1 files changed, 64 insertions, 0 deletions
diff --git a/src/server/reference.h b/src/server/reference.h
new file mode 100644
index 0000000..75a681f
--- /dev/null
+++ b/src/server/reference.h
@@ -0,0 +1,64 @@
+#ifndef _REFERENCE_H_
+#define _REFERENCE_H_
+
+#include "reftypes.h"
+#include <stddef.h>
+#include <stdint.h>
+
+#define container_of(ptr, type, member) \
+	((type *)((char *)(ptr) - (char *)&(((type *)NULL)->member)))
+
+void ref_init( ref *reference, void ( *freefun )( ref * ), long count );
+
+void ref_setref( weakref *weakref, ref *ref );
+
+_Noreturn void _ref_error( const char *message );
+
+static inline ref *ref_get( weakref *weakref )
+{
+	char *old_weakref = (char *)*weakref;
+	do {
+		if ( old_weakref == NULL )
+			return NULL;
+		if ( aligned_ref( old_weakref ) != aligned_ref( old_weakref + 1 ) ) {
+			old_weakref = (char *)*weakref;
+			continue;
+		}
+	} while ( !atomic_compare_exchange_weak( weakref, (void **)&old_weakref, old_weakref + 1 ) );
+	struct _ref_ *ref = aligned_ref( old_weakref )->ref;
+	if ( unlikely( ++ref->count == -1 ) ) {
+		_ref_error( "Reference counter overflow. Aborting." );
+	}
+	char *cur_weakref = ( char * )*weakref;
+	do {
+		if ( aligned_ref( cur_weakref ) != aligned_ref( old_weakref ) ) {
+			ref->count--;
+			break;
+		}
+	} while ( !atomic_compare_exchange_weak( weakref, (void **)&cur_weakref, cur_weakref - 1 ) );
+	return ref;
+}
+
+static inline void ref_inc( ref *ref )
+{
+	++ref->count;
+}
+
+static inline void ref_put( ref *ref )
+{
+	if ( --ref->count == 0 ) {
+		ref->free( ref );
+	}
+}
+
+#define ref_get_uplink(wr) __extension__({ \
+	ref* ref = ref_get( wr ); \
+	ref == NULL ? NULL : container_of(ref, dnbd3_uplink_t, reference); \
+})
+
+#define ref_get_cachemap(image) __extension__({ \
+	ref* ref = ref_get( &(image)->ref_cacheMap ); \
+	ref == NULL ? NULL : container_of(ref, dnbd3_cache_map_t, reference); \
+})
+
+#endif