PPAPI: Implement synchronous postMessage

ppapi/tests/test_message_handler.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ppapi/tests/test_message_handler.h"
+
+#include <stdio.h>  // TODO FIXME Remove this!

[raymes, 2014/06/16 05:33:33]

Is this still intentionally here?

[dmichael (off chromium), 2014/06/17 18:28:29]

Hah, nope, thanks. Sorry for leaving debug junk in here.

+
+#include <string.h>
+#include <algorithm>
+#include <map>
+#include <sstream>
+
+#include "ppapi/c/pp_var.h"
+#include "ppapi/c/ppb_file_io.h"
+#include "ppapi/c/ppp_message_handler.h"
+#include "ppapi/cpp/file_io.h"
+#include "ppapi/cpp/file_ref.h"
+#include "ppapi/cpp/file_system.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/module_impl.h"
+#include "ppapi/cpp/var.h"
+#include "ppapi/cpp/var_array.h"
+#include "ppapi/cpp/var_array_buffer.h"
+#include "ppapi/cpp/var_dictionary.h"
+#include "ppapi/tests/pp_thread.h"
+#include "ppapi/tests/test_utils.h"
+#include "ppapi/tests/testing_instance.h"
+
+// Windows defines 'PostMessage', so we have to undef it.
+#ifdef PostMessage
+#undef PostMessage
+#endif
+
+REGISTER_TEST_CASE(MessageHandler);
+
+namespace {
+
+// Created and destroyed on the main thread. All public methods should be called
+// on the main thread. Most data members are only accessed on the main thread.
+// (Though it handles messages on the background thread).
+class EchoingMessageHandler {
+ public:
+  explicit EchoingMessageHandler(PP_Instance instance,
+                                 const pp::MessageLoop& loop)
+      : pp_instance_(instance),
+        message_handler_loop_(loop),
+        ppb_messaging_if_(static_cast<const PPB_Messaging_1_1*>(
+            pp::Module::Get()->GetBrowserInterface(
+                PPB_MESSAGING_INTERFACE_1_1))),
+        ppp_message_handler_if_(),

[raymes, 2014/06/16 05:33:32]

is this needed?

[dmichael (off chromium), 2014/06/17 18:28:29]

Strictly speaking, no, since I set all the fields in the body. But it makes sure
the struct is zero-initialized, which seems good for code hygiene, and might
make mistakes more obvious in the future if we add another field.

+        is_registered_(false),
+        test_finished_event_(instance),
+        destroy_event_(instance) {
+    AssertOnMainThread();
+    ppp_message_handler_if_.HandleMessage = &HandleMessage;
+    ppp_message_handler_if_.HandleBlockingMessage = &HandleBlockingMessage;
+    ppp_message_handler_if_.Destroy = &Destroy;
+  }
+  void Register() {
+    AssertOnMainThread();
+    assert(!is_registered_);
+    int32_t result = ppb_messaging_if_->RegisterMessageHandler(
+        pp_instance_,
+        this,
+        &ppp_message_handler_if_,
+        message_handler_loop_.pp_resource());
+    if (result == PP_OK) {
+      is_registered_ = true;
+    } else {
+      std::ostringstream stream;
+      stream << "Failed to register message handler; got error " << result;
+      AddError(stream.str());
+      test_finished_event_.Signal();
+    }
+    // Note, at this point, we can't safely read or write errors_ until we wait
+    // on destroy_event_.
+  }
+  void Unregister() {
+    AssertOnMainThread();
+    assert(is_registered_);
+    ppb_messaging_if_->UnregisterMessageHandler(pp_instance_);
+    is_registered_ = false;
+  }
+  void WaitForTestFinishedMessage() {
+    test_finished_event_.Wait();
+    test_finished_event_.Reset();
+  }
+  // Wait for Destroy() to be called on the MessageHandler thread. When it's
+  // done, return any errors that occurred during the time the MessageHandler
+  // was getting messages.
+  std::string WaitForDestroy() {
+    AssertOnMainThread();
+    // If we haven't called Unregister, we'll be waiting forever.
+    assert(!is_registered_);
+    destroy_event_.Wait();
+    destroy_event_.Reset();
+    // Now that we know Destroy() has been called, we know errors_ isn't being
+    // written on the MessageHandler thread anymore. So we can safely read it
+    // here on the main thread (since destroy_event_ gave us a memory barrier).
+    std::string temp_errors;
+    errors_.swap(temp_errors);
+    return temp_errors;
+  }
+ private:
+  static void AssertOnMainThread() {
+    assert(pp::MessageLoop::GetForMainThread() ==
+           pp::MessageLoop::GetCurrent());
+  }
+  void AddError(const std::string& error) {
+    if (!error.empty()) {
+      if (!errors_.empty())
+        errors_ += "<p>";
+      errors_ += error;
+    }
+  }
+  static void HandleMessage(PP_Instance instance,
+                            void* user_data,
+                            struct PP_Var message_data) {
+    pp::Var dbg(message_data);

[raymes, 2014/06/16 05:33:33]

Is this useful?

