From 69e53743393664ed2db59bbe9bbeaf6f124754f3 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Wed, 24 Nov 2021 15:53:00 +0100 Subject: implement more efficient querying of URL patterns --- common/patterns_query_tree.js | 293 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 293 insertions(+) create mode 100644 common/patterns_query_tree.js (limited to 'common/patterns_query_tree.js') diff --git a/common/patterns_query_tree.js b/common/patterns_query_tree.js new file mode 100644 index 0000000..93f74c6 --- /dev/null +++ b/common/patterns_query_tree.js @@ -0,0 +1,293 @@ +/** + * This file is part of Haketilo. + * + * Function: Data structure to query items by URL patterns. + * + * Copyright (C) 2021 Wojtek Kosior + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * As additional permission under GNU GPL version 3 section 7, you + * may distribute forms of that code without the copy of the GNU + * GPL normally required by section 4, provided you include this + * license notice and, in case of non-source distribution, a URL + * through which recipients can access the Corresponding Source. + * If you modify file(s) with this exception, you may extend this + * exception to your version of the file(s), but you are not + * obligated to do so. If you do not wish to do so, delete this + * exception statement from your version. + * + * As a special exception to the GPL, any HTML file which merely + * makes function calls to this code, and for that purpose + * includes it by reference shall be deemed a separate work for + * copyright law purposes. If you modify this code, you may extend + * this exception to your version of the code, but you are not + * obligated to do so. If you do not wish to do so, delete this + * exception statement from your version. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + * + * I, Wojtek Kosior, thereby promise not to sue for violation of this file's + * license. Although I request that you do not make use this code in a + * proprietary program, I am not going to enforce this in court. + */ + +/* + * IMPORTS_START + * IMPORT deconstruct_url + * IMPORTS_END + */ + +/* + * This is a javascript rewrite of Python implementation of the algorithm here: + * https://git.koszko.org/pydrilla/tree/src/pydrilla/pydrilla.py?id=f4edcbe7f4739d6f82a2e1bb180960b003b30862#n205 + */ + +/* "Pattern Tree" is how we refer to the data structure used for querying + * Haketilo patterns. Those look like 'https://*.example.com/ab/***'. The goal + * is to make it possible for given URL to quickly retrieve all known patterns + * that match it. + */ +function make_tree_node() { + return { + wildcard_matches: [null, null, null], + literal_match: null, + children: null + }; +} + +const is_wildcard = segment => ["*", "**", "***"].lastIndexOf(segment) >= 0; + +/* + * Yields all matches of this segments sequence against the tree that starts at + * this node. Results are produces in order from greatest to lowest pattern + * specificity. + */ +function* search_sequence(tree_node, segments) +{ + const nodes = [tree_node]; + + for (const segment of segments) { + const next_node = nodes[nodes.length - 1].children[segment]; + if (next_node === undefined) + break; + + nodes.push(next_node); + } + + const nsegments = segments.length; + + const conds = [ + /* literal pattern match */ + () => nodes.length == nsegments, + /* wildcard pattern matches */ + () => nodes.length + 1 == nsegments && segments[nsegments - 1] != "*", + () => nodes.length + 1 < nsegments, + () => nodes.length + 1 != nsegments || segments[nsegments - 1] != "***" + ]; + + while (nodes.length) { + const node = nodes.pop(); + const items = [node.literal_match, ...node.wildcard_matches]; + + for (let i = 0; i < 4; i++) { + if (items[i] !== null && conds[i]()) + yield items[i]; + } + } +} + +/* + * Make item queryable through (this branch of) the Pattern Tree. If there was + * not yet any item associated with the tree path designated by segments, create + * a new one using item_instantiator() function. Return all items matching this + * path (both the ones that existed and the ones just created). + */ +function add_sequence(tree_node, segments, item_instantiator) +{ + let wildcards; + + for (var segment of segments) { + wildcards = tree_node.wildcard_matches; + + const child = tree_node.children[segment] || make_tree_node(); + tree_node.children[segment] = child; + tree_node = child; + } + + if (tree_node.literal_match === null) + tree_node.literal_match = item_instantiator(); + + if (!is_wildcard(segment)) + return [tree_node.literal_match]; + + if (wildcards[segment.length - 1] === null) + wildcards[segment.length - 1] = item_instantiator(); + + return [tree_node.literal_match, wildcards[segment.length - 1]]; +} + +/* + * Can be used to remove item from (this branch of) the Pattern Tree. + * item_modifier should be a function that accepts 1 argument, the item stored + * in the tree, and returns an item that should be used in place of the first + * one. It is also legal for it to return the same item modifying it first. If + * it returns `undefined`, it means the item should be deleted from the Tree. + * + * item_modifier() will be called with all items in (this branch of) the Pattern + * Tree that correspond to the path designated by segments. The Tree will be + * updated accordingly. + */ +function modify_sequence(tree_node, segments, item_modifier) +{ + const nodes = [tree_node]; + + for (const segment of segments) { + const next_node = nodes[nodes.length - 1].children[segment]; + nodes.push(next_node); + } + + const nsegments = segments.length; + let i = segments.length - 1; + + if (nsegments > 0 && is_wildcard(segments[i])) { + const node = nodes[nodes.length - 2]; + const asterisks = segments[i].length; + } + + ............................ + + for (let i = segments.length - 1; i >= 0; i--) { + + if (i + } + + segments + + const conds = [ + /* literal pattern match */ + () => nodes.length == nsegments, + /* wildcard pattern matches */ + () => nodes.length + 1 == nsegments && segments[nsegments - 1] != "*", + () => nodes.length + 1 < nsegments, + () => nodes.length + 1 != nsegments || segments[nsegments - 1] != "***" + ]; + + while (nodes.length) { + const node = nodes.pop(); + const items = [node.literal_match, ...node.wildcard_matches]; + + for (let i = 0; i < 4; i++) { + if (items[i] !== null && conds[i]()) + yield items[i]; + } + } + ................. +} + +/* + * Make item queryable through the Pattern Tree that starts with the protocols + * dictionary object passed in the first argument. + */ +function pattern_tree_register(patterns_by_proto, pattern, item_name, item) +{ + /* + * We pass 'false' to disable length limits on URL parts. Length limits are + * mostly useful in case of iteration over all patterns matching given URL. + * Here we don't do that. + */ + const deco = deconstruct_url(pattern, false); + + const tree = patterns_by_proto[deco.proto] || make_tree_node(); + patterns_by_proto[deco.proto] = tree; + + let path_trees; + + if (deco.proto === "file") { + path_trees = [tree]; + } else { + /* We need an aray of domain labels ordered most-significant-first. */ + const domain = [...deco.domain].reverse(); + path_trees = add_sequence(tree, domain, make_tree_node); + } + + for (const path_tree of path_trees) { + for (const match_obj of add_sequence(path_tree, deco.path, () => {})) + match_obj[item_name] = item; + } +} + +/* + * Remove registered item from the Pattern Tree that starts with the protocols + * dictionary object passed in the first argument. The remaining 2 arguments + * should be pattern and name that have been earlier passed to + * pattern_tree_register(). + */ +function pattern_tree_deregister(patterns_by_proto, pattern, item_name) +{ + const deco = deconstruct_url(pattern, false); + + const tree = patterns_by_proto[deco.proto] || make_tree_node(); + patterns_by_proto[deco.proto] = tree; + + let path_trees; + + if (deco.proto === "file") { + path_trees = [tree]; + } else { + /* We need an aray of domain labels ordered most-significant-first. */ + const domain = [...deco.domain].reverse(); + .......................... + path_trees = add_sequence(tree, domain, make_tree_node); + } +} + +/* + * Yield registered items (as [item_name, item] arrays) that match url. For + * cosistent behavior, please don't modify the pattern tree while iterating over + * the results. + */ +function* pattern_tree_search(patterns_by_proto, url) +{ + const deco = deconstruct_url(url, false); + + tree = patterns_by_proto[deco.proto] || make_tree_node(); + + let path_trees; + + if (deco.proto === "file") { + path_trees = [tree]; + } else { + /* We need an aray of domain labels ordered most-significant-first. */ + const domain = [...deco.domain].reverse(); + path_trees = search_sequence(tree, domain); + } + + for (const path_tree of path_trees) { + for (const match_obj of search_sequence(path_tree, deco.path)) { + for (const entry of Object.entries(match_obj)) + yield entry; + } + } +} + +const patterns_tree = { + make: () => {}, + register: patterns_tree_register, + search: patterns_tree_search +} + +/* + * EXPORTS_START + * EXPORT patterns_tree + * EXPORTS_END + */ -- cgit v1.2.3