Implement iteration cache, item cache and length cache for node list iteration

NEWS

@@ -44,6 +44,9 @@ PHP                                                                        NEWS
 - Date:
   . Implement More Appropriate Date/Time Exceptions RFC. (Derick)
 
+- DOM:
+  . Fix bug GH-11308 (getElementsByTagName() is O(N^2)). (nielsdos)
+
 - Exif:
   . Removed unneeded codepaths in exif_process_TIFF_in_JPEG(). (nielsdos)
 

UPGRADING.INTERNALS

@@ -120,6 +120,24 @@ PHP 8.3 INTERNALS UPGRADE NOTES
    - A new function dom_get_doc_props_read_only() is added to gather the document
      properties in a read-only way. This function avoids allocation when there are
      no document properties changed yet.
+   - The node list returned by DOMNode::getElementsByTagName() and
+	 DOMNode::getElementsByTagNameNS() now caches the length and the last requested item.
+	 This means that the length and the last requested item are not recalculated
+	 when the node list is iterated over multiple times.
+	 If you do not use the internal PHP dom APIs to modify the document, you need to
+	 manually invalidate the cache using php_libxml_invalidate_node_list_cache_from_doc().
+	 Furthermore, the following internal APIs were added to handle the cache:
+	   . php_dom_is_cache_tag_stale_from_doc_ptr()
+	   . php_dom_is_cache_tag_stale_from_node()
+	   . php_dom_mark_cache_tag_up_to_date_from_node()
+   - The function dom_get_elements_by_tag_name_ns_raw() has an additional parameter to indicate
+     the base node of the node list. This function also no longer accepts -1 as the index argument.
+   - The function dom_namednode_iter() has additional arguments to avoid recomputing the length of
+     the strings.
+
+ g. ext/libxml
+   - Two new functions: php_libxml_invalidate_node_list_cache_from_doc() and
+     php_libxml_invalidate_node_list_cache() were added to invalidate the cache of a node list.
 
 ========================
 4. OpCode changes

ext/dom/document.c

@@ -777,7 +777,6 @@ PHP_METHOD(DOMDocument, getElementsByTagName)
 	size_t name_len;
 	dom_object *intern, *namednode;
 	char *name;
-	xmlChar *local;
 
 	id = ZEND_THIS;
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s", &name, &name_len) == FAILURE) {
@@ -788,8 +787,7 @@ PHP_METHOD(DOMDocument, getElementsByTagName)
 
 	php_dom_create_iterator(return_value, DOM_NODELIST);
 	namednode = Z_DOMOBJ_P(return_value);
-	local = xmlCharStrndup(name, name_len);
-	dom_namednode_iter(intern, 0, namednode, NULL, local, NULL);
+	dom_namednode_iter(intern, 0, namednode, NULL, name, name_len, NULL, 0);
 }
 /* }}} end dom_document_get_elements_by_tag_name */
 
@@ -847,6 +845,8 @@ PHP_METHOD(DOMDocument, importNode)
 		}
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(docp);
+
 	DOM_RET_OBJ((xmlNodePtr) retnodep, &ret, intern);
 }
 /* }}} end dom_document_import_node */
@@ -991,7 +991,6 @@ PHP_METHOD(DOMDocument, getElementsByTagNameNS)
 	size_t uri_len, name_len;
 	dom_object *intern, *namednode;
 	char *uri, *name;
-	xmlChar *local, *nsuri;
 
 	id = ZEND_THIS;
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s!s", &uri, &uri_len, &name, &name_len) == FAILURE) {
@@ -1002,9 +1001,7 @@ PHP_METHOD(DOMDocument, getElementsByTagNameNS)
 
 	php_dom_create_iterator(return_value, DOM_NODELIST);
 	namednode = Z_DOMOBJ_P(return_value);
-	local = xmlCharStrndup(name, name_len);
-	nsuri = xmlCharStrndup(uri ? uri : "", uri_len);
-	dom_namednode_iter(intern, 0, namednode, NULL, local, nsuri);
+	dom_namednode_iter(intern, 0, namednode, NULL, name, name_len, uri ? uri : "", uri_len);
 }
 /* }}} end dom_document_get_elements_by_tag_name_ns */
 
