Consolidate npm utils in the same file

modules/utils/npm.js

@@ -0,0 +1,129 @@
+import url from 'url';
+import https from 'https';
+import gunzip from 'gunzip-maybe';
+import tar from 'tar-stream';
+import LRUCache from 'lru-cache';
+
+import debug from './debug';
+import bufferStream from './bufferStream';
+
+const npmRegistryURL =
+  process.env.NPM_REGISTRY_URL || 'https://registry.npmjs.org';
+
+const agent = new https.Agent({
+  keepAlive: true
+});
+
+function parseJSON(res) {
+  return bufferStream(res).then(JSON.parse);
+}
+
+export function fetchPackageInfo(packageName) {
+  return new Promise((accept, reject) => {
+    const encodedPackageName =
+      packageName.charAt(0) === '@'
+        ? `@${encodeURIComponent(packageName.substring(1))}`
+        : encodeURIComponent(packageName);
+
+    const infoURL = `${npmRegistryURL}/${encodedPackageName}`;
+
+    debug('Fetching package info for %s from %s', packageName, infoURL);
+
+    const { hostname, pathname } = url.parse(infoURL);
+    const options = {
+      agent: agent,
+      hostname: hostname,
+      path: pathname,
+      headers: {
+        Accept: 'application/json'
+      }
+    };
+
+    https
+      .get(options, async res => {
+        if (res.statusCode === 200) {
+          accept(parseJSON(res));
+        } else if (res.statusCode === 404) {
+          accept(null);
+        } else {
+          const data = await bufferStream(res);
+          const content = data.toString('utf-8');
+          const error = new Error(
+            `Failed to fetch info for ${packageName}\nstatus: ${res.statusCode}\ndata: ${content}`
+          );
+
+          reject(error);
+        }
+      })
+      .on('error', reject);
+  });
+}
+
+export function fetchPackage(packageConfig) {
+  return new Promise((accept, reject) => {
+    const tarballURL = packageConfig.dist.tarball;
+
+    debug('Fetching package for %s from %s', packageConfig.name, tarballURL);
+
+    const { hostname, pathname } = url.parse(tarballURL);
+    const options = {
+      agent: agent,
+      hostname: hostname,
+      path: pathname
+    };
+
+    https
+      .get(options, async res => {
+        if (res.statusCode === 200) {
+          accept(res.pipe(gunzip()).pipe(tar.extract()));
+        } else {
+          const data = await bufferStream(res);
+          const spec = `${packageConfig.name}@${packageConfig.version}`;
+          const content = data.toString('utf-8');
+          const error = new Error(
+            `Failed to fetch tarball for ${spec}\nstatus: ${res.statusCode}\ndata: ${content}`
+          );
+
+          reject(error);
+        }
+      })
+      .on('error', reject);
+  });
+}
+
+const oneMegabyte = 1024 * 1024;
+const oneSecond = 1000;
+const oneMinute = oneSecond * 60;
+
+const cache = new LRUCache({
+  max: oneMegabyte * 40,
+  length: Buffer.byteLength,
+  maxAge: oneSecond
+});
+
+const notFound = '';
+
+export async function getPackageInfo(packageName) {
+  const key = `npmPackageInfo-${packageName}`;
+  const value = cache.get(key);
+
+  if (value != null) {
+    return value === notFound ? null : JSON.parse(value);
+  }
+
+  const info = await fetchPackageInfo(packageName);
+
+  if (info == 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.set(key, notFound, oneMinute * 5);
+    return null;
+  }
+
+  // Cache valid package info for 1 minute. In the worst case,
+  // new versions won't be available for 1 minute.
+  cache.set(key, JSON.stringify(info), oneMinute);
+  return info;
+}