That way, you can create a token with an expiration of, let's say, 1 week. And then when the user comes back the next day with the token, you know that user is still logged in to your system.

  public void removalListener() {
    int[] stats = new int[4];

    RemovalListener<Integer, Integer> countingListener =
        notification -> {
          switch (notification.getCause()) {
            case EXPIRED:
              stats[0]++;
              break;
            case EXPLICIT:
              stats[1]++;
              break;
            case REPLACED:
              stats[2]++;
              break;

	if context.Cause(ctx) != nil {
		xioutil.SafeClose(expireCh)
		return context.Cause(ctx)
	}
	pushToExpire()
	// Send any remaining objects downstream
	if len(toDel) > 0 {
		select {
		case <-ctx.Done():
		case expireCh <- toDel:
		}
	}
	xioutil.SafeClose(expireCh)

	<-expireDoneCh // waits for the expire goroutine to complete
	wk.Wait()      // waits for all expire workers to retire

	// when looking up a version by fi.VersionID
	InclFreeVersions bool
	// SkipFreeVersion skips adding a free version when a tiered version is
	// being 'replaced'
	// Note: Used only when a tiered object is being expired.
	SkipFreeVersion bool

	MetadataChg           bool                  // is true if it is a metadata update operation.
	EvalRetentionBypassFn EvalRetentionBypassFn // only set for enforcing retention bypass on DeleteObject.

	NowFunc func() time.Time
	// DryRun generate sql without execute
	DryRun bool
	// PrepareStmt executes the given query in cached statement
	PrepareStmt bool
	// PrepareStmt cache support LRU expired,
	// default maxsize=int64 Max value and ttl=1h
	PrepareStmtMaxSize int
	PrepareStmtTTL     time.Duration

	// DisableAutomaticPing
	DisableAutomaticPing bool
	// DisableForeignKeyConstraintWhenMigrating

        public String propertiesPath;

        /** Number of days after which documents should expire and be cleaned up. */
        @Option(name = "-e", aliases = "--expires", metaVar = "expires", usage = "Expires for documents")
        public String expires;

        /** Interval in milliseconds for hot thread monitoring and logging. */

	return ies.addUser(ctx, user, userType, u, m)
}

func (ies *IAMEtcdStore) addUser(ctx context.Context, user string, userType IAMUserType, u UserIdentity, m map[string]UserIdentity) error {
	if u.Credentials.IsExpired() {
		// Delete expired identity.
		deleteKeyEtcd(ctx, ies.client, getUserIdentityPath(user, userType))
		deleteKeyEtcd(ctx, ies.client, getMappedPolicyPath(user, userType, false))
		return nil
	}

    }
}
```

## 9. Performance Considerations

### 9.1 Memory Management
- Lease entries should be evicted based on LRU when max leases reached
- Implement periodic cleanup of expired leases

### 9.2 Thread Safety
- Use concurrent data structures for lease storage
- Minimize lock contention in hot paths
- Async handling of lease breaks

### 9.3 Network Efficiency

				nonExistentUsers = append(nonExistentUsers, ndn.String())
				continue
			}
			return nil, err
		}
		if len(searchResult.Entries) == 0 {
			// DN was not found - this means this user account is
			// expired.
			ndn, err := ldap.ParseDN(dn)
			if err != nil {
				return nil, err
			}
			nonExistentUsers = append(nonExistentUsers, ndn.String())
		}
	}
	return nonExistentUsers, nil
}

            1000,  // 1 second timeout
            null
        );
        
        assertFalse(info.isExpired());
        
        // Wait for expiration
        Thread.sleep(1500);
        assertTrue(info.isExpired());
        
        // Persistent handles don't expire
        HandleInfo persistent = new HandleInfo(
            "/test/file2.txt",
            new HandleGuid(),