Avoid waste in registerNewlyDiscovered... when there aren't any

RELNOTES: None. PiperOrigin-RevId: 156553687
rabadin · May 22, 2017 · 31dbadf · 31dbadf
1 parent a79015e
commit 31dbadf
Showing 1 changed file with 7 additions and 1 deletion.
diff --git a/src/main/java/com/google/devtools/build/skyframe/ParallelEvaluator.java b/src/main/java/com/google/devtools/build/skyframe/ParallelEvaluator.java
@@ -40,6 +40,7 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -629,8 +630,13 @@ private static void registerNewlyDiscoveredDepsForDoneEntry(
       Set<SkyKey> oldDeps,
       SkyFunctionEnvironment env)
       throws InterruptedException {
+    Iterator<SkyKey> it = env.getNewlyRequestedDeps().iterator();
+    if (!it.hasNext()) {
+      return;
+    }
     Set<SkyKey> unfinishedDeps = new HashSet<>();
-    for (SkyKey dep : env.getNewlyRequestedDeps()) {
+    while (it.hasNext()) {
+      SkyKey dep = it.next();
       if (!isDoneForBuild(newlyRequestedDepMap.get(dep))) {
         unfinishedDeps.add(dep);
       }