Stop computing expensive hash code for StringSetSequence since equals was using NestedSet.equals anyway.
PiperOrigin-RevId: 292907908
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainVariables.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainVariables.java
index 3746a1c..806f9d0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainVariables.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainVariables.java
@@ -969,14 +969,16 @@
* A sequence of simple string values. Exists as a memory optimization - a typical build can
* contain millions of feature values, so getting rid of the overhead of {@code StringValue}
* objects significantly reduces memory overhead.
+ *
+ * <p>Because checking nested set equality is expensive, equality for these sequences is defined
+ * in terms of {@link NestedSet#shallowEquals}, which can miss some value-equal nested sets. In
+ * practice, since equality is needed just for interning when deserializing, this is acceptable.
*/
@Immutable
- @AutoCodec
- static final class StringSetSequence extends VariableValueAdapter {
+ private static final class StringSetSequence extends VariableValueAdapter {
private final NestedSet<String> values;
- private int hash = 0;
- public StringSetSequence(NestedSet<String> values) {
+ StringSetSequence(NestedSet<String> values) {
Preconditions.checkNotNull(values);
this.values = values;
}
@@ -1008,20 +1010,12 @@
if (this == other) {
return true;
}
- return values.equals(((StringSetSequence) other).values);
+ return values.shallowEquals(((StringSetSequence) other).values);
}
@Override
public int hashCode() {
- int h = hash;
- if (h == 0) {
- h = 1;
- for (String s : values.toList()) {
- h = 31 * h + (s == null ? 0 : s.hashCode());
- }
- hash = h;
- }
- return h;
+ return values.shallowHashCode();
}
}
