Issue 20: Optimize CheckoutBuilder's final checkout by caching blob info

Introduces a new RevisionEntry value object, which stores index/tree
entry information such as path, blob ID, and mode.

Signed-off-by: Jonas Fonseca <fonseca@diku.dk>

src/org/nbgit/client/CheckoutBuilder.java

@@ -49,16 +49,18 @@
 import org.spearce.jgit.lib.ObjectId;
 import org.spearce.jgit.lib.Repository;
 import org.spearce.jgit.lib.Tree;
+import org.spearce.jgit.lib.TreeEntry;
 
 /**
  * Build a checkout of files from a revision.
  */
 public class CheckoutBuilder extends ClientBuilder {
 
     private static final String BACKUP_EXT = ".orig";
-    private final HashMap<String, File> fileMappings = new HashMap<String, File>();
+    private final HashMap<RevisionEntry, File> fileMappings = new HashMap<RevisionEntry, File>();
     private boolean backup;
     private Tree tree;
+    private GitIndex index;
 
     private CheckoutBuilder(Repository repository) {
         super(repository);
@@ -108,16 +110,33 @@ public CheckoutBuilder revision(String revision)
      * @param file to be checked out.
      * @param destination where the file should be checked out.
      * @return the builder.
-     * @throws FileNotFoundException if revision has been specified and file
-     *  is not found in the revision's snapshot.
+     * @throws FileNotFoundException if the file cannot be resolved.
      * @throws IOException if checking of file existance fails.
      */
     public CheckoutBuilder file(File file, File destination)
             throws IOException, FileNotFoundException {
         String path = toPath(file);
-        if (tree != null && !tree.existsBlob(path))
+        ObjectId blobId = null;
+        int modeBits = 0;
+
+        if (tree != null) {
+            TreeEntry entry = tree.findBlobMember(path);
+            if (entry != null) {
+                blobId = entry.getId();
+                modeBits = entry.getMode().getBits();
+            }
+        } else {
+            if (index == null)
+                index = repository.getIndex();
+            GitIndex.Entry entry = index.getEntry(path);
+            if (entry != null) {
+                blobId = entry.getObjectId();
+                modeBits = entry.getModeBits();
+            }
+        }
+        if (blobId == null)
             throw new FileNotFoundException(path);
-        fileMappings.put(path, destination);
+        fileMappings.put(RevisionEntry.create(path, blobId, modeBits), destination);
         return this;
     }
 
@@ -128,8 +147,7 @@ public CheckoutBuilder file(File file, File destination)
      *
      * @param files to be checked out.
      * @return the builder.
-     * @throws FileNotFoundException if revision has been specified and file
-     *  is not found in the revision's snapshot.
+     * @throws FileNotFoundException if the file cannot be resolved.
      * @throws IOException if checking of file existance fails.
      */
     public CheckoutBuilder files(Collection<File> files)
@@ -158,17 +176,8 @@ public CheckoutBuilder backup(boolean backup) {
      * @throws IOException if the checkout fails.
      */
     public void checkout() throws IOException {
-        GitIndex index = new GitIndex(repository);
-
-        if (tree != null)
-            index.readTree(tree);
-
-        for (Map.Entry<String, File> mapping : fileMappings.entrySet()) {
-            GitIndex.Entry entry = index.getEntry(mapping.getKey());
-
-            if (entry == null)
-                continue;
-
+        for (Map.Entry<RevisionEntry, File> mapping : fileMappings.entrySet()) {
+            RevisionEntry entry = mapping.getKey();
             File file = mapping.getValue();
             if (backup)
                 backupFile(file);

src/org/nbgit/client/RevisionEntry.java

@@ -0,0 +1,67 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2009 Jonas Fonseca <fonseca@diku.dk>
+ *
+ * The contents of this file are subject to the terms of either the GNU
+ * General Public License Version 2 only ("GPL") or the Common
+ * Development and Distribution License("CDDL") (collectively, the
+ * "License"). You may not use this file except in compliance with the
+ * License. You can obtain a copy of the License at
+ * http://www.netbeans.org/cddl-gplv2.html. See the License for the
+ * specific language governing permissions and limitations under the
+ * License.  When distributing the software, include this License Header
+ * Notice in each file.
+ *
+ * This particular file is subject to the "Classpath" exception as provided
+ * by Sun in the GPL Version 2 section of the License file that
+ * accompanied this code. If applicable, add the following below the
+ * License Header, with the fields enclosed by brackets [] replaced by
+ * your own identifying information:
+ * "Portions Copyrighted [year] [name of copyright owner]"
+ *
+ * Contributor(s):
+ *
+ * If you wish your version of this file to be governed by only the CDDL
+ * or only the GPL Version 2, indicate your decision by adding
+ * "[Contributor] elects to include this software in this distribution
+ * under the [CDDL or GPL Version 2] license." If you do not indicate a
+ * single choice of license, a recipient has the option to distribute
+ * your version of this file under either the CDDL, the GPL Version 2 or
+ * to extend the choice of license to its licensees as provided above.
+ * However, if you add GPL Version 2 code and therefore, elected the GPL
+ * Version 2 license, then the option applies only if the new code is
+ * made subject to such option by the copyright holder.
+ */
+package org.nbgit.client;
+
+import org.spearce.jgit.lib.ObjectId;
+
+public class RevisionEntry {
+
+    private final ObjectId objectId;
+    private final int modeBits;
+    private final String path;
+
+    private RevisionEntry(String path, ObjectId objectId, int modeBits) {
+        this.path = path;
+        this.objectId = objectId;
+        this.modeBits = modeBits;
+    }
+
+    public static RevisionEntry create(String path, ObjectId objectId, int modeBits) {
+        return new RevisionEntry(path, objectId, modeBits);
+    }
+
+    public String getPath() {
+        return path;
+    }
+
+    public ObjectId getObjectId() {
+        return objectId;
+    }
+
+    public int getModeBits() {
+        return modeBits;
+    }
+}