From 8395e821fc1af93d1511bb914bc5448bde262b1c Mon Sep 17 00:00:00 2001
From: Tao He <sighingnow@gmail.com>
Date: Mon, 24 Oct 2022 10:07:53 +0800
Subject: [PATCH] Protect the timer to avoid "cancel" and "refresh" happens at
 the same time.

Signed-off-by: Tao He <sighingnow@gmail.com>
---
 etcd/KeepAlive.hpp | 4 ++++
 src/KeepAlive.cpp  | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/etcd/KeepAlive.hpp b/etcd/KeepAlive.hpp
index 36b586f..f7ea1d3 100644
--- a/etcd/KeepAlive.hpp
+++ b/etcd/KeepAlive.hpp
@@ -5,6 +5,7 @@
 #include <chrono>
 #include <exception>
 #include <functional>
+#include <mutex>
 #include <string>
 #include <thread>
 
@@ -117,6 +118,9 @@ namespace etcd
 
     int ttl;
     int64_t lease_id;
+
+    // protect the initializing status of `timer`.
+    std::mutex mutex_for_refresh_;
     std::atomic_bool continue_next;
 
     // grpc timeout in `refresh()`
diff --git a/src/KeepAlive.cpp b/src/KeepAlive.cpp
index 0d71cb9..43ca87e 100644
--- a/src/KeepAlive.cpp
+++ b/src/KeepAlive.cpp
@@ -124,6 +124,7 @@ etcd::KeepAlive::~KeepAlive()
 
 void etcd::KeepAlive::Cancel()
 {
+  std::lock_guard<std::mutex> scope_lock(mutex_for_refresh_);
   if (!continue_next.exchange(false)) {
     return;
   }
@@ -142,6 +143,7 @@ void etcd::KeepAlive::Check() {
 
 void etcd::KeepAlive::refresh()
 {
+  std::lock_guard<std::mutex> scope_lock(mutex_for_refresh_);
   if (!continue_next.load()) {
     return;
   }