1 files changed, 97 insertions, 0 deletions
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/FileSystemConcurrencyTest.java b/src/test/java/com/google/devtools/build/lib/vfs/FileSystemConcurrencyTest.java
new file mode 100644
index 0000000000..c90de18082
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/FileSystemConcurrencyTest.java
@@ -0,0 +1,97 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.vfs;
+
+import com.google.devtools.build.lib.testutil.TestUtils;
+import com.google.devtools.build.lib.vfs.util.FileSystems;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * (Slow) tests of FileSystem under concurrency.
+ *
+ * These tests are nondeterministic but provide good coverage nonetheless.
+ */
+@RunWith(JUnit4.class)
+public class FileSystemConcurrencyTest {
+
+  Path workingDir;
+
+  @Before
+  public void setUp() throws Exception {
+    FileSystem testFS = FileSystems.initDefaultAsNative();
+
+    // Resolve symbolic links in the temp dir:
+    workingDir = testFS.getPath(new File(TestUtils.tmpDir()).getCanonicalPath());
+  }
+
+  @Test
+  public void testConcurrentSymlinkModifications() throws Exception {
+    final Path xFile = workingDir.getRelative("file");
+    FileSystemUtils.createEmptyFile(xFile);
+
+    final Path xLinkToFile = workingDir.getRelative("link");
+
+    // "Boxed" for pass-by-reference.
+    final boolean[] run = { true };
+    final IOException[] exception = { null };
+    Thread createThread = new Thread() {
+      @Override
+      public void run() {
+        while (run[0]) {
+          if (!xLinkToFile.exists()) {
+            try {
+              xLinkToFile.createSymbolicLink(xFile);
+            } catch (IOException e) {
+              exception[0] = e;
+              return;
+            }
+          }
+        }
+      }
+    };
+    Thread deleteThread = new Thread() {
+      @Override
+      public void run() {
+        while (run[0]) {
+          if (xLinkToFile.exists(Symlinks.NOFOLLOW)) {
+            try {
+              xLinkToFile.delete();
+            } catch (IOException e) {
+              exception[0] = e;
+              return;
+            }
+          }
+        }
+      }
+    };
+    createThread.start();
+    deleteThread.start();
+    Thread.sleep(1000);
+    run[0] = false;
+    createThread.join(0);
+    deleteThread.join(0);
+
+    if (exception[0] != null) {
+      throw exception[0];
+    }
+  }
+
+}