[improve][admin] Unset namespace policy to improve deleting namespace.

[Technoboy-]

Motivation

When there are many partitioned topics under a namespace, deleting the namespace forcibly will fail, because many requests update ns policies simultaneously and cause the metadata store throws BadVersionException.

See internalRemovePartitionsAuthenticationPoliciesAsync

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/PersistentTopicsBase.java

Lines 612 to 629 in 374b3a1

	protected void internalDeletePartitionedTopic(AsyncResponse asyncResponse,
	boolean authoritative,
	boolean force) {
	validateTopicOwnershipAsync(topicName, authoritative)
	.thenCompose(__ -> validateNamespaceOperationAsync(topicName.getNamespaceObject(),
	NamespaceOperation.DELETE_TOPIC))
	.thenCompose(__ -> pulsar().getBrokerService()
	.fetchPartitionedTopicMetadataAsync(topicName)
	.thenCompose(partitionedMeta -> {
	final int numPartitions = partitionedMeta.partitions;
	if (numPartitions < 1){
	return CompletableFuture.completedFuture(null);
	}
	return internalRemovePartitionsAuthenticationPoliciesAsync(numPartitions)
	.thenCompose(unused -> internalRemovePartitionsTopicAsync(numPartitions, force));
	})
	// Only tries to delete the znode for partitioned topic when all its partitions are successfully deleted
	).thenCompose(__ -> namespaceResources()

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/PersistentTopicsBase.java

Lines 704 to 714 in 374b3a1

	private CompletableFuture<Void> internalRemovePartitionsAuthenticationPoliciesAsync(int numPartitions) {
	CompletableFuture<Void> future = new CompletableFuture<>();
	pulsar().getPulsarResources().getNamespaceResources()
	.setPoliciesAsync(topicName.getNamespaceObject(), p -> {
	IntStream.range(0, numPartitions)
	.forEach(i -> p.auth_policies.getTopicAuthentication()
	.remove(topicName.getPartition(i).toString()));
	p.auth_policies.getTopicAuthentication().remove(topicName.toString());
	return p;
	})
	.whenComplete((r, ex) -> {

When deleting the namespace, there is no need to update namespace policies, we can delete the namespace zk node in the end.

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/NamespacesBase.java

Lines 363 to 381 in 374b3a1

	protected CompletableFuture<Void> internalClearZkSources() {
	// clear resource of `/namespace/{namespaceName}` for zk-node
	return namespaceResources().deleteNamespaceAsync(namespaceName)
	.thenCompose(ignore -> namespaceResources().getPartitionedTopicResources()
	.clearPartitionedTopicMetadataAsync(namespaceName))
	// clear resource for manager-ledger z-node
	.thenCompose(ignore -> pulsar().getPulsarResources().getTopicResources()
	.clearDomainPersistence(namespaceName))
	.thenCompose(ignore -> pulsar().getPulsarResources().getTopicResources()
	.clearNamespacePersistence(namespaceName))
	// we have successfully removed all the ownership for the namespace, the policies
	// z-node can be deleted now
	.thenCompose(ignore -> namespaceResources().deletePoliciesAsync(namespaceName))
	// clear z-node of local policies
	.thenCompose(ignore -> getLocalPolicies().deleteLocalPoliciesAsync(namespaceName))
	// clear /loadbalance/bundle-data
	.thenCompose(ignore -> namespaceResources().deleteBundleDataAsync(namespaceName));
	}

Documentation

• doc-not-needed
  (Please explain why)

[gaoran10]

Make sense, LGTM, left a trivial comment.