org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/RacyGitTests.java

/*
 * Copyright (C) 2010, Christian Halstrick <christian.halstrick@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.
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 * without modification, are permitted provided that the following
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package org.eclipse.jgit.lib;

import static java.lang.Long.valueOf;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.TreeSet;

import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.junit.RepositoryTestCase;
import org.eclipse.jgit.treewalk.FileTreeIterator;
import org.eclipse.jgit.treewalk.FileTreeIteratorWithTimeControl;
import org.eclipse.jgit.treewalk.NameConflictTreeWalk;
import org.eclipse.jgit.util.FileUtils;
import org.junit.Test;

public class RacyGitTests extends RepositoryTestCase {
	@Test
	public void testIterator() throws IllegalStateException, IOException,
			InterruptedException {
		TreeSet<Long> modTimes = new TreeSet<>();
		File lastFile = null;
		for (int i = 0; i < 10; i++) {
			lastFile = new File(db.getWorkTree(), "0." + i);
			FileUtils.createNewFile(lastFile);
			if (i == 5)
				fsTick(lastFile);
		}
		modTimes.add(valueOf(fsTick(lastFile)));
		for (int i = 0; i < 10; i++) {
			lastFile = new File(db.getWorkTree(), "1." + i);
			FileUtils.createNewFile(lastFile);
		}
		modTimes.add(valueOf(fsTick(lastFile)));
		for (int i = 0; i < 10; i++) {
			lastFile = new File(db.getWorkTree(), "2." + i);
			FileUtils.createNewFile(lastFile);
			if (i % 4 == 0)
				fsTick(lastFile);
		}
		FileTreeIteratorWithTimeControl fileIt = new FileTreeIteratorWithTimeControl(
				db, modTimes);
		try (NameConflictTreeWalk tw = new NameConflictTreeWalk(db)) {
			tw.addTree(fileIt);
			tw.setRecursive(true);
			FileTreeIterator t;
			long t0 = 0;
			for (int i = 0; i < 10; i++) {
				assertTrue(tw.next());
				t = tw.getTree(0, FileTreeIterator.class);
				if (i == 0) {
					t0 = t.getEntryLastModified();
				} else {
					assertEquals(t0, t.getEntryLastModified());
				}
			}
			long t1 = 0;
			for (int i = 0; i < 10; i++) {
				assertTrue(tw.next());
				t = tw.getTree(0, FileTreeIterator.class);
				if (i == 0) {
					t1 = t.getEntryLastModified();
					assertTrue(t1 > t0);
				} else {
					assertEquals(t1, t.getEntryLastModified());
				}
			}
			long t2 = 0;
			for (int i = 0; i < 10; i++) {
				assertTrue(tw.next());
				t = tw.getTree(0, FileTreeIterator.class);
				if (i == 0) {
					t2 = t.getEntryLastModified();
					assertTrue(t2 > t1);
				} else {
					assertEquals(t2, t.getEntryLastModified());
				}
			}
		}
	}

	@Test
	public void testRacyGitDetection() throws Exception {
		TreeSet<Long> modTimes = new TreeSet<>();
		File lastFile;

		// Reset to force creation of index file
		try (Git git = new Git(db)) {
			git.reset().call();
		}

		// wait to ensure that modtimes of the file doesn't match last index
		// file modtime
		modTimes.add(valueOf(fsTick(db.getIndexFile())));

		// create two files
		addToWorkDir("a", "a");
		lastFile = addToWorkDir("b", "b");

		// wait to ensure that file-modTimes and therefore index entry modTime
		// doesn't match the modtime of index-file after next persistance
		modTimes.add(valueOf(fsTick(lastFile)));

		// now add both files to the index. No racy git expected
		resetIndex(new FileTreeIteratorWithTimeControl(db, modTimes));

		assertEquals(
				"[a, mode:100644, time:t0, length:1, content:a]" +
				"[b, mode:100644, time:t0, length:1, content:b]",
				indexState(SMUDGE | MOD_TIME | LENGTH | CONTENT));

		// Remember the last modTime of index file. All modifications times of
		// further modification are translated to this value so it looks that
		// files have been modified in the same time slot as the index file
		modTimes.add(Long.valueOf(db.getIndexFile().lastModified()));

		// modify one file
		addToWorkDir("a", "a2");
		// now update the index the index. 'a' has to be racily clean -- because
		// it's modification time is exactly the same as the previous index file
		// mod time.
		resetIndex(new FileTreeIteratorWithTimeControl(db, modTimes));

		db.readDirCache();
		// although racily clean a should not be reported as being dirty
		assertEquals(
				"[a, mode:100644, time:t1, smudged, length:0, content:a2]" +
				"[b, mode:100644, time:t0, length:1, content:b]",
				indexState(SMUDGE|MOD_TIME|LENGTH|CONTENT));
	}

	private File addToWorkDir(String path, String content) throws IOException {
		File f = new File(db.getWorkTree(), path);
		FileOutputStream fos = new FileOutputStream(f);
		try {
			fos.write(content.getBytes(Constants.CHARACTER_ENCODING));
			return f;
		} finally {
			fos.close();
		}
	}
}