HADOOP-17493. Revert name of DELEGATION_TOKENS_ISSUED constant/statistic (#2649)

Follow-on to HADOOP-16830/HADOOP-17271.

Contributed by Steve Loughran.

Change-Id: I16db6e788c9fd628d3295671d7c2861c249d5ef1

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/statistics/StoreStatisticNames.java

@@ -325,9 +325,6 @@ public final class StoreStatisticNames {
   public static final String STORE_IO_THROTTLE_RATE
       = "store_io_throttle_rate";
 
-  public static final String DELEGATION_TOKEN_ISSUED
-      = "delegation_token_issued";
-
   public static final String MULTIPART_UPLOAD_INSTANTIATED
       = "multipart_instantiated";
 

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Statistic.java

@@ -494,8 +494,8 @@ public enum Statistic {
   /*
    * Delegation Token Operations.
    */
-  DELEGATION_TOKEN_ISSUED(
-      StoreStatisticNames.DELEGATION_TOKEN_ISSUED,
+  DELEGATION_TOKENS_ISSUED(
+      StoreStatisticNames.DELEGATION_TOKENS_ISSUED,
       "Count of delegation tokens issued",
       TYPE_DURATION),
 

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/auth/delegation/S3ADelegationTokens.java

@@ -45,7 +45,7 @@ import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.service.ServiceOperations;
 import org.apache.hadoop.util.DurationInfo;
 
-import static org.apache.hadoop.fs.s3a.Statistic.DELEGATION_TOKEN_ISSUED;
+import static org.apache.hadoop.fs.s3a.Statistic.DELEGATION_TOKENS_ISSUED;
 import static org.apache.hadoop.fs.statistics.impl.IOStatisticsBinding.trackDuration;
 import static org.apache.hadoop.thirdparty.com.google.common.base.Preconditions.checkArgument;
 import static org.apache.hadoop.thirdparty.com.google.common.base.Preconditions.checkState;
@@ -431,7 +431,7 @@ public class S3ADelegationTokens extends AbstractDTService {
     try(DurationInfo ignored = new DurationInfo(LOG, DURATION_LOG_AT_INFO,
         "Creating New Delegation Token", tokenBinding.getKind())) {
       Token<AbstractS3ATokenIdentifier> token = trackDuration(stats,
-          DELEGATION_TOKEN_ISSUED.getSymbol(), () ->
+          DELEGATION_TOKENS_ISSUED.getSymbol(), () ->
               tokenBinding.createDelegationToken(rolePolicy,
                   encryptionSecrets, renewer));
       if (token != null) {

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/auth/delegation/ITestSessionDelegationInFileystem.java

@@ -214,7 +214,7 @@ public class ITestSessionDelegationInFileystem extends AbstractDelegationIT {
     S3ATestUtils.MetricDiff invocationDiff = new S3ATestUtils.MetricDiff(fs,
         Statistic.INVOCATION_GET_DELEGATION_TOKEN);
     S3ATestUtils.MetricDiff issueDiff = new S3ATestUtils.MetricDiff(fs,
-        Statistic.DELEGATION_TOKEN_ISSUED);
+        Statistic.DELEGATION_TOKENS_ISSUED);
     Token<AbstractS3ATokenIdentifier> token =
         requireNonNull(fs.getDelegationToken(""),
             "no token from filesystem " + fs);
@@ -371,7 +371,7 @@ public class ITestSessionDelegationInFileystem extends AbstractDelegationIT {
 
       S3ATestUtils.MetricDiff issueDiff = new S3ATestUtils.MetricDiff(
           delegatedFS,
-          Statistic.DELEGATION_TOKEN_ISSUED);
+          Statistic.DELEGATION_TOKENS_ISSUED);
 
       // verify that the FS returns the existing token when asked
       // so that chained deployments will work