content/renderer/pepper/message_channel.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_RENDERER_PEPPER_MESSAGE_CHANNEL_H_
   6 #define CONTENT_RENDERER_PEPPER_MESSAGE_CHANNEL_H_
   7
   8 #include <deque>
   9 #include <list>
  10 #include <map>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/weak_ptr.h"
  14 #include "content/renderer/pepper/v8_var_converter.h"
  15 #include "gin/handle.h"
  16 #include "gin/interceptor.h"
  17 #include "gin/wrappable.h"
  18 #include "ppapi/proxy/host_dispatcher.h"
  19 #include "ppapi/shared_impl/resource.h"
  20 #include "third_party/WebKit/public/web/WebSerializedScriptValue.h"
  21 #include "v8/include/v8.h"
  22
  23 struct PP_Var;
  24
  25 namespace gin {
  26 class Arguments;
  27 }  // namespace gin
  28
  29 namespace ppapi {
  30 class ScopedPPVar;
  31 }  // namespace ppapi
  32
  33 namespace content {
  34
  35 class PepperPluginInstanceImpl;
  36 class PluginObject;
  37
  38 // MessageChannel implements bidirectional postMessage functionality, allowing
  39 // calls from JavaScript to plugins and vice-versa. See
  40 // PPB_Messaging::PostMessage and PPP_Messaging::HandleMessage for more
  41 // information.
  42 //
  43 // Currently, only 1 MessageChannel can exist, to implement postMessage
  44 // functionality for the instance interfaces.  In the future, when we create a
  45 // MessagePort type in PPAPI, those may be implemented here as well with some
  46 // refactoring.
  47 //   - Separate message ports won't require the passthrough object.
  48 //   - The message target won't be limited to instance, and should support
  49 //     either plugin-provided or JS objects.
  50 // TODO(dmichael):  Add support for separate MessagePorts.
  51 class MessageChannel :
  52     public gin::Wrappable<MessageChannel>,
  53     public gin::NamedPropertyInterceptor,
  54     public ppapi::proxy::HostDispatcher::SyncMessageStatusObserver {
  55  public:
  56   static gin::WrapperInfo kWrapperInfo;
  57
  58   // Creates a MessageChannel, returning a pointer to it and sets |result| to
  59   // the v8 object which is backed by the message channel. The returned pointer
  60   // is only valid as long as the object in |result| is alive.
  61   static MessageChannel* Create(PepperPluginInstanceImpl* instance,
  62                                 v8::Persistent<v8::Object>* result);
  63
  64   ~MessageChannel() override;
  65
  66   // Called when the instance is deleted. The MessageChannel might outlive the
  67   // plugin instance because it is garbage collected.
  68   void InstanceDeleted();
  69
  70   // Post a message to the onmessage handler for this channel's instance
  71   // asynchronously.
  72   void PostMessageToJavaScript(PP_Var message_data);
  73
  74   // Messages are queued initially. After the PepperPluginInstanceImpl is ready
  75   // to send and handle messages, users of MessageChannel should call
  76   // Start().
  77   void Start();
  78
  79   // Set the V8Object to which we should forward any calls which aren't
  80   // related to postMessage. Note that this can be empty; it only gets set if
  81   // there is a scriptable 'InstanceObject' associated with this channel's
  82   // instance.
  83   void SetPassthroughObject(v8::Handle<v8::Object> passthrough);
  84
  85   PepperPluginInstanceImpl* instance() { return instance_; }
  86
  87   void SetReadOnlyProperty(PP_Var key, PP_Var value);
  88
  89  private:
  90   // Struct for storing the result of a v8 object being converted to a PP_Var.
  91   struct VarConversionResult;
  92
  93   explicit MessageChannel(PepperPluginInstanceImpl* instance);
  94
  95   // gin::NamedPropertyInterceptor
  96   v8::Local<v8::Value> GetNamedProperty(v8::Isolate* isolate,
  97                                         const std::string& property) override;
  98   bool SetNamedProperty(v8::Isolate* isolate,
  99                         const std::string& property,
 100                         v8::Local<v8::Value> value) override;
 101   std::vector<std::string> EnumerateNamedProperties(
 102       v8::Isolate* isolate) override;
 103
 104   // gin::Wrappable
 105   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
 106       v8::Isolate* isolate) override;
 107
 108   // ppapi::proxy::HostDispatcher::SyncMessageStatusObserver
 109   void BeginBlockOnSyncMessage() override;
 110   void EndBlockOnSyncMessage() override;
 111
 112   // Post a message to the plugin's HandleMessage function for this channel's
 113   // instance.
