Change FileContentsProxy to use ctime instead of mtime

This gives us better reliability for detecting file changes; especially in
cases where tools intentionally do not update mtime.

Fixes #1525.

PiperOrigin-RevId: 155490849

3 files changed, 106 insertions, 7 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/FileContentsProxyTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/FileContentsProxyTest.java
new file mode 100644
index 0000000000..0ca3da5f80
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/FileContentsProxyTest.java
@@ -0,0 +1,100 @@
+// Copyright 2017 The Bazel Authors. 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.skyframe;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.testing.EqualsTester;
+import com.google.devtools.build.lib.vfs.FileStatus;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for {@link FileContentsProxy}. */
+@RunWith(JUnit4.class)
+public class FileContentsProxyTest {
+  /** A simple implementation of FileStatus for testing. */
+  public static final class InjectedStat implements FileStatus {
+    private final long mtime;
+    private final long ctime;
+    private final long size;
+    private final long nodeId;
+
+    public InjectedStat(long mtime, long ctime, long size, long nodeId) {
+      this.mtime = mtime;
+      this.ctime = ctime;
+      this.size = size;
+      this.nodeId = nodeId;
+    }
+
+    @Override
+    public boolean isFile() {
+      return true;
+    }
+
+    @Override
+    public boolean isSpecialFile() {
+      return false;
+    }
+
+    @Override
+    public boolean isDirectory() {
+      return false;
+    }
+
+    @Override
+    public boolean isSymbolicLink() {
+      return false;
+    }
+
+    @Override
+    public long getSize() {
+      return size;
+    }
+
+    @Override
+    public long getLastModifiedTime() {
+      return mtime;
+    }
+
+    @Override
+    public long getLastChangeTime() {
+      return ctime;
+    }
+
+    @Override
+    public long getNodeId() {
+      return nodeId;
+    }
+  }
+
+  @Test
+  public void equalsAndHashCode() {
+    new EqualsTester()
+        .addEqualityGroup(new FileContentsProxy(1L, 2L), new FileContentsProxy(1L, 2L))
+        .addEqualityGroup(new FileContentsProxy(1L, 4L))
+        .addEqualityGroup(new FileContentsProxy(3L, 4L))
+        .addEqualityGroup(new FileContentsProxy(-1L, -1L))
+        .testEquals();
+  }
+
+  @Test
+  public void fromStat() throws Exception {
+    FileContentsProxy p1 =
+        FileContentsProxy.create(
+            new InjectedStat(/*mtime=*/1, /*ctime=*/2, /*size=*/3, /*nodeId=*/4));
+    assertThat(p1.getCTime()).isEqualTo(2);
+    assertThat(p1.getNodeId()).isEqualTo(4);
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
index 830b91c786..8e1ff34c53 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
@@ -558,13 +558,15 @@ public class FileFunctionTest {
   }
 
   @Test
-  public void testSymlinkTargetContentsChangeModTime() throws Exception {
+  public void testSymlinkTargetContentsChangeCTime() throws Exception {
     fastDigest = false;
     Path fooPath = file("foo");
     FileSystemUtils.writeContentAsLatin1(fooPath, "foo");
     Path p = symlink("symlink", "foo");
     FileValue a = valueForPath(p);
-    fooPath.setLastModifiedTime(88);
+    manualClock.advanceMillis(1);
+    fooPath.chmod(0555);
+    manualClock.advanceMillis(1);
     FileValue b = valueForPath(p);
     assertThat(b).isNotEqualTo(a);
   }
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
index c682340282..a3853e6540 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/TreeArtifactBuildTest.java
@@ -42,7 +42,6 @@ import com.google.devtools.build.lib.actions.Artifact.SpecialArtifactType;
 import com.google.devtools.build.lib.actions.Artifact.TreeFileArtifact;
 import com.google.devtools.build.lib.actions.BuildFailedException;
 import com.google.devtools.build.lib.actions.Root;
-import com.google.devtools.build.lib.actions.cache.InjectedStat;
 import com.google.devtools.build.lib.actions.cache.MetadataHandler;
 import com.google.devtools.build.lib.actions.util.ActionsTestUtil;
 import com.google.devtools.build.lib.actions.util.TestAction;
@@ -687,13 +686,11 @@ public class TreeArtifactBuildTest extends TimestampBuilderTestCase {
           MetadataHandler md = actionExecutionContext.getMetadataHandler();
           FileStatus stat = outOneFileOne.getPath().stat(Symlinks.NOFOLLOW);
           md.injectDigest(outOneFileOne,
-              new InjectedStat(stat.getLastModifiedTime(), stat.getSize(), stat.getNodeId()),
-              Hashing.md5().hashString("one", Charset.forName("UTF-8")).asBytes());
+              stat, Hashing.md5().hashString("one", Charset.forName("UTF-8")).asBytes());
 
           stat = outOneFileTwo.getPath().stat(Symlinks.NOFOLLOW);
           md.injectDigest(outOneFileTwo,
-              new InjectedStat(stat.getLastModifiedTime(), stat.getSize(), stat.getNodeId()),
-              Hashing.md5().hashString("two", Charset.forName("UTF-8")).asBytes());
+              stat, Hashing.md5().hashString("two", Charset.forName("UTF-8")).asBytes());
         } catch (Exception e) {
           throw new RuntimeException(e);
         }