Convert APIListDataSource to use Future.Then() rather than Get().

I needed to change the behaviour of Future.Then() to implement this.

BUG=306341
R=yoz@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/438403002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287633 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/docs/server2/api_list_data_source.py

@@ -32,22 +32,24 @@ class APIListDataSource(DataSource):
 
   def _GenerateAPIDict(self):
     def make_list_for_content_scripts():
-      content_script_apis = self._platform_bundle.GetAPIModels(
-          'extensions').GetContentScriptAPIs().Get()
-      content_script_apis_list = [csa.__dict__ for api_name, csa
-                                  in content_script_apis.iteritems()
-                                  if self._platform_bundle.GetAPICategorizer(
-                                      'extensions').IsDocumented(api_name)]
+      def convert_to_list(content_script_apis):
+        content_script_apis_list = [csa.__dict__ for api_name, csa
+                                    in content_script_apis.iteritems()
+                                    if self._platform_bundle.GetAPICategorizer(
+                                        'extensions').IsDocumented(api_name)]
+        content_script_apis_list.sort(key=itemgetter('name'))
+        for csa in content_script_apis_list:
+          restricted_nodes = csa['restrictedTo']
+          if restricted_nodes:
+            restricted_nodes.sort(key=itemgetter('node'))
+            MarkFirstAndLast(restricted_nodes)
+          else:
+            del csa['restrictedTo']
+        return content_script_apis_list
 
-      content_script_apis_list.sort(key=itemgetter('name'))
-      for csa in content_script_apis_list:
-        restricted_nodes = csa['restrictedTo']
-        if restricted_nodes:
-          restricted_nodes.sort(key=itemgetter('node'))
-          MarkFirstAndLast(restricted_nodes)
-        else:
-          del csa['restrictedTo']
-      return content_script_apis_list
+      return (self._platform_bundle.GetAPIModels('extensions')
+              .GetContentScriptAPIs()
+              .Then(convert_to_list))
 
     def make_dict_for_platform(platform):
       platform_dict = {
@@ -95,20 +97,24 @@ class APIListDataSource(DataSource):
         platform_dict[key] = apis
 
       return platform_dict
-    api_dict = dict((platform, make_dict_for_platform(platform))
-                     for platform in GetPlatforms())
-    api_dict['contentScripts'] = make_list_for_content_scripts()
-    return api_dict
+
+    def make_api_dict(content_script_apis):
+      api_dict = dict((platform, make_dict_for_platform(platform))
+                       for platform in GetPlatforms())
+      api_dict['contentScripts'] = content_script_apis
+      return api_dict
+
+    return make_list_for_content_scripts().Then(make_api_dict)
 
   def _GetCachedAPIData(self):
-    data_future = self._object_store.Get('api_data')
-    def resolve():
-      data = data_future.Get()
+    def persist_and_return(data):
+      self._object_store.Set('api_data', data)
+      return data
+    def return_or_generate(data):
       if data is None:
-        data = self._GenerateAPIDict()
-        self._object_store.Set('api_data', data)
+        return self._GenerateAPIDict().Then(persist_and_return)
       return data
-    return Future(callback=resolve)
+    return self._object_store.Get('api_data').Then(return_or_generate)
 
   def get(self, key):
     return self._GetCachedAPIData().Get().get(key)

chrome/common/extensions/docs/server2/app.yaml

 application: chrome-apps-doc
-version: 3-39-0
+version: 3-39-1
 runtime: python27
 api_version: 1
 threadsafe: false

chrome/common/extensions/docs/server2/cron.yaml

@@ -2,4 +2,4 @@ cron:
 - description: Repopulates all cached data.
   url: /_cron
   schedule: every 5 minutes
-  target: 3-39-0
+  target: 3-39-1

