SONAR-2291 Implement caching of downloaded Sonar plugins.

* By default cache location is ~/.sonar/.cache
* Cache location can be changed by property sonar.cacheLocation
* To know if a plugin file have to be downloaded there is a checksum (MD5) comparison

7 files changed, 436 insertions, 43 deletions

diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BatchSonarCache.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BatchSonarCache.java
new file mode 100644
index 00000000000..ea2ba927304
--- /dev/null
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/BatchSonarCache.java
@@ -0,0 +1,51 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2012 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.CoreProperties;
+import org.sonar.api.config.Settings;
+import org.sonar.api.task.TaskExtension;
+import org.sonar.batch.cache.SonarCache;
+
+import java.io.File;
+
+public class BatchSonarCache implements TaskExtension {
+
+  private Settings settings;
+  private SonarCache cache;
+
+  public BatchSonarCache(Settings settings) {
+    this.settings = settings;
+  }
+
+  public void start() {
+    String cacheLocation = settings.getString(CoreProperties.CACHE_LOCATION);
+    SonarCache.Builder builder = SonarCache.create();
+    if (cacheLocation != null) {
+      File cacheLocationFolder = new File(cacheLocation);
+      builder.setCacheLocation(cacheLocationFolder);
+    }
+    this.cache = builder.build();
+  }
+
+  public SonarCache getCache() {
+    return cache;
+  }
+}
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 c65099b3f22..39614208ea1 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
@@ -74,6 +74,7 @@ public class BootstrapModule extends Module {
     container.addSingleton(HttpDownloader.class);
     container.addSingleton(UriReader.class);
     container.addSingleton(PluginDownloader.class);
+    container.addSingleton(BatchSonarCache.class);
     for (Object component : boostrapperComponents) {
       if (component != null) {
         container.addSingleton(component);
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/PluginDownloader.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/PluginDownloader.java
index e462afbc10b..d0852e487a2 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/PluginDownloader.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/PluginDownloader.java
@@ -20,14 +20,15 @@
 package org.sonar.batch.bootstrap;
 
 import com.google.common.collect.Lists;
-import org.apache.commons.io.FileUtils;
 import org.apache.commons.lang.CharUtils;
 import org.apache.commons.lang.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.sonar.api.BatchComponent;
 import org.sonar.api.utils.SonarException;
+import org.sonar.batch.cache.SonarCache;
 import org.sonar.core.plugins.RemotePlugin;
+import org.sonar.core.plugins.RemotePluginFile;
 
 import java.io.File;
 import java.util.List;
@@ -36,26 +37,48 @@ public class PluginDownloader implements BatchComponent {
 
   private static final Logger LOG = LoggerFactory.getLogger(PluginDownloader.class);
 
-  private TempDirectories workingDirectories;
   private ServerClient server;
+  private BatchSonarCache batchCache;
 
-  public PluginDownloader(TempDirectories workingDirectories, ServerClient server) {
-    this.workingDirectories = workingDirectories;
+  public PluginDownloader(BatchSonarCache batchCache, ServerClient server) {
     this.server = server;
+    this.batchCache = batchCache;
+  }
+
+  private SonarCache getSonarCache() {
+    return batchCache.getCache();
   }
 
