[mutter] cogl/context: Add API to create named pipelines

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 1f557a502bc1cd0b0421124888cc0ec1def6a070
Author: Robert Mader <robert mader posteo de>
Date:   Mon Aug 10 14:24:58 2020 +0200

    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 |  2 ++
 cogl/cogl/cogl-context.c         | 30 ++++++++++++++++++++++++++++++
 cogl/cogl/cogl-context.h         | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+)
---
diff --git a/cogl/cogl/cogl-context-private.h b/cogl/cogl/cogl-context-private.h
index 2d68793a04..74206a4449 100644
--- a/cogl/cogl/cogl-context-private.h
+++ b/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 */
diff --git a/cogl/cogl/cogl-context.c b/cogl/cogl/cogl-context.c
index c05123580e..1275439b65 100644
--- a/cogl/cogl/cogl-context.c
+++ b/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);
+}
diff --git a/cogl/cogl/cogl-context.h b/cogl/cogl/cogl-context.h
index e5882e7dd4..1baa4145ef 100644
--- a/cogl/cogl/cogl-context.h
+++ b/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__ */