Use Object for what instead of String
The string is only used for error messaging on failure. Instead of constructing
lots of strings allow passing in a generic Object whos toString is used for the
error message. This allows us to bypass a lot of garbage string generation, at
th expense of a little indirection.
Chose Object over some specialized type, since we use inline strings frequently
as well.
--
MOS_MIGRATED_REVID=133741724
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index cba10a7..53aabfa 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -1727,9 +1727,11 @@
*/
private static Object convertFromBuildLangType(Rule rule, Attribute attr, Object buildLangValue)
throws ConversionException {
- String what = "attribute '" + attr.getName() + "' in '" + rule.getRuleClass() + "' rule";
- Object converted =
- BuildType.selectableConvert(attr.getType(), buildLangValue, what, rule.getLabel());
+ Object converted = BuildType.selectableConvert(
+ attr.getType(),
+ buildLangValue,
+ new AttributeConversionContext(attr.getName(), rule.getRuleClass()),
+ rule.getLabel());
if ((converted instanceof SelectorList<?>) && !attr.isConfigurable()) {
throw new ConversionException(
@@ -1749,6 +1751,28 @@
}
/**
+ * Provides a {@link #toString()} description of the attribute being converted for
+ * {@link BuildType#selectableConvert}. This is preferred over a raw string to avoid uselessly
+ * constructing strings which are never used. A separate class instead of inline to avoid
+ * accidental memory leaks.
+ */
+ private static class AttributeConversionContext {
+ private final String attrName;
+ private final String ruleClass;
+
+ AttributeConversionContext(String attrName, String ruleClass) {
+ this.attrName = attrName;
+ this.ruleClass = ruleClass;
+ }
+
+ @Override
+ public String toString() {
+ return "attribute '" + attrName + "' in '" + ruleClass + "' rule";
+ }
+ }
+
+
+ /**
* Verifies that the rule has a valid value for the attribute according to its allowed values.
*
* <p>If the value for the given attribute on the given rule is invalid, an error will be recorded
