1 files changed, 18 insertions, 39 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/LocalDiffAwareness.java b/src/main/java/com/google/devtools/build/lib/skyframe/LocalDiffAwareness.java
index 753f920cab..cae5cdebd4 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/LocalDiffAwareness.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/LocalDiffAwareness.java
@@ -14,20 +14,18 @@
 
 package com.google.devtools.build.lib.skyframe;
 
-import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.util.OS;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.vfs.ModifiedFileSet;
 import com.google.devtools.build.lib.vfs.PathFragment;
-import com.google.devtools.common.options.Option;
-import com.google.devtools.common.options.OptionsBase;
+
 import java.io.IOException;
 import java.nio.file.FileSystems;
 import java.nio.file.Path;
+import java.nio.file.WatchService;
 import java.util.Set;
 
 /**
@@ -40,19 +38,6 @@ import java.util.Set;
  * {@link WatchServiceDiffAwareness}.
  */
 public abstract class LocalDiffAwareness implements DiffAwareness {
-  /**
-   * Option to enable / disable local diff awareness.
-   */
-  public static final class Options extends OptionsBase {
-    @Option(
-        name = "watchfs",
-        defaultValue = "false",
-        category = "server startup",
-        help = "If true, %{product} tries to use the operating system's file watch service for "
-            + "local changes instead of scanning every file for a change."
-    )
-    public boolean watchFS;
-  }
 
   /** Factory for creating {@link LocalDiffAwareness} instances. */
   public static class Factory implements DiffAwareness.Factory {
@@ -88,26 +73,16 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
         return new MacOSXFsEventsDiffAwareness(resolvedPathEntryFragment.toString());
       }
 
-      return new WatchServiceDiffAwareness(resolvedPathEntryFragment.toString());
+      WatchService watchService;
+      try {
+        watchService = FileSystems.getDefault().newWatchService();
+      } catch (IOException e) {
+        return null;
+      }
+      return new WatchServiceDiffAwareness(resolvedPathEntryFragment.toString(), watchService);
     }
   }
 
-  /**
-   * A view that results in any subsequent getDiff calls returning
-   * {@link ModifiedFileSet#EVERYTHING_MODIFIED}. Use this if --watchFs is disabled.
-   *
-   * <p>The position is set to -2 in order for {@link #areInSequence} below to always return false
-   * if this view is passed to it. Any negative number would work; we don't use -1 as the other
-   * view may have a position of 0.
-   */
-  protected static final View EVERYTHING_MODIFIED =
-      new SequentialView(/*owner=*/null, /*position=*/-2, ImmutableSet.<Path>of());
-
-  public static boolean areInSequence(SequentialView oldView, SequentialView newView) {
-    // Keep this in sync with the EVERYTHING_MODIFIED View above.
-    return oldView.owner == newView.owner && (oldView.position + 1) == newView.position;
-  }
-
   private int numGetCurrentViewCalls = 0;
 
   /** Root directory to watch. This is an absolute path. */
@@ -121,8 +96,7 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
    * The WatchService is inherently sequential and side-effectful, so we enforce this by only
    * supporting {@link #getDiff} calls that happen to be sequential.
    */
-  @VisibleForTesting
-  static class SequentialView implements DiffAwareness.View {
+  private static class SequentialView implements DiffAwareness.View {
     private final LocalDiffAwareness owner;
     private final int position;
     private final Set<Path> modifiedAbsolutePaths;
@@ -133,6 +107,10 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
       this.modifiedAbsolutePaths = modifiedAbsolutePaths;
     }
 
+    public static boolean areInSequence(SequentialView oldView, SequentialView newView) {
+      return oldView.owner == newView.owner && (oldView.position + 1) == newView.position;
+    }
+
     @Override
     public String toString() {
       return String.format("SequentialView[owner=%s, position=%d, modifiedAbsolutePaths=%s]", owner,
@@ -141,7 +119,7 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
   }
 
   /**
-   * Returns true on any call before first call to {@link #newView}.
+   * Returns true on any call before first call to {@link #newView(Set<Path>)}.
    */
   protected boolean isFirstCall() {
     return numGetCurrentViewCalls == 0;
@@ -151,7 +129,8 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
    * Create a new views using a list of modified absolute paths. This will increase the view
    * counter.
    */
-  protected SequentialView newView(Set<Path> modifiedAbsolutePaths) {
+  protected SequentialView newView(Set<Path> modifiedAbsolutePaths)
+      throws BrokenDiffAwarenessException {
     numGetCurrentViewCalls++;
     return new SequentialView(this, numGetCurrentViewCalls, modifiedAbsolutePaths);
   }
@@ -167,7 +146,7 @@ public abstract class LocalDiffAwareness implements DiffAwareness {
     } catch (ClassCastException e) {
       throw new IncompatibleViewException("Given views are not from LocalDiffAwareness");
     }
-    if (!areInSequence(oldSequentialView, newSequentialView)) {
+    if (!SequentialView.areInSequence(oldSequentialView, newSequentialView)) {
       return ModifiedFileSet.EVERYTHING_MODIFIED;
     }
     return ModifiedFileSet.builder()