Merge pull request #412 from apache/cpc_teardown

register cpc teardown functions for std::atexit

cpc/include/cpc_compressor.hpp

@@ -44,6 +44,10 @@ template<typename A> class cpc_compressor;
 template<typename A>
 inline cpc_compressor<A>& get_compressor();
 
+// function called atexit to clean up compression tables
+template<typename A>
+void destroy_compressor();
+
 template<typename A>
 class cpc_compressor {
 public:
@@ -109,8 +113,10 @@ class cpc_compressor {
   };
 
   cpc_compressor();
-  template<typename T> friend cpc_compressor<T>& get_compressor();
+  friend cpc_compressor& get_compressor<A>();
+
   ~cpc_compressor();
+  friend void destroy_compressor<A>();
 
   void make_decoding_tables(); // call this at startup
   void free_decoding_tables(); // call this at the end

cpc/include/cpc_compressor_impl.hpp

@@ -22,9 +22,11 @@
 #ifndef CPC_COMPRESSOR_IMPL_HPP_
 #define CPC_COMPRESSOR_IMPL_HPP_
 
+#include <cstdlib>
 #include <memory>
 #include <stdexcept>
 
+#include "common_defs.hpp"
 #include "compression_data.hpp"
 #include "cpc_util.hpp"
 #include "cpc_common.hpp"
@@ -36,9 +38,17 @@ namespace datasketches {
 template<typename A>
 cpc_compressor<A>& get_compressor() {
   static cpc_compressor<A>* instance = new cpc_compressor<A>(); // use new for global initialization
+  static int reg_result = std::atexit(destroy_compressor<A>); // just to clean up a little more nicely; don't worry if it fails
+  unused(reg_result);
   return *instance;
 }
 
+// register to call compressor destructor at exit
+template<typename A>
+void destroy_compressor() {
+  delete std::addressof(get_compressor<A>());
+}
+
 template<typename A>
 cpc_compressor<A>::cpc_compressor() {
   make_decoding_tables();