Merge remote branch 'upstream/master'

6 files changed, 201 insertions, 58 deletions

diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapClassLoader.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapClassLoader.java
deleted file mode 100644
index ca00f9a0691..00000000000
--- a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapClassLoader.java
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Sonar, open source software quality management tool.
- * Copyright (C) 2008-2011 SonarSource
- * mailto:contact AT sonarsource DOT com
- *
- * Sonar is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 3 of the License, or (at your option) any later version.
- *
- * Sonar is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with Sonar; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
- */
-package org.sonar.batch.bootstrap;
-
-import org.sonar.api.utils.SonarException;
-
-import java.io.File;
-import java.net.MalformedURLException;
-import java.net.URL;
-import java.net.URLClassLoader;
-
-/**
- * ClassLoader extended with the JDBC Driver hosted on the server-side.
- */
-public class BootstrapClassLoader {
-
-  private URLClassLoader classLoader;
-
-  public BootstrapClassLoader(ArtifactDownloader extensionDownloader) {
-    this(extensionDownloader.downloadJdbcDriver());
-  }
-
-  BootstrapClassLoader(File jdbcDriver) {
-    try {
-      ClassLoader parentClassLoader = BootstrapClassLoader.class.getClassLoader();
-      classLoader = URLClassLoader.newInstance(new URL[]{jdbcDriver.toURI().toURL()}, parentClassLoader);
-
-    } catch (MalformedURLException e) {
-      throw new SonarException("Fail to get URL of : " + jdbcDriver.getAbsolutePath(), e);
-    }
-  }
-
-  public URLClassLoader getClassLoader() {
-    return classLoader;
-  }
-}
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapModule.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapModule.java
index 0eaf338f8fa..fc09ef25dd0 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapModule.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BootstrapModule.java
@@ -55,9 +55,9 @@ public class BootstrapModule extends Module {
     addComponent(TempDirectories.class);// registered here because used by BootstrapClassLoader
     addComponent(HttpDownloader.class);// registered here because used by BootstrapClassLoader
     addComponent(ArtifactDownloader.class);// registered here because used by BootstrapClassLoader
-    addComponent(BootstrapClassLoader.class);
+    addComponent(JdbcDriverHolder.class);
 
-    URLClassLoader bootstrapClassLoader = getComponent(BootstrapClassLoader.class).getClassLoader();
+    URLClassLoader bootstrapClassLoader = getComponent(JdbcDriverHolder.class).getClassLoader();
     // set as the current context classloader for hibernate, else it does not find the JDBC driver.
     Thread.currentThread().setContextClassLoader(bootstrapClassLoader);
 
