*/
package org.eclipse.jgit.internal.storage.file;
+import static org.eclipse.jgit.junit.JGitTestUtil.read;
+import static org.eclipse.jgit.junit.JGitTestUtil.write;
+import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
+import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.attribute.FileTime;
import java.time.Duration;
import java.time.Instant;
+import java.util.ArrayList;
import java.util.concurrent.TimeUnit;
import org.eclipse.jgit.util.FS;
import org.eclipse.jgit.util.FileUtils;
+import org.eclipse.jgit.util.Stats;
import org.eclipse.jgit.util.SystemReader;
import org.junit.After;
import org.junit.Assume;
import org.junit.Before;
import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
public class FileSnapshotTest {
+ private static final Logger LOG = LoggerFactory
+ .getLogger(FileSnapshotTest.class);
private Path trash;
assertTrue(fs2.equals(fs1));
}
+ @SuppressWarnings("boxing")
+ @Test
+ public void detectFileModified() throws IOException {
+ int failures = 0;
+ long racyNanos = 0;
+ final int COUNT = 10000;
+ ArrayList<Long> deltas = new ArrayList<>();
+ File f = createFile("test").toFile();
+ for (int i = 0; i < COUNT; i++) {
+ write(f, "a");
+ FileSnapshot snapshot = FileSnapshot.save(f);
+ assertEquals("file should contain 'a'", "a", read(f));
+ write(f, "b");
+ if (!snapshot.isModified(f)) {
+ deltas.add(snapshot.lastDelta());
+ racyNanos = snapshot.lastRacyNanos();
+ failures++;
+ }
+ assertEquals("file should contain 'b'", "b", read(f));
+ }
+ if (failures > 0) {
+ Stats stats = new Stats();
+ LOG.debug(
+ "delta [ns] since modification FileSnapshot failed to detect");
+ for (Long d : deltas) {
+ stats.add(d);
+ LOG.debug(String.format("%,d", d));
+ }
+ LOG.error(
+ "count, failures, racy limit [ns], delta min [ns],"
+ + " delta max [ns], delta avg [ns],"
+ + " delta stddev [ns]");
+ LOG.error(String.format(
+ "%,d, %,d, %,d, %,.0f, %,.0f, %,.0f, %,.0f", COUNT,
+ failures, racyNanos, stats.min(), stats.max(),
+ stats.avg(), stats.stddev()));
+ }
+ assertTrue(
+ "FileSnapshot: number of failures to detect file modifications should be 0",
+ failures == 0);
+ }
+
private Path createFile(String string) throws IOException {
Files.createDirectories(trash);
return Files.createTempFile(trash, string, "tdat");
--- /dev/null
+/*
+ * Copyright (C) 2019, Matthias Sohn <matthias.sohn@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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import org.eclipse.jgit.util.Stats;
+import org.junit.Test;
+
+public class StatsTest {
+ @Test
+ public void testStatsTrivial() {
+ Stats s = new Stats();
+ s.add(1);
+ s.add(1);
+ s.add(1);
+ assertEquals(3, s.count());
+ assertEquals(1.0, s.min(), 1E-6);
+ assertEquals(1.0, s.max(), 1E-6);
+ assertEquals(1.0, s.avg(), 1E-6);
+ assertEquals(0.0, s.var(), 1E-6);
+ assertEquals(0.0, s.stddev(), 1E-6);
+ }
+
+ @Test
+ public void testStats() {
+ Stats s = new Stats();
+ s.add(1);
+ s.add(2);
+ s.add(3);
+ s.add(4);
+ assertEquals(4, s.count());
+ assertEquals(1.0, s.min(), 1E-6);
+ assertEquals(4.0, s.max(), 1E-6);
+ assertEquals(2.5, s.avg(), 1E-6);
+ assertEquals(1.666667, s.var(), 1E-6);
+ assertEquals(1.290994, s.stddev(), 1E-6);
+ }
+
+ @Test
+ /**
+ * see
+ * https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Example
+ */
+ public void testStatsCancellationExample1() {
+ Stats s = new Stats();
+ s.add(1E8 + 4);
+ s.add(1E8 + 7);
+ s.add(1E8 + 13);
+ s.add(1E8 + 16);
+ assertEquals(4, s.count());
+ assertEquals(1E8 + 4, s.min(), 1E-6);
+ assertEquals(1E8 + 16, s.max(), 1E-6);
+ assertEquals(1E8 + 10, s.avg(), 1E-6);
+ assertEquals(30, s.var(), 1E-6);
+ assertEquals(5.477226, s.stddev(), 1E-6);
+ }
+
+ @Test
+ /**
+ * see
+ * https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Example
+ */
+ public void testStatsCancellationExample2() {
