til_module_context: refcount module contexts

This becomes necessary in a world with
externall-discoverable-on-stream-contexts that can be arbitrarily
referenced by other contexts.

There will probably be more complexity necessary for invalidating
references, but this is a start.

2 files changed, 46 insertions, 4 deletions

diff --git a/src/til_module_context.c b/src/til_module_context.c
index 98a32cd..092e3e1 100644
--- a/src/til_module_context.c
+++ b/src/til_module_context.c
@@ -50,6 +50,7 @@ void * til_module_context_new(const til_module_t *module, size_t size, til_strea
 	module_context->ticks = ticks;
 	module_context->n_cpus = n_cpus;
 	module_context->setup = til_setup_ref(setup);
+	module_context->refcount = 1;
 
 	return module_context;
 }
@@ -60,13 +61,13 @@ void * til_module_context_new(const til_module_t *module, size_t size, til_strea
  *
  * Note this replaces til_module_destroy_context(), which has been removed.
  */
-void * til_module_context_free(til_module_context_t *module_context)
+static inline void * module_context_free(til_module_context_t *module_context)
 {
 	til_stream_t	*stream;
 	til_setup_t	*setup;
 
-	if (!module_context)
-		return NULL;
+	assert(module_context);
+	assert(!module_context->refcount);
 
 	stream = module_context->stream;
 	setup = module_context->setup;
@@ -87,3 +88,41 @@ void * til_module_context_free(til_module_context_t *module_context)
 
 	return NULL;
 }
+
+
+/* bump refcount on context */
+void * til_module_context_ref(til_module_context_t *module_context)
+{
+	assert(module_context);
+
+	module_context->refcount++;
+
+	return module_context;
+}
+
+
+/* unref the module_context, returns non-NULL when module_context persists */
+static void * til_module_context_unref(til_module_context_t *module_context)
+{
+/* XXX this is kept private until there's a real use case in need of the distinct return values vs. free.
+ * til_setup is the same way, which this is basically mirroring
+ */
+	if (!module_context)
+		return NULL;
+
+	assert(module_context->refcount > 0);
+
+	module_context->refcount--;
+	if (!module_context->refcount)
+		return module_context_free(module_context);
+
+	return module_context;
+}
+
+
+void * til_module_context_free(til_module_context_t *module_context)
+{
+	(void) til_module_context_unref(module_context);
+
+	return NULL;
+}
diff --git a/src/til_module_context.h b/src/til_module_context.h
index cbbfb8e..05f77ab 100644
--- a/src/til_module_context.h
+++ b/src/til_module_context.h
@@ -8,16 +8,19 @@ typedef struct til_stream_t til_stream_t;
 
 struct til_module_context_t {
 	const til_module_t	*module;
-	til_stream_t		*stream; /* optional stream this context is part of */
+	til_stream_t		*stream; /* optional stream this context is part of (module_contexts are discoverable @setup->path when part of a stream) */
 	unsigned		seed;
 	unsigned		ticks;
 	unsigned		n_cpus;
 	til_setup_t		*setup; /* Baked setup this context was made from, reffed by context.
 					 * Always present as it provides the path, which is generally derived from a settings instance.
 					 */
+
+	unsigned                refcount;
 };
 
 void * til_module_context_new(const til_module_t *module, size_t size, til_stream_t *stream, unsigned seed, unsigned ticks, unsigned n_cpus, til_setup_t *setup);
+void * til_module_context_ref(til_module_context_t *module_context);
 void * til_module_context_free(til_module_context_t *module_context);
 
 #endif