precompile generate_gradle_lockfile script BEFORE updating pub dependencies (#160059)

Avoid situations like https://github.com/flutter/flutter/issues/160055

dev/conductor/core/lib/src/packages_autoroller.dart

@@ -85,6 +85,7 @@ This PR was generated by the automated
   final String orgName;
 
   Future<void> roll() async {
+    final Directory tempDir = framework.fileSystem.systemTempDirectory.createTempSync();
     try {
       await authLogin();
       final bool openPrAlready = await hasOpenPrs();
@@ -92,18 +93,26 @@ This PR was generated by the automated
         // Don't open multiple roll PRs.
         return;
       }
+      final Directory frameworkDir = await framework.checkoutDirectory;
+      final String regenerateBinary = await _prebuildRegenerateGradleLockfilesBinary(frameworkDir, tempDir);
       final bool didUpdate = await updatePackages();
       if (!didUpdate) {
         log('Packages are already at latest.');
         return;
       }
-      await _regenerateGradleLockfiles(await framework.checkoutDirectory);
+      await _regenerateGradleLockfiles(frameworkDir, regenerateBinary);
       await pushBranch();
       await createPr(repository: await framework.checkoutDirectory);
       await authLogout();
     } on Exception catch (exception) {
       final String message = _redactToken(exception.toString());
       throw Exception('${exception.runtimeType}: $message');
+    } finally {
+      try {
+        tempDir.deleteSync(recursive: true);
+      } on FileSystemException {
+        // Ignore failures
+      }
     }
   }
 
@@ -139,12 +148,58 @@ This PR was generated by the automated
     return true;
   }
 
-  Future<void> _regenerateGradleLockfiles(Directory repoRoot) async {
+  Future<String> _prebuildRegenerateGradleLockfilesBinary(Directory repoRoot, Directory tempDir) async {
+    final String entrypoint = '${repoRoot.path}/dev/tools/bin/generate_gradle_lockfiles.dart';
+    final File target = tempDir.childFile('generate_gradle_lockfiles');
+    await framework.streamDart(
+      <String>['pub', 'get'],
+      workingDirectory: '${repoRoot.path}/dev/tools',
+    );
     await framework.streamDart(<String>[
-      '${repoRoot.path}/dev/tools/bin/generate_gradle_lockfiles.dart',
+      'compile',
+      'exe',
+      entrypoint,
+      '-o',
+      target.path,
+    ]);
+
+    assert(
+      target.existsSync(),
+      'expected ${target.path} to exist after compilation, but it did not.',
+    );
+
+    processManager.runSync(<String>['chmod', '+x', target.path]);
+
+    return target.path;
+  }
+
+  Future<void> _regenerateGradleLockfiles(Directory repoRoot, String regenerateBinary) async {
+    final List<String> cmd = <String>[
+      regenerateBinary,
       '--no-gradle-generation',
       '--no-exclusion',
-    ]);
+    ];
+    final io.Process regenerateProcess = await processManager.start(cmd);
+    regenerateProcess
+      .stdout
+      .transform(utf8.decoder)
+      .transform(const LineSplitter())
+      .listen((String line) => stdio.printTrace('[stdout] $line'));
+    regenerateProcess
+      .stderr
+      .transform(utf8.decoder)
+      .transform(const LineSplitter())
+      .listen((String line) => stdio.printTrace('[stderr] $line'));
+
+    final int exitCode = await regenerateProcess.exitCode;
+    if (exitCode != 0) {
+      throw io.ProcessException(
+        cmd.first,
+        cmd.sublist(1),
+        'Process failed',
+        exitCode,
+      );
+    }
     switch (CheckoutStatePostGradleRegeneration(await framework.gitStatus(), framework.fileSystem.path)) {
       // If the git checkout is clean, we did not update any lockfiles and we do
       // not need an additional commit.

dev/conductor/core/lib/src/repository.dart

@@ -671,16 +671,23 @@ class FrameworkRepository extends Repository {
       cmd,
       workingDirectory: workingDirectory,
     );
-    process
+    final StreamSubscription<String> stdoutSub = process
         .stdout
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .listen(stdoutCallback ?? stdio.printTrace);
-    process
+    final StreamSubscription<String> stderrSub = process
         .stderr
         .transform(utf8.decoder)
         .transform(const LineSplitter())
         .listen(stderrCallback ?? stdio.printError);
+    await Future.wait<void>(<Future<void>>[
+      stdoutSub.asFuture<void>(),
+      stderrSub.asFuture<void>(),
+    ]);
+    unawaited(stdoutSub.cancel());
+    unawaited(stderrSub.cancel());
+
     final int exitCode = await process.exitCode;
     if (exitCode != 0) {
       throw io.ProcessException(

dev/conductor/core/test/packages_autoroller_test.dart

@@ -281,6 +281,27 @@ void main() {
         'rev-parse',
         'HEAD',
       ], stdout: 'deadbeef'),
+      const FakeCommand(
+        command: <String>[
+          '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/dart',
+          'pub',
+          'get',
+        ],
+        workingDirectory: '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/dev/tools',
+      ),
+      FakeCommand(command: const <String>[
+        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/dart',
+        'compile',
+        'exe',
+        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/dev/tools/bin/generate_gradle_lockfiles.dart',
+        '-o',
+        '/.tmp_rand0/rand0/generate_gradle_lockfiles',
+      ], onRun: (_) => fileSystem.file('/.tmp_rand0/rand0/generate_gradle_lockfiles').createSync()),
+      const FakeCommand(command: <String>[
+        'chmod',
+        '+x',
+        '/.tmp_rand0/rand0/generate_gradle_lockfiles',
+      ]),
       const FakeCommand(command: <String>[
         'git',
         'ls-remote',
@@ -373,6 +394,27 @@ void main() {
         'rev-parse',
         'HEAD',
       ], stdout: 'deadbeef'),
+      const FakeCommand(
+        command: <String>[
+          '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/dart',
+          'pub',
+          'get',
+        ],
+        workingDirectory: '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/dev/tools',
+      ),
+      FakeCommand(command: const <String>[
+        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/dart',
+        'compile',
+        'exe',
+        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/dev/tools/bin/generate_gradle_lockfiles.dart',
+        '-o',
+        '/.tmp_rand0/rand0/generate_gradle_lockfiles',
+      ], onRun: (_) => fileSystem.file('/.tmp_rand0/rand0/generate_gradle_lockfiles').createSync()),
+      const FakeCommand(command: <String>[
+        'chmod',
+        '+x',
+        '/.tmp_rand0/rand0/generate_gradle_lockfiles',
+      ]),
       const FakeCommand(command: <String>[
         'git',
         'ls-remote',
@@ -427,8 +469,7 @@ void main() {
         'HEAD',
       ], stdout: '000deadbeef'),
       const FakeCommand(command: <String>[
-        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/bin/dart',
+        '/.tmp_rand0/rand0/generate_gradle_lockfiles',
-        '$checkoutsParentDirectory/flutter_conductor_checkouts/framework/dev/tools/bin/generate_gradle_lockfiles.dart',
         '--no-gradle-generation',
         '--no-exclusion',
       ]),