   public List<File> downloadPlugin(RemotePlugin remote) {
     try {
-      File targetDir = workingDirectories.getDir("plugins/" + remote.getKey());
-      FileUtils.forceMkdir(targetDir);
-      LOG.debug("Downloading plugin " + remote.getKey() + " into " + targetDir);
-
       List<File> files = Lists.newArrayList();
-      for (String filename : remote.getFilenames()) {
-        String url = "/deploy/plugins/" + remote.getKey() + "/" + filename;
-        File toFile = new File(targetDir, filename);
-        server.download(url, toFile);
-        files.add(toFile);
+      for (RemotePluginFile file : remote.getFiles()) {
+        LOG.debug("Looking if plugin file {} with md5 {} is already in cache", file.getFilename(), file.getMd5());
+        File fileInCache = getSonarCache().getFileFromCache(file.getFilename(), file.getMd5());
+        if (fileInCache != null) {
+          LOG.debug("File is already cached at location {}", fileInCache.getAbsolutePath());
+        }
+        else {
+          LOG.debug("File is not cached");
+          File tmpDownloadFile = getSonarCache().getTemporaryFile();
+          String url = "/deploy/plugins/" + remote.getKey() + "/" + file.getFilename();
+          if (LOG.isDebugEnabled()) {
+            LOG.debug("Downloading {} to {}", url, tmpDownloadFile.getAbsolutePath());
+          }
+          else {
+            LOG.info("Downloading {}", file.getFilename());
+          }
+          server.download(url, tmpDownloadFile);
+          LOG.debug("Trying to cache file");
+          String md5 = getSonarCache().cacheFile(tmpDownloadFile, file.getFilename());
+          fileInCache = getSonarCache().getFileFromCache(file.getFilename(), md5);
+          if (!md5.equals(file.getMd5())) {
+            LOG.warn("INVALID CHECKSUM: File {} was expected to have checksum {} but was cached with checksum {}",
+                new String[] {fileInCache.getAbsolutePath(), file.getMd5(), md5});
+          }
+          LOG.debug("File cached at location {}", fileInCache.getAbsolutePath());
+        }
+        files.add(fileInCache);
       }
       return files;
 
