Merge "Fix FileSnapShot"

org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileSnapshotTest.java

@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2010, Robin Rosenberg
+ * 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.storage.file;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.jgit.util.FileUtils;
+import org.junit.Before;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class FileSnapshotTest {
+
+	private List<File> files = new ArrayList<File>();
+
+	private final File trash = new File(new File("target"), "trash");
+
+	@Before
+	public void tearDown() throws Exception {
+		FileUtils.delete(trash, FileUtils.RECURSIVE | FileUtils.SKIP_MISSING);
+	}
+
+	private void waitNextSec(File f) {
+		long initialLastModified = f.lastModified();
+		do {
+			f.setLastModified(System.currentTimeMillis());
+		} while (f.lastModified() == initialLastModified);
+	}
+
+	/**
+	 * Change data and time stamp.
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testActuallyIsModifiedTrivial() throws Exception {
+		File f1 = createFile("simple");
+		waitNextSec(f1);
+		FileSnapshot save = FileSnapshot.save(f1);
+		append(f1, (byte) 'x');
+		waitNextSec(f1);
+		assertTrue(save.isModified(f1));
+	}
+
+	/**
+	 * Create a file, wait long enough and verify that it has not been modified.
+	 * 3.5 seconds mean any difference between file system timestamp and system
+	 * clock should be significant.
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testOldFile() throws Exception {
+		File f1 = createFile("oldfile");
+		waitNextSec(f1);
+		FileSnapshot save = FileSnapshot.save(f1);
+		Thread.sleep(3500);
+		assertFalse(save.isModified(f1));
+	}
+
+	/**
+	 * Create a file, but don't wait long enough for the difference between file
+	 * system clock and system clock to be significant. Assume the file may have
+	 * been modified. It may have been, but the clock alone cannot determine
+	 * this
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testNewFileWithWait() throws Exception {
+		File f1 = createFile("newfile");
+		waitNextSec(f1);
+		FileSnapshot save = FileSnapshot.save(f1);
+		Thread.sleep(1500);
+		assertTrue(save.isModified(f1));
+	}
+
+	/**
+	 * Same as {@link #testNewFileWithWait()} but do not wait at all
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testNewFileNoWait() throws Exception {
+		File f1 = createFile("newfile");
+		waitNextSec(f1);
+		FileSnapshot save = FileSnapshot.save(f1);
+		Thread.sleep(1500);
+		assertTrue(save.isModified(f1));
+	}
+
+	private File createFile(String string) throws IOException {
+		trash.mkdirs();
+		File f = File.createTempFile(string, "tdat", trash);
+		files.add(f);
+		return f;
+	}
+
+	private void append(File f, byte b) throws IOException {
+		FileOutputStream os = new FileOutputStream(f, true);
+		try {
+			os.write(b);
+		} finally {
+			os.close();
+		}
+	}
+
+}

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileSnapshot.java

@@ -45,8 +45,6 @@ package org.eclipse.jgit.storage.file;
 
 import java.io.File;
 
-import org.eclipse.jgit.util.SystemReader;
-
 /**
  * Caches when a file was last read, making it possible to detect future edits.
  * <p>
@@ -84,7 +82,7 @@ public class FileSnapshot {
 	 * @return the snapshot.
 	 */
 	public static FileSnapshot save(File path) {
-		final long read = SystemReader.getInstance().getCurrentTime();
+		final long read = System.currentTimeMillis();
 		final long modified = path.lastModified();
 		return new FileSnapshot(read, modified);
 	}
@@ -109,7 +107,7 @@ public class FileSnapshot {
 	}
 
 	/**
-	 * Check if the path has been modified since the snapshot was saved.
+	 * Check if the path may have been modified since the snapshot was saved.
 	 * 
 	 * @param path
 	 *            the path the snapshot describes.
@@ -203,6 +201,12 @@ public class FileSnapshot {
 			return false;
 		}
 
+		// Our lastRead flag may be old, refresh and retry
+		lastRead = System.currentTimeMillis();
+		if (notRacyClean(lastRead)) {
+			return false;
+		}
+
 		// We last read this path too close to its last observed
 		// modification time. We may have missed a modification.
 		// Scan again, to ensure we still see the same state.