From 0faf59b6634a064cba10541149b8cd42af6e12c6 Mon Sep 17 00:00:00 2001
From: Kevin Heifner <heifnerk@objectcomputing.com>
Date: Fri, 1 Jul 2022 20:43:35 -0500
Subject: [PATCH] GH-590 Fix race condition on shutdown

---
 .../include/eosio/trace_api/store_provider.hpp        |  4 ++--
 plugins/trace_api_plugin/store_provider.cpp           | 11 +++++++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/plugins/trace_api_plugin/include/eosio/trace_api/store_provider.hpp b/plugins/trace_api_plugin/include/eosio/trace_api/store_provider.hpp
index 1acf288b15..adfbac6892 100644
--- a/plugins/trace_api_plugin/include/eosio/trace_api/store_provider.hpp
+++ b/plugins/trace_api_plugin/include/eosio/trace_api/store_provider.hpp
@@ -251,11 +251,11 @@ namespace eosio::trace_api {
       std::optional<uint32_t> _last_compressed_slice;
       const size_t _compression_seek_point_stride;
 
-      std::atomic<uint32_t> _best_known_lib{0};
       std::mutex _maintenance_mtx;
       std::condition_variable _maintenance_condition;
       std::thread _maintenance_thread;
-      std::atomic_bool _maintenance_shutdown{false};
+      bool _maintenance_shutdown{false};
+      uint32_t _best_known_lib{0};
    };
 
    /**
diff --git a/plugins/trace_api_plugin/store_provider.cpp b/plugins/trace_api_plugin/store_provider.cpp
index 7dfc4efc41..f87f79b006 100644
--- a/plugins/trace_api_plugin/store_provider.cpp
+++ b/plugins/trace_api_plugin/store_provider.cpp
@@ -289,7 +289,10 @@ namespace eosio::trace_api {
    }
 
    void slice_directory::set_lib(uint32_t lib) {
-      _best_known_lib = lib;
+      {
+         std::scoped_lock lock(_maintenance_mtx);
+         _best_known_lib = lib;
+      }
       _maintenance_condition.notify_one();
    }
 
@@ -306,6 +309,7 @@ namespace eosio::trace_api {
 
             uint32_t best_known_lib = _best_known_lib;
             bool shutdown = _maintenance_shutdown;
+            lock.unlock();
 
             log(std::string("Waking up to handle lib: ") + std::to_string(best_known_lib));
 
@@ -324,7 +328,10 @@ namespace eosio::trace_api {
    }
 
    void slice_directory::stop_maintenance_thread() {
-      _maintenance_shutdown = true;
+      {
+         std::scoped_lock lock(_maintenance_mtx);
+         _maintenance_shutdown = true;
+      }
       _maintenance_condition.notify_one();
       _maintenance_thread.join();
    }