gstreamer/plugins/indexers/gstmemindex.c

/* GStreamer
 * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
 *
 * 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <gst/gst.h>

#define GST_TYPE_MEM_INDEX		\
  (gst_index_get_type ())
#define GST_MEM_INDEX(obj)		\
  (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_MEM_INDEX, GstMemIndex))
#define GST_MEM_INDEX_CLASS(klass)	\
  (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_MEM_INDEX, GstMemIndexClass))
#define GST_IS_MEM_INDEX(obj)		\
  (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_MEM_INDEX))
#define GST_IS_MEM_INDEX_CLASS(obj)	\
  (GST_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_MEM_INDEX))
	
/*
 * Object model:
 *
 * All entries are simply added to a GList first. Then we build
 * an index to each entry for each id/format
 * 
 *
 *  memindex
 *    -----------------------------...
 *    !                  !         
 *   id1                 id2        
 *    ------------
 *    !          !
 *   format1  format2
 *    !          !
 *   GTree      GTree
 *
 *
 * The memindex creates a MemIndexId object for each writer id, a
 * Hashtable is kept to map the id to the MemIndexId
 *
 * The MemIndexId keeps a MemIndexFormatIndex for each format the
 * specific writer wants indexed.
 *
 * The MemIndexFormatIndex keeps all the values of the particular 
 * format in a GTree, The values of the GTree point back to the entry. 
 *
 * Finding a value for an id/format requires locating the correct GTree,
 * then do a lookup in the Tree to get the required value.
 */

typedef struct {
  GstFormat 	 format;
  gint		 offset;
  GTree		*tree;
} GstMemIndexFormatIndex;

typedef struct {
  gint 		 id;
  GHashTable	*format_index;
} GstMemIndexId;

typedef struct _GstMemIndex GstMemIndex;
typedef struct _GstMemIndexClass GstMemIndexClass;

struct _GstMemIndex {
  GstIndex		 parent;

  GList			*associations;

  GHashTable		*id_index;
};

struct _GstMemIndexClass {
  GstIndexClass parent_class;
};

/* Index signals and args */
enum {
  LAST_SIGNAL
};

enum {
  ARG_0,
  /* FILL ME */
};

static void		gst_mem_index_class_init	(GstMemIndexClass *klass);
static void		gst_mem_index_init		(GstMemIndex *index);
static void 		gst_mem_index_dispose 		(GObject *object);

static void 		gst_mem_index_add_entry 	(GstIndex *index, GstIndexEntry *entry);
static GstIndexEntry* 	gst_mem_index_get_assoc_entry 	(GstIndex *index, gint id,
                              				 GstIndexLookupMethod method, GstAssocFlags flags,
                              				 GstFormat format, gint64 value,
                              				 GCompareDataFunc func,
                              				 gpointer user_data);

#define CLASS(mem_index)  GST_MEM_INDEX_CLASS (G_OBJECT_GET_CLASS (mem_index))

static GstIndex *parent_class = NULL;
/*static guint gst_mem_index_signals[LAST_SIGNAL] = { 0 }; */

GType
gst_mem_index_get_type(void) {
  static GType mem_index_type = 0;

  if (!mem_index_type) {
    static const GTypeInfo mem_index_info = {
      sizeof(GstMemIndexClass),
      NULL,
      NULL,
      (GClassInitFunc)gst_mem_index_class_init,
      NULL,
      NULL,
      sizeof(GstMemIndex),
      1,
      (GInstanceInitFunc)gst_mem_index_init,
      NULL
    };
    mem_index_type = g_type_register_static(GST_TYPE_INDEX, "GstMemIndex", &mem_index_info, 0);
  }
  return mem_index_type;
}

static void
gst_mem_index_class_init (GstMemIndexClass *klass)
{
  GObjectClass *gobject_class;
  GstIndexClass *gstindex_class;

  gobject_class = (GObjectClass*)klass;
  gstindex_class = (GstIndexClass*)klass;

