Provide file utilities for file deletion

Provide file helper methods in a reusable utility class to
replace many local implementations. java.io.File has some
methods reporting failure by returning false. We prefer to
throw IOException on failure so that callers can't forget
checking the return value.

Change-Id: I430c77b5d2cffcf8b47584326ad4817a7291845e
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties

@@ -132,6 +132,7 @@ credentialPassword=Password
 credentialUsername=Username
 daemonAlreadyRunning=Daemon already running
 deleteBranchUnexpectedResult=Delete branch returned unexpected result {0}
+deleteFileFailed=Could not delete file {0}
 deletingNotSupported=Deleting {0} not supported.
 destinationIsNotAWildcard=Destination is not a wildcard.
 detachedHeadDetected=HEAD is detached

org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java

@@ -192,6 +192,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String credentialUsername;
 	/***/ public String daemonAlreadyRunning;
 	/***/ public String deleteBranchUnexpectedResult;
+	/***/ public String deleteFileFailed;
 	/***/ public String deletingNotSupported;
 	/***/ public String destinationIsNotAWildcard;
 	/***/ public String detachedHeadDetected;
@@ -425,7 +426,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String repositoryState_rebaseOrApplyMailbox;
 	/***/ public String repositoryState_rebaseWithMerge;
 	/***/ public String requiredHashFunctionNotAvailable;
-	/***/ public String resettingHead;	
+	/***/ public String resettingHead;
 	/***/ public String resolvingDeltas;
 	/***/ public String resultLengthIncorrect;
 	/***/ public String rewinding;

org.eclipse.jgit/src/org/eclipse/jgit/util/FileUtils.java

@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2010, Google Inc.
+ * Copyright (C) 2010, Matthias Sohn <matthias.sohn@sap.com>
+ * Copyright (C) 2010, Jens Baumgart <jens.baumgart@sap.com>
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - 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.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. 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 COPYRIGHT OWNER 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.
+ */
+
+package org.eclipse.jgit.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.text.MessageFormat;
+
+import org.eclipse.jgit.JGitText;
+
+/**
+ * File Utilities
+ */
+public class FileUtils {
+
+	/**
+	 * Option to delete given {@code File}
+	 */
+	public static final int NONE = 0;
+
+	/**
+	 * Option to recursively delete given {@code File}
+	 */
+	public static final int RECURSIVE = 1;
+
+	/**
+	 * Option to retry deletion if not successful
+	 */
+	public static final int RETRY = 2;
+
+	/**
+	 * Delete file or empty folder
+	 *
+	 * @param f
+	 *            {@code File} to be deleted
+	 * @throws IOException
+	 *             if deletion of {@code f} fails. This may occur if {@code f}
+	 *             didn't exist when the method was called. This can therefore
+	 *             cause IOExceptions during race conditions when multiple
+	 *             concurrent threads all try to delete the same file.
+	 */
+	public static void delete(final File f) throws IOException {
+		delete(f, NONE);
+	}
+
+	/**
+	 * Delete file or folder
+	 *
+	 * @param f
+	 *            {@code File} to be deleted
+	 * @param options
+	 *            deletion options, {@code RECURSIVE} for recursive deletion of
+	 *            a subtree, {@code RETRY} to retry when deletion failed.
+	 *            Retrying may help if the underlying file system doesn't allow
+	 *            deletion of files being read by another thread.
+	 * @throws IOException
+	 *             if deletion of {@code f} fails. This may occur if {@code f}
+	 *             didn't exist when the method was called. This can therefore
+	 *             cause IOExceptions during race conditions when multiple
+	 *             concurrent threads all try to delete the same file.
+	 */
+	public static void delete(final File f, int options) throws IOException {
+		if ((options & RECURSIVE) != 0 && f.isDirectory()) {
+			final File[] items = f.listFiles();
+			if (items != null) {
+				for (File c : items)
+					delete(c, options);
+			}
+		}
+		if (!f.delete()) {
+			if ((options & RETRY) != 0 && f.exists()) {
+				for (int i = 1; i < 10; i++) {
+					try {
+						Thread.sleep(100);
+					} catch (InterruptedException e) {
+						// ignore
+					}
+					if (f.delete())
+						return;
+				}
+			}
+			throw new IOException(MessageFormat.format(
+					JGitText.get().deleteFileFailed, f.getAbsolutePath()));
+		}
+	}
+
+}