Shared cache for affected tables in layergroup and map controllers

lib/cartodb/api/query_tables_api.js

@@ -48,7 +48,7 @@ QueryTablesApi.prototype.getAffectedTablesAndLastUpdatedTime = function (usernam
 function handleAffectedTablesAndLastUpdatedTimeRows(err, rows, callback) {
     if (err || rows.length === 0) {
         var msg = err.message ? err.message : err;
-        callback(new Error('could not fetch affected tables and last updated time: ' + msg));
+        callback(new Error('could not fetch affected tables or last updated time: ' + msg));
         return;
     }
 
@@ -65,6 +65,35 @@ function handleAffectedTablesAndLastUpdatedTimeRows(err, rows, callback) {
     });
 }
 
+QueryTablesApi.prototype.getLastUpdatedTime = function (username, tableNames, callback) {
+    if (!Array.isArray(tableNames) || tableNames.length === 0) {
+        return callback(null, 0);
+    }
+
+    var query = [
+        'SELECT EXTRACT(EPOCH FROM max(updated_at)) as max',
+        'FROM CDB_TableMetadata m WHERE m.tabname = any (ARRAY[',
+            tableNames.map(function(t) { return "'" + t + "'::regclass"; }).join(','),
+        '])'
+    ].join(' ');
+
+    this.pgQueryRunner.run(username, query, handleLastUpdatedTimeRows, callback);
+};
+
+function handleLastUpdatedTimeRows(err, rows, callback) {
+    if (err) {
+        var msg = err.message ? err.message : err;
+        return callback(new Error('could not fetch affected tables or last updated time: ' + msg));
+    }
+    // when the table has not updated_at means it hasn't been changed so a default last_updated is set
+    var lastUpdated = 0;
+    if (rows.length !== 0) {
+        lastUpdated = rows[0].max || 0;
+    }
+
+    return callback(null, lastUpdated*1000);
+}
+
 function prepareSql(sql) {
     return sql
         .replace(affectedTableRegexCache.bbox, 'ST_MakeEnvelope(0,0,0,0)')