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