  parent_class = g_type_class_ref(GST_TYPE_INDEX);

  gobject_class->dispose = gst_mem_index_dispose;

  gstindex_class->add_entry 	  = gst_mem_index_add_entry;
  gstindex_class->get_assoc_entry = gst_mem_index_get_assoc_entry;
}

static void
gst_mem_index_init (GstMemIndex *index)
{
  GST_DEBUG ( "created new mem index");

  index->associations = NULL;
  index->id_index = g_hash_table_new (g_int_hash, g_int_equal);
}

static void
gst_mem_index_dispose (GObject *object)
{
  //GstMemIndex *memindex = GST_MEM_INDEX (object);

  G_OBJECT_CLASS (parent_class)->dispose (object);
}

static void
gst_mem_index_add_id (GstIndex *index, GstIndexEntry *entry)
{
  GstMemIndex *memindex = GST_MEM_INDEX (index);
  GstMemIndexId *id_index;

  id_index = g_hash_table_lookup (memindex->id_index, &entry->id);

  if (!id_index) {
    id_index = g_new0 (GstMemIndexId, 1);

    id_index->id = entry->id;
    id_index->format_index = g_hash_table_new (g_int_hash, g_int_equal);
    g_hash_table_insert (memindex->id_index, &id_index->id, id_index);
  }
}

static gint
mem_index_compare (gconstpointer a,
		   gconstpointer b,
		   gpointer user_data)
{
  GstMemIndexFormatIndex *index = user_data;
  gint64 val1, val2;
  gint64 diff;

  val1 = GST_INDEX_ASSOC_VALUE (((GstIndexEntry *)a), index->offset);
  val2 = GST_INDEX_ASSOC_VALUE (((GstIndexEntry *)b), index->offset);
	  
  diff = (val2 - val1);

  return (diff == 0 ? 0 : (diff > 0 ? 1 : -1));
}

static void
gst_mem_index_index_format (GstMemIndexId *id_index, GstIndexEntry *entry, gint assoc)
{
  GstMemIndexFormatIndex *index;
  GstFormat *format;

  format = &GST_INDEX_ASSOC_FORMAT (entry, assoc);

  index = g_hash_table_lookup (id_index->format_index, format);

  if (!index) {
    index = g_new0 (GstMemIndexFormatIndex, 1);

    index->format = *format;
    index->offset = assoc;
    index->tree = g_tree_new_with_data (mem_index_compare, index);

    g_hash_table_insert (id_index->format_index, &index->format, index);
  }

  g_tree_insert (index->tree, entry, entry);
}

static void
gst_mem_index_add_association (GstIndex *index, GstIndexEntry *entry)
{
  GstMemIndex *memindex = GST_MEM_INDEX (index);
  GstMemIndexId *id_index;

  memindex->associations = g_list_prepend (memindex->associations, entry);

  id_index = g_hash_table_lookup (memindex->id_index, &entry->id);
  if (id_index) {
    gint i;

    for (i = 0; i < GST_INDEX_NASSOCS (entry); i++) {
      gst_mem_index_index_format (id_index, entry, i);
    }
  }
}

static void
gst_mem_index_add_object (GstIndex *index, GstIndexEntry *entry)
{
}

static void
gst_mem_index_add_format (GstIndex *index, GstIndexEntry *entry)
{
}

static void
gst_mem_index_add_entry (GstIndex *index, GstIndexEntry *entry)
{
  GST_LOG_OBJECT (index, "added this entry");

  switch (entry->type){
     case GST_INDEX_ENTRY_ID:
       gst_mem_index_add_id (index, entry);
       break;
     case GST_INDEX_ENTRY_ASSOCIATION:
       gst_mem_index_add_association (index, entry);
       break;
     case GST_INDEX_ENTRY_OBJECT:
       gst_mem_index_add_object (index, entry);
       break;
     case GST_INDEX_ENTRY_FORMAT:
       gst_mem_index_add_format (index, entry);
       break;
     default:
       break;
  }
}