+ Stats s = new Stats();
+ s.add(1E9 + 4);
+ s.add(1E9 + 7);
+ s.add(1E9 + 13);
+ s.add(1E9 + 16);
+ assertEquals(4, s.count());
+ assertEquals(1E9 + 4, s.min(), 1E-6);
+ assertEquals(1E9 + 16, s.max(), 1E-6);
+ assertEquals(1E9 + 10, s.avg(), 1E-6);
+ assertEquals(30, s.var(), 1E-6);
+ assertEquals(5.477226, s.stddev(), 1E-6);
+ }
+
+ @Test
+ public void testNoValues() {
+ Stats s = new Stats();
+ assertTrue(Double.isNaN(s.var()));
+ assertTrue(Double.isNaN(s.stddev()));
+ assertTrue(Double.isNaN(s.avg()));
+ assertTrue(Double.isNaN(s.min()));
+ assertTrue(Double.isNaN(s.max()));
+ s.add(42.3);
+ assertTrue(Double.isNaN(s.var()));
+ assertTrue(Double.isNaN(s.stddev()));
+ assertEquals(42.3, s.avg(), 1E-6);
+ assertEquals(42.3, s.max(), 1E-6);
+ assertEquals(42.3, s.min(), 1E-6);
+ s.add(42.3);
+ assertEquals(0, s.var(), 1E-6);
+ assertEquals(0, s.stddev(), 1E-6);
+ }
+}
</message_arguments>
</filter>
</resource>
+ <resource path="src/org/eclipse/jgit/util/Stats.java" type="org.eclipse.jgit.util.Stats">
+ <filter id="1109393411">
+ <message_arguments>
+ <message_argument value="5.1.9"/>
+ <message_argument value="org.eclipse.jgit.util.Stats"/>
+ </message_arguments>
+ </filter>
+ </resource>
</component>
private boolean wasRacyClean;
+ private long delta;
+
+ private long racyNanos;
+
private FileSnapshot(Instant read, Instant modified, long size,
@NonNull Duration fsTimestampResolution, @NonNull Object fileKey) {
this.file = null;
return wasRacyClean;
}
+ /**
+ * @return the delta in nanoseconds between lastModified and lastRead during
+ * last racy check
+ */
+ long lastDelta() {
+ return delta;
+ }
+
+ /**
+ * @return the racyNanos threshold in nanoseconds during last racy check
+ */
+ long lastRacyNanos() {
+ return racyNanos;
+ }
+
/** {@inheritDoc} */
@SuppressWarnings("nls")
@Override
private boolean isRacyClean(Instant read) {
// add a 10% safety margin
- long racyNanos = (fsTimestampResolution.toNanos() + 1) * 11 / 10;
- long delta = Duration.between(lastModified, read).toNanos();
+ racyNanos = (fsTimestampResolution.toNanos() + 1) * 11 / 10;
+ delta = Duration.between(lastModified, read).toNanos();
wasRacyClean = delta <= racyNanos;
if (LOG.isDebugEnabled()) {
LOG.debug(
--- /dev/null
+/*
+ * Copyright (C) 2019, Matthias Sohn <matthias.sohn@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;
+
+/**
+ * Simple double statistics, computed incrementally, variance and standard
+ * deviation using Welford's online algorithm, see
+ * https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm
+ *
+ * @since 5.1.9
+ */
+public class Stats {
+ private int n = 0;
+
+ private double avg = 0.0;
+
+ private double min = 0.0;
+
+ private double max = 0.0;
+
+ private double sum = 0.0;
+
+ /**
+ * Add a value
+ *
+ * @param x
+ * value
+ */
+ public void add(double x) {
+ n++;
+ min = n == 1 ? x : Math.min(min, x);
+ max = n == 1 ? x : Math.max(max, x);
+ double d = x - avg;
+ avg += d / n;
+ sum += d * d * (n - 1) / n;
+ }
+
+ /**
+ * @return number of the added values
+ */
+ public int count() {
+ return n;
+ }
+
+ /**
+ * @return minimum of the added values
+ */
+ public double min() {
+ if (n < 1) {
+ return Double.NaN;
+ }
+ return min;
+ }
+
+ /**
+ * @return maximum of the added values
+ */
+ public double max() {
+ if (n < 1) {
+ return Double.NaN;
+ }
+ return max;
+ }
+
+ /**
+ * @return average of the added values
+ */
+
+ public double avg() {
+ if (n < 1) {
+ return Double.NaN;
+ }
+ return avg;
+ }
+
+ /**
+ * @return variance of the added values
+ */
+ public double var() {
+ if (n < 2) {
+ return Double.NaN;
+ }
+ return sum / (n - 1);
+ }
+
+ /**
+ * @return standard deviation of the added values
+ */
+ public double stddev() {
+ return Math.sqrt(this.var());
+ }
+}
projects / jgit.git / commitdiff