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Posted to dev@reef.apache.org by "Won Wook SONG (JIRA)" <ji...@apache.org> on 2016/05/15 03:51:12 UTC
[jira] [Assigned] (REEF-1390) Make Optional's toString() and
hashCode() computed on demand
[ https://issues.apache.org/jira/browse/REEF-1390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Won Wook SONG reassigned REEF-1390:
-----------------------------------
Assignee: Won Wook SONG
> Make Optional's toString() and hashCode() computed on demand
> ------------------------------------------------------------
>
> Key: REEF-1390
> URL: https://issues.apache.org/jira/browse/REEF-1390
> Project: REEF
> Issue Type: Improvement
> Components: REEF
> Reporter: WooYeonLee
> Assignee: Won Wook SONG
> Priority: Minor
> Labels: easyfix, performance
>
> {{Optional}}'s constructor preloads {{valueStr}} and {{valueHash}} for its {{toString()}} and {{hashCode()}} methods respectively, even when those methods never be invoked during the life of the object.
> {code}
> private Optional(final T value) {
> this.value = value;
> this.valueStr = "Optional:{" + value + '}';
> this.valueHash = value.hashCode();
> }
> {code}
> It incurs unnecessary overhead, and the problem becomes worse if the size of value is huge and T's hashcode() requires heavy computation.
> They should be done in {{toString()}} and {{hashCode()}} methods on demand, respectively like below:
> {code}
> private Optional(final T value) {
> this.value = value;
> }
> @Override
> public String toString() {
> return "Optional:{" + this.value + '}';
> }
> @Override
> public int hashCode() {
> return this.value.hashCode();
> }
> {code}
> +As a related issue, when {{value}} is null, it's better to return a reference of a {{static}} variable for empty Optional, not making separate objects every time. The following is the current code.
> {code}
> public static <T> Optional<T> empty() {
> return new Optional<>();
> }
> {code}
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