glupload/egl: Extract EGL image cache and make it public

Extract the EGLImage cache from gstglupload.c, place it in a separate
source file gsteglimagecache.c, and make the API public, so it can be
reused by the gldownload element.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6792>

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gsteglimagecache.c

@@ -0,0 +1,201 @@
+/*
+ * GStreamer
+ * Copyright (C) 2024 Pengutronix, Philipp Zabel <graphics@pengutronix.de>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gsteglimage.h"
+#include "gsteglimage_private.h"
+#include "gsteglimagecache.h"
+
+struct _GstEGLImageCacheEntry
+{
+  GstEGLImage *eglimage[GST_VIDEO_MAX_PLANES];
+};
+
+struct _GstEGLImageCache
+{
+  gint ref_count;
+  GHashTable *hash_table;       /* for GstMemory -> GstEGLImageCacheEntry lookup */
+  GMutex lock;                  /* protects hash_table */
+};
+
+/**
+ * gst_egl_image_cache_ref:
+ * @cache: a #GstEGLImageCache.
+ *
+ * Increases the refcount of the given image cache by one.
+ *
+ * Returns: (transfer full): @cache
+ *
+ * Since: 1.26
+ */
+GstEGLImageCache *
+gst_egl_image_cache_ref (GstEGLImageCache * cache)
+{
+  g_atomic_int_inc (&cache->ref_count);
+  return cache;
+}
+
+/**
+ * gst_egl_image_cache_unref:
+ * @cache: (transfer full): a #GstEGLImageCache.
+ *
+ * Decreases the refcount of the image cache. If the refcount reaches 0, the
+ * image cache will be freed and all cached images will be unreffed.
+ *
+ * Since: 1.26
+ */
+void
+gst_egl_image_cache_unref (GstEGLImageCache * cache)
+{
+  if (g_atomic_int_dec_and_test (&cache->ref_count)) {
+    g_hash_table_unref (cache->hash_table);
+    g_mutex_clear (&cache->lock);
+    g_free (cache);
+  }
+}
+
+static void
+gst_egl_image_cache_entry_remove (GstEGLImageCache * cache, GstMiniObject * mem)
+{
+  g_mutex_lock (&cache->lock);
+  g_hash_table_remove (cache->hash_table, mem);
+  g_mutex_unlock (&cache->lock);
+  gst_egl_image_cache_unref (cache);
+}
+
+static GstEGLImageCacheEntry *
+gst_egl_image_cache_entry_add (GstEGLImageCache * cache, GstMemory * mem)
+{
+  GstEGLImageCacheEntry *cache_entry;
+
+  cache_entry = g_new0 (GstEGLImageCacheEntry, 1);
+  gst_egl_image_cache_ref (cache);
+  gst_mini_object_weak_ref (GST_MINI_OBJECT (mem),
+      (GstMiniObjectNotify) gst_egl_image_cache_entry_remove, cache);
+  g_mutex_lock (&cache->lock);
+  g_hash_table_insert (cache->hash_table, mem, cache_entry);
+  g_mutex_unlock (&cache->lock);
+
+  return cache_entry;
+}
+
+/*
+ * Called with the cache lock taken.
+ */
+static void
+gst_egl_image_cache_entry_free (GstEGLImageCacheEntry * cache_entry)
+{
+  gint i;
+
+  for (i = 0; i < GST_VIDEO_MAX_PLANES; i++) {
+    if (cache_entry->eglimage[i])
+      gst_egl_image_unref (cache_entry->eglimage[i]);
+  }
+  g_free (cache_entry);
+}
+
+/**
+ * gst_egl_image_cache_lookup:
+ * @cache: a #GstEGLImageCache.
+ * @mem: a #GstMemory to look a cached #GetEGLImage up for
+ * @plane: the plane to select which cached #GstEGLImage to look up for @mem
+ * @previous_mem:
+ * @cache_entry:
+ *
+ * Looks up a @cache_entry for @mem if mem is different from @previous_mem.
+ * If @mem is the same as @previous_mem, the costly lookup is skipped and the
+ * provided (previous) @cache_entry is used instead. In this case, @cache_entry
+ * must have been returned by a previous call of @gst_egl_image_cache_lookup
+ * with the same @mem.
+ *
+ * Returns: (nullable): a cached #GstEGLImage for @mem and @plane or %NULL.
+ * @previous_mem is set to @mem.
+ *
+ * Since: 1.26
+ */
+GstEGLImage *
+gst_egl_image_cache_lookup (GstEGLImageCache * cache, GstMemory * mem,
+    gint plane, GstMemory ** previous_mem, GstEGLImageCacheEntry ** cache_entry)
+{
+  if (mem != *previous_mem) {
+    g_mutex_lock (&cache->lock);
+    *cache_entry = g_hash_table_lookup (cache->hash_table, mem);
+    g_mutex_unlock (&cache->lock);
+    *previous_mem = mem;
+  }
+
+  if (*cache_entry)
+    return (*cache_entry)->eglimage[plane];
+
+  return NULL;
+}
+
+/**
+ * gst_egl_image_cache_store:
+ * @cache: a #GstEGLImageCache.
+ * @mem: a #GstMemory to store @eglimage for
+ * @plane: the plane slot to store @eglimage in
+ * @eglimage: a #GstEGLImage to be cached for @mem and @plane
+ * @cache_entry: a #GstEGLImageCacheEntry looked up for @mem, or %NULL
+ *
+ * Creates a new cache_entry for mem if no cache_entry is provided.
+ * Stores the eglimage for the given plane in the cache_entry. If an
+ * existing cache entry is provided, it must be returned by a
+ * @gst_egl_image_cache_lookup call with the same @mem.
+ *
+ * Since: 1.26
+ */
+void
+gst_egl_image_cache_store (GstEGLImageCache * cache, GstMemory * mem,
+    gint plane, GstEGLImage * eglimage, GstEGLImageCacheEntry ** cache_entry)
+{
+  if (!(*cache_entry))
+    *cache_entry = gst_egl_image_cache_entry_add (cache, mem);
+  (*cache_entry)->eglimage[plane] = eglimage;
+}
+
+/**
+ * gst_egl_image_cache_new:
+ *
+ * Creates an EGL image cache that holds references to EGL images
+ * until the cache is freed. Each cache entry can be looked up by
+ * GstMemory and holds one or more EGL images derived from it.
+ *
+ * Returns: (nullable): an empty #GstEGLImageCache or %NULL on failure
+ *
+ * Since: 1.26
+ */
+GstEGLImageCache *
+gst_egl_image_cache_new (void)
+{
+  GstEGLImageCache *cache;
+
+  cache = g_new0 (GstEGLImageCache, 1);
+  cache->ref_count = 1;
+
+  cache->hash_table = g_hash_table_new_full (g_direct_hash, g_direct_equal,
+      NULL, (GDestroyNotify) gst_egl_image_cache_entry_free);
+  g_mutex_init (&cache->lock);
+
+  return cache;
+}

