Log SkyKeys detected changed across builds

Similar to previous approach, except diff-awareness agnostic. Log
SkyKeys as is for simplicity- this is all for human consumption anyway.

--
MOS_MIGRATED_REVID=96428248

2 files changed, 4 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/skyframe/Differencer.java b/src/main/java/com/google/devtools/build/skyframe/Differencer.java
index f6433acde3..b520f16203 100644
--- a/src/main/java/com/google/devtools/build/skyframe/Differencer.java
+++ b/src/main/java/com/google/devtools/build/skyframe/Differencer.java
@@ -13,6 +13,7 @@
 // limitations under the License.
 package com.google.devtools.build.skyframe;
 
+import java.util.Collection;
 import java.util.Map;
 
 /**
@@ -27,7 +28,7 @@ public interface Differencer {
     /**
      * Returns the value keys whose values have changed, but for which we don't have the new values.
      */
-    Iterable<SkyKey> changedKeysWithoutNewValues();
+    Collection<SkyKey> changedKeysWithoutNewValues();
 
     /**
      * Returns the value keys whose values have changed, along with their new values.
diff --git a/src/main/java/com/google/devtools/build/skyframe/ImmutableDiff.java b/src/main/java/com/google/devtools/build/skyframe/ImmutableDiff.java
index 46ab29e851..987d03cddc 100644
--- a/src/main/java/com/google/devtools/build/skyframe/ImmutableDiff.java
+++ b/src/main/java/com/google/devtools/build/skyframe/ImmutableDiff.java
@@ -16,6 +16,7 @@ package com.google.devtools.build.skyframe;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 
+import java.util.Collection;
 import java.util.Map;
 
 /**
@@ -32,7 +33,7 @@ public class ImmutableDiff implements Differencer.Diff {
   }
 
   @Override
-  public Iterable<SkyKey> changedKeysWithoutNewValues() {
+  public Collection<SkyKey> changedKeysWithoutNewValues() {
     return valuesToInvalidate;
   }