X-Git-Url: https://git.openstreetmap.org./rails.git/blobdiff_plain/03fb042591bf60cd74aa277ee3de98f02d8486d3..b6b2fe6b8d943a561646995d6b3a7aa6584a4250:/lib/diff_reader.rb diff --git a/lib/diff_reader.rb b/lib/diff_reader.rb index 9b3e01b86..2784646af 100644 --- a/lib/diff_reader.rb +++ b/lib/diff_reader.rb @@ -4,14 +4,12 @@ # Uses the streaming LibXML "Reader" interface to cut down on memory # usage, so hopefully we can process fairly large diffs. class DiffReader - include ConsistencyValidations - # maps each element type to the model class which handles it - MODELS = { - "node" => Node, - "way" => Way, + MODELS = { + "node" => Node, + "way" => Way, "relation" => Relation - } + }.freeze ## # Construct a diff reader by giving it a bunch of XML +data+ to parse @@ -20,6 +18,10 @@ class DiffReader def initialize(data, changeset) @reader = XML::Reader.string(data) @changeset = changeset + # document that's (re-)used to handle elements expanded out of the + # diff processing stream. + @doc = XML::Document.new + @doc.root = XML::Node.new("osm") end ## @@ -28,15 +30,13 @@ class DiffReader def read_or_die # NOTE: XML::Reader#read returns false for EOF and raises an # exception if an error occurs. - begin - @reader.read - rescue LibXML::XML::Error => ex - raise OSM::APIBadXMLError.new("changeset", xml, ex.message) - end + @reader.read + rescue LibXML::XML::Error => e + raise OSM::APIBadXMLError.new("changeset", xml, e.message) end ## - # An element-block mapping for using the LibXML reader interface. + # An element-block mapping for using the LibXML reader interface. # # Since a lot of LibXML reader usage is boilerplate iteration through # elements, it would be better to DRY and do this in a block. This @@ -48,34 +48,58 @@ class DiffReader # read the first element read_or_die - while @reader.node_type != 15 do # end element + while @reader.node_type != 15 # end element # because we read elements in DOM-style to reuse their DOM # parsing code, we don't always read an element on each pass # as the call to @reader.next in the innermost loop will take # care of that for us. if @reader.node_type == 1 # element - yield @reader.name + name = @reader.name + attributes = {} + + if @reader.has_attributes? + attributes[@reader.name] = @reader.value while @reader.move_to_next_attribute == 1 + + @reader.move_to_element + end + + yield name, attributes else read_or_die end - end + end end read_or_die end ## - # An element-block mapping for using the LibXML reader interface. + # An element-block mapping for using the LibXML reader interface. # # Since a lot of LibXML reader usage is boilerplate iteration through # elements, it would be better to DRY and do this in a block. This # could also help with error handling...? def with_model - with_element do |model_name| + with_element do |model_name, _model_attributes| model = MODELS[model_name] - raise OSM::APIBadUserInput.new("Unexpected element type #{model_name}, " + - "expected node, way or relation.") if model.nil? - yield model, @reader.expand + if model.nil? + raise OSM::APIBadUserInput, "Unexpected element type #{model_name}, " \ + "expected node, way or relation." + end + # new in libxml-ruby >= 2, expand returns an element not associated + # with a document. this means that there's no encoding parameter, + # which means basically nothing works. + expanded = @reader.expand + + # create a new, empty document to hold this expanded node + new_node = @doc.import(expanded) + @doc.root << new_node + + yield model, new_node @reader.next + + # remove element from doc - it will be garbage collected and the + # rest of the document is re-used in the next iteration. + @doc.root.child.remove! end end @@ -84,9 +108,7 @@ class DiffReader # such as save_ and delete_with_history. def check(model, xml, new) raise OSM::APIBadXMLError.new(model, xml) if new.nil? - unless new.changeset_id == @changeset.id - raise OSM::APIChangesetMismatchError.new(new.changeset_id, @changeset.id) - end + raise OSM::APIChangesetMismatchError.new(new.changeset_id, @changeset.id) unless new.changeset_id == @changeset.id end ## @@ -94,39 +116,38 @@ class DiffReader # is *not* transactional, so code which calls it should ensure that the # appropriate transaction block is in place. # - # On a failure to meet preconditions (e.g: optimistic locking fails) + # On a failure to meet preconditions (e.g: optimistic locking fails) # an exception subclassing OSM::APIError will be thrown. def commit - # data structure used for mapping placeholder IDs to real IDs - node_ids, way_ids, rel_ids = {}, {}, {} - ids = { :node => node_ids, :way => way_ids, :relation => rel_ids} + ids = { :node => {}, :way => {}, :relation => {} } # take the first element and check that it is an osmChange element @reader.read - raise OSM::APIBadUserInput.new("Document element should be 'osmChange'.") if @reader.name != 'osmChange' + raise OSM::APIBadUserInput, "Document element should be 'osmChange'." if @reader.name != "osmChange" - result = OSM::API.new.get_xml_doc + result = OSM::API.new.xml_doc result.root.name = "diffResult" # loop at the top level, within the element - with_element do |action_name| - if action_name == 'create' + with_element do |action_name, action_attributes| + case action_name + when "create" # create a new element. this code is agnostic of the element type # because all the elements support the methods that we're using. with_model do |model, xml| - new = model.from_xml_node(xml, true) + new = model.from_xml_node(xml, :create => true) check(model, xml, new) # when this element is saved it will get a new ID, so we save it # to produce the mapping which is sent to other elements. - placeholder_id = xml['id'].to_i + placeholder_id = xml["id"].to_i raise OSM::APIBadXMLError.new(model, xml) if placeholder_id.nil? # check if the placeholder ID has been given before and throw # an exception if it has - we can't create the same element twice. model_sym = model.to_s.downcase.to_sym - raise OSM::APIBadUserInput.new("Placeholder IDs must be unique for created elements.") if ids[model_sym].include? placeholder_id + raise OSM::APIBadUserInput, "Placeholder IDs must be unique for created elements." if ids[model_sym].include? placeholder_id # some elements may have placeholders for other elements in the # diff, so we must fix these before saving the element. @@ -134,7 +155,7 @@ class DiffReader # create element given user new.create_with_history(@changeset.user) - + # save placeholder => allocated ID map ids[model_sym][placeholder_id] = new.id @@ -145,13 +166,13 @@ class DiffReader xml_result["new_version"] = new.version.to_s result.root << xml_result end - - elsif action_name == 'modify' + + when "modify" # modify an existing element. again, this code doesn't directly deal # with types, but uses duck typing to handle them transparently. with_model do |model, xml| # get the new element from the XML payload - new = model.from_xml_node(xml, false) + new = model.from_xml_node(xml, :create => false) check(model, xml, new) # if the ID is a placeholder then map it to the real ID @@ -171,20 +192,20 @@ class DiffReader xml_result = XML::Node.new model.to_s.downcase xml_result["old_id"] = client_id.to_s - xml_result["new_id"] = id.to_s + xml_result["new_id"] = id.to_s # version is updated in "old" through the update, so we must not # return new.version here but old.version! xml_result["new_version"] = old.version.to_s result.root << xml_result end - elsif action_name == 'delete' + when "delete" # delete action. this takes a payload in API 0.6, so we need to do # most of the same checks that are done for the modify. with_model do |model, xml| # delete doesn't have to contain a full payload, according to # the wiki docs, so we just extract the things we need. - new_id = xml['id'].to_i + new_id = xml["id"].to_i raise OSM::APIBadXMLError.new(model, xml, "ID attribute is required") if new_id.nil? # if the ID is a placeholder then map it to the real ID @@ -194,8 +215,8 @@ class DiffReader # build the "new" element by modifying the existing one new = model.find(id) - new.changeset_id = xml['changeset'].to_i - new.version = xml['version'].to_i + new.changeset_id = xml["changeset"].to_i + new.version = xml["version"].to_i check(model, xml, new) # fetch the matching old element from the DB @@ -204,23 +225,33 @@ class DiffReader # can a delete have placeholders under any circumstances? # if a way is modified, then deleted is that a valid diff? new.fix_placeholders!(ids) - old.delete_with_history!(new, @changeset.user) xml_result = XML::Node.new model.to_s.downcase # oh, the irony... the "new" element actually contains the "old" ID # a better name would have been client/server, but anyway... xml_result["old_id"] = new_id.to_s + + if action_attributes["if-unused"] + begin + old.delete_with_history!(new, @changeset.user) + rescue OSM::APIAlreadyDeletedError, OSM::APIPreconditionFailedError + xml_result["new_id"] = old.id.to_s + xml_result["new_version"] = old.version.to_s + end + else + old.delete_with_history!(new, @changeset.user) + end + result.root << xml_result end else # no other actions to choose from, so it must be the users fault! - raise OSM::APIChangesetActionInvalid.new(action_name) + raise OSM::APIChangesetActionInvalid, action_name end end # return the XML document to be rendered back to the client - return result + result end - end