fragend-arbfp: Move the pipeline cache to a separate file

The pipeline cache is now handled in CoglPipelineCache instead of
directly in the ARBfp fragend. The flags needed to hash a pipeline
should be exactly the same for the ARBfp and GLSL fragends so it's
convenient to share the code. The hash table now stores the actual
pipeline as the value instead of the private data so that the two
fragends can attach their data to it. That way it's possible to use
the same pipeline key with ancestors that are using different
fragends.

The hash table is created with g_hash_table_new_full to set a
destructor for the key and value and there is a destructor for
CoglPipelineCache that gets called when the CoglContext is
destroyed. That way we no longer leak the pipelines and shader state
when the context is desroyed.

1 files changed, 146 insertions, 0 deletions

diff --git a/cogl/cogl-pipeline-cache.c b/cogl/cogl-pipeline-cache.c
new file mode 100644
index 00000000..f5e32a77
--- /dev/null
+++ b/cogl/cogl-pipeline-cache.c
@@ -0,0 +1,146 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2011 Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Authors:
+ *   Neil Roberts <neil@linux.intel.com>
+ *   Robert Bragg <robert@linux.intel.com>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "cogl-pipeline-private.h"
+#include "cogl-pipeline-cache.h"
+#include "cogl-context-private.h"
+
+struct _CoglPipelineCache
+{
+  GHashTable *fragment_hash;
+};
+
+static unsigned int
+pipeline_fragment_hash (const void *data)
+{
+  unsigned int fragment_state;
+  unsigned int layer_fragment_state;
+
+  _COGL_GET_CONTEXT (ctx, 0);
+
+  fragment_state =
+    _cogl_pipeline_get_state_for_fragment_codegen (ctx);
+  layer_fragment_state =
+    _cogl_pipeline_get_layer_state_for_fragment_codegen (ctx);
+
+  return _cogl_pipeline_hash ((CoglPipeline *)data,
+                              fragment_state, layer_fragment_state,
+                              0);
+}
+
+static gboolean
+pipeline_fragment_equal (const void *a, const void *b)
+{
+  unsigned int fragment_state;
+  unsigned int layer_fragment_state;
+
+  _COGL_GET_CONTEXT (ctx, 0);
+
+  fragment_state =
+    _cogl_pipeline_get_state_for_fragment_codegen (ctx);
+  layer_fragment_state =
+    _cogl_pipeline_get_layer_state_for_fragment_codegen (ctx);
+
+  return _cogl_pipeline_equal ((CoglPipeline *)a, (CoglPipeline *)b,
+                               fragment_state, layer_fragment_state,
+                               0);
+}
+
+CoglPipelineCache *
+cogl_pipeline_cache_new (void)
+{
+  CoglPipelineCache *cache = g_new (CoglPipelineCache, 1);
+
+  cache->fragment_hash = g_hash_table_new_full (pipeline_fragment_hash,
+                                                pipeline_fragment_equal,
+                                                cogl_object_unref,
+                                                cogl_object_unref);
+
+  return cache;
+}
+
+void
+cogl_pipeline_cache_free (CoglPipelineCache *cache)
+{
+  g_hash_table_destroy (cache->fragment_hash);
+  g_free (cache);
+}
+
+CoglPipeline *
+_cogl_pipeline_cache_get_fragment_template (CoglPipelineCache *cache,
+                                            CoglPipeline *key_pipeline)
+{
+  CoglPipeline *template =
+    g_hash_table_lookup (cache->fragment_hash, key_pipeline);
+
+  if (template == NULL)
+    {
+      /* XXX: I wish there was a way to insert into a GHashTable with
+       * a pre-calculated hash value since there is a cost to
+       * calculating the hash of a CoglPipeline and in this case we
+       * know we have already called _cogl_pipeline_hash during the
+       * lookup so we could pass the value through to here to avoid
+       * hashing it again.
+       */
+
+      /* XXX: Any keys referenced by the hash table need to remain
+       * valid all the while that there are corresponding values,
+       * so for now we simply make a copy of the current authority
+       * pipeline.
+       *
+       * FIXME: A problem with this is that our key into the cache may
+       * hold references to some arbitrary user textures which will
+       * now be kept alive indefinitly which is a shame. A better
+       * solution will be to derive a special "key pipeline" from the
+       * authority which derives from the base Cogl pipeline (to avoid
+       * affecting the lifetime of any other pipelines) and only takes
+       * a copy of the state that relates to the fragment shader and
+       * references small dummy textures instead of potentially large
+       * user textures. */
+      template = cogl_pipeline_copy (key_pipeline);
+
+      g_hash_table_insert (cache->fragment_hash,
+                           template,
+                           cogl_object_ref (template));
+
+      if (G_UNLIKELY (g_hash_table_size (cache->fragment_hash) > 50))
+        {
+          static gboolean seen = FALSE;
+          if (!seen)
+            g_warning ("Over 50 separate fragment shaders have been "
+                       "generated which is very unusual, so something "
+                       "is probably wrong!\n");
+          seen = TRUE;
+        }
+    }
+
+  return template;
+}