Rename server => modules

modules/utils/getNpmPackageInfo.js

@@ -0,0 +1,40 @@
+const cache = require("./cache");
+const fetchNpmPackageInfo = require("./fetchNpmPackageInfo");
+
+const notFound = "PackageNotFound";
+
+function getNpmPackageInfo(packageName) {
+  return new Promise((resolve, reject) => {
+    const key = `npmPackageInfo-${packageName}`;
+
+    cache.get(key, (error, value) => {
+      if (error) {
+        reject(error);
+      } else if (value != null) {
+        resolve(value === notFound ? null : JSON.parse(value));
+      } else {
+        fetchNpmPackageInfo(packageName).then(value => {
+          if (value == null) {
+            resolve(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.setex(key, 300, notFound);
+          } else {
+            resolve(value);
+
+            // Cache valid package info for 1 minute. In the worst case,
+            // new versions won't be available for 1 minute.
+            cache.setnx(key, JSON.stringify(value), (error, reply) => {
+              if (reply === 1) cache.expire(key, 60);
+            });
+          }
+        }, reject);
+      }
+    });
+  });
+}
+
+module.exports = getNpmPackageInfo;