feat: cache github datasource results for 10 minutes

lib/datasource/github.js

+const cacache = require('cacache/en');
+const os = require('os');
+const { DateTime } = require('luxon');
+
 const ghGot = require('../platform/github/gh-got-wrapper');
 const versioning = require('../versioning');
 
 module.exports = {
   getPreset,
   getPkgReleases,
+  rmAllCache,
 };
 
+const datasourceCache =
+  (process.env.RENOVATE_TMPDIR || os.tmpdir()) +
+  '/renovate-gh-datasource-cache-v1';
+
+async function getCachedResult(repo, type) {
+  try {
+    const cacheVal = await cacache.get(datasourceCache, `${repo}-${type}`);
+    const cachedResult = JSON.parse(cacheVal.data.toString());
+    if (cachedResult) {
+      if (DateTime.local() < DateTime.fromISO(cachedResult.expiry)) {
+        logger.debug(
+          { repo, type },
+          'Returning cached github datasource result'
+        );
+        delete cachedResult.expiry;
+        return cachedResult;
+      }
+      // istanbul ignore next
+      logger.debug('Cache expiry');
+    }
+  } catch (err) {
+    logger.debug('Cache miss');
+  }
+  return null;
+}
+
+async function setCachedResult(repo, type, res) {
+  logger.debug({ repo, type }, 'Saving cached github datasource');
+  await cacache.put(
+    datasourceCache,
+    `${repo}-${type}`,
+    JSON.stringify({ ...res, expiry: DateTime.local().plus({ minutes: 10 }) })
+  );
+}
+
+async function rmAllCache() {
+  await cacache.rm.all(datasourceCache);
+}
+
 const map = new Map();
 
 async function getPreset(pkgName, presetName = 'default') {
@@ -35,6 +79,10 @@ async function getPkgReleases(purl, config) {
   const { versionScheme } = config || {};
   const { fullname: repo, qualifiers: options } = purl;
   let versions;
+  const cachedResult = await getCachedResult(repo, options.ref);
+  if (cachedResult) {
+    return cachedResult;
+  }
   try {
     if (options.ref === 'release') {
       const url = `repos/${repo}/releases?per_page=100`;
@@ -69,5 +117,6 @@ async function getPkgReleases(purl, config) {
     version: options.sanitize === 'true' ? isVersion(version) : version,
     gitRef: version,
   }));
+  setCachedResult(repo, options.ref, dependency);
   return dependency;
 }

test/datasource/__snapshots__/github.spec.js.snap

@@ -31,3 +31,19 @@ Object {
   "repositoryUrl": "https://github.com/some/dep",
 }
 `;
+
+exports[`datasource/github getPkgReleases returns releases from cache 1`] = `
+Object {
+  "releases": Array [
+    Object {
+      "gitRef": "1.0.0",
+      "version": "1.0.0",
+    },
+    Object {
+      "gitRef": "v1.1.0",
+      "version": "v1.1.0",
+    },
+  ],
+  "repositoryUrl": "https://github.com/some/dep",
+}
+`;

test/datasource/github.spec.js

+const delay = require('delay');
+
 const datasource = require('../../lib/datasource');
 const github = require('../../lib/datasource/github');
 const ghGot = require('../../lib/platform/github/gh-got-wrapper');
@@ -37,6 +39,7 @@ describe('datasource/github', () => {
     });
   });
   describe('getPkgReleases', () => {
+    beforeAll(() => github.rmAllCache());
     it('returns cleaned tags', async () => {
       const body = [
         { name: 'a' },
@@ -71,6 +74,17 @@ describe('datasource/github', () => {
         res.releases.find(release => release.version === 'v1.1.0')
       ).toBeDefined();
     });
+    it('returns releases from cache', async () => {
+      await delay(1000);
+      const res = await datasource.getPkgReleases(
+        'pkg:github/some/dep?ref=release'
+      );
+      expect(res).toMatchSnapshot();
+      expect(res.releases).toHaveLength(2);
+      expect(
+        res.releases.find(release => release.version === 'v1.1.0')
+      ).toBeDefined();
+    });
     it('returns null for invalid ref', async () => {
       expect(
         await datasource.getPkgReleases('pkg:github/some/dep?ref=invalid')