Add a static method GroupedList#numElements to allow to count the number of deps from a compressed GroupedList without uncompressing it. Also some minor GC improvements.

PiperOrigin-RevId: 177338852

3 files changed, 37 insertions, 4 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/util/GroupedList.java b/src/main/java/com/google/devtools/build/lib/util/GroupedList.java
index c1985cd57c..475e38518b 100644
--- a/src/main/java/com/google/devtools/build/lib/util/GroupedList.java
+++ b/src/main/java/com/google/devtools/build/lib/util/GroupedList.java
@@ -18,6 +18,7 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
 import com.google.devtools.build.lib.collect.compacthashset.CompactHashSet;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -57,6 +58,11 @@ public class GroupedList<T> implements Iterable<Collection<T>> {
     this.elements = new ArrayList<>(elements);
   }
 
+  private GroupedList(int size, Object[] elements) {
+    this.size = size;
+    this.elements = Lists.newArrayList(elements);
+  }
+
   /**
    * Appends the list constructed in {@code helper} to this list. Returns the elements of {@code
    * helper}, uniquified.
@@ -210,18 +216,32 @@ public class GroupedList<T> implements Iterable<Collection<T>> {
       return new GroupedList<>();
     }
     if (compressed.getClass().isArray()) {
-      List<Object> elements = new ArrayList<>();
       int size = 0;
-      for (Object item : (Object[]) compressed) {
+      Object[] compressedArray = ((Object[]) compressed);
+      for (Object item : compressedArray) {
         size += sizeOf(item);
-        elements.add(item);
       }
-      return new GroupedList<>(size, elements);
+      return new GroupedList<>(size, compressedArray);
     }
     // Just a single element.
     return new GroupedList<>(1, ImmutableList.of(compressed));
   }
 
+  public static int numElements(Object compressed) {
+    if (compressed == EMPTY_LIST) {
+      return 0;
+    }
+    if (compressed.getClass().isArray()) {
+      int size = 0;
+      for (Object item : (Object[]) compressed) {
+        size += sizeOf(item);
+      }
+      return size;
+    }
+    // Just a single element.
+    return 1;
+  }
+
   @Override
   public int hashCode() {
     // Hashing requires getting an order-independent hash for each element of this.elements. That
diff --git a/src/main/java/com/google/devtools/build/skyframe/DirtyBuildingState.java b/src/main/java/com/google/devtools/build/skyframe/DirtyBuildingState.java
index 53e43f0513..d802c3d673 100644
--- a/src/main/java/com/google/devtools/build/skyframe/DirtyBuildingState.java
+++ b/src/main/java/com/google/devtools/build/skyframe/DirtyBuildingState.java
@@ -55,6 +55,9 @@ public abstract class DirtyBuildingState {
    */
   protected abstract int getNumOfGroupsInLastBuildDirectDeps();
 
+  /** The number of total dependencies requested the last time the node was built. */
+  public abstract int getNumElementsInLastBuildDirectDeps();
+
   /**
    * The value of the node the last time it was built.
    *
@@ -237,6 +240,11 @@ public abstract class DirtyBuildingState {
     }
 
     @Override
+    public int getNumElementsInLastBuildDirectDeps() {
+      return lastBuildDirectDeps.numElements();
+    }
+
+    @Override
     protected MoreObjects.ToStringHelper getStringHelper() {
       return super.getStringHelper()
           .add("lastBuildDirectDeps", lastBuildDirectDeps)
diff --git a/src/main/java/com/google/devtools/build/skyframe/InMemoryNodeEntry.java b/src/main/java/com/google/devtools/build/skyframe/InMemoryNodeEntry.java
index ee80c29637..2ad10d285e 100644
--- a/src/main/java/com/google/devtools/build/skyframe/InMemoryNodeEntry.java
+++ b/src/main/java/com/google/devtools/build/skyframe/InMemoryNodeEntry.java
@@ -233,6 +233,11 @@ public class InMemoryNodeEntry implements NodeEntry {
     return GroupedList.create(directDeps);
   }
 
+  public int getNumDirectDeps() {
+    Preconditions.checkState(isDone(), "no deps until done. NodeEntry: %s", this);
+    return GroupedList.numElements(directDeps);
+  }
+
   @Override
   @Nullable
   public synchronized ErrorInfo getErrorInfo() {