Fix #4. Fix bug in locks handling.

Author: cyrille-leclerc

src/main/java/com/cloudbees/syslog/util/CachingReference.java

@@ -82,11 +82,11 @@ public E get() {
                         object = newObject();
                         lastCreationInNanos = System.nanoTime();
                     }
+                } finally {
                     // Downgrade by acquiring read lock before releasing write lock
                     rwl.readLock().lock();
-                } finally {
                     rwl.writeLock().unlock();
-                }
+                 }
             }
             return object;
         } finally {

src/test/java/com/cloudbees/syslog/util/CachingReferenceTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2010-2013, CloudBees Inc.
+ *
+ * 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 com.cloudbees.syslog.util;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.annotation.Nullable;
+import java.util.concurrent.TimeUnit;
+
+public class CachingReferenceTest {
+    /**
+     * Test that the locks are properly released.
+     */
+    @Test
+    public void test_return_value() {
+
+        CachingReference<String> cachingReference = new CachingReference<String>(5, TimeUnit.SECONDS) {
+            @Nullable
+            @Override
+            protected String newObject() {
+                return "value";
+            }
+        };
+
+        String actual = cachingReference.get();
+        Assert.assertThat(actual, Matchers.equalTo("value"));
+    }
+
+    /**
+     * Test that the locks are properly released.
+     */
+    @Test(expected = MyRuntimeException.class)
+    public void test_throw_exception_in_get_object() {
+
+        CachingReference<String> cachingReference = new CachingReference<String>(5, TimeUnit.SECONDS) {
+            @Nullable
+            @Override
+            protected String newObject() {
+                throw new MyRuntimeException();
+            }
+        };
+
+        cachingReference.get();
+    }
+
+
+    private static class MyRuntimeException extends RuntimeException {
+        public MyRuntimeException() {
+            super();
+        }
+
+        public MyRuntimeException(Throwable cause) {
+            super(cause);
+        }
+
+        public MyRuntimeException(String message) {
+            super(message);
+        }
+
+        public MyRuntimeException(String message, Throwable cause) {
+            super(message, cause);
+        }
+
+        protected MyRuntimeException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
+            super(message, cause, enableSuppression, writableStackTrace);
+        }
+    }
+}