From 1f03839830c1ec92b912bab6cdcfba6908780ccf Mon Sep 17 00:00:00 2001
From: Val <valeryxbaturin@gmail.com>
Date: Sun, 24 May 2020 20:12:59 +0300
Subject: [PATCH] add zookeeper tryRemoveChildren method

---
 src/Common/ZooKeeper/ZooKeeper.cpp | 17 +++++++++++++++++
 src/Common/ZooKeeper/ZooKeeper.h   |  5 +++++
 2 files changed, 22 insertions(+)

diff --git a/src/Common/ZooKeeper/ZooKeeper.cpp b/src/Common/ZooKeeper/ZooKeeper.cpp
index 476e88d7e72..541625149dd 100644
--- a/src/Common/ZooKeeper/ZooKeeper.cpp
+++ b/src/Common/ZooKeeper/ZooKeeper.cpp
@@ -579,6 +579,23 @@ void ZooKeeper::removeChildren(const std::string & path)
 }
 
 
+void ZooKeeper::tryRemoveChildren(const std::string & path)
+{
+    Strings children;
+    if (tryGetChildren(path, children) != Coordination::ZOK)
+        return;
+    while (!children.empty())
+    {
+        Coordination::Requests ops;
+        for (size_t i = 0; i < MULTI_BATCH_SIZE && !children.empty(); ++i)
+        {
+            ops.emplace_back(makeRemoveRequest(path + "/" + children.back(), -1));
+            children.pop_back();
+        }
+        multi(ops);
+    }
+}
+
 void ZooKeeper::removeChildrenRecursive(const std::string & path)
 {
     Strings children = getChildren(path);
diff --git a/src/Common/ZooKeeper/ZooKeeper.h b/src/Common/ZooKeeper/ZooKeeper.h
index 416e40c2da4..cb28f442392 100644
--- a/src/Common/ZooKeeper/ZooKeeper.h
+++ b/src/Common/ZooKeeper/ZooKeeper.h
@@ -187,7 +187,12 @@ public:
     /// Remove all children nodes (non recursive).
     void removeChildren(const std::string & path);
 
+    /// Remove all children nodes (non recursive).
+    /// If there're no children, this method doesn't throw an exception
+    void tryRemoveChildren(const std::string & path);
+
     using WaitCondition = std::function<bool()>;
+
     /// Wait for the node to disappear or return immediately if it doesn't exist.
     /// If condition is speficied, it is used to return early (when condition returns false)
     /// The function returns true if waited and false if waiting was interrupted by condition.