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gsteglimagecache.h

@@ -0,0 +1,46 @@
+/*
+ * GStreamer
+ * Copyright (C) 2024 Pengutronix, Philipp Zabel <graphics@pengutronix.de>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef _GST_EGL_IMAGECACHE_H_
+#define _GST_EGL_IMAGECACHE_H_
+
+G_BEGIN_DECLS
+
+typedef struct _GstEGLImageCacheEntry GstEGLImageCacheEntry;
+typedef struct _GstEGLImageCache GstEGLImageCache;
+
+GST_GL_API
+GstEGLImageCache * gst_egl_image_cache_ref (GstEGLImageCache * cache);
+
+GST_GL_API
+void gst_egl_image_cache_unref (GstEGLImageCache * cache);
+
+GST_GL_API
+GstEGLImage * gst_egl_image_cache_lookup (GstEGLImageCache * cache, GstMemory * mem, gint plane, GstMemory ** previous_mem, GstEGLImageCacheEntry ** cache_entry);
+
+GST_GL_API
+void gst_egl_image_cache_store (GstEGLImageCache * cache, GstMemory * mem, gint plane, GstEGLImage * eglimage, GstEGLImageCacheEntry ** cache_entry);
+
+GST_GL_API
+GstEGLImageCache * gst_egl_image_cache_new (void);
+
+G_END_DECLS
+
+#endif /* _GST_EGL_IMAGECACHE_H_ */

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglupload.c

@@ -32,6 +32,7 @@
 #if GST_GL_HAVE_PLATFORM_EGL
 #include "egl/gsteglimage.h"
 #include "egl/gsteglimage_private.h"
+#include "egl/gsteglimagecache.h"
 #include "egl/gstglmemoryegl.h"
 #include "egl/gstglcontext_egl.h"
 #endif
@@ -717,18 +718,6 @@ static const UploadMethod _gl_memory_upload = {
 
 #if GST_GL_HAVE_DMABUF
 
-typedef struct _GstEGLImageCacheEntry
-{
-  GstEGLImage *eglimage[GST_VIDEO_MAX_PLANES];
-} GstEGLImageCacheEntry;
-
-typedef struct _GstEGLImageCache
-{
-  gint ref_count;
-  GHashTable *hash_table;       /* for GstMemory -> GstEGLImageCacheEntry lookup */
-  GMutex lock;                  /* protects hash_table */
-} GstEGLImageCache;
-
 struct DmabufUpload
 {
   GstGLUpload *upload;
@@ -747,112 +736,6 @@ struct DmabufUpload
   gpointer out_caps;
 };
 
