+ 
+    
     @BeforeClass
     public static void setUpClass() {
         AbstractLazyLoadRunMap.LOGGER.setLevel(Level.OFF);
@@ -134,6 +149,18 @@ public class AbstractLazyLoadRunMapTest extends Assert {
         assertNull(a.search(-99, Direction.DESC));
     }
 
+    @Test
+    public void searchExactWhenIndexedButSoftReferenceExpired() throws IOException {
+        final FakeMap m = localExpiredBuilder.add(1, "A").add(2, "B").make();
+
+        // force index creation
+        m.entrySet();
+
+        m.search(1, Direction.EXACT).asserts(1, "A");
+        assertNull(m.search(3, Direction.EXACT));
+        assertNull(m.search(0, Direction.EXACT));
+    }
+
     /**
      * If load fails, search needs to gracefully handle it
      */

core/src/test/java/jenkins/model/lazy/FakeMapBuilder.java

@@ -39,6 +39,10 @@ import java.io.IOException;
 public class FakeMapBuilder implements TestRule {
     private File dir;
 
+    protected File getDir() {
+        return dir;
+    }
+
     public FakeMapBuilder() {
     }