From c02546a1418cf011cde988cc456cc95bff5ce9c6 Mon Sep 17 00:00:00 2001
From: Nghia Truong <nghiat@nvidia.com>
Date: Mon, 29 Jul 2024 11:23:24 -0700
Subject: [PATCH] Use `shared_mutex` and `shared_lock`

Signed-off-by: Nghia Truong <nghiat@nvidia.com>
---
 cpp/include/cudf/utilities/prefetch.hpp | 4 ++--
 cpp/src/utilities/prefetch.cpp          | 9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/cpp/include/cudf/utilities/prefetch.hpp b/cpp/include/cudf/utilities/prefetch.hpp
index d794ef7d015..1bf838bc3c2 100644
--- a/cpp/include/cudf/utilities/prefetch.hpp
+++ b/cpp/include/cudf/utilities/prefetch.hpp
@@ -21,7 +21,7 @@
 #include <rmm/device_uvector.hpp>
 
 #include <map>
-#include <mutex>
+#include <shared_mutex>
 #include <string>
 #include <string_view>
 
@@ -73,7 +73,7 @@ class prefetch_config {
  private:
   prefetch_config() = default;                //< Private constructor to enforce singleton pattern
   std::map<std::string, bool> config_values;  //< Map of configuration keys to values
-  std::mutex config_mtx;                      //< Mutex for thread-safe config access
+  std::shared_mutex config_mtx;               //< Mutex for thread-safe config access
 };
 
 /**
diff --git a/cpp/src/utilities/prefetch.cpp b/cpp/src/utilities/prefetch.cpp
index bf803e788a1..173ac886232 100644
--- a/cpp/src/utilities/prefetch.cpp
+++ b/cpp/src/utilities/prefetch.cpp
@@ -34,15 +34,16 @@ prefetch_config& prefetch_config::instance()
 
 bool prefetch_config::get(std::string_view key) const
 {
-  std::scoped_lock lock(config_mtx);
-  // Default to not prefetching
-  if (config_values.find(key.data()) == config_values.end()) { return false; }
+  std::shared_lock<std::shared_mutex> lock(config_mtx);
+  if (config_values.find(key.data()) == config_values.end()) {
+    return false;  // default to not prefetching
+  }
   return config_values.at(key.data());
 }
 
 void prefetch_config::set(std::string_view key, bool value)
 {
-  std::scoped_lock lock(config_mtx);
+  std::lock_guard<std::shared_mutex> lock(config_mtx);
   config_values[key.data()] = value;
 }