Sandro Santilli
e8cbc666e2
SQL api is used to determine the list of source tables affected by a query. Before this commit, the X-Cache-Channel header set on sql api error was an arbitrary 'table' string, now the header is omitted, the error logged and Cache-Control and Pragma headers are sent as an attempt to request no caching. The code includes test for this mechanism.
97 lines
3.5 KiB
JavaScript
97 lines
3.5 KiB
JavaScript
var _ = require('underscore'),
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Varnish = require('node-varnish'),
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request = require('request'),
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crypto = require('crypto'),
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channelCache = {},
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varnish_queue = null;
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function init(host, port) {
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varnish_queue = new Varnish.VarnishQueue(host, port);
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}
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function invalidate_db(dbname, table) {
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try{
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varnish_queue.run_cmd('purge obj.http.X-Cache-Channel ~ "^' + dbname + ':(.*'+ table +'.*)|(table)$"');
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console.log('[SUCCESS FLUSHING CACHE]');
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} catch (e) {
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console.log("[ERROR FLUSHING CACHE] Is enable_cache set to true? Failed for: " + 'purge obj.http.X-Cache-Channel ~ "^' + dbname + ':(.*'+ table +'.*)|(table)$"');
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}
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}
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function generateCacheChannel(req, callback){
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var cacheChannel = "";
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// use key to call sql api with sql request if present, else just return dbname and table name
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// base key
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var tableNames = req.params.table;
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var dbName = req.params.dbname;
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var username = req.headers.host.split('.')[0];
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// replace tableNames with the results of the explain if present
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if (_.isString(req.params.sql) && req.params.sql != ''){
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// initialise MD5 key of sql for cache lookups
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var sql_md5 = generateMD5(req.params.sql);
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var api = global.environment.sqlapi;
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var qs = {};
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// use cache if present
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if (!_.isNull(channelCache[sql_md5]) && !_.isUndefined(channelCache[sql_md5])) {
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callback(null, channelCache[sql_md5]);
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} else{
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// strip out windshaft/mapnik inserted sql if present
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var sql = req.params.sql.match(/^\((.*)\)\sas\scdbq$/);
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sql = (sql != null) ? sql[1] : req.params.sql;
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// build up api string
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var sqlapi = api.protocol + '://' + username + '.' + api.host + ':' + api.port + '/api/' + api.version + '/sql'
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// add query to querystring
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qs.q = 'SELECT CDB_QueryTables($windshaft$' + sql + '$windshaft$)';
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// add api_key if present in tile request (means table is private)
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if (_.isString(req.params.map_key) && req.params.map_key != ''){
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qs.api_key = req.params.map_key;
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}
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// call sql api
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request.get({url:sqlapi, qs:qs, json:true}, function(err, res, body){
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var epref = 'could not detect source tables using SQL api at ' + sqlapi;
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if (err){
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var msg = err.message ? err.message : err;
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callback(new Error(epref + ': ' + msg));
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return;
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}
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if (res.statusCode != 200) {
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var msg = res.body.error ? res.body.error : res.body;
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callback(new Error(epref + ': ' + msg));
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return;
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}
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var qtables = body.rows[0].cdb_querytables;
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tableNames = qtables.split(/^\{(.*)\}$/)[1];
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cacheChannel = buildCacheChannel(dbName,tableNames);
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channelCache[sql_md5] = cacheChannel; // store for caching
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callback(null, cacheChannel);
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});
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}
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} else {
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cacheChannel = buildCacheChannel(dbName,tableNames);
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callback(null, cacheChannel);
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}
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}
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function buildCacheChannel(dbName, tableNames){
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return dbName + ':' + tableNames;
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}
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function generateMD5(data){
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var hash = crypto.createHash('md5');
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hash.update(data);
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return hash.digest('hex');
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}
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module.exports = {
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init: init,
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invalidate_db: invalidate_db,
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generateCacheChannel: generateCacheChannel
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}
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