+    EchoingMessageHandler* thiz =
+        static_cast<EchoingMessageHandler*>(user_data);
+    if (pp::MessageLoop::GetCurrent() != thiz->message_handler_loop_)
+      thiz->AddError("HandleMessage was called on the wrong thread!");
+    if (instance != thiz->pp_instance_)
+      thiz->AddError("HandleMessage was passed the wrong instance!");
+    pp::Var var(message_data);
+    if (var.is_string() && var.AsString() == "FINISHED_TEST")
+      thiz->test_finished_event_.Signal();
+    else
+      thiz->ppb_messaging_if_->PostMessage(instance, message_data);
+  }
+
+  static PP_Var HandleBlockingMessage(PP_Instance instance,
+                                      void* user_data,
+                                      struct PP_Var message_data) {
+    pp::Var dbg(message_data);

[raymes, 2014/06/16 05:33:32]

Same here.

+
+    EchoingMessageHandler* thiz =
+        static_cast<EchoingMessageHandler*>(user_data);
+    if (pp::MessageLoop::GetCurrent() != thiz->message_handler_loop_)
+      thiz->AddError("HandleBlockingMessage was called on the wrong thread!");
+    if (instance != thiz->pp_instance_)
+      thiz->AddError("HandleBlockingMessage was passed the wrong instance!");
+    // We always need to add a ref when returning a PP_Var, to pass to the
+    // caller.
+    pp::Var take_ref(message_data);
+    take_ref.Detach();
+    return message_data;

[raymes, 2014/06/16 05:33:32]

Why do we need to add a ref? Shouldn't the function be passed a var with a
single ref? Shouldn't we then just return the var with its single ref? I'm
probably missing something :)

[dmichael (off chromium), 2014/06/17 18:28:29]

I tried improving the comment to explain better.

+  }
+
+  static void Destroy(PP_Instance instance, void* user_data) {
+    EchoingMessageHandler* thiz =
+        static_cast<EchoingMessageHandler*>(user_data);
+    if (pp::MessageLoop::GetCurrent() != thiz->message_handler_loop_)
+      thiz->AddError("Destroy was called on the wrong thread!");
+    if (instance != thiz->pp_instance_)
+      thiz->AddError("Destroy was passed the wrong instance!");
+    thiz->destroy_event_.Signal();
+  }
+
+  // These data members are initialized on the main thread, but don't change for
+  // the life of the object, so are safe to access on the background thread,
+  // because there will be a memory barrier before the the MessageHandler calls
+  // are invoked.
+  const PP_Instance pp_instance_;
+  const pp::MessageLoop message_handler_loop_;
+  const pp::MessageLoop main_loop_;
+  const PPB_Messaging_1_1* const ppb_messaging_if_;
+  // Spiritually, this member is const, but we can't initialize it in C++03,
+  // so it has to be non-const to be set in the constructor body.
+  PPP_MessageHandler_0_1 ppp_message_handler_if_;
+
+  // is_registered_ is only read/written on the main thread.
+  bool is_registered_;
+
+  // errors_ is written on the MessageHandler thread. When Destroy() is
+  // called, we stop writing to errors_ and signal destroy_event_. This causes
+  // a memory barrier, so it's safe to read errors_ after that.
+  std::string errors_;
+  NestedEvent test_finished_event_;
+  NestedEvent destroy_event_;
+
+  // Undefined & private to disallow copy and assign.
+  EchoingMessageHandler(const EchoingMessageHandler&);
+  EchoingMessageHandler& operator=(const EchoingMessageHandler&);
+};
+
+void FakeHandleMessage(PP_Instance instance,
+                   void* user_data,
+                   struct PP_Var message_data) {}