diff --git a/sonar-batch/src/main/java/org/sonar/batch/cache/SonarCache.java b/sonar-batch/src/main/java/org/sonar/batch/cache/SonarCache.java
new file mode 100644
index 00000000000..bd203b2d17b
--- /dev/null
+++ b/sonar-batch/src/main/java/org/sonar/batch/cache/SonarCache.java
@@ -0,0 +1,192 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2012 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.cache;
+
+import com.google.common.io.Files;
+import org.apache.commons.codec.digest.DigestUtils;
+import org.apache.commons.io.FileUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.sonar.api.utils.SonarException;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+/**
+ * This class is responsible for managing Sonar batch file cache. You can put file into cache and
+ * later try to retrieve them. MD5 is used to differentiate files (name is not secure as files may come
+ * from different Sonar servers and have same name but be actually different, and same for SNAPSHOTs).
+ * Default location of cache is 
+ * @author Julien HENRY
+ *
+ */
+public class SonarCache {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SonarCache.class);
+
+  private static final int TEMP_FILE_ATTEMPTS = 10000;
+
+  private File cacheLocation;
+  /**
+   * Temporary directory where files should be stored before be inserted in the cache.
+   * Having a temporary close to the final location (read on same FS) will assure
+   * the move will be atomic.
+   */
+  private File tmpDir;
+
+  private SonarCache(File cacheLocation) {
+    this.cacheLocation = cacheLocation;
+    tmpDir = new File(cacheLocation, ".tmp");
+    if (!cacheLocation.exists()) {
+      LOG.debug("Creating cache directory: " + cacheLocation.getAbsolutePath());
+      try {
+        FileUtils.forceMkdir(cacheLocation);
+      } catch (IOException e) {
+        throw new SonarException("Unable to create cache directory " + cacheLocation.getAbsolutePath(), e);
+      }
+    }
+  }
+
+  public static class Builder {
+
+    private File cacheLocation;
+
+    public Builder setCacheLocation(File cacheLocation) {
+      this.cacheLocation = cacheLocation;
+      return this;
+    }
+
+    public SonarCache build() {
+      if (cacheLocation == null) {
+        File sonarHome = new File(System.getProperty("user.home"), ".sonar");
+        return new SonarCache(new File(sonarHome, ".cache"));
+      }
+      else {
+        return new SonarCache(cacheLocation);
+      }
+    }
+
+  }
+
+  public static Builder create() {
+    return new Builder();
+  }
+
+  /**
+   * Move the given file inside the cache. Return the MD5 of the cached file.
+   * @param sourceFile
+   * @throws IOException 
+   */
+  public String cacheFile(File sourceFile, String filename) throws IOException {
+    File tmpFileName = null;
+    try {
+      if (!sourceFile.getParentFile().equals(getTmpDir())) {
+        // Provided file is not close to the cache so we will move it first in a temporary file (could be non atomic)
+        tmpFileName = getTemporaryFile();
+        Files.move(sourceFile, tmpFileName);
+      }
+      else {
+        tmpFileName = sourceFile;
+      }
+      // Now compute the md5 to find the final destination
+      FileInputStream fis = new FileInputStream(tmpFileName);
+      String md5 = DigestUtils.md5Hex(fis);
+      File finalDir = new File(cacheLocation, md5);
+      File finalFileName = new File(finalDir, filename);
+      // Try to create final destination folder
+      FileUtils.forceMkdir(finalDir);
+      // Now try to move the file from temporary folder to final location
+      boolean rename = tmpFileName.renameTo(finalFileName);
+      if (!rename) {
+        // Check if the file was already in cache
+        if (!finalFileName.exists()) {
+          LOG.warn("Unable to rename " + tmpFileName.getAbsolutePath() + " to " + finalFileName.getAbsolutePath());
+          LOG.warn("A copy/delete will be tempted but with no garantee of atomicity");
+          FileUtils.moveFile(tmpFileName, finalFileName);
+        }
+      }
+      return md5;
+    } finally {
+      FileUtils.deleteQuietly(tmpFileName);
+    }
+
+  }
+
+  /**
+   * Look for a file in the cache by its filename and md5 checksum. If the file is not
+   * present then return null.
+   */
+  public File getFileFromCache(String filename, String md5) {
+    File location = new File(new File(cacheLocation, md5), filename);
+    if (location.exists()) {
+      return location;
+    }
+    LOG.debug("No file found in the cache with name {} and checksum {}", filename, md5);
+    return null;
+  }
+
+  /**
+   * Return a temporary file that caller can use to store file content before
+   * asking for caching it with {@link #cacheFile(File)}.
+   * This is to avoid extra copy.
+   * @return
+   * @throws IOException 
+   */
+  public File getTemporaryFile() throws IOException {
+    return createTempFile(getTmpDir());
+  }
+
+  /**
+   * Create a temporary file in the given directory.
+   * @param baseDir
+   * @return
+   * @throws IOException 
+   */
+  private static File createTempFile(File baseDir) throws IOException {
+    String baseName = System.currentTimeMillis() + "-";
+
+    for (int counter = 0; counter < TEMP_FILE_ATTEMPTS; counter++) {
+      File tempFile = new File(baseDir, baseName + counter);
+      if (tempFile.createNewFile()) {
+        return tempFile;
+      }
+    }
+    throw new IOException("Failed to create temporary file in " + baseDir.getAbsolutePath() + " within "
+      + TEMP_FILE_ATTEMPTS + " attempts (tried "
+      + baseName + "0 to " + baseName + (TEMP_FILE_ATTEMPTS - 1) + ')');
+  }
+
+  public File getTmpDir() {
+    if (!tmpDir.exists()) {
+      LOG.debug("Creating temporary cache directory: " + tmpDir.getAbsolutePath());
+      try {
+        FileUtils.forceMkdir(tmpDir);
+      } catch (IOException e) {
+        throw new SonarException("Unable to create temporary cache directory " + tmpDir.getAbsolutePath(), e);
+      }
+    }
+    return tmpDir;
+  }
+
+  public File getCacheLocation() {
+    return cacheLocation;
+  }
+}
diff --git a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BatchPluginRepositoryTest.java b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BatchPluginRepositoryTest.java
index 6da2f0192bf..f0cf8a22478 100644
--- a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BatchPluginRepositoryTest.java
+++ b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/BatchPluginRepositoryTest.java
@@ -26,6 +26,7 @@ import org.junit.Test;
 import org.sonar.api.CoreProperties;
 import org.sonar.api.config.Settings;
 import org.sonar.core.plugins.RemotePlugin;
+import org.sonar.core.plugins.RemotePluginFile;
 import org.sonar.test.TestUtils;
 
 import java.io.File;
@@ -87,8 +88,8 @@ public class BatchPluginRepositoryTest {
 
   @Test
   public void shouldLoadPluginDeprecatedExtensions() throws IOException {
-    RemotePlugin checkstyle = new RemotePlugin("checkstyle", true)
-      .addFilename("checkstyle-ext.xml");
+    RemotePlugin checkstyle = new RemotePlugin("checkstyle", true);
+    checkstyle.getFiles().add(new RemotePluginFile("checkstyle-ext.xml", "fakemd5"));
 
