Add regression test for JavaIoFileSystem#createDirectory.

PiperOrigin-RevId: 179584358

1 files changed, 68 insertions, 6 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/vfs/JavaIoFileSystemTest.java b/src/test/java/com/google/devtools/build/lib/vfs/JavaIoFileSystemTest.java
index 80c1981fcd..056b5f0f1a 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/JavaIoFileSystemTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/JavaIoFileSystemTest.java
@@ -15,11 +15,24 @@ package com.google.devtools.build.lib.vfs;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.collect.Iterables;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.ListeningExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
 import com.google.devtools.build.lib.testutil.ManualClock;
+import com.google.devtools.build.lib.testutil.TestUtils;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.LinkOption;
+import java.nio.file.Paths;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -66,15 +79,64 @@ public class JavaIoFileSystemTest extends SymlinkAwareFileSystemTest {
   @Override
   protected boolean isHardLinked(Path a, Path b) throws IOException {
     return Files.readAttributes(
-            java.nio.file.Paths.get(a.toString()),
-            BasicFileAttributes.class,
-            LinkOption.NOFOLLOW_LINKS)
+            Paths.get(a.toString()), BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS)
         .fileKey()
         .equals(
             Files.readAttributes(
-                    java.nio.file.Paths.get(b.toString()),
-                    BasicFileAttributes.class,
-                    LinkOption.NOFOLLOW_LINKS)
+                    Paths.get(b.toString()), BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS)
                 .fileKey());
   }
+
+  /**
+   * This test has a large number of threads racing to create the same subdirectories.
+   *
+   * <p>We create N number of distinct directory trees, eg. the tree "0-0/0-1/0-2/0-3/0-4" followed
+   * by the tree "1-0/1-1/1-2/1-3/1-4" etc. If there is race we should quickly get a deadlock.
+   *
+   * <p>A timeout of this test is likely because of a deadlock.
+   */
+  @Test
+  public void testCreateDirectoriesThreadSafety() throws Exception {
+    int threadCount = 200;
+    int directoryCreationCount = 500; // We create this many sets of directories
+    int subDirectoryCount = 5; // Each directory tree is this deep
+    ListeningExecutorService executor =
+        MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(threadCount));
+    List<ListenableFuture<IOException>> futures = new ArrayList<>();
+    for (int threadIndex = 0; threadIndex < threadCount; ++threadIndex) {
+      futures.add(
+          executor.submit(
+              () -> {
+                try {
+                  for (int loopi = 0; loopi < directoryCreationCount; ++loopi) {
+                    List<Path> subDirs =
+                        getSubDirectories(xEmptyDirectory, loopi, subDirectoryCount);
+                    Path lastDir = Iterables.getLast(subDirs);
+                    FileSystemUtils.createDirectoryAndParents(lastDir);
+                  }
+                } catch (IOException e) {
+                  return e;
+                }
+                return null;
+              }));
+    }
+    ListenableFuture<List<IOException>> all = Futures.allAsList(futures);
+    // If the test times out here then there's likely to be a deadlock
+    List<IOException> exceptions =
+        all.get(TestUtils.WAIT_TIMEOUT_MILLISECONDS, TimeUnit.MILLISECONDS);
+    Optional<IOException> error = exceptions.stream().filter(Objects::nonNull).findFirst();
+    if (error.isPresent()) {
+      throw error.get();
+    }
+  }
+
+  private static List<Path> getSubDirectories(Path base, int loopi, int subDirectoryCount) {
+    Path path = base;
+    List<Path> subDirs = new ArrayList<>();
+    for (int subDirIndex = 0; subDirIndex < subDirectoryCount; ++subDirIndex) {
+      path = path.getChild(String.format("%d-%d", loopi, subDirIndex));
+      subDirs.add(path);
+    }
+    return subDirs;
+  }
 }