explore-services/services/cache/mecache/cache.js

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'use strict';
const axios = require('axios');
let express = require('express');
let app = express();
const { LRUCache } = require('lru-cache');
const request = require('superagent');
const prom = require('prom-client');
const URL = require('url');
let compression = require("compression");
const PropertiesReader = require('properties-reader');
const properties = PropertiesReader('./properties.file');
const environment = properties.get("environment");
const preloadRequests = properties.get("preloadRequests").split(',');;
const cacheMaxSize = 1000;
let cors = require('cors');
app.use(cors());
app.use(compression());
const lruCache = new LRUCache({ max: cacheMaxSize });
const register = new prom.Registry();
prom.collectDefaultMetrics({register: register});
const responses = new prom.Counter({
name: 'cache_http_responses_total',
help: 'A counter for cache response codes for every API request.',
labelNames: ['scheme', 'target', 'code'],
registers: [register]
});
const entries = new prom.Gauge({
name: 'cache_used_entries',
help: 'A counter to count cache entries',
registers: [register]
});
const histogram = new prom.Histogram({
name: 'cache_http_request_duration_seconds',
help: 'A Histogram for cache. Providing information about a cache request and load latency in seconds.',
labelNames: ['scheme', 'target', 'cache'],
registers: [register],
buckets: [0.1, 0.2, 0.5, 1, 2]
});
let cache = () => {
return (req, res, next) => {
if (req.query.url) {
let key = req.query.url;
const url = new URL.parse(req.query.url);
// console.log(req.headers.origin, req.headers.referrer, req.headers.origin)
const cacheControlHeader = req.headers['cache-control'];
// Log the Cache-Control header
// console.log('Cache-Control header sent by client:', cacheControlHeader);
let forceReload = req.query.forceReload && req.query.forceReload == 'true'?true:false;
forceReload = forceReload || (cacheControlHeader && (cacheControlHeader.indexOf("no-cache") || cacheControlHeader.indexOf("no-store") || cacheControlHeader.indexOf("must-revalidate")))?true:false;
const target = url.host + '/' + url.pathname.split('/')[1];
const scheme = url.protocol.replace(':', '');
if (lruCache.has(key) && !forceReload) {
// console.log( key, "hit")
const end = histogram.startTimer({scheme: scheme, target: target, cache: 'hit'});
res.send(JSON.parse(lruCache.get(key)));
responses.inc({scheme: scheme, target: target, code: res.statusCode});
end();
} else {
// console.log( key, "miss", forceReload)
const end = histogram.startTimer({scheme: scheme, target: target, cache: 'miss'});
res.sendResponse = res.send;
res.send = (body) => {
if(isAllowedToBeCached(decodeURI(scheme), decodeURI(target))) {
let alreadyCached = lruCache.has(key);
entries.set(lruCache.size);
if (!alreadyCached) {
responses.inc({scheme: scheme, target: target, code: res.statusCode});
end();
}
if (res.statusCode === 200) {
lruCache.set(key, body);
entries.set(lruCache.size);
}
res.sendResponse(body);
}else{
res.statusCode = 405;
res.sendResponse(JSON.stringify( {code: 405, message: "Method not Allowed"}));
}
};
next();
}
} else {
next();
}
};
};
function isAllowedToBeCached(scheme, target){
if(environment != "development"){
return scheme.indexOf("https")!=-1 && ( target.indexOf(".openaire.eu/") !=-1 || target.indexOf("zenodo.org/api") !=-1 || target.indexOf("lab.idiap.ch/enermaps" != -1))
} else if(environment == "development"){
return target.indexOf(".openaire.eu/") !=-1 || target.indexOf(".di.uoa.gr") !=-1 || target.indexOf("zenodo.org/api") !=-1 || target.indexOf("dev-openaire.d4science.org") !=-1 || target.indexOf("lab.idiap.ch/enermaps") != -1
}
return true;
}
app.get('/clear', (req, res) => {
let c = lruCache.size;
const url = req.query.url;
let message = "";
if (url) {
let key = '__express__' + req.query.url;
lruCache.delete(key);
message = "Delete entry with key " + url;
entries.set(lruCache.size);
} else {
clearCache();
message = "Delete " + c + " entries. Now there are: " + lruCache.size
}
res.header("Access-Control-Allow-Headers", "Origin, Content-Type, Content-Length");
res.header("Access-Control-Allow-Methods", "GET, OPTIONS");
res.header("Access-Control-Allow-Methods", "GET, OPTIONS");
res.header("Content-Type", "application/json");
res.status(200).send(getResponse(200, message));
});
app.get('/metrics', (req, res) => {
res.set('Content-Type', register.contentType);
res.end(register.metrics());
});
app.get('/info', (req, res) => {
res.status(200).send(getResponse(200, {size:lruCache.size, keys: Array.from(lruCache.keys())}));
});
app.get('/get', cache(), cors(), (req, res) => {
setTimeout(() => {
const url = (req.query) ? req.query.url : null;
if (!url) {
res.status(404).send(getResponse(404, "Not Found ")) //not found
} else {
request.get(url, function (err, response) {
res.header("Access-Control-Allow-Headers", "Origin, Content-Type, Content-Length");
res.header("Access-Control-Allow-Methods", "GET, OPTIONS");
res.header("Access-Control-Allow-Methods", "GET, OPTIONS");
res.header("Content-Type", "application/json");
if (!response && err) {
res.status(500).send(getResponse(500, "An error occurred for " + url))
} else {
res.status(response.status).send(response.body);
}
})
}
})
});
app.use((req, res) => {
res.status(404).send(getResponse(404, "Not Found")); //not found
});
const server = app.listen(properties.get('port'), function () {
console.log(`Example app listening on port`, server.address().port)
//run the timer
resetAtMidnight();
initCache();
});
function getResponse(code, message) {
var response = {};
response["code"] = code;
response["message"] = message;
return response;
}
function clearCache() {
console.log("cache is cleared!");
lruCache.clear();
entries.set(lruCache.size);
initCache();
}
async function initCache() {
try {
const requests = await axios.get(properties.get('utilsService') + '/grouped-requests');
const additionalDataPromises = requests.data.map((url) => axios.get('http://localhost:'+properties.get('port') + '/get?url=' + properties.get('utilsService') + url));
const additionalDataResponses = await Promise.all(additionalDataPromises);
console.log("Cache initialized group queries!")
} catch (error) {
console.error('Error fetching data: Cache initialize failed', error);
}
try{
const additionalDataPromisesPreloadRequests = preloadRequests.map((url) => axios.get('http://localhost:'+properties.get('port') + '/get?url=' + url));
const additionalDataResponsesPreloadRequests = await Promise.all(additionalDataPromisesPreloadRequests);
console.log("Cache initialized preload requests!")
} catch (error) {
console.error('Error fetching data: Cache initialize failed', error);
}
}
function resetAtMidnight() {
console.log("Run Reset timer");
var now = new Date();
var night = new Date(
now.getFullYear(),
now.getMonth(),
now.getDate() + 1, // the next day, ...
0, 0, 0 // ...at 00:00:00 hours
);
var msToMidnight = night.getTime() - now.getTime();
setTimeout(function () {
clearCache(); // <-- This is the function being called at midnight.
resetAtMidnight(); // Then, reset again next midnight.
}, msToMidnight);
}