Deduplicate the AsNode attribute key and value using a hash table

This saves about 1Mb of RSS when loading the Fedora AppStream file.

2 files changed, 96 insertions, 31 deletions

diff --git a/Makefile.am b/Makefile.am
index a513f48..2f116eb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -81,6 +81,12 @@ DISTCHECK_CONFIGURE_FLAGS =				\
 	--enable-builder				\
 	--with-bashcompletiondir=/${prefix}/share/bash-completion/completions
 
+massif:
+	make && \
+	time ./client/appstream-util search gimp --help > /dev/null && \
+	valgrind --massif-out-file=massif.out --tool=massif ./client/.libs/lt-appstream-util search gimp --profile && \
+	ms_print massif.out | head -n 30
+
 .PHONY: ChangeLog
 
 -include $(top_srcdir)/git.mk
diff --git a/libappstream-glib/as-node.c b/libappstream-glib/as-node.c
index cbf2364..127081e 100644
--- a/libappstream-glib/as-node.c
+++ b/libappstream-glib/as-node.c
@@ -41,19 +41,30 @@
 #include "as-node-private.h"
 #include "as-utils-private.h"
 
+typedef struct {
+	GHashTable		*interned_hash;
+} AsNodeRoot;
+
 typedef struct
 {
-	GList		*attrs;
-	gchar		*name;		/* only used if tag == AS_TAG_UNKNOWN */
-	gchar		*cdata;
-	guint8		 cdata_escaped:1;
-	guint8		 cdata_ignore:1;
-	AsTag		 tag;
+	GList			*attrs;
+	union {
+		AsTag		 tag;
+		gchar		*name;	/* only used if tag_is_valid = FALSE */
+	};
+	union {
+		AsNodeRoot	*root;	/* only used if is_root_node = TRUE */
+		gchar		*cdata;
+	};
+	guint8			 is_root_node:1;
+	guint8			 cdata_escaped:1;
+	guint8			 cdata_ignore:1;
+	guint8			 tag_is_valid:1;
 } AsNodeData;
 
 typedef struct {
-	const gchar	*key;
-	gchar		*value;
+	const gchar		*key;
+	const gchar		*value;
 } AsNodeAttr;
 
 /**
@@ -71,23 +82,45 @@ as_node_new (void)
 	AsNodeData *data;
 	data = g_slice_new0 (AsNodeData);
 	data->tag = AS_TAG_LAST;
+	data->tag_is_valid = TRUE;
+	data->is_root_node = TRUE;
+	data->root = g_new0 (AsNodeRoot, 1);
+	data->root->interned_hash = g_hash_table_new_full (g_str_hash,
+							   g_str_equal,
+							   g_free,
+							   NULL);
 	return g_node_new (data);
 }
 
 static void
 as_node_attr_free (AsNodeAttr *attr)
 {
-	g_free (attr->value);
 	g_slice_free (AsNodeAttr, attr);
 }
 
