diff options
Diffstat (limited to 'web/js/nms-data.js')
| -rw-r--r-- | web/js/nms-data.js | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/web/js/nms-data.js b/web/js/nms-data.js index 9242313..5a219e8 100644 --- a/web/js/nms-data.js +++ b/web/js/nms-data.js @@ -224,13 +224,31 @@ nmsData._genericUpdater = function(name, cacheok) { heads['Cache-Control'] = "max-age=0, no-cache, stale-while-revalidate=0"; } + /* + * Note that we intentionally set dataType: "text" here. + * + * We can be smarter than jQuery here. We know that the ETag can be + * used to evaluate against our cached copy. If the ETag is a + * match, we never have to do the potentially extensive JSON + * parsing. + * + * Also note that we accept weakened ETags too (ETags with W/ + * prefixed). This is typically if the intermediate cache has + * compressed the content for us, so this is fine. + * + * This is particularly important because we poll everything even + * though we _know_ it will hit both browser cache and most likely + * Varnish. JSON.Parse was one of the biggest CPU hogs before this. + */ $.ajax({ type: "GET", headers: heads, url: this._sources[name].target + now, - dataType: "json", - success: function (data, textStatus, jqXHR) { - if (nmsData[name] == undefined || nmsData[name]['hash'] != data['hash']) { + dataType: "text", + success: function (indata, textStatus, jqXHR) { + let etag = jqXHR.getResponseHeader("ETag"); + if (nmsData[name] == undefined || (nmsData[name]['hash'] != etag && nmsData[name]['hash'] != etag.slice(2))) { + var data = JSON.parse(indata); if (name == "ping") { nmsData._last = data['time']; nmsMap.drawNow(); |