chrome/common/extensions/docs/server2/future.py

@@ -69,13 +69,38 @@ class Future(object):
     '''Creates and returns a future that runs |callback| on the value of this
     future, or runs optional |error_handler| if resolving this future results in
     an exception.
+
+    If |callback| returns a non-Future value then the returned Future will
+    resolve to that value.
+
+    If |callback| returns a Future then it gets chained to the current Future.
+    This means that the returned Future will resolve to *that* Future's value.
+    This behaviour is transitive.
+
+    For example,
+
+      def fortytwo():
+        return Future(value=42)
+
+      def inc(x):
+        return x + 1
+
+      def inc_future(x):
+        return Future(value=x + 1)
+
+    fortytwo().Then(inc).Get()                         ==> 43
+    fortytwo().Then(inc_future).Get()                  ==> 43
+    fortytwo().Then(inc_future).Then(inc_future).Get() ==> 44
     '''
     def then():
+      val = None
       try:
         val = self.Get()
       except Exception as e:
-        return error_handler(e)
-      return callback(val)
+        val = error_handler(e)
+      else:
+        val = callback(val)
+      return val.Get() if isinstance(val, Future) else val
     return Future(callback=then)
 
   def Get(self):

chrome/common/extensions/docs/server2/future_test.py

@@ -161,11 +161,12 @@ class FutureTest(unittest.TestCase):
 
   def testThen(self):
     def assertIs42(val):
-      self.assertEquals(val, 42)
+      self.assertEqual(val, 42)
+      return val
 
     then = Future(value=42).Then(assertIs42)
     # Shouldn't raise an error.
-    then.Get()
+    self.assertEqual(42, then.Get())
 
     # Test raising an error.
     then = Future(value=41).Then(assertIs42)
@@ -184,7 +185,7 @@ class FutureTest(unittest.TestCase):
       raise Exception
 
     then = Future(callback=raiseValueError).Then(assertIs42, handle)
-    self.assertEquals(then.Get(), 'Caught')
+    self.assertEqual('Caught', then.Get())
     then = Future(callback=raiseException).Then(assertIs42, handle)
     self.assertRaises(Exception, then.Get)
 
@@ -192,7 +193,7 @@ class FutureTest(unittest.TestCase):
     addOne = lambda val: val + 1
     then = Future(value=40).Then(addOne).Then(addOne).Then(assertIs42)
     # Shouldn't raise an error.
-    then.Get()
+    self.assertEqual(42, then.Get())
 
     # Test error in chain.
     then = Future(value=40).Then(addOne).Then(assertIs42).Then(addOne)
@@ -216,6 +217,46 @@ class FutureTest(unittest.TestCase):
                                                                        myHandle)
     self.assertEquals(then.Get(), 10)
 
+  def testThenResolvesReturnedFutures(self):
+    def returnsFortyTwo():
+      return Future(value=42)
+    def inc(x):
+      return x + 1
+    def incFuture(x):
+      return Future(value=x + 1)
+
+    self.assertEqual(43, returnsFortyTwo().Then(inc).Get())
+    self.assertEqual(43, returnsFortyTwo().Then(incFuture).Get())
+    self.assertEqual(44, returnsFortyTwo().Then(inc).Then(inc).Get())
+    self.assertEqual(44, returnsFortyTwo().Then(inc).Then(incFuture).Get())
+    self.assertEqual(44, returnsFortyTwo().Then(incFuture).Then(inc).Get())
+    self.assertEqual(
+        44, returnsFortyTwo().Then(incFuture).Then(incFuture).Get())
+
+    # The same behaviour should apply to error handlers.
+    def raisesSomething():
+      def boom(): raise ValueError
+      return Future(callback=boom)
+    def shouldNotHappen(_):
+      raise AssertionError()
+    def oops(error):
+      return 'oops'
+    def oopsFuture(error):
+      return Future(value='oops')
+
+    self.assertEqual(
+        'oops', raisesSomething().Then(shouldNotHappen, oops).Get())
+    self.assertEqual(
+        'oops', raisesSomething().Then(shouldNotHappen, oopsFuture).Get())
+    self.assertEqual(
+        'oops',
+        raisesSomething().Then(shouldNotHappen, raisesSomething)
+                         .Then(shouldNotHappen, oops).Get())
+    self.assertEqual(
+        'oops',
+        raisesSomething().Then(shouldNotHappen, raisesSomething)
+                         .Then(shouldNotHappen, oopsFuture).Get())
+
 
 if __name__ == '__main__':
   unittest.main()