perf(core): skip await if response has already resolved (#1422)

* perf(core): avoid unnecessary await when get response is in cache

* chore: versions

.yarn/versions/8c6a6df8.yml

@@ -0,0 +1,30 @@
+releases:
+  "@yarnpkg/cli": prerelease
+  "@yarnpkg/core": prerelease
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-http"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-node-modules"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/pnpify"

packages/yarnpkg-core/sources/httpUtils.ts

@@ -12,7 +12,7 @@ const NETWORK_CONCURRENCY = 8;
 
 const limit = plimit(NETWORK_CONCURRENCY);
 
-const cache = new Map<string, Promise<Response<Buffer>>>();
+const cache = new Map<string, Promise<Buffer> | Buffer>();
 
 const globalHttpAgent = new HttpAgent({keepAlive: true});
 const globalHttpsAgent = new HttpsAgent({keepAlive: true});
@@ -97,16 +97,20 @@ export async function get(target: string, {configuration, json, ...rest}: Option
   let entry = cache.get(target);
 
   if (!entry) {
-    entry = request(target, null, {configuration, ...rest});
+    entry = request(target, null, {configuration, ...rest}).then(response => {
+      cache.set(target, response.body);
+      return response.body;
+    });
     cache.set(target, entry);
   }
 
-  const response = await entry;
+  if (Buffer.isBuffer(entry) === false)
+    entry = await entry;
 
   if (json) {
-    return JSON.parse(response.body.toString());
+    return JSON.parse(entry.toString());
   } else {
-    return response.body;
+    return entry;
   }
 }