Github user ctubbsii commented on a diff in the pull request: https://github.com/apache/accumulo/pull/292#discussion_r133059580 --- Diff: core/src/main/java/org/apache/accumulo/core/client/impl/Table.java --- @@ -16,24 +16,59 @@ */ package org.apache.accumulo.core.client.impl; +import java.lang.ref.WeakReference; +import java.util.WeakHashMap; + import org.apache.accumulo.core.client.Instance; public class Table { /** * Object representing an internal table ID. This class was created to help with type safety. For help obtaining the value of a table ID from Zookeeper, see * {@link Tables#getTableId(Instance, String)} + * + * Uses an internal WeakHashMap and private constructor for storing a WeakReference of every Table.ID. Therefore, a Table.ID can't be instantiated outside + * this class and is accessed by calling Table.ID.{@link #of(String)}. */ public static class ID extends AbstractId { private static final long serialVersionUID = 7399913185860577809L; + static final WeakHashMap<String,WeakReference<Table.ID>> tableIds = new WeakHashMap<>(); - public static final ID METADATA = new ID("!0"); - public static final ID REPLICATION = new ID("+rep"); - public static final ID ROOT = new ID("+r"); + public static final ID METADATA = of("!0"); + public static final ID REPLICATION = of("+rep"); + public static final ID ROOT = of("+r"); - public ID(final String canonical) { + private ID(final String canonical) { super(canonical); } + + /** + * Get a Table.ID object for the provided canonical string. + * + * @param canonical + * table ID string + * @return Table.ID object + */ + public static Table.ID of(final String canonical) { + return dedupeTableId(canonical); + } + + private static Table.ID dedupeTableId(String tableIdString) { --- End diff -- Passing in a `Function<String,T>` might be a nice compromise. Or a `Supplier<T>`: ```java protected static <T extends AbstractId> T dedupe(WeakHashMap<String,WeakReference<T>> cache, Supplier<T> newInstanceFunction) { //.... } ``` In Table.ID: ```java public ID of(String canonical) { return dedupe(cache, () -> new ID(canonical)); } ``` Shared implementation. No reflection. No unnecessary construction.
--- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---