Make a bunch of stuff in pub synchronous.

utils/pub/oauth2.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library oauth2;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:uri';
 
@@ skipping 33 matching lines @@
 
 /// The OAuth2 scopes that the pub client needs. Currently the client only needs
 /// the user's email so that the server can verify their identity.
 final _scopes = ['https://www.googleapis.com/auth/userinfo.email'];
 
 /// An in-memory cache of the user's OAuth2 credentials. This should always be
 /// the same as the credentials file stored in the system cache.
 Credentials _credentials;
 
 /// Delete the cached credentials, if they exist.
-Future clearCredentials(SystemCache cache) {
+void clearCredentials(SystemCache cache) {
   _credentials = null;
   var credentialsFile = _credentialsFile(cache);
-  return fileExists(credentialsFile).then((exists) {
-    if (exists) return deleteFile(credentialsFile);
-  });
+  if (!fileExists(credentialsFile)) return;
+
+  deleteFile(credentialsFile);
 }
 
 /// Asynchronously passes an OAuth2 [Client] to [fn], and closes the client when
 /// the [Future] returned by [fn] completes.
 ///
 /// This takes care of loading and saving the client's credentials, as well as
 /// prompting the user for their authorization. It will also re-authorize and
 /// re-run [fn] if a recoverable authorization error is detected.
 Future withClient(SystemCache cache, Future fn(Client client)) {
-  return _getClient(cache).then((client) {
+  // Make sure all errors propagate through future.
+  return defer(() {
+    var client = _getClient(cache);
     var completer = new Completer();
     return fn(client).whenComplete(() {
       client.close();
       // Be sure to save the credentials even when an error happens.
-      return _saveCredentials(cache, client.credentials);
+      _saveCredentials(cache, client.credentials);
     });
   }).catchError((asyncError) {
     if (asyncError.error is ExpirationException) {
       log.error("Pub's authorization to upload packages has expired and "
           "can't be automatically refreshed.");
       return withClient(cache, fn);
     } else if (asyncError.error is AuthorizationException) {
       var message = "OAuth2 authorization failed";
       if (asyncError.error.description != null) {
         message = "$message (${asyncError.error.description})";
       }
       log.error("$message.");
-      return clearCredentials(cache).then((_) => withClient(cache, fn));
+      clearCredentials(cache);
+      return withClient(cache, fn);
     } else {
       throw asyncError;
     }
   });
 }
 
 /// Gets a new OAuth2 client. If saved credentials are available, those are
 /// used; otherwise, the user is prompted to authorize the pub client.
-Future<Client> _getClient(SystemCache cache) {
-  return _loadCredentials(cache).then((credentials) {
-    if (credentials == null) return _authorize();
-    return new Client(_identifier, _secret, credentials,
-        httpClient: curlClient);
-  }).then((client) {
-    return _saveCredentials(cache, client.credentials).then((_) => client);
-  });
+Client _getClient(SystemCache cache) {
+  var credentials = _loadCredentials(cache);
+  if (credentials == null) return _authorize();
+  var client = new Client(_identifier, _secret, credentials,
+      httpClient: curlClient);
+  _saveCredentials(cache, client.credentials);
+  return client;
 }
 
 /// Loads the user's OAuth2 credentials from the in-memory cache or the
 /// filesystem if possible. If the credentials can't be loaded for any reason,
 /// the returned [Future] will complete to null.
-Future<Credentials> _loadCredentials(SystemCache cache) {
+Credentials _loadCredentials(SystemCache cache) {
   log.fine('Loading OAuth2 credentials.');
 
-  if (_credentials != null) {
-    log.fine('Using already-loaded credentials.');
-    return new Future.immediate(_credentials);
-  }
+  try {
+    if (_credentials != null) return _credentials;

[nweiz, 2013/02/01 02:05:55]

Why no more logging?

[Bob Nystrom, 2013/02/01 23:17:21]

Two reasons:

1. The logging is most helpful when asynchrony has made us lose state. The more
sync we have, the more useful the callstack is. So I think we can ditch some of
the logging.

2. The current logs seem a bit more verbose than is useful. I littered a bunch
of logging in, but it needs some tuning, so I figured I'd dial it back a bit.