+static const gchar *
+as_node_intern (GHashTable *hash, const gchar *key)
+{
+	gchar *value = g_hash_table_lookup (hash, key);
+	if (value == NULL) {
+		value = g_strdup (key);
+		g_hash_table_insert (hash, value, value);
+	}
+	return value;
+}
+
 static AsNodeAttr *
-as_node_attr_insert (AsNodeData *data, const gchar *key, const gchar *value)
+as_node_attr_insert (AsNode *root,
+		     AsNodeData *data,
+		     const gchar *key,
+		     const gchar *value)
 {
 	AsNodeAttr *attr;
+	AsNodeRoot *root_data = ((AsNodeData *)root->data)->root;
+
 	attr = g_slice_new0 (AsNodeAttr);
-	attr->key = g_intern_string (key);
-	attr->value = g_strdup (value);
+	attr->key = as_node_intern (root_data->interned_hash, key);
+	attr->value = as_node_intern (root_data->interned_hash, value);
 	data->attrs = g_list_prepend (data->attrs, attr);
 	return attr;
 }
@@ -122,8 +155,14 @@ as_node_destroy_node_cb (AsNode *node, gpointer user_data)
 	AsNodeData *data = node->data;
 	if (data == NULL)
 		return FALSE;
-	g_free (data->name);
-	g_free (data->cdata);
+	if (!data->tag_is_valid)
+		g_free (data->name);
+	if (data->is_root_node) {
+		g_hash_table_unref (data->root->interned_hash);
+		g_free (data->root);
+	} else {
+		g_free (data->cdata);
+	}
 	g_list_free_full (data->attrs, (GDestroyNotify) as_node_attr_free);
 	g_slice_free (AsNodeData, data);
 	return FALSE;
@@ -183,6 +222,8 @@ as_node_string_replace_inplace (gchar *text,
 static void
 as_node_cdata_to_raw (AsNodeData *data)
 {
+	if (data->is_root_node)
+		return;
 	if (!data->cdata_escaped)
 		return;
 	as_node_string_replace_inplace (data->cdata, "&", '&');
@@ -195,6 +236,8 @@ static void
 as_node_cdata_to_escaped (AsNodeData *data)
 {
 	GString *str;
+	if (data->is_root_node)
+		return;
 	if (data->cdata_escaped)
 		return;
 	str = g_string_new (data->cdata);
@@ -254,7 +297,7 @@ as_node_get_attr_string (AsNodeData *data)
 static const gchar *
 as_tag_data_get_name (AsNodeData *data)
 {
-	if (data->name == NULL)
+	if (data->tag_is_valid)
 		return as_tag_to_string (data->tag);
 	return data->name;
 }
@@ -264,12 +307,18 @@ as_node_data_set_name (AsNodeData *data, const gchar *name, AsNodeInsertFlags fl
 {
 	if ((flags & AS_NODE_INSERT_FLAG_MARK_TRANSLATABLE) == 0) {
 		/* only store the name if the tag is not recognised */
-		data->tag = as_tag_from_string (name);
-		if (data->tag == AS_TAG_UNKNOWN)
+		AsTag tag = as_tag_from_string (name);
+		if (tag == AS_TAG_UNKNOWN) {
 			data->name = g_strdup (name);
+			data->tag_is_valid = FALSE;
+		} else {
+			data->tag = tag;
+			data->tag_is_valid = TRUE;
+		}
 	} else {
 		/* always store the translated tag */
 		data->name = g_strdup_printf ("_%s", name);
+		data->tag_is_valid = FALSE;
 	}
 }
 
@@ -517,9 +566,11 @@ as_node_start_element_cb (GMarkupParseContext *context,
 
 	/* create the new node data */
 	if (!data->cdata_ignore) {
+		AsNode *root = g_node_get_root (helper->current);
+		g_assert (root != NULL);
 		as_node_data_set_name (data, element_name, AS_NODE_INSERT_FLAG_NONE);
 		for (i = 0; attribute_names[i] != NULL; i++) {
-			as_node_attr_insert (data,
+			as_node_attr_insert (root, data,
 					     attribute_names[i],
 					     attribute_values[i]);
 		}
@@ -929,8 +980,10 @@ as_node_set_name (AsNode *node, const gchar *name)
 		return;
 
 	/* overwrite */
-	g_free (data->name);
-	data->name = NULL;
+	if (!data->tag_is_valid) {
+		g_free (data->name);
+		data->name = NULL;
+	}
 	as_node_data_set_name (data, name, AS_NODE_INSERT_FLAG_NONE);
 }
 
@@ -952,6 +1005,8 @@ as_node_get_data (const AsNode *node)
 	if (node->data == NULL)
 		return NULL;
 	data = (AsNodeData *) node->data;
+	if (data->is_root_node)
+		return NULL;
 	if (data->cdata == NULL || data->cdata[0] == '\0')
 		return NULL;
 	as_node_cdata_to_raw (data);
@@ -997,7 +1052,7 @@ as_node_get_tag (const AsNode *node)
 		return AS_TAG_UNKNOWN;
 