 114   void PostMessageToNative(gin::Arguments* args);
 115   // Post a message to the plugin's HandleBlocking Message function for this
 116   // channel's instance synchronously, and return a result.
 117   void PostBlockingMessageToNative(gin::Arguments* args);
 118
 119   // Post a message to the onmessage handler for this channel's instance
 120   // synchronously.  This is used by PostMessageToJavaScript.
 121   void PostMessageToJavaScriptImpl(
 122       const blink::WebSerializedScriptValue& message_data);
 123
 124   PluginObject* GetPluginObject(v8::Isolate* isolate);
 125
 126   void EnqueuePluginMessage(v8::Handle<v8::Value> v8_value);
 127
 128   void FromV8ValueComplete(VarConversionResult* result_holder,
 129                            const ppapi::ScopedPPVar& result_var,
 130                            bool success);
 131
 132   // Drain the queue of messages that are going to the plugin. All "completed"
 133   // messages at the head of the queue will be sent; any messages awaiting
 134   // conversion as well as messages after that in the queue will not be sent.
 135   void DrainCompletedPluginMessages();
 136   // Drain the queue of messages that are going to JavaScript.
 137   void DrainJSMessageQueue();
 138   // PostTask to call DrainJSMessageQueue() soon. Use this when you want to
 139   // send the messages, but can't immediately (e.g., because the instance is
 140   // not ready or JavaScript is on the stack).
 141   void DrainJSMessageQueueSoon();
 142
 143   void UnregisterSyncMessageStatusObserver();
 144
 145   PepperPluginInstanceImpl* instance_;
 146
 147   // We pass all non-postMessage calls through to the passthrough_object_.
 148   // This way, a plugin can use PPB_Class or PPP_Class_Deprecated and also
 149   // postMessage.  This is necessary to support backwards-compatibility, and
 150   // also trusted plugins for which we will continue to support synchronous
 151   // scripting.
 152   v8::Persistent<v8::Object> passthrough_object_;
 153
 154   enum MessageQueueState {
 155     WAITING_TO_START,  // Waiting for Start() to be called. Queue messages.
 156     QUEUE_MESSAGES,  // Queue messages temporarily.
 157     SEND_DIRECTLY,   // Post messages directly.
 158   };
 159
 160   // This queue stores values being posted to JavaScript.
 161   std::deque<blink::WebSerializedScriptValue> js_message_queue_;
 162   MessageQueueState js_message_queue_state_;
 163   // When the renderer is sending a blocking message to the plugin, we will
 164   // queue Plugin->JS messages temporarily to avoid re-entering JavaScript. This
 165   // counts how many blocking renderer->plugin messages are on the stack so that
 166   // we only begin sending messages to JavaScript again when the depth reaches
 167   // zero.
 168   int blocking_message_depth_;
 169
 170   // This queue stores vars that are being sent to the plugin. Because
 171   // conversion can happen asynchronously for object types, the queue stores
 172   // the var until all previous vars have been converted and sent. This
 173   // preserves the order in which JS->plugin messages are processed.
 174   //
 175   // Note we rely on raw VarConversionResult* pointers remaining valid after
 176   // calls to push_back or pop_front; hence why we're using list. (deque would
 177   // probably also work, but is less clearly specified).
 178   std::list<VarConversionResult> plugin_message_queue_;
 179   MessageQueueState plugin_message_queue_state_;
 180
 181   std::map<std::string, ppapi::ScopedPPVar> internal_named_properties_;
 182
 183   V8VarConverter var_converter_;
 184
 185   // A callback to invoke at shutdown to ensure we unregister ourselves as
 186   // Observers for sync messages.
 187   base::Closure unregister_observer_callback_;
 188
 189   // This is used to ensure pending tasks will not fire after this object is
 190   // destroyed.
 191   base::WeakPtrFactory<MessageChannel> weak_ptr_factory_;
 192
 193   DISALLOW_COPY_AND_ASSIGN(MessageChannel);
 194 };
 195
 196 }  // namespace content
 197
 198 #endif  // CONTENT_RENDERER_PEPPER_MESSAGE_CHANNEL_H_