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Check Redis cache inside of process mutex

This commit is contained in:
Michael Jackson 2018-05-22 21:16:10 -04:00
parent 2f7f805cd6
commit 5b1750c182
2 changed files with 50 additions and 56 deletions
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8
server/utils/fetchPackageInfo.js
View File

@ -3,7 +3,6 @@ require("isomorphic-fetch");
const config = require("../config"); const config = require("../config");
function fetchPackageInfo(packageName) { function fetchPackageInfo(packageName) {
return new Promise(resolve => {
let encodedPackageName; let encodedPackageName;
if (packageName.charAt(0) === "@") { if (packageName.charAt(0) === "@") {
encodedPackageName = `@${encodeURIComponent(packageName.substring(1))}`; encodedPackageName = `@${encodeURIComponent(packageName.substring(1))}`;
@ -15,14 +14,11 @@ function fetchPackageInfo(packageName) {
console.log(`info: Fetching package info from ${url}`); console.log(`info: Fetching package info from ${url}`);
resolve( return fetch(url, {
fetch(url, {
headers: { headers: {
Accept: "application/json" Accept: "application/json"
} }
}).then(res => (res.status === 404 ? null : res.json())) }).then(res => (res.status === 404 ? null : res.json()));
);
});
} }
module.exports = fetchPackageInfo; module.exports = fetchPackageInfo;

28
server/utils/getPackageInfo.js
View File

@ -2,12 +2,16 @@ const createCache = require("./createCache");
const createMutex = require("./createMutex"); const createMutex = require("./createMutex");
const fetchPackageInfo = require("./fetchPackageInfo"); const fetchPackageInfo = require("./fetchPackageInfo");
const packageInfoCache = createCache("packageInfo"); const cache = createCache("packageInfo");
const packageNotFound = "PackageNotFound"; const notFound = "PackageNotFound";
// This mutex prevents multiple concurrent requests to
// the registry for the same package info.
const fetchMutex = createMutex((packageName, callback) => { const fetchMutex = createMutex((packageName, callback) => {
cache.get(packageName, (error, value) => {
if (error) {
callback(error);
} else if (value != null) {
callback(null, value === notFound ? null : value);
} else {
fetchPackageInfo(packageName).then( fetchPackageInfo(packageName).then(
value => { value => {
if (value == null) { if (value == null) {
@ -15,33 +19,29 @@ const fetchMutex = createMutex((packageName, callback) => {
// unnecessary requests to the registry for bad package names. // unnecessary requests to the registry for bad package names.
// In the worst case, a brand new package's info will be // In the worst case, a brand new package's info will be
// available within 5 minutes. // available within 5 minutes.
packageInfoCache.set(packageName, packageNotFound, 300, () => { cache.set(packageName, notFound, 300, () => {
callback(null, value); callback(null, value);
}); });
} else { } else {
// Cache valid package info for 1 minute. // Cache valid package info for 1 minute.
packageInfoCache.set(packageName, value, 60, () => { cache.set(packageName, value, 60, () => {
callback(null, value); callback(null, value);
}); });
} }
}, },
error => { error => {
// Do not cache errors. // Do not cache errors.
packageInfoCache.del(packageName, () => { cache.del(packageName, () => {
callback(error); callback(error);
}); });
} }
); );
}
});
}); });
function getPackageInfo(packageName) { function getPackageInfo(packageName) {
return new Promise((resolve, reject) => { return new Promise((resolve, reject) => {
packageInfoCache.get(packageName, (error, value) => {
if (error) {
reject(error);
} else if (value != null) {
resolve(value === packageNotFound ? null : value);
} else {
fetchMutex(packageName, (error, value) => { fetchMutex(packageName, (error, value) => {
if (error) { if (error) {
reject(error); reject(error);
@ -49,8 +49,6 @@ function getPackageInfo(packageName) {
resolve(value); resolve(value);
} }
}); });
}
});
}); });
} }