google_apis/gcm/base/mcs_message.h

   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_