From aea4e5c9b569144b58194538005aa5d525c34d2e Mon Sep 17 00:00:00 2001 From: Michajlo Matijkiw Date: Tue, 14 Mar 2017 16:56:05 +0000 Subject: Avoid expanding NestedSets in IterablesChain Builder Iterables.isEmpty winds up expanding the NestedSet, which isn't cheap. -- PiperOrigin-RevId: 150079225 MOS_MIGRATED_REVID=150079225 --- .../com/google/devtools/build/lib/collect/IterablesChain.java | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'src/main') diff --git a/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java b/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java index 69abf331cb..0286798e2a 100644 --- a/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java +++ b/src/main/java/com/google/devtools/build/lib/collect/IterablesChain.java @@ -18,7 +18,7 @@ import com.google.common.base.Joiner; import com.google.common.collect.AbstractIterator; import com.google.common.collect.ImmutableList; import com.google.common.collect.Iterables; - +import com.google.devtools.build.lib.collect.nestedset.NestedSet; import java.util.ArrayList; import java.util.HashSet; import java.util.Iterator; @@ -77,7 +77,11 @@ public final class IterablesChain implements Iterable { */ public Builder add(Iterable iterable) { CollectionUtils.checkImmutable(iterable); - if (!Iterables.isEmpty(iterable)) { + // Avoid unnecessarily expanding a NestedSet. + boolean isEmpty = iterable instanceof NestedSet + ? ((NestedSet) iterable).isEmpty() + : Iterables.isEmpty(iterable); + if (!isEmpty) { iterables.add(iterable); } return this; -- cgit v1.2.3