[raymes, 2014/06/16 05:33:32]

nit:indentation

+PP_Var FakeHandleBlockingMessage(PP_Instance instance,
+                                 void* user_data,
+                                 struct PP_Var message_data) {
+  return PP_MakeUndefined();
+}
+void FakeDestroy(PP_Instance instance, void* user_data) {}
+
+}  // namespace
+
+TestMessageHandler::TestMessageHandler(TestingInstance* instance)
+    : TestCase(instance),
+      ppb_messaging_if_(NULL),
+      handler_thread_(instance) {
+}
+
+TestMessageHandler::~TestMessageHandler() {
+  handler_thread_.Join();
+}
+
+bool TestMessageHandler::Init() {
+  ppb_messaging_if_ = static_cast<const PPB_Messaging_1_1*>(
+      pp::Module::Get()->GetBrowserInterface(PPB_MESSAGING_INTERFACE_1_1));
+  return ppb_messaging_if_ &&
+         CheckTestingInterface() &&
+         handler_thread_.Start();
+}
+
+void TestMessageHandler::RunTests(const std::string& filter) {
+  RUN_TEST(RegisterErrorConditions, filter);
+  RUN_TEST(PostMessageAndAwaitResponse, filter);
+}
+
+void TestMessageHandler::HandleMessage(const pp::Var& message_data) {
+  // All messages should go to the background thread message handler.
+  assert(false);
+}
+
+std::string TestMessageHandler::TestRegisterErrorConditions() {
+  {
+    // Test registering with the main thread as the message loop.
+    PPP_MessageHandler_0_1 fake_ppp_message_handler = {
+      &FakeHandleMessage, &FakeHandleBlockingMessage, &FakeDestroy
+    };
+    pp::MessageLoop main_loop = pp::MessageLoop::GetForMainThread();
+    int32_t result = ppb_messaging_if_->RegisterMessageHandler(
+        instance()->pp_instance(),
+        reinterpret_cast<void*>(0xdeadbeef),
+        &fake_ppp_message_handler,
+        main_loop.pp_resource());
+    ASSERT_EQ(PP_ERROR_WRONG_THREAD, result);
+  }
+  {
+    // Test registering with incomplete PPP_Messaging interface.
+    PPP_MessageHandler_0_1 bad_ppp_ifs[] = {
+        { NULL, &FakeHandleBlockingMessage, &FakeDestroy },
+        { &FakeHandleMessage, NULL, &FakeDestroy },
+        { &FakeHandleMessage, &FakeHandleBlockingMessage, NULL }};
+    for (size_t i = 0; i < sizeof(bad_ppp_ifs)/sizeof(bad_ppp_ifs[0]); ++i) {
+      int32_t result = ppb_messaging_if_->RegisterMessageHandler(
+          instance()->pp_instance(),
+          reinterpret_cast<void*>(0xdeadbeef),
+          &bad_ppp_ifs[i],
+          handler_thread_.message_loop().pp_resource());
+      ASSERT_EQ(PP_ERROR_BADARGUMENT, result);
+    }
+  }
+  PASS();
+}
+
+std::string TestMessageHandler::TestPostMessageAndAwaitResponse() {
+  EchoingMessageHandler handler(instance()->pp_instance(),
+                                handler_thread_.message_loop());
+  handler.Register();
+  std::string js_code("var plugin = document.getElementById('plugin');\n");
+  js_code += "var result = undefined;\n";
+  const char* const values_to_test[] = {
+      "5",
+      "undefined",
+      "1.5",
+      "'hello'",
+      // TODO(dmichael): There's not an easy way to do a deep comparison in
+      // JavaScript, and no obvious place to put the function to do the
+      // comparison.

[raymes, 2014/06/16 05:33:33]

Could you put it inside test_case.html? Could you write a simple function which
just does a single level comparison with a TODO?

+      // "{'key': 'value', 'array_key': [1, 2, 3, 4, 5]}",
+      NULL
+  };
+  for (size_t i = 0; values_to_test[i]; ++i) {
+    js_code += "result = plugin.postMessageAndAwaitResponse(";
+    js_code +=     values_to_test[i];
+    js_code += ");\n";
+    js_code += "if (result !== ";
+    js_code +=     values_to_test[i];
+    js_code += ")\n";
+    js_code += "  InternalError(\" Failed postMessageAndAwaitResponse for: ";
+    js_code +=      values_to_test[i];
+    js_code +=    " result: \" + result);\n";
+  }
+  // TODO/FIXME: Setting a property uses GetInstanceObject, which sends sync
+  // message, which can get interrupted with message to eval script, etc.
+  // FINISHED_WAITING message can therefore jump ahead.
+  // So checking that postMessageAndAwaitResponse is happening might not be
+  // good enough. Note that HandleFilteredEvent is sync, too.
+  // Maybe add way to check with PepperHungPluginFilter to see if we have any
+  // outbound sync messages. Maybe seperate CL?
+  js_code += "plugin.postMessage('FINISHED_TEST');\n";
+  instance_->EvalScript(js_code);
+  handler.WaitForTestFinishedMessage();
+  handler.Unregister();
+  ASSERT_SUBTEST_SUCCESS(handler.WaitForDestroy());
+
+  PASS();
+}
+