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      1 // Copyright 2013 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 GOOGLE_APIS_GCM_BASE_MCS_MESSAGE_H_
      6 #define GOOGLE_APIS_GCM_BASE_MCS_MESSAGE_H_
      7 
      8 #include <string>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/memory/ref_counted.h"
     12 #include "base/memory/scoped_ptr.h"
     13 #include "google_apis/gcm/base/gcm_export.h"
     14 
     15 namespace google {
     16 namespace protobuf {
     17 class MessageLite;
     18 }  // namespace protobuf
     19 }  // namespace google
     20 
     21 namespace gcm {
     22 
     23 // A wrapper for MCS protobuffers that encapsulates their tag, size and data
     24 // in an immutable and thread-safe format. If a mutable version is desired,
     25 // CloneProtobuf() should use used to create a new copy of the protobuf.
     26 //
     27 // Note: default copy and assign welcome.
     28 class GCM_EXPORT MCSMessage {
     29  public:
     30   // Creates an invalid MCSMessage.
     31   MCSMessage();
     32   // Infers tag from |message|.
     33   explicit MCSMessage(const google::protobuf::MessageLite& protobuf);
     34   // |tag| must match |protobuf|'s message type.
     35   MCSMessage(uint8 tag, const google::protobuf::MessageLite& protobuf);
     36   // |tag| must match |protobuf|'s message type. Takes ownership of |protobuf|.
     37   MCSMessage(uint8 tag,
     38              scoped_ptr<const google::protobuf::MessageLite> protobuf);
     39   ~MCSMessage();
     40 
     41   // Returns whether this message is valid or not (whether a protobuf was
     42   // provided at construction time or not).
     43   bool IsValid() const;
     44 
     45   // Getters for serialization.
     46   uint8 tag() const { return tag_; }
     47   int size() const {return size_; }
     48   std::string SerializeAsString() const;
     49 
     50   // Getter for accessing immutable probotuf fields.
     51   const google::protobuf::MessageLite& GetProtobuf() const;
     52 
     53   // Getter for creating a mutated version of the protobuf.
     54   scoped_ptr<google::protobuf::MessageLite> CloneProtobuf() const;
     55 
     56  private:
     57   class Core : public base::RefCountedThreadSafe<MCSMessage::Core> {
     58    public:
     59     Core();
     60     Core(uint8 tag, const google::protobuf::MessageLite& protobuf);
     61     Core(uint8 tag, scoped_ptr<const google::protobuf::MessageLite> protobuf);
     62 
     63     const google::protobuf::MessageLite& Get() const;
     64 
     65    private:
     66     friend class base::RefCountedThreadSafe<MCSMessage::Core>;
     67     ~Core();
     68 
     69     // The immutable protobuf.
     70     scoped_ptr<const google::protobuf::MessageLite> protobuf_;
     71 
     72     DISALLOW_COPY_AND_ASSIGN(Core);
     73   };
     74 
     75   // These are cached separately to avoid having to recompute them.
     76   const uint8 tag_;
     77   const int size_;
     78 
     79   // The refcounted core, containing the protobuf memory.
     80   scoped_refptr<const Core> core_;
     81 };
     82 
     83 }  // namespace gcm
     84 
     85 #endif  // GOOGLE_APIS_GCM_BASE_MCS_MESSAGE_H_
     86