Add specific option to select radix tree implementation for subscriptions (#3304)

* Add specific option to select radix tree implementation for subscriptions (defaults to ON if draft API enabled).

CMakeLists.txt

@@ -114,12 +114,19 @@ else()
   option(ENABLE_DRAFTS "Build and install draft classes and methods" OFF)
 endif()
 if(ENABLE_DRAFTS)
+  option (ENABLE_RADIX_TREE "Use radix tree implementation to manage subscriptions" ON)
   add_definitions(-DZMQ_BUILD_DRAFT_API)
   set(pkg_config_defines "-DZMQ_BUILD_DRAFT_API=1")
 else()
+  option (ENABLE_RADIX_TREE "Use radix tree implementation to manage subscriptions" OFF)
   set(pkg_config_defines "")
 endif()
 
+if (ENABLE_RADIX_TREE)
+   message(STATUS "Using radix tree implementation to manage subscriptions")
+   add_definitions(-DZMQ_USE_RADIX_TREE)
+endif()
+
 option(WITH_MILITANT "Enable militant assertions" OFF)
 if(WITH_MILITANT)
   add_definitions(-DZMQ_ACT_MILITANT)

src/xsub.hpp

@@ -34,7 +34,7 @@
 #include "session_base.hpp"
 #include "dist.hpp"
 #include "fq.hpp"
-#ifdef ZMQ_BUILD_DRAFT_API
+#ifdef ZMQ_USE_RADIX_TREE
 #include "radix_tree.hpp"
 #else
 #include "trie.hpp"
@@ -82,7 +82,7 @@ class xsub_t : public socket_base_t
     dist_t _dist;
 
     //  The repository of subscriptions.
-#ifdef ZMQ_BUILD_DRAFT_API
+#ifdef ZMQ_USE_RADIX_TREE
     radix_tree _subscriptions;
 #else
     trie_t _subscriptions;