     PluginDownloader downloader = mock(PluginDownloader.class);
     when(downloader.downloadPlugin(checkstyle)).thenReturn(copyFiles("sonar-checkstyle-plugin-2.8.jar", "checkstyle-ext.xml"));
@@ -143,8 +144,8 @@ public class BatchPluginRepositoryTest {
   @Test
   public void whiteListShouldTakePrecedenceOverBlackList() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs")
-      .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "cobertura,pmd");
+        .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs")
+        .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "cobertura,pmd");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("pmd")).isTrue();
   }
@@ -152,7 +153,7 @@ public class BatchPluginRepositoryTest {
   @Test
   public void corePluginShouldAlwaysBeInWhiteList() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
+        .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("core")).isTrue();
   }
@@ -160,7 +161,7 @@ public class BatchPluginRepositoryTest {
   @Test
   public void corePluginShouldNeverBeInBlackList() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "core,findbugs");
+        .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "core,findbugs");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("core")).isTrue();
   }
@@ -169,7 +170,7 @@ public class BatchPluginRepositoryTest {
   @Test
   public void englishPackPluginShouldNeverBeInBlackList() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "l10nen,findbugs");
+        .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "l10nen,findbugs");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("l10nen")).isTrue();
   }
@@ -177,7 +178,7 @@ public class BatchPluginRepositoryTest {
   @Test
   public void shouldCheckWhitelist() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
+        .setProperty(CoreProperties.BATCH_INCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("checkstyle")).isTrue();
     assertThat(filter.accepts("pmd")).isTrue();
@@ -187,7 +188,7 @@ public class BatchPluginRepositoryTest {
   @Test
   public void shouldCheckBlackListIfNoWhiteList() {
     Settings settings = new Settings()
-      .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
+        .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "checkstyle,pmd,findbugs");
     BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
     assertThat(filter.accepts("checkstyle")).isFalse();
     assertThat(filter.accepts("pmd")).isFalse();
@@ -195,14 +196,14 @@ public class BatchPluginRepositoryTest {
   }
 
   @Test
-    public void should_concatenate_dry_run_filters() {
-      Settings settings = new Settings()
+  public void should_concatenate_dry_run_filters() {
+    Settings settings = new Settings()
         .setProperty(CoreProperties.DRY_RUN, true)
         .setProperty(CoreProperties.DRY_RUN_INCLUDE_PLUGINS, "cockpit")
         .setProperty(CoreProperties.DRY_RUN_EXCLUDE_PLUGINS, "views")
         .setProperty(CoreProperties.BATCH_EXCLUDE_PLUGINS, "checkstyle,pmd");
-      BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
-      assertThat(filter.whites).containsOnly("cockpit");
-      assertThat(filter.blacks).containsOnly("views", "checkstyle", "pmd");
-    }
+    BatchPluginRepository.PluginFilter filter = new BatchPluginRepository.PluginFilter(settings);
+    assertThat(filter.whites).containsOnly("cockpit");
+    assertThat(filter.blacks).containsOnly("views", "checkstyle", "pmd");
+  }
 }
diff --git a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/PluginDownloaderTest.java b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/PluginDownloaderTest.java
index ad32777a15b..65c9fdbe149 100644
--- a/sonar-batch/src/test/java/org/sonar/batch/bootstrap/PluginDownloaderTest.java
+++ b/sonar-batch/src/test/java/org/sonar/batch/bootstrap/PluginDownloaderTest.java
@@ -23,7 +23,10 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
+import org.mockito.Mockito;
+import org.sonar.api.config.Settings;
 import org.sonar.api.utils.SonarException;
+import org.sonar.batch.cache.SonarCache;
 import org.sonar.core.plugins.RemotePlugin;
 
 import java.io.File;
@@ -32,6 +35,7 @@ import java.util.List;
 import static org.fest.assertions.Assertions.assertThat;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -45,10 +49,9 @@ public class PluginDownloaderTest {
 