@@ -1070,6 +1067,8 @@ PHP_METHOD(DOMDocument, normalizeDocument)
 
 	DOM_GET_OBJ(docp, id, xmlDocPtr, intern);
 
+	php_libxml_invalidate_node_list_cache_from_doc(docp);
+
 	dom_normalize((xmlNodePtr) docp);
 }
 /* }}} end dom_document_normalize_document */
@@ -1328,10 +1327,14 @@ static void dom_parse_document(INTERNAL_FUNCTION_PARAMETERS, int mode) {
 
 	if (id != NULL) {
 		intern = Z_DOMOBJ_P(id);
+		size_t old_modification_nr = 0;
 		if (intern != NULL) {
 			docp = (xmlDocPtr) dom_object_get_node(intern);
 			doc_prop = NULL;
 			if (docp != NULL) {
+				const php_libxml_doc_ptr *doc_ptr = docp->_private;
+				ZEND_ASSERT(doc_ptr != NULL); /* Must exist, we have a document */
+				old_modification_nr = doc_ptr->cache_tag.modification_nr;
 				php_libxml_decrement_node_ptr((php_libxml_node_object *) intern);
 				doc_prop = intern->document->doc_props;
 				intern->document->doc_props = NULL;
@@ -1348,6 +1351,12 @@ static void dom_parse_document(INTERNAL_FUNCTION_PARAMETERS, int mode) {
 		}
 
 		php_libxml_increment_node_ptr((php_libxml_node_object *)intern, (xmlNodePtr)newdoc, (void *)intern);
+		/* Since iterators should invalidate, we need to start the modification number from the old counter */
+		if (old_modification_nr != 0) {
+			php_libxml_doc_ptr* doc_ptr = (php_libxml_doc_ptr*) ((php_libxml_node_object*) intern)->node; /* downcast */
+			doc_ptr->cache_tag.modification_nr = old_modification_nr;
+			php_libxml_invalidate_node_list_cache(doc_ptr);
+		}
 
 		RETURN_TRUE;
 	} else {
@@ -1563,6 +1572,8 @@ PHP_METHOD(DOMDocument, xinclude)
 		php_dom_remove_xinclude_nodes(root);
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(docp);
+
 	if (err) {
 		RETVAL_LONG(err);
 	} else {
@@ -1871,10 +1882,14 @@ static void dom_load_html(INTERNAL_FUNCTION_PARAMETERS, int mode) /* {{{ */
 
 	if (id != NULL && instanceof_function(Z_OBJCE_P(id), dom_document_class_entry)) {
 		intern = Z_DOMOBJ_P(id);
+		size_t old_modification_nr = 0;
 		if (intern != NULL) {
 			docp = (xmlDocPtr) dom_object_get_node(intern);
 			doc_prop = NULL;
 			if (docp != NULL) {
+				const php_libxml_doc_ptr *doc_ptr = docp->_private;
+				ZEND_ASSERT(doc_ptr != NULL); /* Must exist, we have a document */
+				old_modification_nr = doc_ptr->cache_tag.modification_nr;
 				php_libxml_decrement_node_ptr((php_libxml_node_object *) intern);
 				doc_prop = intern->document->doc_props;
 				intern->document->doc_props = NULL;
@@ -1891,6 +1906,12 @@ static void dom_load_html(INTERNAL_FUNCTION_PARAMETERS, int mode) /* {{{ */
 		}
 
 		php_libxml_increment_node_ptr((php_libxml_node_object *)intern, (xmlNodePtr)newdoc, (void *)intern);
+		/* Since iterators should invalidate, we need to start the modification number from the old counter */
+		if (old_modification_nr != 0) {
+			php_libxml_doc_ptr* doc_ptr = (php_libxml_doc_ptr*) ((php_libxml_node_object*) intern)->node; /* downcast */
+			doc_ptr->cache_tag.modification_nr = old_modification_nr;
+			php_libxml_invalidate_node_list_cache(doc_ptr);
+		}
 
