[mojo] Use base::Pickle for Message storage.

mojo/public/cpp/bindings/message.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_
 
 #include <vector>
 
+#include "base/memory/scoped_ptr.h"
 #include "mojo/public/cpp/bindings/lib/message_internal.h"
+#include "mojo/public/cpp/bindings/lib/pickle_buffer.h"
 #include "mojo/public/cpp/environment/logging.h"
 
 namespace mojo {
 
 // Message is a holder for the data and handles to be sent over a MessagePipe.
 // Message owns its data and handles, but a consumer of Message is free to
 // mutate the data and handles. The message's data is comprised of a header
 // followed by payload.
 class Message {
  public:
   Message();
   ~Message();
 
   void Reset();
 
-  void AllocData(uint32_t num_bytes);
-  void AllocUninitializedData(uint32_t num_bytes);
+  // These methods preallocate capacity in underlying storage, but they *DO NOT*
+  // claim the allocated space. Use the interface exposed by buffer() to claim
+  // bytes.
+  //
+  // Exactly one call is permitted to either of these methods on a single
+  // instance of Message, and it must be made prior to accessing message
+  // data (including header) or using the buffer() interface.
+  void ReserveCapacity(uint32_t num_bytes);
+  void ReserveUninitializedCapacity(uint32_t num_bytes);
 
   // Transfers data and handles to |destination|.
   void MoveTo(Message* destination);
 
-  uint32_t data_num_bytes() const { return data_num_bytes_; }
+  uint32_t data_num_bytes() const { return buffer_->data_num_bytes(); }
 
   // Access the raw bytes of the message.
   const uint8_t* data() const {
-    return reinterpret_cast<const uint8_t*>(data_);
+    return reinterpret_cast<const uint8_t*>(buffer_->data());
   }
-  uint8_t* mutable_data() { return reinterpret_cast<uint8_t*>(data_); }
+  uint8_t* mutable_data() {
+    return reinterpret_cast<uint8_t*>(buffer_->data());
+  }
 
   // Access the header.
-  const internal::MessageHeader* header() const { return &data_->header; }
+  const internal::MessageHeader* header() const {
+    return reinterpret_cast<const internal::MessageHeader*>(buffer_->data());
+  }
 
-  uint32_t interface_id() const { return data_->header.interface_id; }
-  void set_interface_id(uint32_t id) { data_->header.interface_id = id; }
+  internal::MessageHeader* header() {
+    return const_cast<internal::MessageHeader*>(
+        static_cast<const Message*>(this)->header());
+  }
 
-  uint32_t name() const { return data_->header.name; }
-  bool has_flag(uint32_t flag) const { return !!(data_->header.flags & flag); }
+  uint32_t interface_id() const { return header()->interface_id; }
+  void set_interface_id(uint32_t id) { header()->interface_id = id; }
+
+  uint32_t name() const { return header()->name; }
+  bool has_flag(uint32_t flag) const { return !!(header()->flags & flag); }
 
   // Access the request_id field (if present).
-  bool has_request_id() const { return data_->header.version >= 1; }
+  bool has_request_id() const { return header()->version >= 1; }
   uint64_t request_id() const {
     MOJO_DCHECK(has_request_id());
     return static_cast<const internal::MessageHeaderWithRequestID*>(
-               &data_->header)->request_id;
+               header())->request_id;
   }
   void set_request_id(uint64_t request_id) {
     MOJO_DCHECK(has_request_id());
-    static_cast<internal::MessageHeaderWithRequestID*>(&data_->header)
+    static_cast<internal::MessageHeaderWithRequestID*>(header())
         ->request_id = request_id;
   }
 
   // Access the payload.
-  const uint8_t* payload() const {
-    return reinterpret_cast<const uint8_t*>(data_) + data_->header.num_bytes;
-  }
-  uint8_t* mutable_payload() {
-    return reinterpret_cast<uint8_t*>(data_) + data_->header.num_bytes;
-  }
+  const uint8_t* payload() const { return data() + header()->num_bytes; }
+  uint8_t* mutable_payload() { return const_cast<uint8_t*>(payload()); }
   uint32_t payload_num_bytes() const {
-    MOJO_DCHECK(data_num_bytes_ >= data_->header.num_bytes);
-    return data_num_bytes_ - data_->header.num_bytes;
+    MOJO_DCHECK(buffer_->data_num_bytes() >= header()->num_bytes);
+    return buffer_->data_num_bytes() - header()->num_bytes;
   }
 
   // Access the handles.
   const std::vector<Handle>* handles() const { return &handles_; }
   std::vector<Handle>* mutable_handles() { return &handles_; }
 
+  // Access the underlying Buffer interface.
+  internal::Buffer* buffer() { return buffer_.get(); }
+
  private:
   void Initialize();
-  void FreeDataAndCloseHandles();
+  void CloseHandles();
 
-  uint32_t data_num_bytes_;
-  internal::MessageData* data_;
+  scoped_ptr<internal::PickleBuffer> buffer_;
   std::vector<Handle> handles_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Message);
 };
 
 class MessageReceiver {
  public:
   virtual ~MessageReceiver() {}
 
   // The receiver may mutate the given message.  Returns true if the message
@@ skipping 59 matching lines @@
 // otherwise returns an error code if something went wrong.
 //
 // NOTE: The message hasn't been validated and may be malformed!
 MojoResult ReadAndDispatchMessage(MessagePipeHandle handle,
                                   MessageReceiver* receiver,
                                   bool* receiver_result);
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_