Read-only cown

Author: vishalgupta97

src/rt/CMakeLists.txt

@@ -43,7 +43,7 @@ endif()
 
 if(USE_EXECINFO)
   if (${CMAKE_BUILD_TYPE} MATCHES "Debug|RelWithDebInfo")
-    target_link_libraries(verona_rt INTERFACE -rdynamic)
+    target_link_libraries(verona_rt INTERFACE -rdynamic -g -fno-omit-frame-pointer)
   endif()
 
   find_library(LIBEXECINFO execinfo)

src/rt/cpp/cown_array.h

@@ -64,4 +64,25 @@ namespace verona::cpp
     cown_array& operator=(cown_array&&) = delete;
     cown_array& operator=(const cown_array&) = delete;
   };
+
+  /* A cown_array<const T> is used to mark that the cown is being accessed as
+   * read-only. (This combines the type as the capability. We do not have deep
+   * immutability in C++, so acquired_cown<const T> is an approximation.)
+   *
+   * We use inheritance to allow us to construct a cown_array<const T> from a
+   * cown_array<T>.
+   */
+  template<typename T>
+  class cown_array<const T> : public cown_array<T>
+  {
+  public:
+    cown_array(const cown_array<T>& other) : cown_array<T>(other){};
+  };
+
+  template<typename T>
+  cown_array<const T> read(cown_array<T> cown)
+  {
+    Logging::cout() << "Read returning const array ptr" << Logging::endl;
+    return cown;
+  }
 }

src/rt/debug/harness.h

@@ -84,6 +84,8 @@ class SystematicTestHarness
   size_t seed_upper;
   high_resolution_clock::time_point start;
 
+  void (*run_at_termination)(void) = nullptr;
+
   SystematicTestHarness(int argc, const char* const* argv) : opt(argc, argv)
   {
     std::cout << "Harness starting." << std::endl;
@@ -155,7 +157,11 @@ class SystematicTestHarness
 #else
       UNUSED(seed);
 #endif
-      sched.init(cores);
+
+      if (run_at_termination)
+        sched.init(cores, run_at_termination);
+      else
+        sched.init(cores);
 
       f(std::forward<Args>(args)...);
 

src/rt/sched/behaviour.h

@@ -101,6 +101,8 @@ namespace verona::rt
         auto* s = new (&slots[i]) Slot(requests[i].cown());
         if (requests[i].is_move())
           s->set_move();
+        if (requests[i].is_read())
+          s->set_read_only();
       }
 
       return body;