merge cache configuration from default location, config directory and plugins

scm-webapp/src/main/java/sonia/scm/cache/EhCacheConfigurationReader.java

@@ -0,0 +1,477 @@
+/**
+ * Copyright (c) 2010, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.cache;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Objects;
+import com.google.common.collect.Iterators;
+import com.google.common.collect.Maps;
+import com.google.common.io.Closeables;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import sonia.scm.SCMContext;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.Map;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+public class EhCacheConfigurationReader
+{
+
+  /** Field description */
+  private static final String ATTRIBUTE_NAME = "name";
+
+  /** Field description */
+  private static final String DEFAULT = "/config/ehcache.xml";
+
+  /** Field description */
+  private static final String MANUAL_RESOURCE =
+    "ext".concat(File.separator).concat("cache.xml");
+
+  /** Field description */
+  private static final String MODULE_RESOURCES = "/META-INF/scm/cache.xml";
+
+  /**
+   * the logger for EhCacheConfigurationReader
+   */
+  private static final Logger logger =
+    LoggerFactory.getLogger(EhCacheConfigurationReader.class);
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   */
+  public EhCacheConfigurationReader()
+  {
+    try
+    {
+      builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
+    }
+    catch (ParserConfigurationException ex)
+    {
+      throw new RuntimeException("could not create document builder", ex);
+    }
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public InputStream read()
+  {
+    URL defaultConfig = getDefaultResource();
+
+    if (defaultConfig == null)
+    {
+      throw new IllegalStateException(
+        "could not find default cache configuration");
+    }
+
+    readConfiguration(defaultConfig, true);
+
+    Iterator<URL> it = getModuleResources();
+
+    while (it.hasNext())
+    {
+      readConfiguration(it.next(), false);
+    }
+
+    File manualFile = getManualFileResource();
+
+    if (manualFile.exists())
+    {
+      try
+      {
+        readConfiguration(manualFile.toURI().toURL(), false);
+      }
+      catch (MalformedURLException ex)
+      {
+        logger.error("malformed url", ex);
+      }
+    }
+    else
+    {
+      logger.warn("could not find manual configuration at {}", manualFile);
+    }
+
+    Document doc = createMergedConfiguration();
+
+    return createInputStream(doc);
+  }
+
+  //~--- get methods ----------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param path
+   *
+   * @return
+   */
+  @VisibleForTesting
+  protected URL getDefaultResource()
+  {
+    return EhCacheConfigurationReader.class.getResource(DEFAULT);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  @VisibleForTesting
+  protected File getManualFileResource()
+  {
+    return new File(SCMContext.getContext().getBaseDirectory(),
+      MANUAL_RESOURCE);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param path
+   *
+   * @return
+   */
+  @VisibleForTesting
+  protected Iterator<URL> getModuleResources()
+  {
+    Iterator<URL> it = null;
+
+    try
+    {
+      ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+
+      if (classLoader == null)
+      {
+        classLoader = EhCacheConfigurationReader.class.getClassLoader();
+      }
+
+      Enumeration<URL> enm = classLoader.getResources(MODULE_RESOURCES);
+
+      if (enm != null)
+      {
+        it = Iterators.forEnumeration(enm);
+      }
+
+    }
+    catch (IOException ex)
+    {
+      logger.error("could not read cache module resources", ex);
+    }
+
+    if (it == null)
+    {
+      it = Iterators.emptyIterator();
+    }
+
+    return it;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param doc
+   *
+   * @return
+   */
+  private InputStream createInputStream(Document doc)
+  {
+    InputStream stream;
+    Transformer transformer;
+
+    try
+    {
+      transformer = TransformerFactory.newInstance().newTransformer();
+      transformer.setOutputProperty(OutputKeys.INDENT, "yes");
+
+      ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+      transformer.transform(new DOMSource(doc), new StreamResult(baos));