 
-  var path = _credentialsFile(cache);
-  return fileExists(path).then((credentialsExist) {
-    if (!credentialsExist) {
-      log.fine('No credentials found at $path.');
-      return;
+    var path = _credentialsFile(cache);
+    var credentialsExist = fileExists(path);
+    if (!credentialsExist) return;

[nweiz, 2013/02/01 02:05:55]

Style nit: merge this and the previous line.

[Bob Nystrom, 2013/02/01 23:17:21]

Done.

+
+    var credentials = new Credentials.fromJson(
+        readTextFile(_credentialsFile(cache)));

[nweiz, 2013/02/01 02:05:55]

"_credentialsFile(cache)" -> "path"

[Bob Nystrom, 2013/02/01 23:17:21]

Done.

+    if (credentials.isExpired && !credentials.canRefresh) {
+      log.error("Pub's authorization to upload packages has expired and "
+          "can't be automatically refreshed.");
+      return null; // null means re-authorize.
     }
 
-    return readTextFile(_credentialsFile(cache)).then((credentialsJson) {
-      var credentials = new Credentials.fromJson(credentialsJson);
-      if (credentials.isExpired && !credentials.canRefresh) {
-        log.error("Pub's authorization to upload packages has expired and "
-            "can't be automatically refreshed.");
-        return null; // null means re-authorize
-      }
-
-      return credentials;
-    });
-  }).catchError((e) {
+    return credentials;
+  } catch (e) {
     log.error('Warning: could not load the saved OAuth2 credentials: $e\n'
         'Obtaining new credentials...');
-    return null; // null means re-authorize
-  });
+    return null; // null means re-authorize.
+  }
 }
 
 /// Save the user's OAuth2 credentials to the in-memory cache and the
 /// filesystem.
-Future _saveCredentials(SystemCache cache, Credentials credentials) {
+void _saveCredentials(SystemCache cache, Credentials credentials) {
   log.fine('Saving OAuth2 credentials.');
   _credentials = credentials;
   var path = _credentialsFile(cache);
-  return ensureDir(dirname(path)).then((_) =>
-      writeTextFile(path, credentials.toJson(), dontLogContents: true));
+  ensureDir(dirname(path));
+  writeTextFile(path, credentials.toJson(), dontLogContents: true);
 }
 
 /// The path to the file in which the user's OAuth2 credentials are stored.
 String _credentialsFile(SystemCache cache) =>
   join(cache.rootDir, 'credentials.json');
 
 /// Gets the user to authorize pub as a client of pub.dartlang.org via oauth2.
 /// Returns a Future that will complete to a fully-authorized [Client].
 Future<Client> _authorize() {
   // Allow the tests to inject their own token endpoint URL.
@@ skipping 11 matching lines @@
       tokenEndpoint,
       httpClient: curlClient);
 
   // Spin up a one-shot HTTP server to receive the authorization code from the
   // Google OAuth2 server via redirect. This server will close itself as soon as
   // the code is received.
   var completer = new Completer();
   var server = new HttpServer();
   server.addRequestHandler((request) => request.path == "/",
       (request, response) {
-    chainToCompleter(new Future.immediate(null).then((_) {
+    chainToCompleter(defer(() {
       log.message('Authorization received, processing...');
       var queryString = request.queryString;
       if (queryString == null) queryString = '';
       response.statusCode = 302;
       response.headers.set('location', 'http://pub.dartlang.org/authorized');
       response.outputStream.close();
       return grant.handleAuthorizationResponse(queryToMap(queryString));
     }).then((client) {
       server.close();
       return client;
     }), completer);
   });
   server.listen('127.0.0.1', 0);
 
   var authUrl = grant.getAuthorizationUrl(
       Uri.parse('http://localhost:${server.port}'), scopes: _scopes);
 
   log.message(
       'Pub needs your authorization to upload packages on your behalf.\n'
       'In a web browser, go to $authUrl\n'
       'Then click "Allow access".\n\n'
       'Waiting for your authorization...');
 
   return completer.future.then((client) {
     log.message('Successfully authorized.\n');
     return client;
   });
 }