Hermes: Use pre-built artifacts in hermes-engine

Summary:
Update `hermes-engine.podspec` to use pre-built Hermes artifacts from the corresponding React Native GitHub Release when targeting a specific React Native release.
Otherwise, fallback to building Hermes from source.

Changelog: [Internal]

Reviewed By: cortinico, cipolleschi

Differential Revision: D36609257

fbshipit-source-id: 6179c9e255558c7eaf1417ff46a2e7db120295f0

scripts/__tests__/hermes-utils-test.js

@@ -11,6 +11,7 @@ import * as path from 'path';
 
 const {
   copyBuildScripts,
+  copyPodSpec,
   downloadHermesTarball,
   expandHermesTarball,
   getHermesTagSHA,
@@ -193,45 +194,42 @@ describe('hermes-utils', () => {
     it('should fail if Hermes tarball does not exist', () => {
       expect(() => {
         expandHermesTarball();
-      }).toThrow('[Hermes] Failed to expand Hermes tarball.');
+      }).toThrow('[Hermes] Could not locate Hermes tarball.');
       expect(execCalls.tar).toBeUndefined();
     });
   });
   describe('copyBuildScripts', () => {
     it('should copy React Native Hermes build scripts to Hermes source directory', () => {
-      fs.mkdirSync(path.join(SDKS_DIR, 'hermes', 'utils'), {
-        recursive: true,
-      });
       copyBuildScripts();
-      expect(
-        fs.readFileSync(
-          path.join(
-            ROOT_DIR,
-            'sdks',
-            'hermes',
-            'utils',
-            'build-mac-framework.sh',
+
+      [
+        'build-apple-framework.sh',
+        'build-ios-framework.sh',
+        'build-mac-framework.sh',
+      ].forEach(buildScript => {
+        expect(
+          fs.readFileSync(
+            path.join(ROOT_DIR, 'sdks', 'hermes', 'utils', buildScript),
+            {
+              encoding: 'utf8',
+              flag: 'r',
+            },
           ),
-          {
-            encoding: 'utf8',
-            flag: 'r',
-          },
-        ),
-      ).toEqual(
-        fs.readFileSync(
-          path.join(
-            ROOT_DIR,
-            'sdks',
-            'hermes-engine',
-            'utils',
-            'build-mac-framework.sh',
+        ).toEqual(
+          fs.readFileSync(
+            path.join(ROOT_DIR, 'sdks', 'hermes-engine', 'utils', buildScript),
+            {
+              encoding: 'utf8',
+              flag: 'r',
+            },
           ),
-          {
-            encoding: 'utf8',
-            flag: 'r',
-          },
-        ),
-      );
+        );
+      });
+    });
+  });
+  describe('copyPodSpec', () => {
+    it('should copy React Native Hermes Podspec to Hermes source directory', () => {
+      copyPodSpec();
       expect(
         fs.readFileSync(
           path.join(SDKS_DIR, 'hermes', 'hermes-engine.podspec'),

scripts/hermes/hermes-utils.js

@@ -15,6 +15,7 @@ const {execSync} = require('child_process');
 
 const SDKS_DIR = path.normalize(path.join(__dirname, '..', '..', 'sdks'));
 const HERMES_DIR = path.join(SDKS_DIR, 'hermes');
+const DEFAULT_HERMES_TAG = 'main';
 const HERMES_TAG_FILE_PATH = path.join(SDKS_DIR, '.hermesversion');
 const HERMES_TARBALL_BASE_URL = 'https://github.com/facebook/hermes/tarball/';
 const HERMES_TARBALL_DOWNLOAD_DIR = path.join(SDKS_DIR, 'download');
@@ -25,20 +26,6 @@ const MACOS_IMPORT_HERMESC_PATH = path.join(
   'ImportHermesc.cmake',
 );
 
-function prepareFileSystem() {
-  if (!fs.existsSync(SDKS_DIR)) {
-    fs.mkdirSync(SDKS_DIR, {recursive: true});
-  }
-
-  if (!fs.existsSync(HERMES_DIR)) {
-    fs.mkdirSync(HERMES_DIR, {recursive: true});
-  }
-
-  if (!fs.existsSync(HERMES_TARBALL_DOWNLOAD_DIR)) {
-    fs.mkdirSync(HERMES_TARBALL_DOWNLOAD_DIR, {recursive: true});
-  }
-}
-
 function readHermesTag() {
   if (fs.existsSync(HERMES_TAG_FILE_PATH)) {
     const data = fs
@@ -64,8 +51,9 @@ function setHermesTag(hermesTag) {
     return;
   }
 
-  prepareFileSystem();
-
+  if (!fs.existsSync(SDKS_DIR)) {
+    fs.mkdirSync(SDKS_DIR, {recursive: true});
+  }
   fs.writeFileSync(HERMES_TAG_FILE_PATH, hermesTag.trim());
   console.log('Hermes tag has been updated. Please commit your changes.');
 }
@@ -89,12 +77,14 @@ function downloadHermesTarball() {
   const hermesTarballDownloadPath = getHermesTarballDownloadPath(hermesTag);
   let hermesTarballUrl = HERMES_TARBALL_BASE_URL + hermesTag;
 
-  prepareFileSystem();
-
   if (fs.existsSync(hermesTarballDownloadPath)) {
     return;
   }
 
