jiajunwang commented on a change in pull request #1526:
URL: https://github.com/apache/helix/pull/1526#discussion_r535760887
##########
File path:
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/ZkConnection.java
##########
@@ -192,4 +230,53 @@ public String getServers() {
public void addAuthInfo(String scheme, byte[] auth) {
_zk.addAuthInfo(scheme, auth);
}
+
+ private void lookupGetChildrenMethod() {
+ if (_getChildrenMethod != null) {
+ // Method is already cached.
+ return;
+ }
+ try {
+ if (GETCHILDREN_PAGINATION_DISABLED) {
+ lookupNonPaginatedGetChildren();
+ } else {
+ // Lookup the paginated getChildren API
+ _getChildrenMethod =
+ ZooKeeper.class.getMethod("getAllChildrenPaginated", String.class,
boolean.class);
+ }
+ } catch (NoSuchMethodException e1) {
+ // Pagination API is not supported, fall back to non-paginated API
+ lookupNonPaginatedGetChildren();
+ }
+ LOG.info("Pagination config {}={}, method to be invoked: {}",
+ ZkSystemPropertyKeys.ZK_GETCHILDREN_PAGINATION_DISABLED,
GETCHILDREN_PAGINATION_DISABLED,
+ _getChildrenMethod.getName());
+ }
+
+ private void lookupNonPaginatedGetChildren() {
+ try {
+ _getChildrenMethod = ZooKeeper.class.getMethod("getChildren",
String.class, boolean.class);
+ } catch (NoSuchMethodException e2) {
+ // We should not expect this exception here.
+ LOG.error("getChildren is not supported in this zookeeper version!");
+ }
+ }
+
+ private void handleInvokedMethodException(Throwable cause)
+ throws KeeperException, InterruptedException {
+ if (cause instanceof KeeperException.UnimplementedException) {
+ LOG.warn("Paginated getChildren is unimplemented in ZK server! "
+ + "Falling back to non-paginated getChildren");
+ lookupNonPaginatedGetChildren();
Review comment:
This is hacky but I don't have any better way. Let's add a TODO here for
the record. But the logic itself should be safe.
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