 		RETURN_TRUE;
 	} else {

ext/dom/documenttype.c

@@ -65,7 +65,7 @@ int dom_documenttype_entities_read(dom_object *obj, zval *retval)
 	entityht = (xmlHashTable *) doctypep->entities;
 
 	intern = Z_DOMOBJ_P(retval);
-	dom_namednode_iter(obj, XML_ENTITY_NODE, intern, entityht, NULL, NULL);
+	dom_namednode_iter(obj, XML_ENTITY_NODE, intern, entityht, NULL, 0, NULL, 0);
 
 	return SUCCESS;
 }
@@ -93,7 +93,7 @@ int dom_documenttype_notations_read(dom_object *obj, zval *retval)
 	notationht = (xmlHashTable *) doctypep->notations;
 
 	intern = Z_DOMOBJ_P(retval);
-	dom_namednode_iter(obj, XML_NOTATION_NODE, intern, notationht, NULL, NULL);
+	dom_namednode_iter(obj, XML_NOTATION_NODE, intern, notationht, NULL, 0, NULL, 0);
 
 	return SUCCESS;
 }

ext/dom/dom_iterators.c

@@ -179,7 +179,7 @@ static void php_dom_iterator_move_forward(zend_object_iterator *iter) /* {{{ */
 	dom_object *intern;
 	dom_object *nnmap;
 	dom_nnodemap_object *objmap;
-	int previndex=0;
+	int previndex;
 	HashTable *nodeht;
 	zval *entry;
 	bool do_curobj_undef = 1;
@@ -205,23 +205,32 @@ static void php_dom_iterator_move_forward(zend_object_iterator *iter) /* {{{ */
 					do_curobj_undef = 0;
 				}
 			} else {
-				curnode = (xmlNodePtr)((php_libxml_node_ptr *)intern->ptr)->node;
 				if (objmap->nodetype == XML_ATTRIBUTE_NODE ||
 					objmap->nodetype == XML_ELEMENT_NODE) {
+					curnode = (xmlNodePtr)((php_libxml_node_ptr *)intern->ptr)->node;
 					curnode = curnode->next;
 				} else {
-					/* Nav the tree evey time as this is LIVE */
+					/* The collection is live, we nav the tree from the base object if we cannot
+					 * use the cache to restart from the last point. */
 					basenode = dom_object_get_node(objmap->baseobj);
-					if (basenode && (basenode->type == XML_DOCUMENT_NODE ||
-						basenode->type == XML_HTML_DOCUMENT_NODE)) {
-						basenode = xmlDocGetRootElement((xmlDoc *) basenode);
-					} else if (basenode) {
-						basenode = basenode->children;
-					} else {
+					if (UNEXPECTED(!basenode)) {
 						goto err;
 					}
+					if (php_dom_is_cache_tag_stale_from_node(&iterator->cache_tag, basenode)) {
+						php_dom_mark_cache_tag_up_to_date_from_node(&iterator->cache_tag, basenode);
+						previndex = 0;
+						if (basenode && (basenode->type == XML_DOCUMENT_NODE ||
+										 basenode->type == XML_HTML_DOCUMENT_NODE)) {
+							curnode = xmlDocGetRootElement((xmlDoc *) basenode);
+						} else {
+							curnode = basenode->children;
+						}
+					} else {
+						previndex = iter->index - 1;
+						curnode = (xmlNodePtr)((php_libxml_node_ptr *)intern->ptr)->node;
+					}
 					curnode = dom_get_elements_by_tag_name_ns_raw(
-						basenode, (char *) objmap->ns, (char *) objmap->local, &previndex, iter->index);
+						basenode, curnode, (char *) objmap->ns, (char *) objmap->local, &previndex, iter->index);
 				}
 			}
 		} else {
@@ -258,7 +267,7 @@ zend_object_iterator *php_dom_get_iterator(zend_class_entry *ce, zval *object, i
 {
 	dom_object *intern;
 	dom_nnodemap_object *objmap;
-	xmlNodePtr nodep, curnode=NULL;
+	xmlNodePtr curnode=NULL;
 	int curindex = 0;
 	HashTable *nodeht;
 	zval *entry;
@@ -270,6 +279,7 @@ zend_object_iterator *php_dom_get_iterator(zend_class_entry *ce, zval *object, i
 	}
 	iterator = emalloc(sizeof(php_dom_iterator));
 	zend_iterator_init(&iterator->intern);
+	iterator->cache_tag.modification_nr = 0;
 
