yarn-plugin: memoize manifest fetching

Signed-off-by: MT Lewis <mtlewis@users.noreply.github.com>

packages/yarn-plugin/package.json

@@ -35,6 +35,7 @@
     "@yarnpkg/core": "^4.0.3",
     "@yarnpkg/fslib": "^3.0.2",
     "chalk": "^4.0.0",
+    "lodash": "^4.17.21",
     "semver": "^7.6.0"
   },
   "devDependencies": {

packages/yarn-plugin/src/resolver/BackstageResolver.test.ts

@@ -16,6 +16,7 @@
 
 import { structUtils } from '@yarnpkg/core';
 import { npath, ppath } from '@yarnpkg/fslib';
+import { getManifestByVersion } from '@backstage/release-manifests';
 import { BackstageResolver } from './BackstageResolver';
 import { createMockDirectory } from '@backstage/backend-test-utils';
 
@@ -31,6 +32,10 @@ jest.mock('@backstage/release-manifests', () => ({
   }),
 }));
 
+const getManifestByVersionMock = getManifestByVersion as jest.MockedFunction<
+  typeof getManifestByVersion
+>;
+
 describe('BackstageResolver', () => {
   const mockDir = createMockDirectory();
   let backstageResolver: BackstageResolver;
@@ -177,5 +182,29 @@ describe('BackstageResolver', () => {
         ),
       ).rejects.toThrow(/invalid backstage version/i);
     });
+
+    it('memoizes manifest retrieval', async () => {
+      const descriptor1 = structUtils.makeDescriptor(
+        structUtils.makeIdent('backstage', 'core'),
+        'backstage:1.23.45',
+      );
+
+      for (let i = 0; i < 5; i++) {
+        await backstageResolver.getCandidates(descriptor1);
+      }
+
+      expect(getManifestByVersionMock).toHaveBeenCalledTimes(1);
+
+      const descriptor2 = structUtils.makeDescriptor(
+        structUtils.makeIdent('backstage', 'core'),
+        'backstage:6.78.90',
+      );
+
+      for (let i = 0; i < 5; i++) {
+        await backstageResolver.getCandidates(descriptor2);
+      }
+
+      expect(getManifestByVersionMock).toHaveBeenCalledTimes(2);
+    });
   });
 });

packages/yarn-plugin/src/util.ts

@@ -16,11 +16,17 @@
 
 import { ppath, xfs } from '@yarnpkg/fslib';
 import { valid as semverValid } from 'semver';
-import { getManifestByVersion } from '@backstage/release-manifests';
+import { memoize } from 'lodash';
+import { getManifestByVersion as getManifestByVersionBase } from '@backstage/release-manifests';
 import { BACKSTAGE_JSON, findPaths } from '@backstage/cli-common';
 import { Descriptor, structUtils } from '@yarnpkg/core';
 import { PROTOCOL } from './constants';
 
+const getManifestByVersion = memoize(
+  getManifestByVersionBase,
+  ({ version }) => version,
+);
+
 export const getCurrentBackstageVersion = () => {
   const workspaceRoot = ppath.resolve(findPaths(ppath.cwd()).targetRoot);
 

yarn.lock

@@ -45239,6 +45239,7 @@ __metadata:
     "@yarnpkg/core": ^4.0.3
     "@yarnpkg/fslib": ^3.0.2
     chalk: ^4.0.0
+    lodash: ^4.17.21
     nodemon: ^3.0.1
     semver: ^7.6.0
   languageName: unknown