Performance improvements for "build-plugin" task

Summary:
Few improvements for "build-plugin" task which together with Sandcastle command changes (D26872427) helps to build all plugins in CI ~30% faster if most of them has not changed (which is usually the case):
1) compute package checksum in the same script to not call additional yarn scripts for each plugin
2) avoid packaging plugin if it's checksum has not changed since last release

Reviewed By: mweststrate

Differential Revision: D26872253

fbshipit-source-id: 968102d32a1550ea7503f1169f0ef2863296383f

desktop/pkg-lib/src/runBuild.ts

@@ -11,6 +11,7 @@ import Metro from 'metro';
 import getWatchFolders from './getWatchFolders';
 import path from 'path';
 import fs from 'fs-extra';
+import {getInstalledPluginDetails} from 'flipper-plugin-lib';
 
 let metroDir: string | undefined;
 const metroDirPromise = getMetroDir().then((dir) => (metroDir = dir));
@@ -30,19 +31,29 @@ async function getMetroDir() {
   return __dirname;
 }
 
-export default async function runBuild(
-  inputDirectory: string,
-  entry: string,
-  out: string,
-  dev: boolean,
-) {
+export default async function bundlePlugin(pluginDir: string, dev: boolean) {
+  const stat = await fs.lstat(pluginDir);
+  if (!stat.isDirectory()) {
+    throw new Error(`Plugin source ${pluginDir} is not a directory.`);
+  }
+  const packageJsonPath = path.join(pluginDir, 'package.json');
+  if (!(await fs.pathExists(packageJsonPath))) {
+    throw new Error(
+      `package.json is not found in plugin source directory ${pluginDir}.`,
+    );
+  }
+  const plugin = await getInstalledPluginDetails(pluginDir);
+  const entry = plugin.source;
+  const out = path.resolve(pluginDir, plugin.main);
+  await fs.ensureDir(path.dirname(out));
+
   const sourceMapUrl = null; // inline source map
   const baseConfig = await Metro.loadConfig();
   const config = Object.assign({}, baseConfig, {
     reporter: {update: () => {}},
-    projectRoot: inputDirectory,
+    projectRoot: pluginDir,
     watchFolders: [metroDir || (await metroDirPromise)].concat(
-      await getWatchFolders(inputDirectory),
+      await getWatchFolders(pluginDir),
     ),
     serializer: {
       ...baseConfig.serializer,