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SOLR-14579: reverting incorrect comments

This commit is contained in:
Erick Erickson 2020-09-01 18:59:08 -04:00
parent 8bd79ec301
commit 594d676a95
1 changed files with 0 additions and 35 deletions
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35
solr/solrj/src/java/org/apache/solr/common/util/Utils.java
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@ -96,41 +96,6 @@ import static java.util.concurrent.TimeUnit.NANOSECONDS;
public class Utils { public class Utils {
// Why static lambdas? Even though they require SuppressWarnings? This is
// purely an optimization. Comparing:
//
// mapObject.computeIfAbsent(key, o -> new HashMap<>());
//
// vs.
//
// mapObject.computeIfAbsent(key, Utils.NEW_HASHMAP_FUN)
//
//
// The first code fragment is executed as following
//
// s.computeIfAbsent(key, new Function() {
// @Override
// public Object apply(String key) {
// return new HashMap<>();
// }
// }
//
// So, there are two problems with this
//
// A new anonymous inner class is created for that lambda. This one extra
// class becomes a part of your binary a new instance of that class is
// created everytime the computeIfAbsent() method is invoked, irrespective
// of whether the value is absent for that key or not. Now imagine that
// method getting called millions of times and creating millions of such
// objects for no reason
//
// OTOH
//
// Utils.NEW_HASHMAP_FUN
// Only a single anonymous class is created for the entire codebase
// Only single instance of that object is created in the VM
//
// See SOLR-14579.
@SuppressWarnings({"rawtypes"}) @SuppressWarnings({"rawtypes"})
public static final Function NEW_HASHMAP_FUN = o -> new HashMap<>(); public static final Function NEW_HASHMAP_FUN = o -> new HashMap<>();