cogl/context: Add API to create named pipelines

In certain situations it's desirable to keep pipelines around for
the whole lifetime of the session. In order to not leak them and
properly clean them up on shutdown, introduce a new mechanism to
create named pipelines that are bound to their correstponding
context and may be used across file boundries.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1372

cogl/cogl/cogl-context-private.h

@@ -256,6 +256,8 @@ struct _CoglContext
   CoglPollSource *fences_poll_source;
   CoglList fences;
 
+  GHashTable *named_pipelines;
+
   /* This defines a list of function pointers that Cogl uses from
      either GL or GLES. All functions are accessed indirectly through
      these pointers rather than linking to them directly */

cogl/cogl/cogl-context.c

@@ -308,6 +308,9 @@ cogl_context_new (CoglDisplay *display,
 
   _cogl_list_init (&context->fences);
 
+  context->named_pipelines =
+    g_hash_table_new_full (NULL, NULL, NULL, cogl_object_unref);
+
   return context;
 }
 
@@ -382,6 +385,9 @@ _cogl_context_free (CoglContext *context)
 
   cogl_object_unref (context->display);
 
+  g_hash_table_remove_all (context->named_pipelines);
+  g_hash_table_destroy (context->named_pipelines);
+
   g_free (context);
 }
 
@@ -472,3 +478,27 @@ cogl_context_format_supports_upload (CoglContext *ctx,
 {
   return ctx->texture_driver->format_supports_upload (ctx, format);
 }
+
+void
+cogl_context_set_named_pipeline (CoglContext     *context,
+                                 CoglPipelineKey *key,
+                                 CoglPipeline    *pipeline)
+{
+  if (pipeline)
+    {
+      g_debug ("Adding named pipeline %s", *key);
+      g_hash_table_insert (context->named_pipelines, (gpointer) key, pipeline);
+    }
+  else
+    {
+      g_debug ("Removing named pipeline %s", *key);
+      g_hash_table_remove (context->named_pipelines, (gpointer) key);
+    }
+}
+
+CoglPipeline *
+cogl_context_get_named_pipeline (CoglContext     *context,
+                                 CoglPipelineKey *key)
+{
+  return g_hash_table_lookup (context->named_pipelines, key);
+}

cogl/cogl/cogl-context.h

@@ -44,6 +44,7 @@ typedef struct _CoglContext CoglContext;
 
 #include <cogl/cogl-defines.h>
 #include <cogl/cogl-display.h>
+#include <cogl/cogl-pipeline.h>
 #include <cogl/cogl-primitive.h>
 
 #include <glib-object.h>
@@ -367,6 +368,38 @@ cogl_get_graphics_reset_status (CoglContext *context);
 COGL_EXPORT gboolean
 cogl_context_is_hardware_accelerated (CoglContext *context);
 
+typedef const char * const CoglPipelineKey;
+
+/**
+ * cogl_context_set_named_pipeline:
+ * @context: a #CoglContext pointer
+ * @key: a #CoglPipelineKey pointer
+ * @pipeline: (nullable): a #CoglPipeline to associate with the @context and
+ *            @key
+ *
+ * Associate a #CoglPipeline with a @context and @key. This will not take a new
+ * reference to the @pipeline, but will unref all associated pipelines when
+ * the @context gets destroyed. Similarly, if a pipeline gets overwritten,
+ * it will get unreffed as well.
+ */
+COGL_EXPORT void
+cogl_context_set_named_pipeline (CoglContext     *context,
+                                 CoglPipelineKey *key,
+                                 CoglPipeline    *pipeline);
+
+/**
+ * cogl_context_get_named_pipeline:
+ * @context: a #CoglContext pointer
+ * @key: a #CoglPipelineKey pointer
+ *
+ * Return value: (transfer none): The #CoglPipeline associated with the
+ *               given @context and @key, or %NULL if no such #CoglPipeline
+ *               was found.
+ */
+COGL_EXPORT CoglPipeline *
+cogl_context_get_named_pipeline (CoglContext     *context,
+                                 CoglPipelineKey *key);
+
 G_END_DECLS
 
 #endif /* __COGL_CONTEXT_H__ */