 	ZVAL_OBJ_COPY(&iterator->intern.data, Z_OBJ_P(object));
 	iterator->intern.funcs = &php_dom_iterator_funcs;
@@ -288,24 +298,25 @@ zend_object_iterator *php_dom_get_iterator(zend_class_entry *ce, zval *object, i
 					ZVAL_COPY(&iterator->curobj, entry);
 				}
 			} else {
-				nodep = (xmlNode *)dom_object_get_node(objmap->baseobj);
-				if (!nodep) {
+				xmlNodePtr basep = (xmlNode *)dom_object_get_node(objmap->baseobj);
+				if (!basep) {
 					goto err;
 				}
 				if (objmap->nodetype == XML_ATTRIBUTE_NODE || objmap->nodetype == XML_ELEMENT_NODE) {
 					if (objmap->nodetype == XML_ATTRIBUTE_NODE) {
-						curnode = (xmlNodePtr) nodep->properties;
+						curnode = (xmlNodePtr) basep->properties;
 					} else {
-						curnode = (xmlNodePtr) nodep->children;
+						curnode = (xmlNodePtr) basep->children;
 					}
 				} else {
+					xmlNodePtr nodep = basep;
 					if (nodep->type == XML_DOCUMENT_NODE || nodep->type == XML_HTML_DOCUMENT_NODE) {
 						nodep = xmlDocGetRootElement((xmlDoc *) nodep);
 					} else {
 						nodep = nodep->children;
 					}
 					curnode = dom_get_elements_by_tag_name_ns_raw(
-						nodep, (char *) objmap->ns, (char *) objmap->local, &curindex, 0);
+						basep, nodep, (char *) objmap->ns, (char *) objmap->local, &curindex, 0);
 				}
 			}
 		} else {

ext/dom/element.c

@@ -511,7 +511,6 @@ PHP_METHOD(DOMElement, getElementsByTagName)
 	size_t name_len;
 	dom_object *intern, *namednode;
 	char *name;
-	xmlChar *local;
 
 	id = ZEND_THIS;
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s", &name, &name_len) == FAILURE) {
@@ -522,8 +521,7 @@ PHP_METHOD(DOMElement, getElementsByTagName)
 
 	php_dom_create_iterator(return_value, DOM_NODELIST);
 	namednode = Z_DOMOBJ_P(return_value);
-	local = xmlCharStrndup(name, name_len);
-	dom_namednode_iter(intern, 0, namednode, NULL, local, NULL);
+	dom_namednode_iter(intern, 0, namednode, NULL, name, name_len, NULL, 0);
 }
 /* }}} end dom_element_get_elements_by_tag_name */
 
@@ -930,7 +928,6 @@ PHP_METHOD(DOMElement, getElementsByTagNameNS)
 	size_t uri_len, name_len;
 	dom_object *intern, *namednode;
 	char *uri, *name;
-	xmlChar *local, *nsuri;
 
 	id = ZEND_THIS;
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s!s", &uri, &uri_len, &name, &name_len) == FAILURE) {
@@ -941,9 +938,7 @@ PHP_METHOD(DOMElement, getElementsByTagNameNS)
 
 	php_dom_create_iterator(return_value, DOM_NODELIST);
 	namednode = Z_DOMOBJ_P(return_value);
-	local = xmlCharStrndup(name, name_len);
-	nsuri = xmlCharStrndup(uri ? uri : "", uri_len);
-	dom_namednode_iter(intern, 0, namednode, NULL, local, nsuri);
+	dom_namednode_iter(intern, 0, namednode, NULL, name, name_len, uri ? uri : "", uri_len);
 
