[Lldb-commits] [lldb] [lldb] Make the PluginManager thread safe (PR #184452)

[John Harrison via lldb-commits]

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@@ -548,45 +580,52 @@ template <typename Instance> class PluginInstances {
   // to the returned instances will not be reflected back to instances
   // stored by the PluginInstances object.
   std::vector<Instance> GetSnapshot() {
+    std::lock_guard<std::mutex> lock(m_mutex);
     std::vector<Instance> enabled_instances;
-    for (const auto &instance : m_instances) {
+    for (const Instance &instance : m_instances) {
       if (instance.enabled)
         enabled_instances.push_back(instance);
     }
     return enabled_instances;
   }
 
-  const Instance *GetInstanceAtIndex(uint32_t idx) {
+  // Return a field from the idx-th enabled instance, or default_val if none.
+  template <typename Ret, typename Callback>
+  Ret GetFieldAtIndex(uint32_t idx, Ret default_val, Callback callback) {
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ashgti wrote:

Should we use `std::optional<Ret>` to make it more explicit that `std::nullopt`? 

At the call site, you can do `GetFieldAtIndex(idx, callback).value_or(default_val)`, which pushes the default value handling to the call site and better supports move only types.

https://github.com/llvm/llvm-project/pull/184452