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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrFakeRefObj_DEFINED
      9 #define GrFakeRefObj_DEFINED
     10 
     11 #include <atomic>
     12 #include "SkTypes.h"
     13 #include "gl/GrGLInterface.h"
     14 
     15 ////////////////////////////////////////////////////////////////////////////////
     16 // This object is used to track the OpenGL objects. We don't use real
     17 // reference counting (i.e., we don't free the objects when their ref count
     18 // goes to 0) so that we can detect invalid memory accesses. The refs we
     19 // are tracking in this class are actually OpenGL's references to the objects
     20 // not "ours"
     21 // Each object also gets a unique globally identifying ID
     22 class GrFakeRefObj : SkNoncopyable {
     23 public:
     24     GrFakeRefObj()
     25         : fRef(0)
     26         , fMarkedForDeletion(false)
     27         , fDeleted(false) {
     28 
     29         // source for globally unique IDs - 0 is reserved!
     30         static std::atomic<int> fNextID{0};
     31 
     32         fID = ++fNextID;
     33     }
     34     virtual ~GrFakeRefObj() {}
     35 
     36     void ref() {
     37         fRef++;
     38     }
     39     void unref() {
     40         fRef--;
     41         GrAlwaysAssert(fRef >= 0);
     42 
     43         // often in OpenGL a given object may still be in use when the
     44         // delete call is made. In these cases the object is marked
     45         // for deletion and then freed when it is no longer in use
     46         if (0 == fRef && fMarkedForDeletion) {
     47             this->deleteAction();
     48         }
     49     }
     50     int getRefCount() const             { return fRef; }
     51 
     52     GrGLuint getID() const              { return fID; }
     53 
     54     void setMarkedForDeletion()         { fMarkedForDeletion = true; }
     55     bool getMarkedForDeletion() const   { return fMarkedForDeletion; }
     56 
     57     bool getDeleted() const             { return fDeleted; }
     58 
     59     // The deleteAction fires if the object has been marked for deletion but
     60     // couldn't be deleted earlier due to refs
     61     virtual void deleteAction() {
     62         this->setDeleted();
     63     }
     64 
     65 protected:
     66 private:
     67     int         fRef;               // ref count
     68     GrGLuint    fID;                // globally unique ID
     69     bool        fMarkedForDeletion;
     70     // The deleted flag is only set when OpenGL thinks the object is deleted
     71     // It is obviously still allocated w/in this framework
     72     bool        fDeleted;
     73 
     74     // setDeleted should only ever appear in the deleteAction method!
     75     void setDeleted()                   { fDeleted = true; }
     76 };
     77 
     78 ////////////////////////////////////////////////////////////////////////////////
     79 // Each class derived from GrFakeRefObj should use this macro to add a
     80 // factory creation entry point. This entry point is used by the GrGLDebug
     81 // object to instantiate the various objects
     82 // all globally unique IDs
     83 #define GR_DEFINE_CREATOR(className) \
     84 public:                              \
     85     static GrFakeRefObj *create##className() { return new className; }
     86 
     87 #endif // GrFakeRefObj_DEFINED
     88