 }
 /* }}} end dom_element_get_elements_by_tag_name_ns */

ext/dom/node.c

@@ -195,6 +195,8 @@ int dom_node_node_value_write(dom_object *obj, zval *newval)
 			break;
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
+
 	zend_string_release_ex(str, 0);
 	return SUCCESS;
 }
@@ -274,7 +276,7 @@ int dom_node_child_nodes_read(dom_object *obj, zval *retval)
 
 	php_dom_create_iterator(retval, DOM_NODELIST);
 	intern = Z_DOMOBJ_P(retval);
-	dom_namednode_iter(obj, XML_ELEMENT_NODE, intern, NULL, NULL, NULL);
+	dom_namednode_iter(obj, XML_ELEMENT_NODE, intern, NULL, NULL, 0, NULL, 0);
 
 	return SUCCESS;
 }
@@ -482,7 +484,7 @@ int dom_node_attributes_read(dom_object *obj, zval *retval)
 	if (nodep->type == XML_ELEMENT_NODE) {
 		php_dom_create_iterator(retval, DOM_NAMEDNODEMAP);
 		intern = Z_DOMOBJ_P(retval);
-		dom_namednode_iter(obj, XML_ATTRIBUTE_NODE, intern, NULL, NULL, NULL);
+		dom_namednode_iter(obj, XML_ATTRIBUTE_NODE, intern, NULL, NULL, 0, NULL, 0);
 	} else {
 		ZVAL_NULL(retval);
 	}
@@ -769,6 +771,8 @@ int dom_node_text_content_write(dom_object *obj, zval *newval)
 		return FAILURE;
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
+
 	const xmlChar *xmlChars = (const xmlChar *) ZSTR_VAL(str);
 	int type = nodep->type;
 
@@ -897,6 +901,8 @@ PHP_METHOD(DOMNode, insertBefore)
 		php_libxml_increment_doc_ref((php_libxml_node_object *)childobj, NULL);
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(parentp->doc);
+
 	if (ref != NULL) {
 		DOM_GET_OBJ(refp, ref, xmlNodePtr, refpobj);
 		if (refp->parent != parentp) {
@@ -1086,6 +1092,7 @@ PHP_METHOD(DOMNode, replaceChild)
 			nodep->doc->intSubset = (xmlDtd *) newchild;
 		}
 	}
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
 	DOM_RET_OBJ(oldchild, &ret, intern);
 }
 /* }}} end dom_node_replace_child */
@@ -1127,6 +1134,7 @@ PHP_METHOD(DOMNode, removeChild)
 	}
 
 	xmlUnlinkNode(child);
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
 	DOM_RET_OBJ(child, &ret, intern);
 }
 /* }}} end dom_node_remove_child */
@@ -1230,6 +1238,8 @@ PHP_METHOD(DOMNode, appendChild)
 
 	dom_reconcile_ns(nodep->doc, new_child);
 
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
+
 	DOM_RET_OBJ(new_child, &ret, intern);
 }
 /* }}} end dom_node_append_child */
@@ -1339,6 +1349,8 @@ PHP_METHOD(DOMNode, normalize)
 
 	DOM_GET_OBJ(nodep, id, xmlNodePtr, intern);
 
+	php_libxml_invalidate_node_list_cache_from_doc(nodep->doc);
+
 	dom_normalize(nodep);
 
 }
@@ -1571,6 +1583,8 @@ static void dom_canonicalization(INTERNAL_FUNCTION_PARAMETERS, int mode) /* {{{
 		RETURN_THROWS();
 	}
 
+	php_libxml_invalidate_node_list_cache_from_doc(docp);
+
 	if (xpath_array == NULL) {
 		if (nodep->type != XML_DOCUMENT_NODE) {
 			ctxp = xmlXPathNewContext(docp);