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcDriverHolder.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcDriverHolder.java
new file mode 100644
index 00000000000..427ac20e3ab
--- /dev/null
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcDriverHolder.java
@@ -0,0 +1,132 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2011 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * Sonar is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * Sonar is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sonar; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
+ */
+package org.sonar.batch.bootstrap;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.sonar.api.utils.SonarException;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.List;
+
+/**
+ * Contains and provides class loader extended with the JDBC Driver hosted on the server-side.
+ */
+public class JdbcDriverHolder {
+
+  private static Logger LOG = LoggerFactory.getLogger(JdbcDriverHolder.class);
+  private JdbcDriverClassLoader classLoader;
+
+  public JdbcDriverHolder(ArtifactDownloader extensionDownloader) {
+    this(extensionDownloader.downloadJdbcDriver());
+  }
+
+  JdbcDriverHolder(File jdbcDriver) {
+    try {
+      ClassLoader parentClassLoader = JdbcDriverHolder.class.getClassLoader();
+      classLoader = new JdbcDriverClassLoader(jdbcDriver.toURI().toURL(), parentClassLoader);
+
+    } catch (MalformedURLException e) {
+      throw new SonarException("Fail to get URL of : " + jdbcDriver.getAbsolutePath(), e);
+    }
+  }
+
+  public URLClassLoader getClassLoader() {
+    return classLoader;
+  }
+
+  /**
+   * This method automatically invoked by PicoContainer and deregisters JDBC drivers, which were forgotten.
+   * <p>
+   * Dynamically loaded JDBC drivers can not be simply used and this is a well known problem of {@link java.sql.DriverManager},
+   * so <a href="http://stackoverflow.com/questions/288828/how-to-use-a-jdbc-driver-from-an-arbitrary-location">workaround is to use proxy</a>.
+   * However DriverManager also contains memory leak, thus not only proxy, but also original driver must be deregistered,
+   * otherwise our class loader would be kept in memory.
+   * </p>
+   * <p>
+   * This operation contains unnecessary complexity because:
+   * <ul>
+   * <li>DriverManager checks the class loader of the calling class. Thus we can't simply ask it about deregistration.</li>
+   * <li>We can't use reflection against DriverManager, since it would create a dependency on DriverManager implementation,
+   * which can be changed (like it was done - compare Java 1.5 and 1.6).</li>
+   * <li>So we use companion - {@link JdbcLeakPrevention}. But we can't just create an instance,
+   * since it will be loaded by parent class loader and again will not pass DriverManager's check.
+   * So, we load the bytes via our parent class loader, but define the class with this class loader
+   * thus JdbcLeakPrevention looks like our class to the DriverManager.</li>
+   * </li>
+   * </p>
+   */
+  public void stop() {
+    classLoader.clearReferencesJdbc();
+    classLoader = null;
+  }
+
+  private static class JdbcDriverClassLoader extends URLClassLoader {
+
+    public JdbcDriverClassLoader(URL jdbcDriver, ClassLoader parent) {
+      super(new URL[] { jdbcDriver }, parent);
+    }
+
+    public void clearReferencesJdbc() {
+      InputStream is = getResourceAsStream("org/sonar/batch/bootstrap/JdbcLeakPrevention.class");
+      byte[] classBytes = new byte[2048];
+      int offset = 0;
+      try {
+        int read = is.read(classBytes, offset, classBytes.length - offset);
+        while (read > -1) {
+          offset += read;
+          if (offset == classBytes.length) {
+            // Buffer full - double size
+            byte[] tmp = new byte[classBytes.length * 2];
+            System.arraycopy(classBytes, 0, tmp, 0, classBytes.length);
+            classBytes = tmp;
+          }
+          read = is.read(classBytes, offset, classBytes.length - offset);
+        }
+
+        Class<?> lpClass = defineClass("org.sonar.batch.bootstrap.JdbcLeakPrevention", classBytes, 0, offset, this.getClass().getProtectionDomain());
+        Object obj = lpClass.newInstance();
+
+        @SuppressWarnings("unchecked")
+        List<String> driverNames = (List<String>) obj.getClass().getMethod("clearJdbcDriverRegistrations").invoke(obj);
+
+        for (String name : driverNames) {
+          LOG.debug("To prevent a memory leak, the JDBC Driver [{}] has been forcibly deregistered", name);
+        }
+      } catch (Exception e) {
+        LOG.warn("JDBC driver deregistration failed", e);
+      } finally {
+        if (is != null) {
+          try {
+            is.close();
+          } catch (IOException ioe) {
+            LOG.warn(ioe.getMessage(), ioe);
+          }
+        }
+      }
+    }
+  }
+
+}
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcLeakPrevention.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcLeakPrevention.java
new file mode 100644
index 00000000000..6da6514d45e
--- /dev/null
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/JdbcLeakPrevention.java
@@ -0,0 +1,64 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2011 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * Sonar is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * Sonar is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sonar; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
+ */
+package org.sonar.batch.bootstrap;
+
+import java.sql.Driver;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.List;
+
+/**
+ * Companion of {@link JdbcDriverHolder} and allows it to deregister JDBC drivers.
+ * <p>
+ * Some hacks are involved in the loading of the class - see {@link JdbcDriverHolder#stop()},
+ * so this class can refer to classes only from java.* package and must not be referred from other classes.
+ * Placement and naming of this class and methods are very important, since it loaded and invoked via reflection.
+ * </p>
+ */
+public class JdbcLeakPrevention {
+
+  /**
+   * @return list of names of deregistered drivers
+   */
+  public List<String> clearJdbcDriverRegistrations() throws SQLException {
+    List<String> driverNames = new ArrayList<String>();
+    HashSet<Driver> originalDrivers = new HashSet<Driver>();
+    Enumeration<Driver> drivers = DriverManager.getDrivers();
+    while (drivers.hasMoreElements()) {
+      originalDrivers.add(drivers.nextElement());
+    }
+    drivers = DriverManager.getDrivers();
+    while (drivers.hasMoreElements()) {
+      Driver driver = drivers.nextElement();
+      if (driver.getClass().getClassLoader() != this.getClass().getClassLoader()) {
+        continue;
+      }
+      if (originalDrivers.contains(driver)) {
+        driverNames.add(driver.getClass().getCanonicalName());
+      }
+      DriverManager.deregisterDriver(driver);
+    }
+    return driverNames;
+  }
+
+}
diff --git a/sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinder.java b/sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinder.java
index 4962be2b8e6..dd59bb2009d 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinder.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinder.java
@@ -63,8 +63,8 @@ public class PastSnapshotFinder implements BatchExtension {
       case 1: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_1; break;
       case 2: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_2; break;
       case 3: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_3; break;
-      case 4: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_4; break;
-      case 5: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_5; break;// NOSONAR false-positive: constant 5 is the same than 4 (empty string)
+      case 4: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_4; break; // NOSONAR false-positive: constant 4 is the same than 5 (empty string)
+      case 5: defaultValue = CoreProperties.TIMEMACHINE_DEFAULT_PERIOD_5; break; // NOSONAR false-positive: constant 5 is the same than 4 (empty string)
     }
     return conf.getString(CoreProperties.TIMEMACHINE_PERIOD_PREFIX + index, defaultValue);
   }
diff --git a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BootstrapClassLoaderTest.java b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BootstrapClassLoaderTest.java
index b28a4c33431..dfee29db761 100644
--- a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BootstrapClassLoaderTest.java
+++ b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BootstrapClassLoaderTest.java
@@ -37,7 +37,7 @@ public class BootstrapClassLoaderTest {
     assertNull(getClass().getClassLoader().getResource("foo/foo.txt"));
 
     URL url = getClass().getResource("/org/sonar/batch/bootstrap/BootstrapClassLoaderTest/foo.jar");
-    BootstrapClassLoader classloader = new BootstrapClassLoader(new File(url.toURI()));
+    JdbcDriverHolder classloader = new JdbcDriverHolder(new File(url.toURI()));
     assertNotNull(classloader.getClassLoader());
     assertNotNull(classloader.getClassLoader().getResource("foo/foo.txt"));