   @Test
   public void should_request_list_of_plugins() {
-    TempDirectories tempDirs = mock(TempDirectories.class);
     ServerClient server = mock(ServerClient.class);
     when(server.request("/deploy/plugins/index.txt")).thenReturn("checkstyle,true\nsqale,false");
-    PluginDownloader downloader = new PluginDownloader(tempDirs, server);
+    PluginDownloader downloader = new PluginDownloader(new BatchSonarCache(new Settings()), server);
 
     List<RemotePlugin> plugins = downloader.downloadPluginIndex();
     assertThat(plugins).hasSize(2);
@@ -59,24 +62,52 @@ public class PluginDownloaderTest {
   }
 
   @Test
-  public void should_download_plugin() throws Exception {
-    TempDirectories tempDirs = mock(TempDirectories.class);
-    File toDir = temp.newFolder();
-    when(tempDirs.getDir("plugins/checkstyle")).thenReturn(toDir);
+  public void should_download_plugin_if_not_cached() throws Exception {
+    SonarCache cache = mock(SonarCache.class);
+    BatchSonarCache batchCache = mock(BatchSonarCache.class);
+    when(batchCache.getCache()).thenReturn(cache);
+
+    File fileInCache = temp.newFile();
+    when(cache.cacheFile(Mockito.any(File.class), Mockito.anyString())).thenReturn("fakemd51").thenReturn("fakemd52");
+    when(cache.getFileFromCache(Mockito.anyString(), Mockito.anyString()))
+        .thenReturn(null)
+        .thenReturn(fileInCache)
+        .thenReturn(null)
+        .thenReturn(fileInCache);
+    ServerClient server = mock(ServerClient.class);
+    PluginDownloader downloader = new PluginDownloader(batchCache, server);
+
+    RemotePlugin plugin = new RemotePlugin("checkstyle", true)
+        .addFile("checkstyle-plugin.jar", "fakemd51")
+        .addFile("checkstyle-extensions.jar", "fakemd52");
+    List<File> files = downloader.downloadPlugin(plugin);
+
+    assertThat(files).hasSize(2);
+    verify(server).download(Mockito.eq("/deploy/plugins/checkstyle/checkstyle-plugin.jar"), Mockito.any(File.class));
+    verify(server).download(Mockito.eq("/deploy/plugins/checkstyle/checkstyle-extensions.jar"), Mockito.any(File.class));
+  }
+
+  @Test
+  public void should_not_download_plugin_if_cached() throws Exception {
+    SonarCache cache = mock(SonarCache.class);
+    BatchSonarCache batchCache = mock(BatchSonarCache.class);
+    when(batchCache.getCache()).thenReturn(cache);
+
+    File fileInCache = temp.newFile();
+    when(cache.getFileFromCache(Mockito.anyString(), Mockito.anyString()))
+        .thenReturn(fileInCache)
+        .thenReturn(fileInCache);
     ServerClient server = mock(ServerClient.class);
-    PluginDownloader downloader = new PluginDownloader(tempDirs, server);
+    PluginDownloader downloader = new PluginDownloader(batchCache, server);
 
     RemotePlugin plugin = new RemotePlugin("checkstyle", true)
-      .addFilename("checkstyle-plugin.jar")
-      .addFilename("checkstyle-extensions.jar");
+        .addFile("checkstyle-plugin.jar", "fakemd51")
+        .addFile("checkstyle-extensions.jar", "fakemd52");
     List<File> files = downloader.downloadPlugin(plugin);
 
-    File pluginFile = new File(toDir, "checkstyle-plugin.jar");
-    File extFile = new File(toDir, "checkstyle-extensions.jar");
     assertThat(files).hasSize(2);
-    assertThat(files).containsOnly(pluginFile, extFile);
-    verify(server).download("/deploy/plugins/checkstyle/checkstyle-plugin.jar", pluginFile);
-    verify(server).download("/deploy/plugins/checkstyle/checkstyle-extensions.jar", extFile);
+    verify(server, never()).download(Mockito.anyString(), Mockito.any(File.class));
+    verify(cache, never()).cacheFile(Mockito.any(File.class), Mockito.anyString());
   }
 
