extend region config

fairmq/UnmanagedRegion.h

@@ -16,6 +16,7 @@
 
 #include <functional>   // std::function
 #include <memory>       // std::unique_ptr
+#include <optional>     // std::optional
 #include <ostream>
 #include <string>
 #include <vector>
@@ -118,6 +119,13 @@ inline std::ostream& operator<<(std::ostream& os, const RegionEvent& event)
     }
 }
 
+enum class RegionConstruction : int
+{
+    open,
+    create,
+    open_or_create
+};
+
 struct RegionConfig
 {
     RegionConfig() = default;
@@ -129,9 +137,12 @@ struct RegionConfig
 
     bool lock = false; /// mlock region after creation
     bool zero = false; /// zero region content after creation
+    bool removeOnDestruction = true; /// remove the region on object destruction
+    RegionConstruction constructionMode = RegionConstruction::create; /// how to construct the region: create/open/open_or_create
     int creationFlags = 0; /// flags passed to the underlying transport on region creation
     int64_t userFlags = 0; /// custom flags that have no effect on the transport, but can be retrieved from the region by the user
     std::string path = ""; /// file path, if the region is backed by a file
+    std::optional<uint16_t> id = std::nullopt; /// region id
     uint32_t linger = 100; /// delay in ms before region destruction to collect outstanding events
 };