From 1ff90c510a5777e6559e62a905fcc97fbad0ed6d Mon Sep 17 00:00:00 2001
From: Matteo Merli <mmerli@apache.org>
Date: Fri, 19 Nov 2021 06:53:39 -0800
Subject: [PATCH] Remove unneeded ZK operations for setting watches (#12866)

---
 .../pulsar/metadata/impl/ZKMetadataStore.java | 38 +------------------
 1 file changed, 2 insertions(+), 36 deletions(-)

diff --git a/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/ZKMetadataStore.java b/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/ZKMetadataStore.java
index 2cee1c7a627f62..03ac79fc6c9f3f 100644
--- a/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/ZKMetadataStore.java
+++ b/pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/ZKMetadataStore.java
@@ -138,23 +138,6 @@ public CompletableFuture<Optional<GetResult>> get(String path) {
                     if (code == Code.OK) {
                         future.complete(Optional.of(new GetResult(data, getStat(path1, stat))));
                     } else if (code == Code.NONODE) {
-                        // Place a watch on the non-existing node, so we'll get notified
-                        // when it gets created and we can invalidate the negative cache.
-                        existsFromStore(path).thenAccept(exists -> {
-                            if (exists) {
-                                get(path).thenAccept(c -> future.complete(c))
-                                        .exceptionally(ex -> {
-                                            future.completeExceptionally(ex);
-                                            return null;
-                                        });
-                            } else {
-                                // Z-node does not exist
-                                future.complete(Optional.empty());
-                            }
-                        }).exceptionally(ex -> {
-                            future.completeExceptionally(ex);
-                            return null;
-                        });
                         future.complete(Optional.empty());
                     } else {
                         future.completeExceptionally(getException(code, path));
@@ -180,25 +163,8 @@ public CompletableFuture<List<String>> getChildrenFromStore(String path) {
                         Collections.sort(children);
                         future.complete(children);
                     } else if (code == Code.NONODE) {
-                        // The node we want may not exist yet, so put a watcher on its existence
-                        // before throwing up the exception. Its possible that the node could have
-                        // been created after the call to getChildren, but before the call to exists().
-                        // If this is the case, exists will return true, and we just call getChildren
-                        // again.
-                        existsFromStore(path).thenAccept(exists -> {
-                            if (exists) {
-                                getChildrenFromStore(path).thenAccept(c -> future.complete(c)).exceptionally(ex -> {
-                                    future.completeExceptionally(ex);
-                                    return null;
-                                });
-                            } else {
-                                // Z-node does not exist
-                                future.complete(Collections.emptyList());
-                            }
-                        }).exceptionally(ex -> {
-                            future.completeExceptionally(ex);
-                            return null;
-                        });
+                        // Z-node does not exist
+                        future.complete(Collections.emptyList());
                     } else {
                         future.completeExceptionally(getException(code, path));
                     }