   @Test
@@ -86,6 +117,6 @@ public class PluginDownloaderTest {
     ServerClient server = mock(ServerClient.class);
     doThrow(new SonarException()).when(server).request("/deploy/plugins/index.txt");
 
-    new PluginDownloader(mock(TempDirectories.class), server).downloadPluginIndex();
+    new PluginDownloader(new BatchSonarCache(new Settings()), server).downloadPluginIndex();
   }
 }
diff --git a/sonar-batch/src/test/java/org/sonar/batch/cache/SonarCacheTest.java b/sonar-batch/src/test/java/org/sonar/batch/cache/SonarCacheTest.java
new file mode 100644
index 00000000000..2566de8e6bf
--- /dev/null
+++ b/sonar-batch/src/test/java/org/sonar/batch/cache/SonarCacheTest.java
@@ -0,0 +1,94 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2012 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.cache;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.File;
+import java.io.IOException;
+
+import static org.fest.assertions.Assertions.assertThat;
+
+public class SonarCacheTest {
+
+  @Rule
+  public TemporaryFolder tempFolder = new TemporaryFolder();
+
+  private SonarCache cache;
+
+  @Before
+  public void prepare() throws IOException {
+    cache = SonarCache.create().setCacheLocation(tempFolder.newFolder()).build();
+  }
+
+  @Test
+  public void testCacheExternalFile() throws IOException {
+    // Create a file outside the cache
+    File fileToCache = tempFolder.newFile();
+    FileUtils.write(fileToCache, "Sample data");
+    // Put it in the cache
+    String md5 = cache.cacheFile(fileToCache, "foo.txt");
+    // Verify the temporary location was created to do the copy in the cache in 2 stages
+    File tmpCache = new File(cache.getCacheLocation(), ".tmp");
+    assertThat(tmpCache).exists();
+    // The tmp location should be empty as the file was moved inside the cache
+    assertThat(tmpCache.list()).isEmpty();
+    // Verify it is present in the cache folder
+    File fileInCache = new File(new File(cache.getCacheLocation(), md5), "foo.txt");
+    assertThat(fileInCache).exists();
+    String content = FileUtils.readFileToString(fileInCache);
+    assertThat(content).isEqualTo("Sample data");
+    // Now retrieve from cache API
+    File fileFromCache = cache.getFileFromCache("foo.txt", md5);
+    assertThat(fileFromCache.getCanonicalPath()).isEqualTo(fileInCache.getCanonicalPath());
+  }
+
+  @Test
+  public void testCacheInternalFile() throws IOException {
+    // Create a file in the cache temp location
+    File fileToCache = cache.getTemporaryFile();
+    // Verify the temporary location was created
+    File tmpCache = new File(cache.getCacheLocation(), ".tmp");
+    assertThat(tmpCache).exists();
+    assertThat(tmpCache.list().length).isEqualTo(1);
+
+    FileUtils.write(fileToCache, "Sample data");
+    String md5 = cache.cacheFile(fileToCache, "foo.txt");
+    // Verify it is present in the cache folder
+    File fileInCache = new File(new File(cache.getCacheLocation(), md5), "foo.txt");
+    assertThat(fileInCache).exists();
+    String content = FileUtils.readFileToString(fileInCache);
+    assertThat(content).isEqualTo("Sample data");
+    // Now retrieve from cache API
+    File fileFromCache = cache.getFileFromCache("foo.txt", md5);
+    assertThat(fileFromCache.getCanonicalPath()).isEqualTo(fileInCache.getCanonicalPath());
+  }
+
+  @Test
+  public void testGetFileNotInCache() throws IOException {
+    File fileFromCache = cache.getFileFromCache("foo.txt", "mockmd5");
+    assertThat(fileFromCache).isNull();
+  }
+
+}