From c1c4d8748b2649814322fb47c69042168e308f27 Mon Sep 17 00:00:00 2001
From: Sirius <alpha.canis.majoris@outlook.com>
Date: Thu, 6 Jul 2023 20:59:05 +0800
Subject: [PATCH 1/2] ZOOKEEPER-4712: Follower.shutdown() and
 Observer.shutdown() do not correctly shutdown the syncProcessor, which may
 lead to data inconsistency

---
 .../zookeeper/server/ZooKeeperServer.java     | 25 ++++++++++++++++---
 .../server/quorum/LearnerZooKeeperServer.java | 14 +++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
index f460b2d5bb4..e67ef66e371 100644
--- a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
+++ b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
@@ -933,12 +933,23 @@ public void shutdown() {
      * @param fullyShutDown true if another server using the same database will not replace this one in the same process
      */
     public synchronized void shutdown(boolean fullyShutDown) {
+        if (shutdownZKServer(fullyShutDown)) {
+            updateZKDatabase(fullyShutDown);
+        }
+    }
+
+    /**
+     * Shut down the server instance
+     * @param fullyShutDown true if another server using the same database will not replace this one in the same process
+     * @return true if the server is successfully shutdown, false if the server cannot be shutdown.
+     */
+    public synchronized boolean shutdownZKServer(boolean fullyShutDown) {
         if (!canShutdown()) {
             if (fullyShutDown && zkDb != null) {
                 zkDb.clear();
             }
             LOG.debug("ZooKeeper server is not running, so not proceeding to shutdown!");
-            return;
+            return false;
         }
         LOG.info("shutting down");
 
@@ -965,7 +976,16 @@ public synchronized void shutdown(boolean fullyShutDown) {
         if (jvmPauseMonitor != null) {
             jvmPauseMonitor.serviceStop();
         }
+        requestPathMetricsCollector.shutdown();
+        unregisterJMX();
+        return true;
+    }
 
+    /**
+     * Update zk database during shutdown
+     * @param fullyShutDown true if another server using the same database will not replace this one in the same process
+     */
+    public synchronized void updateZKDatabase(boolean fullyShutDown) {
         if (zkDb != null) {
             if (fullyShutDown) {
                 zkDb.clear();
@@ -984,9 +1004,6 @@ public synchronized void shutdown(boolean fullyShutDown) {
                 }
             }
         }
-
-        requestPathMetricsCollector.shutdown();
-        unregisterJMX();
     }
 
     protected void unregisterJMX() {
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerZooKeeperServer.java b/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerZooKeeperServer.java
index efd2e376208..440a1917f95 100644
--- a/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerZooKeeperServer.java
+++ b/zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerZooKeeperServer.java
@@ -172,4 +172,18 @@ public synchronized void shutdown() {
         }
     }
 
+    @Override
+    public void shutdown(boolean fullyShutDown) {
+        if (shutdownZKServer(fullyShutDown)) {
+            try {
+                if (syncProcessor != null) {
+                    syncProcessor.shutdown();
+                }
+            } catch (Exception e) {
+                LOG.warn("Ignoring unexpected exception in syncprocessor shutdown", e);
+            }
+            updateZKDatabase(fullyShutDown);
+        }
+    }
+
 }

From 7a101128c82f2d33cc26f4a0ad8e6c929f5c3bdb Mon Sep 17 00:00:00 2001
From: Sirius <alpha.canis.majoris@outlook.com>
Date: Fri, 7 Jul 2023 01:04:31 +0800
Subject: [PATCH 2/2] ZOOKEEPER-4712: Follower.shutdown() and
 Observer.shutdown() do not correctly shutdown the syncProcessor, which may
 lead to data inconsistency

---
 .../java/org/apache/zookeeper/server/ZooKeeperServer.java     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
index e67ef66e371..43d06816661 100644
--- a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
+++ b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
@@ -943,7 +943,7 @@ public synchronized void shutdown(boolean fullyShutDown) {
      * @param fullyShutDown true if another server using the same database will not replace this one in the same process
      * @return true if the server is successfully shutdown, false if the server cannot be shutdown.
      */
-    public synchronized boolean shutdownZKServer(boolean fullyShutDown) {
+    protected synchronized boolean shutdownZKServer(boolean fullyShutDown) {
         if (!canShutdown()) {
             if (fullyShutDown && zkDb != null) {
                 zkDb.clear();
@@ -985,7 +985,7 @@ public synchronized boolean shutdownZKServer(boolean fullyShutDown) {
      * Update zk database during shutdown
      * @param fullyShutDown true if another server using the same database will not replace this one in the same process
      */
-    public synchronized void updateZKDatabase(boolean fullyShutDown) {
+    protected synchronized void updateZKDatabase(boolean fullyShutDown) {
         if (zkDb != null) {
             if (fullyShutDown) {
                 zkDb.clear();