add shutdown hook to resolve #1027

dependency-check-core/src/main/java/org/owasp/dependencycheck/utils/H2DBCleanupHook.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2017 OWASP.
+ *
+ * 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 org.owasp.dependencycheck.utils;
+
+/**
+ *
+ * @author jeremy
+ */
+public class H2DBCleanupHook extends Thread {
+
+    private final H2DBLock lock;
+
+    public H2DBCleanupHook(H2DBLock lock) {
+        this.lock = lock;
+    }
+
+    @Override
+    public void run() {
+        lock.release();
+    }
+}

dependency-check-core/src/main/java/org/owasp/dependencycheck/utils/H2DBLock.java

@@ -69,6 +69,8 @@ public class H2DBLock {
      */
     private final String magic;
     
+    private H2DBCleanupHook hook = null;
+
     /**
      * Constructs a new H2DB Lock object with the configured settings.
      *
@@ -126,6 +128,7 @@ public class H2DBLock {
                             lock = null;
                             LOGGER.debug("Another process obtained a lock first ({})", Thread.currentThread().getName());
                         } else {
+                            addShutdownHook();
                             final Timestamp timestamp = new Timestamp(System.currentTimeMillis());
                             LOGGER.debug("Lock file created ({}) {} @ {}", Thread.currentThread().getName(), magic, timestamp.toString());
                         }
@@ -196,6 +199,7 @@ public class H2DBLock {
             }
         }
         lockFile = null;
+        removeShutdownHook();
         final Timestamp timestamp = new Timestamp(System.currentTimeMillis());
         LOGGER.debug("Lock released ({}) {} @ {}", Thread.currentThread().getName(), magic, timestamp.toString());
     }
@@ -213,4 +217,22 @@ public class H2DBLock {
         LOGGER.debug("Lock file age is {} minutes", time);
         return time;
     }
+    
+    private void addShutdownHook() {
+        if (hook == null) {
+            hook = new H2DBCleanupHook(this);
+            Runtime.getRuntime().addShutdownHook(hook);
+        }
+    }
+    
+    private void removeShutdownHook() {
+        if (hook != null) {
+            try {
+                Runtime.getRuntime().removeShutdownHook(hook);
+            } catch (IllegalStateException ex) {
+                LOGGER.trace("ignore as we are likely shutting down", ex);
+            }
+            hook = null;
+        }
+    }
 }