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Merge "Fix FileSnapShot"

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Shawn Pearce 2010-12-30 15:31:06 -05:00 committed by Code Review
parent 488307ada7 c3f52c62a8
commit 7a1bd7adb1
2 changed files with 161 additions and 5 deletions
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152
org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileSnapshotTest.java Normal file
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@ -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();
}
}
}

14
org.eclipse.jgit/src/org/eclipse/jgit/storage/file/FileSnapshot.java
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@ -45,8 +45,6 @@
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);
}
@ -109,8 +107,8 @@ long lastModified() {
}
/**
* 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.
* @return true if the path needs to be read again.
@ -203,6 +201,12 @@ private boolean isModified(final long currLastModified) {
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.