PR157: ARM memory barrier

[cacao.git] / src / mm / gc.hpp

diff --git a/src/mm/gc.hpp b/src/mm/gc.hpp
index 60d5c3ae58d75ac8d2577d9780abb34b2585a993..0a0791205e7cb1e8a18ad94bf4bdf250c072be7c 100644 (file)
--- a/src/mm/gc.hpp
+++ b/src/mm/gc.hpp
@@ -28,14 +28,90 @@
 
 #include "config.h"
 
+#include <assert.h>
 #include <stdint.h>
 
+
 #ifdef __cplusplus
-extern "C" {
+
+class GC {
+public:
+};
+
+
+/**
+ * Critical section for the GC.
+ */
+class GCCriticalSection {
+public:
+       GCCriticalSection()  { enter(); }
+       ~GCCriticalSection() { leave(); }
+
+       inline static void enter ();
+       inline static void leave ();
+       inline static bool inside();
+};
+
+
+// Includes.
+#if defined(ENABLE_GC_CACAO)
+# include "threads/thread.hpp"
 #endif
 
-#include "vm/global.h"
-#include "vm/method.h"
+
+/**
+ * Enters a LLNI critical section which prevents the GC from moving
+ * objects around on the collected heap.
+ *
+ * There are no race conditions possible while entering such a critical
+ * section, because each thread only modifies its own thread local flag
+ * and the GC reads the flags while the world is stopped.
+ */
+void GCCriticalSection::enter()
+{
+#if defined(ENABLE_GC_CACAO)
+       threadobject* t = thread_get_current();
+
+       // Sanity check.
+       assert(t->gc_critical == false);
+
+       t->gc_critical = true;
+#endif
+}
+
+/**
+ * Leaves a LLNI critical section and allows the GC to move objects
+ * around on the collected heap again.
+ */
+void GCCriticalSection::leave()
+{
+#if defined(ENABLE_GC_CACAO)
+       threadobject* t = thread_get_current();
+
+       // Sanity check.
+       assert(t->gc_critical == true);
+
+       t->gc_critical = false;
+#endif
+}
+
+
+/**
+ * Checks if the calling thread is inside a GC critical section.
+ *
+ * @return true if inside, false otherwise.
+ */
+bool GCCriticalSection::inside()
+{
+#if defined(ENABLE_GC_CACAO)
+       threadobject* t = thread_get_current();
+       return t->gc_critical;
+#else
+       return true;
+#endif
+}
+
+#endif
 
 
 /* reference types ************************************************************/
@@ -52,8 +128,17 @@ enum {
 };
 
 
+// Includes.
+#include "vm/global.h"
+#include "vm/method.hpp"
+
+
 /* function prototypes ********************************************************/
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void    gc_init(size_t heapmaxsize, size_t heapstartsize);
 
 void*   heap_alloc_uncollectable(size_t size);
@@ -83,7 +168,7 @@ void*   gc_out_of_memory(size_t bytes_requested);
 
 /* inlined functions **********************************************************/
 
-static inline int32_t heap_hashcode(java_object_t *obj)
+static inline int32_t heap_hashcode(java_object_t* obj)
 {
 #if defined(ENABLE_GC_CACAO)
        return heap_get_hashcode(obj);
@@ -93,10 +178,10 @@ static inline int32_t heap_hashcode(java_object_t *obj)
 }
 
 #ifdef __cplusplus
-}
+} // extern "C"
 #endif
 
-#endif /* _GC_HPP */
+#endif // _GC_HPP
 
 
 /*
@@ -105,9 +190,10 @@ static inline int32_t heap_hashcode(java_object_t *obj)
  * Emacs will automagically detect them.
  * ---------------------------------------------------------------------
  * Local variables:
- * mode: c
+ * mode: c++
  * indent-tabs-mode: t
  * c-basic-offset: 4
  * tab-width: 4
  * End:
+ * vim:noexpandtab:sw=4:ts=4:
  */