+
+      if (logger.isTraceEnabled())
+      {
+        logger.trace("effective ehcache configuration: {}", baos.toString());
+      }
+
+      stream = new ByteArrayInputStream(baos.toByteArray());
+    }
+    catch (Exception ex)
+    {
+      throw new IllegalStateException("could not create transformer", ex);
+    }
+
+    return stream;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  private Document createMergedConfiguration()
+  {
+    Document merged = builder.newDocument();
+
+    Element rootEl = merged.createElementNS("http://ehcache.org/ehcache.xsd",
+                       "ehcache");
+
+    for (Node node : map.values())
+    {
+      Node mergedNode = merged.adoptNode(node);
+
+      rootEl.appendChild(mergedNode);
+    }
+
+    merged.appendChild(rootEl);
+
+    return merged;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param url
+   * @param throwException
+   */
+  private void readConfiguration(URL url, boolean throwException)
+  {
+    logger.debug("read cache configuration from url {}", url.toExternalForm());
+
+    InputStream stream = null;
+
+    try
+    {
+      stream = url.openStream();
+
+      Document document = builder.parse(stream);
+      Element rootEl = document.getDocumentElement();
+
+      readConfiguration(rootEl);
+    }
+    catch (Exception ex)
+    {
+      if (throwException)
+      {
+        throw new RuntimeException(
+          "could not read configuration at ".concat(url.toExternalForm()), ex);
+      }
+      else
+      {
+        logger.warn("could not read configuration at {}", url.toExternalForm());
+      }
+    }
+    finally
+    {
+      Closeables.closeQuietly(stream);
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param rootEl
+   */
+  private void readConfiguration(Element rootEl)
+  {
+    NodeList list = rootEl.getChildNodes();
+
+    for (int i = 0; i < list.getLength(); i++)
+    {
+      Node node = list.item(i);
+
+      if (Node.ELEMENT_NODE == node.getNodeType())
+      {
+        String element = node.getNodeName();
+        String name = null;
+        Node nameNode = node.getAttributes().getNamedItem(ATTRIBUTE_NAME);
+
+        if (nameNode != null)
+        {
+          name = nameNode.getNodeValue();
+        }
+
+        map.put(new Id(element, name), node);
+      }
+    }
+  }
+
+  //~--- inner classes --------------------------------------------------------
+
+  /**
+   * Class description
+   *
+   *
+   * @version        Enter version here..., 13/03/19
+   * @author         Enter your name here...
+   */
+  private static class Id
+  {
+
+    /**
+     * Constructs ...
+     *
+     *
+     * @param element
+     * @param name
+     */
+    public Id(String element, String name)
+    {
+      this.element = element;
+      this.name = name;
+    }
+
+    //~--- methods ------------------------------------------------------------
+
+    /**
+     * Method description
+     *
+     *
+     * @param obj
+     *
+     * @return
+     */
+    @Override
+    public boolean equals(Object obj)
+    {
+      if (obj == null)
+      {
+        return false;
+      }
+
+      if (getClass() != obj.getClass())
+      {
+        return false;
+      }
+
+      final Id other = (Id) obj;
+
+      return Objects.equal(element, other.element)
+        && Objects.equal(name, other.name);
+    }
+
+    /**
+     * Method description
+     *
+     *
+     * @return
+     */
+    @Override
+    public int hashCode()
+    {
+      return Objects.hashCode(element, name);
+    }
+
+    /**
+     * Method description
+     *
+     *
+     * @return
+     */
+    @Override
+    public String toString()
+    {
+
+      //J-
+      return Objects.toStringHelper(this)
+                    .add("element", element)
+                    .add("name", name)
+                    .toString();
+      //J+
+    }
+
+    //~--- fields -------------------------------------------------------------
+
+    /** Field description */
+    private String element;
+
+    /** Field description */
+    private String name;
+  }
+
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** Field description */
+  private DocumentBuilder builder;
+
+  /** Field description */
+  private Map<Id, Node> map = Maps.newLinkedHashMap();
+}