GrGpuResourceRef.h revision 89af44a0f1323dc136b238c00ccf143e15abb243 
1/*
2 * Copyright 2014 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 GrGpuResourceRef_DEFINED
9#define GrGpuResourceRef_DEFINED
10
11#include "GrGpuResource.h"
12#include "SkRefCnt.h"
13
14/**
15 * This class is intended only for internal use in core Gr code.
16 *
17 * Class that wraps a resource referenced by a GrProgramElement or GrDrawState. It manages
18 * converting refs to pending IO operations. It allows a resource ownership to be in three
19 * states:
20 *          1. Owns a single ref
21 *          2. Owns a single ref and a pending IO operation (read, write, or read-write)
22 *          3. Owns a single pending IO operation.
23 *
24 * It is legal to destroy the GrGpuResourceRef in any of these states. It starts in state
25 * 1. Calling markPendingIO() converts it from state 1 to state 2. Calling removeRef() goes from
26 * state 2 to state 3. Calling pendingIOComplete() moves from state 2 to state 1. There is no
27 * valid way of going from state 3 back to 2 or 1.
28 *
29 * Like SkAutoTUnref, its constructor and setter adopt a ref from their caller.
30 *
31 * TODO: Once GrDODrawState no longer exists and therefore GrDrawState and GrOptDrawState no
32 * longer share an instance of this class, attempt to make the resource owned by GrGpuResourceRef
33 * only settable via the constructor.
34 */
35class GrGpuResourceRef : SkNoncopyable {
36public:
37    SK_DECLARE_INST_COUNT_ROOT(GrGpuResourceRef);
38
39    ~GrGpuResourceRef();
40
41    GrGpuResource* getResource() const { return fResource; }
42
43    /** Does this object own a pending read or write on the resource it is wrapping. */
44    bool ownsPendingIO() const { return fPendingIO; }
45
46    /** Shortcut for calling setResource() with NULL. It cannot be called after markingPendingIO
47        is called. */
48    void reset();
49
50protected:
51    GrGpuResourceRef();
52
53    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
54        pending on the resource when markPendingIO is called. */
55    GrGpuResourceRef(GrGpuResource*, GrIORef::IOType);
56
57    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
58        pending on the resource when markPendingIO is called. */
59    void setResource(GrGpuResource*, GrIORef::IOType);
60
61private:
62    /** Called by owning GrProgramElement when the program element is first scheduled for
63        execution. It can only be called once. */
64    void markPendingIO() const;
65
66    /** Called when the program element/draw state is no longer owned by GrDrawTarget-client code.
67        This lets the cache know that the drawing code will no longer schedule additional reads or
68        writes to the resource using the program element or draw state. It can only be called once.
69      */
70    void removeRef() const;
71
72    /** Called to indicate that the previous pending IO is complete. Useful when the owning object
73        still has refs, so it is not about to destroy this GrGpuResourceRef, but its previously
74        pending executions have been complete. Can only be called if removeRef() was not previously
75        called. */
76    void pendingIOComplete() const;
77
78    friend class GrDrawState;
79    friend class GrOptDrawState;
80    friend class GrProgramElement;
81
82    GrGpuResource*      fResource;
83    mutable bool        fOwnRef;
84    mutable bool        fPendingIO;
85    GrIORef::IOType     fIOType;
86
87    typedef SkNoncopyable INHERITED;
88};
89
90/**
91 * Templated version of GrGpuResourceRef to enforce type safety.
92 */
93template <typename T> class GrTGpuResourceRef : public GrGpuResourceRef {
94public:
95    GrTGpuResourceRef() {}
96
97    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
98        pending on the resource when markPendingIO is called. */
99    GrTGpuResourceRef(T* resource, GrIORef::IOType ioType) : INHERITED(resource, ioType) {}
100
101    T* get() const { return static_cast<T*>(this->getResource()); }
102
103    /** Adopts a ref from the caller. ioType expresses what type of IO operations will be marked as
104        pending on the resource when markPendingIO is called. */
105    void set(T* resource, GrIORef::IOType ioType) { this->setResource(resource, ioType); }
106
107private:
108    typedef GrGpuResourceRef INHERITED;
109};
110
111/**
112 * This is similar to GrTGpuResourceRef but can only be in the pending IO state. It never owns a
113 * ref.
114 */
115template <typename T, GrIORef::IOType IO_TYPE> class GrPendingIOResource : SkNoncopyable {
116public:
117    GrPendingIOResource(T* resource) : fResource(resource) {
118        if (NULL != fResource) {
119            switch (IO_TYPE) {
120                case GrIORef::kRead_IOType:
121                    fResource->addPendingRead();
122                    break;
123                case GrIORef::kWrite_IOType:
124                    fResource->addPendingWrite();
125                    break;
126                case GrIORef::kRW_IOType:
127                    fResource->addPendingRead();
128                    fResource->addPendingWrite();
129                    break;
130            }
131        }
132    }
133
134    ~GrPendingIOResource() {
135        if (NULL != fResource) {
136            switch (IO_TYPE) {
137                case GrIORef::kRead_IOType:
138                    fResource->completedRead();
139                    break;
140                case GrIORef::kWrite_IOType:
141                    fResource->completedWrite();
142                    break;
143                case GrIORef::kRW_IOType:
144                    fResource->completedRead();
145                    fResource->completedWrite();
146                    break;
147            }
148        }
149    }
150
151    T* get() const { return fResource; }
152
153private:
154    T*      fResource;
155};
156#endif
157