[NaCl SDK] Messaging example (demonstrates postMessageAndAwaitResponse)

native_client_sdk/src/examples/api/messaging/messaging.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/cpp/instance.h"
+#include "ppapi/cpp/instance_handle.h"
+#include "ppapi/cpp/message_handler.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/cpp/var.h"
+#include "ppapi/cpp/var_array.h"
+#include "ppapi/utility/threading/simple_thread.h"
+
+#ifdef WIN32
+#undef PostMessage
+// Allow 'this' in initializer list
+#pragma warning(disable : 4355)
+#endif
+
+class MessageHandler : public pp::MessageHandler {
+ public:
+  virtual void HandleMessage(pp::InstanceHandle instance,
+                             const pp::Var& message_data) {
+    if (!message_data.is_array()) {
+      return;
+    }
+
+    pp::VarArray array(message_data);
+    pp::Var response = SumArray(array);
+
+    // Send the response back to JavaScript asynchronously.
+    pp::Instance(instance.pp_instance()).PostMessage(response);
+  }
+
+  virtual pp::Var HandleBlockingMessage(pp::InstanceHandle instance,
+                                        const pp::Var& message_data) {
+    if (!message_data.is_array()) {
+      // Return an undefined value.
+      return pp::Var();
+    }
+
+    pp::VarArray array(message_data);
+
+    // Send the response back to JavaScript synchronously.
+    return SumArray(array);
+  }
+
+  virtual void WasUnregistered(pp::InstanceHandle instance) {}
+
+  pp::Var SumArray(const pp::VarArray& array) {
+    int32_t result = 0;
+    for (uint32_t i = 0, length = array.GetLength(); i < length; ++i) {
+      if (!array.Get(i).is_int()) {
+        continue;
+      }
+
+      result += array.Get(i).AsInt();
+    }
+
+    return pp::Var(result);
+  }
+};
+
+class Instance : public pp::Instance {
+ public:
+  explicit Instance(PP_Instance instance)
+      : pp::Instance(instance), thread_(this) {}
+
+  virtual bool Init(uint32_t /*argc*/,
+                    const char* /*argn*/ [],
+                    const char* /*argv*/ []) {
+    thread_.Start();
+
+    // The message handler must be registered using a message loop that is not
+    // the main thread's messaging loop. This call will fail otherwise.
+    RegisterMessageHandler(&message_handler_, thread_.message_loop());
+    return true;
+  }
+
+ private:
+  pp::SimpleThread thread_;
+  MessageHandler message_handler_;
+};
+
+class Module : public pp::Module {
+ public:
+  Module() : pp::Module() {}
+  virtual ~Module() {}
+
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new Instance(instance);
+  }
+};
+
+namespace pp {
+Module* CreateModule() { return new ::Module(); }
+}  // namespace pp