 	/* try to match with a fallback */
-	if (data->tag == AS_TAG_UNKNOWN) {
+	if (!data->tag_is_valid) {
 		tmp = as_tag_data_get_name (data);
 		return as_tag_from_string_full (tmp, AS_TAG_FLAG_USE_FALLBACKS);
 	}
@@ -1028,6 +1083,8 @@ as_node_set_data (AsNode *node,
 		return;
 
 	data = (AsNodeData *) node->data;
+	if (data->is_root_node)
+		return;
 	g_free (data->cdata);
 	data->cdata = g_strdup (cdata);
 	data->cdata_escaped = insert_flags & AS_NODE_INSERT_FLAG_PRE_ESCAPED;
@@ -1067,6 +1124,8 @@ as_node_take_data (const AsNode *node)
 	if (node->data == NULL)
 		return NULL;
 	data = (AsNodeData *) node->data;
+	if (data->is_root_node)
+		return NULL;
 	if (data->cdata == NULL || data->cdata[0] == '\0')
 		return NULL;
 	as_node_cdata_to_raw (data);
@@ -1185,9 +1244,7 @@ as_node_take_attribute (const AsNode *node, const gchar *key)
 	attr = as_node_attr_find (data, key);
 	if (attr == NULL)
 		return NULL;
-	tmp = attr->value;
-	attr->value = NULL;
-	return tmp;
+	return g_strdup (attr->value);
 }
 
 /**
@@ -1234,7 +1291,7 @@ as_node_add_attribute (AsNode *node,
 		       const gchar *value)
 {
 	AsNodeData *data;
-	AsNodeAttr *attr;
+	AsNode *root = g_node_get_root (node);
 
 	g_return_if_fail (node != NULL);
 	g_return_if_fail (key != NULL);
@@ -1242,8 +1299,7 @@ as_node_add_attribute (AsNode *node,
 	if (node->data == NULL)
 		return;
 	data = (AsNodeData *) node->data;
-	attr = as_node_attr_insert (data, key, NULL);
-	attr->value = g_strdup (value);
+	as_node_attr_insert (root, data, key, value);
 }
 
 /**
@@ -1393,6 +1449,7 @@ as_node_insert (AsNode *parent,
 	const gchar *key;
 	const gchar *value;
 	AsNodeData *data;
+	AsNode *root = g_node_get_root (parent);
 	guint i;
 	va_list args;
 
@@ -1417,7 +1474,7 @@ as_node_insert (AsNode *parent,
 		value = va_arg (args, const gchar *);
 		if (value == NULL)
 			break;
-		as_node_attr_insert (data, key, value);
+		as_node_attr_insert (root, data, key, value);
 	}
 	va_end (args);
 
@@ -1448,6 +1505,7 @@ as_node_insert_localized (AsNode *parent,
 			  AsNodeInsertFlags insert_flags)
 {
 	AsNodeData *data;
+	AsNode *root = g_node_get_root (parent);
 	GList *l;
 	const gchar *key;
 	const gchar *value;
@@ -1485,7 +1543,7 @@ as_node_insert_localized (AsNode *parent,
 		    g_strcmp0 (value_c, value) == 0)
 			continue;
 		data = g_slice_new0 (AsNodeData);
-		as_node_attr_insert (data, "xml:lang", key);
+		as_node_attr_insert (root, data, "xml:lang", key);
 		as_node_data_set_name (data, name, insert_flags);
 		if (insert_flags & AS_NODE_INSERT_FLAG_NO_MARKUP) {
 			data->cdata = as_markup_convert_simple (value, NULL);
@@ -1518,6 +1576,7 @@ as_node_insert_hash (AsNode *parent,
 		     AsNodeInsertFlags insert_flags)
 {
 	AsNodeData *data;
+	AsNode *root = g_node_get_root (parent);
 	GList *l;
 	GList *list;
 	const gchar *key;
@@ -1537,10 +1596,10 @@ as_node_insert_hash (AsNode *parent,
 		data->cdata_escaped = insert_flags & AS_NODE_INSERT_FLAG_PRE_ESCAPED;
 		if (!swapped) {
 			if (key != NULL && key[0] != '\0')
-				as_node_attr_insert (data, attr_key, key);
+				as_node_attr_insert (root, data, attr_key, key);
 		} else {
 			if (value != NULL && value[0] != '\0')
-				as_node_attr_insert (data, attr_key, value);
+				as_node_attr_insert (root, data, attr_key, value);
 		}
 		g_node_insert_data (parent, -1, data);
 	}