pkuwm commented on a change in pull request #1526:
URL: https://github.com/apache/helix/pull/1526#discussion_r535645083
##########
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:
The cached method is changed here, and later when zkClient retries
calling `getChildren()`, it'll used the fallback API.
We cannot retry calling zk server right now because the connection is loss.
ZkClient has to wait for re-connected. So zkclient is the right place to retry
the operation.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