+  if (!fs.existsSync(HERMES_TARBALL_DOWNLOAD_DIR)) {
+    fs.mkdirSync(HERMES_TARBALL_DOWNLOAD_DIR, {recursive: true});
+  }
+
   console.info(
     `[Hermes] Downloading Hermes source code for commit ${hermesTagSHA}`,
   );
@@ -110,12 +100,13 @@ function expandHermesTarball() {
   const hermesTagSHA = getHermesTagSHA(hermesTag);
   const hermesTarballDownloadPath = getHermesTarballDownloadPath(hermesTag);
 
-  prepareFileSystem();
-
   if (!fs.existsSync(hermesTarballDownloadPath)) {
-    throw new Error(`[Hermes] Failed to expand Hermes tarball.`);
+    throw new Error('[Hermes] Could not locate Hermes tarball.');
   }
 
+  if (!fs.existsSync(HERMES_DIR)) {
+    fs.mkdirSync(HERMES_DIR, {recursive: true});
+  }
   console.info(`[Hermes] Expanding Hermes tarball for commit ${hermesTagSHA}`);
   try {
     execSync(
@@ -127,16 +118,16 @@ function expandHermesTarball() {
 }
 
 function copyBuildScripts() {
-  if (!fs.existsSync(HERMES_DIR)) {
+  if (!fs.existsSync(SDKS_DIR)) {
     throw new Error(
-      '[Hermes] Failed to copy Hermes build scripts, no Hermes source directory found.',
+      '[Hermes] Failed to copy Hermes build scripts, no SDKs directory found.',
     );
   }
 
-  fs.copyFileSync(
-    `${SDKS_DIR}/hermes-engine/hermes-engine.podspec`,
-    `${HERMES_DIR}/hermes-engine.podspec`,
-  );
+  if (!fs.existsSync(HERMES_DIR)) {
+    fs.mkdirSync(path.join(HERMES_DIR, 'utils'), {recursive: true});
+  }
+
   fs.copyFileSync(
     `${SDKS_DIR}/hermes-engine/utils/build-apple-framework.sh`,
     `${HERMES_DIR}/utils/build-apple-framework.sh`,
@@ -151,6 +142,27 @@ function copyBuildScripts() {
   );
 }
 
+function copyPodSpec() {
+  if (!fs.existsSync(SDKS_DIR)) {
+    throw new Error(
+      '[Hermes] Failed to copy Hermes Podspec, no SDKs directory found.',
+    );
+  }
+
+  if (!fs.existsSync(HERMES_DIR)) {
+    fs.mkdirSync(HERMES_DIR, {recursive: true});
+  }
+  fs.copyFileSync(
+    path.join(SDKS_DIR, 'hermes-engine', 'hermes-engine.podspec'),
+    path.join(HERMES_DIR, 'hermes-engine.podspec'),
+  );
+}
+
+function shouldBuildHermesFromSource() {
+  const hermesTag = readHermesTag();
+  return hermesTag === DEFAULT_HERMES_TAG;
+}
+
 function shouldUsePrebuiltHermesC(os) {
   if (os === 'macos') {
     return fs.existsSync(MACOS_HERMESC_PATH);
@@ -178,10 +190,12 @@ set_target_properties(native-hermesc PROPERTIES
 module.exports = {
   configureMakeForPrebuiltHermesC,
   copyBuildScripts,
+  copyPodSpec,
   downloadHermesTarball,
   expandHermesTarball,
   getHermesTagSHA,
   readHermesTag,
   setHermesTag,
+  shouldBuildHermesFromSource,
   shouldUsePrebuiltHermesC,
 };

scripts/hermes/prepare-hermes-for-build.js

@@ -16,16 +16,30 @@
 const {
   configureMakeForPrebuiltHermesC,
   copyBuildScripts,
+  copyPodSpec,
   downloadHermesTarball,
   expandHermesTarball,
   shouldUsePrebuiltHermesC,
+  shouldBuildHermesFromSource,
 } = require('./hermes-utils');
 
-downloadHermesTarball();
-expandHermesTarball();
-copyBuildScripts();
+async function main() {
+  if (!shouldBuildHermesFromSource()) {
+    copyPodSpec();
+    return;
+  }
 
-if (shouldUsePrebuiltHermesC('macos')) {
-  console.log('[Hermes] Using pre-built HermesC');
-  configureMakeForPrebuiltHermesC();
+  downloadHermesTarball();
+  expandHermesTarball();
+  copyPodSpec();
+  copyBuildScripts();
+
+  if (shouldUsePrebuiltHermesC('macos')) {
+    console.log('[Hermes] Using pre-built HermesC');
+    configureMakeForPrebuiltHermesC();
+  }
 }
+
+main().then(() => {
+  process.exit(0);
+});

scripts/react_native_pods.rb

@@ -113,6 +113,8 @@ def use_react_native! (options={})
     pod 'React-hermes', :path => "#{prefix}/ReactCommon/hermes"
     pod 'hermes-engine', :path => "#{prefix}/sdks/hermes/hermes-engine.podspec"
     pod 'libevent', '~> 2.1.12'
+    system("(cd #{prefix} && node scripts/hermes/prepare-hermes-for-build)")
+    pod 'hermes-engine', :path => "#{prefix}/sdks/hermes/hermes-engine.podspec"
   end
 
   pods_to_update = LocalPodspecPatch.pods_to_update(options)