fengnanli commented on a change in pull request #2110:
URL: https://github.com/apache/hadoop/pull/2110#discussion_r447993824
##########
File path:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/token/delegation/AbstractDelegationTokenSecretManager.java
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@@ -726,4 +732,41 @@ public TokenIdent decodeTokenIdentifier(Token<TokenIdent>
token) throws IOExcept
return token.decodeIdentifier();
}
+ /**
+ * Return top token real owners list as well as the tokens count.
+ *
+ * @param n top number of users
+ * @return map of owners to counts
+ */
+ public List<NameValuePair> getTopTokenRealOwners(int n) {
+ Map<String, Integer> tokenOwnerMap = new HashMap<>();
+ for (TokenIdent id : currentTokens.keySet()) {
+ String realUser;
+ if (id.getRealUser() != null && !id.getRealUser().toString().isEmpty()) {
+ realUser = id.getRealUser().toString();
+ } else {
+ // if there is no real user -> this is a non proxy user
+ // the user itself is the real owner
+ realUser = id.getUser().getUserName();
+ }
+ tokenOwnerMap.put(realUser, tokenOwnerMap.getOrDefault(realUser, 0)+1);
+ }
+ n = Math.min(n, tokenOwnerMap.size());
+ if (n == 0) {
+ return new LinkedList<>();
+ }
+
+ TopN topN = new TopN(n);
+ for (Map.Entry<String, Integer> entry : tokenOwnerMap.entrySet()) {
+ topN.offer(new NameValuePair(
+ entry.getKey(), entry.getValue()));
+ }
+
+ List<NameValuePair> list = new LinkedList<>();
Review comment:
There is a reverse op and I think reverse linked list is faster without
additional space.
Not sure how java implement the reverse array list, but I think it will
introduce copy and reassign.
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