-static void
-gst_egl_image_cache_ref (GstEGLImageCache * cache)
-{
-  g_atomic_int_inc (&cache->ref_count);
-}
-
-static void
-gst_egl_image_cache_unref (GstEGLImageCache * cache)
-{
-  if (g_atomic_int_dec_and_test (&cache->ref_count)) {
-    g_hash_table_unref (cache->hash_table);
-    g_mutex_clear (&cache->lock);
-    g_free (cache);
-  }
-}
-
-static void
-gst_egl_image_cache_entry_remove (GstEGLImageCache * cache, GstMiniObject * mem)
-{
-  g_mutex_lock (&cache->lock);
-  g_hash_table_remove (cache->hash_table, mem);
-  g_mutex_unlock (&cache->lock);
-  gst_egl_image_cache_unref (cache);
-}
-
-static GstEGLImageCacheEntry *
-gst_egl_image_cache_entry_new (GstEGLImageCache * cache, GstMemory * mem)
-{
-  GstEGLImageCacheEntry *cache_entry;
-
-  cache_entry = g_new0 (GstEGLImageCacheEntry, 1);
-  gst_egl_image_cache_ref (cache);
-  gst_mini_object_weak_ref (GST_MINI_OBJECT (mem),
-      (GstMiniObjectNotify) gst_egl_image_cache_entry_remove, cache);
-  g_mutex_lock (&cache->lock);
-  g_hash_table_insert (cache->hash_table, mem, cache_entry);
-  g_mutex_unlock (&cache->lock);
-
-  return cache_entry;
-}
-
-static void
-gst_egl_image_cache_entry_free (GstEGLImageCacheEntry * cache_entry)
-{
-  gint i;
-
-  for (i = 0; i < GST_VIDEO_MAX_PLANES; i++) {
-    if (cache_entry->eglimage[i])
-      gst_egl_image_unref (cache_entry->eglimage[i]);
-  }
-  g_free (cache_entry);
-}
-
-/*
- * Looks up a cache_entry for mem if mem is different from previous_mem.
- * If mem is the same as previous_mem, the costly lookup is skipped and the
- * provided (previous) cache_entry is used instead.
- *
- * Returns the cached eglimage for the given plane from the cache_entry, or
- * NULL. previous_mem is set to mem.
- */
-static GstEGLImage *
-gst_egl_image_cache_lookup (GstEGLImageCache * cache, GstMemory * mem,
-    gint plane, GstMemory ** previous_mem, GstEGLImageCacheEntry ** cache_entry)
-{
-  if (mem != *previous_mem) {
-    g_mutex_lock (&cache->lock);
-    *cache_entry = g_hash_table_lookup (cache->hash_table, mem);
-    g_mutex_unlock (&cache->lock);
-    *previous_mem = mem;
-  }
-
-  if (*cache_entry)
-    return (*cache_entry)->eglimage[plane];
-
-  return NULL;
-}
-
-/*
- * Creates a new cache_entry for mem if no cache_entry is provided.
- * Stores the eglimage for the given plane in the cache_entry.
- */
-static void
-gst_egl_image_cache_store (GstEGLImageCache * cache, GstMemory * mem,
-    gint plane, GstEGLImage * eglimage, GstEGLImageCacheEntry ** cache_entry)
-{
-  if (!(*cache_entry))
-    *cache_entry = gst_egl_image_cache_entry_new (cache, mem);
-  (*cache_entry)->eglimage[plane] = eglimage;
-}
-
-static GstEGLImageCache *
-gst_egl_image_cache_new (void)
-{
-  GstEGLImageCache *cache;
-
-  cache = g_new0 (GstEGLImageCache, 1);
-  cache->ref_count = 1;
-
-  cache->hash_table = g_hash_table_new_full (g_direct_hash, g_direct_equal,
-      NULL, (GDestroyNotify) gst_egl_image_cache_entry_free);
-  g_mutex_init (&cache->lock);
-
-  return cache;
-}
-
 static GstStaticCaps _dma_buf_upload_caps =
     GST_STATIC_CAPS (GST_VIDEO_DMA_DRM_CAPS_MAKE ";"
     GST_VIDEO_CAPS_MAKE (GST_GL_MEMORY_VIDEO_FORMATS_STR));

subprojects/gst-plugins-base/gst-libs/gst/gl/meson.build

@@ -551,6 +551,7 @@ if need_platform_egl != 'no'
     gl_egl_sources += files([
       'egl/gstegl.c',
       'egl/gsteglimage.c',
+      'egl/gsteglimagecache.c',
       'egl/gstglcontext_egl.c',
       'egl/gstgldisplay_egl.c',
       'egl/gstglmemoryegl.c',