[accumulo] branch main updated: Update documentation with purpose of the "cache" (#2714)

[edcoleman]

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edcoleman pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/accumulo.git


The following commit(s) were added to refs/heads/main by this push:
     new ed5e188a92 Update documentation with purpose of the "cache" (#2714)
ed5e188a92 is described below

commit ed5e188a92bcd8d0be191b2d1a2380b72b2c998b
Author: EdColeman <d...@etcoleman.com>
AuthorDate: Tue May 17 16:58:03 2022 -0400

    Update documentation with purpose of the "cache" (#2714)
    
    * Update documentation with purpose of the "cache"
    
        - Remove the TODO with an explanation that the class supports legacy
    clients.
    
    * Update 
core/src/main/java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java
    
    Co-authored-by: Christopher Tubbs <ctubb...@apache.org>
    
    * Fix formatting
    
    Co-authored-by: Ed Coleman etcoleman <edcole...@apache.org>
    Co-authored-by: Christopher Tubbs <ctubb...@apache.org>
---
 .../java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java   | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git 
a/core/src/main/java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java 
b/core/src/main/java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java
index 76bb3f09c8..c2957b9b32 100644
--- a/core/src/main/java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java
+++ b/core/src/main/java/org/apache/accumulo/fate/zookeeper/ZooCacheFactory.java
@@ -26,9 +26,14 @@ import org.apache.accumulo.core.singletons.SingletonService;
 
 /**
  * A factory for {@link ZooCache} instances.
+ * <p>
+ * Implementation note: We are using the instances map to track all the 
instances that have been
+ * created, so we can explicitly close them when the last legacy client has 
gone away. This is part
+ * of the "SingletonManager" code, and it is likely that ZooCacheFactory and 
ZooKeeperInstance can
+ * be removed when legacy client code support is no longer required.
  */
 public class ZooCacheFactory {
-  // TODO: make this better - LRU, soft references, ...
+
   private static Map<String,ZooCache> instances = new HashMap<>();
   private static boolean enabled = true;