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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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34
server/utils/fetchPackageInfo.js
View File

@ -3,26 +3,22 @@ require("isomorphic-fetch");
const config = require("../config");
function fetchPackageInfo(packageName) {
return new Promise(resolve => {
let encodedPackageName;
if (packageName.charAt(0) === "@") {
encodedPackageName = `@${encodeURIComponent(packageName.substring(1))}`;
} else {
encodedPackageName = encodeURIComponent(packageName);
let encodedPackageName;
if (packageName.charAt(0) === "@") {
encodedPackageName = `@${encodeURIComponent(packageName.substring(1))}`;
} else {
encodedPackageName = encodeURIComponent(packageName);
}
const url = `${config.registryURL}/${encodedPackageName}`;
console.log(`info: Fetching package info from ${url}`);
return fetch(url, {
headers: {
Accept: "application/json"
}
const url = `${config.registryURL}/${encodedPackageName}`;
console.log(`info: Fetching package info from ${url}`);
resolve(
fetch(url, {
headers: {
Accept: "application/json"
}
}).then(res => (res.status === 404 ? null : res.json()))
);
});
}).then(res => (res.status === 404 ? null : res.json()));
}
module.exports = fetchPackageInfo;

72
server/utils/getPackageInfo.js
View File

@ -2,53 +2,51 @@ const createCache = require("./createCache");
const createMutex = require("./createMutex");
const fetchPackageInfo = require("./fetchPackageInfo");
const packageInfoCache = createCache("packageInfo");
const packageNotFound = "PackageNotFound";
const cache = createCache("packageInfo");
const notFound = "PackageNotFound";
// This mutex prevents multiple concurrent requests to
// the registry for the same package info.
const fetchMutex = createMutex((packageName, callback) => {
fetchPackageInfo(packageName).then(
value => {
if (value == null) {
// Cache 404s for 5 minutes. This prevents us from making
// unnecessary requests to the registry for bad package names.
// In the worst case, a brand new package's info will be
// available within 5 minutes.
packageInfoCache.set(packageName, packageNotFound, 300, () => {
callback(null, value);
});
} else {
// Cache valid package info for 1 minute.
packageInfoCache.set(packageName, value, 60, () => {
callback(null, value);
});
}
},
error => {
// Do not cache errors.
packageInfoCache.del(packageName, () => {
callback(error);
});
cache.get(packageName, (error, value) => {
if (error) {
callback(error);
} else if (value != null) {
callback(null, value === notFound ? null : value);
} else {
fetchPackageInfo(packageName).then(
value => {
if (value == null) {
// Cache 404s for 5 minutes. This prevents us from making
// unnecessary requests to the registry for bad package names.
// In the worst case, a brand new package's info will be
// available within 5 minutes.
cache.set(packageName, notFound, 300, () => {
callback(null, value);
});
} else {
// Cache valid package info for 1 minute.
cache.set(packageName, value, 60, () => {
callback(null, value);
});
}
},
error => {
// Do not cache errors.
cache.del(packageName, () => {
callback(error);
});
}
);
}
);
});
});
function getPackageInfo(packageName) {
return new Promise((resolve, reject) => {
packageInfoCache.get(packageName, (error, value) => {
fetchMutex(packageName, (error, value) => {
if (error) {
reject(error);
} else if (value != null) {
resolve(value === packageNotFound ? null : value);
} else {
fetchMutex(packageName, (error, value) => {
if (error) {
reject(error);
} else {
resolve(value);
}
});
resolve(value);
}
});
});