typedef struct {
  gint64	 	  value;
  GstMemIndexFormatIndex *index;
  gboolean		  exact;
  GstIndexEntry 	 *lower;
  gint64		  low_diff;
  GstIndexEntry 	 *higher;
  gint64		  high_diff;
} GstMemIndexSearchData;

static gint
mem_index_search (gconstpointer a,
		  gconstpointer b)
{
  GstMemIndexSearchData *data = (GstMemIndexSearchData *) b;
  GstMemIndexFormatIndex *index = data->index;
  gint64 val1, val2;
  gint64 diff;

  val1 = GST_INDEX_ASSOC_VALUE (((GstIndexEntry *)a), index->offset);
  val2 = data->value;
	  
  diff = (val1 - val2);
  if (diff == 0)
    return 0;

  /* exact matching, don't update low/high */
  if (data->exact)
    return (diff > 0 ? 1 : -1);

  if (diff < 0) {
    if (diff > data->low_diff) {
      data->low_diff = diff;
      data->lower = (GstIndexEntry *) a;
    }
    diff = -1;
  }
  else {
    if (diff < data->high_diff) {
      data->high_diff = diff;
      data->higher = (GstIndexEntry *) a;
    }
    diff = 1;
  }

  return diff;
}

static GstIndexEntry*
gst_mem_index_get_assoc_entry (GstIndex *index, gint id,
                               GstIndexLookupMethod method, 
			       GstAssocFlags flags,
                               GstFormat format, gint64 value,
                               GCompareDataFunc func,
                               gpointer user_data)
{
  GstMemIndex *memindex = GST_MEM_INDEX (index);
  GstMemIndexId *id_index;
  GstMemIndexFormatIndex *format_index;
  GstIndexEntry *entry;
  GstMemIndexSearchData data;

  id_index = g_hash_table_lookup (memindex->id_index, &id);
  if (!id_index)
    return NULL;

  format_index = g_hash_table_lookup (id_index->format_index, &format);
  if (!format_index)
    return NULL;

  data.value = value;
  data.index = format_index;
  data.exact = (method == GST_INDEX_LOOKUP_EXACT);

  /* setup data for low/high checks if we are not looking 
   * for an exact match */
  if (!data.exact) {
    data.low_diff = G_MININT64;
    data.lower = NULL;
    data.high_diff = G_MAXINT64;
    data.higher = NULL;
  }

  entry = g_tree_search (format_index->tree, mem_index_search, &data);

  /* get the low/high values if we're not exact */
  if (entry == NULL && !data.exact) { 
    if (method == GST_INDEX_LOOKUP_BEFORE)
      entry = data.lower;
    else if (method == GST_INDEX_LOOKUP_AFTER) {
      entry = data.higher;
    }
  }

  if (entry) {
    if ((GST_INDEX_ASSOC_FLAGS (entry) & flags) != flags) {
      GList *l_entry = g_list_find (memindex->associations, entry);

      entry = NULL;

      while (l_entry) {
	entry = (GstIndexEntry *) l_entry->data;

        if (entry->id == id &&
	    (GST_INDEX_ASSOC_FLAGS (entry) & flags) == flags)
          break;

        if (method == GST_INDEX_LOOKUP_BEFORE)
          l_entry = g_list_next (l_entry);
        else if (method == GST_INDEX_LOOKUP_AFTER) {
          l_entry = g_list_previous (l_entry);
        }
      }
    }
  }

  return entry;
}

gboolean
gst_mem_index_plugin_init (GModule *module, GstPlugin *plugin)
{
  GstIndexFactory *factory;

  gst_plugin_set_longname (plugin, "A memory index");

  factory = gst_index_factory_new ("memindex",
	                           "A index that stores entries in memory",
                                   gst_mem_index_get_type());

  if (factory != NULL) {
    gst_plugin_add_feature (plugin, GST_PLUGIN_FEATURE (factory));
  }
  else {
    g_warning ("could not register memindex");
  }
  return TRUE;
}