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 GrGpuResource_DEFINED
9#define GrGpuResource_DEFINED
10
11#include "SkInstCnt.h"
12#include "SkTInternalLList.h"
13#include "GrResourceKey.h"
14
15class GrResourceCacheEntry;
16class GrResourceCache2;
17class GrGpu;
18class GrContext;
19
20/**
21 * Base class for GrGpuResource. Handles the various types of refs we need. Separated out as a base
22 * class to isolate the ref-cnting behavior and provide friendship without exposing all of
23 * GrGpuResource.
24 *
25 * Gpu resources can have three types of refs:
26 *   1) Normal ref (+ by ref(), - by unref()): These are used by code that is issuing draw calls
27 *      that read and write the resource via GrDrawTarget and by any object that must own a
28 *      GrGpuResource and is itself owned (directly or indirectly) by Skia-client code.
29 *   2) Pending read (+ by addPendingRead(), - by readCompleted()): GrContext has scheduled a read
30 *      of the resource by the GPU as a result of a skia API call but hasn't executed it yet.
31 *   3) Pending write (+ by addPendingWrite(), - by writeCompleted()): GrContext has scheduled a
32 *      write to the resource by the GPU as a result of a skia API call but hasn't executed it yet.
33 *
34 * The latter two ref types are private and intended only for Gr core code.
35 */
36class GrIORef : public SkNoncopyable {
37public:
38    SK_DECLARE_INST_COUNT_ROOT(GrIORef)
39
40    enum IOType {
41        kRead_IOType,
42        kWrite_IOType,
43        kRW_IOType
44    };
45
46    virtual ~GrIORef();
47
48    // Some of the signatures are written to mirror SkRefCnt so that GrGpuResource can work with
49    // templated helper classes (e.g. SkAutoTUnref). However, we have different categories of
50    // refs (e.g. pending reads). We also don't require thread safety as GrCacheable objects are
51    // not intended to cross thread boundaries.
52    // internal_dispose() exists because of GrTexture's reliance on it. It will be removed
53    // soon.
54    void ref() const {
55        ++fRefCnt;
56        // pre-validate once internal_dispose is removed (and therefore 0 ref cnt is not allowed).
57        this->validate();
58    }
59
60    void unref() const {
61        this->validate();
62        --fRefCnt;
63        if (0 == fRefCnt && 0 == fPendingReads && 0 == fPendingWrites) {
64            this->internal_dispose();
65        }
66    }
67
68    virtual void internal_dispose() const { SkDELETE(this); }
69
70    /** This is exists to service the old mechanism for recycling scratch textures. It will
71        be removed soon. */
72    bool unique() const { return 1 == (fRefCnt + fPendingReads + fPendingWrites); }
73
74    void validate() const {
75#ifdef SK_DEBUG
76        SkASSERT(fRefCnt >= 0);
77        SkASSERT(fPendingReads >= 0);
78        SkASSERT(fPendingWrites >= 0);
79        SkASSERT(fRefCnt + fPendingReads + fPendingWrites > 0);
80#endif
81    }
82
83
84protected:
85    GrIORef() : fRefCnt(1), fPendingReads(0), fPendingWrites(0) {}
86
87    bool internalHasPendingRead() const { return SkToBool(fPendingReads); }
88    bool internalHasPendingWrite() const { return SkToBool(fPendingWrites); }
89    bool internalHasPendingIO() const { return SkToBool(fPendingWrites | fPendingReads); }
90
91private:
92    void addPendingRead() const {
93        this->validate();
94        ++fPendingReads;
95    }
96
97    void completedRead() const {
98        this->validate();
99        --fPendingReads;
100        if (0 == fRefCnt && 0 == fPendingReads && 0 == fPendingWrites) {
101            this->internal_dispose();
102        }
103    }
104
105    void addPendingWrite() const {
106        this->validate();
107        ++fPendingWrites;
108    }
109
110    void completedWrite() const {
111        this->validate();
112        --fPendingWrites;
113        if (0 == fRefCnt && 0 == fPendingReads && 0 == fPendingWrites) {
114            this->internal_dispose();
115        }
116    }
117
118private:
119    mutable int32_t fRefCnt;
120    mutable int32_t fPendingReads;
121    mutable int32_t fPendingWrites;
122
123    // This class is used to manage conversion of refs to pending reads/writes.
124    friend class GrGpuResourceRef;
125    template <typename, IOType> friend class GrPendingIOResource;
126};
127
128/**
129 * Base class for objects that can be kept in the GrResourceCache.
130 */
131class GrGpuResource : public GrIORef {
132public:
133    SK_DECLARE_INST_COUNT(GrGpuResource)
134
135    /**
136     * Frees the object in the underlying 3D API. It must be safe to call this
137     * when the object has been previously abandoned.
138     */
139    void release();
140
141    /**
142     * Removes references to objects in the underlying 3D API without freeing
143     * them. Used when the API context has been torn down before the GrContext.
144     */
145    void abandon();
146
147    /**
148     * Tests whether a object has been abandoned or released. All objects will
149     * be in this state after their creating GrContext is destroyed or has
150     * contextLost called. It's up to the client to test wasDestroyed() before
151     * attempting to use an object if it holds refs on objects across
152     * ~GrContext, freeResources with the force flag, or contextLost.
153     *
154     * @return true if the object has been released or abandoned,
155     *         false otherwise.
156     */
157    bool wasDestroyed() const { return NULL == fGpu; }
158
159    /**
160     * Retrieves the context that owns the object. Note that it is possible for
161     * this to return NULL. When objects have been release()ed or abandon()ed
162     * they no longer have an owning context. Destroying a GrContext
163     * automatically releases all its resources.
164     */
165    const GrContext* getContext() const;
166    GrContext* getContext();
167
168    /**
169     * Retrieves the amount of GPU memory used by this resource in bytes. It is
170     * approximate since we aren't aware of additional padding or copies made
171     * by the driver.
172     *
173     * @return the amount of GPU memory used in bytes
174     */
175    virtual size_t gpuMemorySize() const = 0;
176
177    void setCacheEntry(GrResourceCacheEntry* cacheEntry) { fCacheEntry = cacheEntry; }
178    GrResourceCacheEntry* getCacheEntry() { return fCacheEntry; }
179
180    /**
181     * If this resource can be used as a scratch resource this returns a valid
182     * scratch key. Otherwise it returns a key for which isNullScratch is true.
183     */
184    const GrResourceKey& getScratchKey() const { return fScratchKey; }
185
186    /**
187     * Gets an id that is unique for this GrGpuResource object. It is static in that it does
188     * not change when the content of the GrGpuResource object changes. This will never return
189     * 0.
190     */
191    uint32_t getUniqueID() const { return fUniqueID; }
192
193protected:
194    // This must be called by every GrGpuObject. It should be called once the object is fully
195    // initialized (i.e. not in a base class constructor).
196    void registerWithCache();
197
198    GrGpuResource(GrGpu*, bool isWrapped);
199    virtual ~GrGpuResource();
200
201    bool isInCache() const { return SkToBool(fCacheEntry); }
202
203    GrGpu* getGpu() const { return fGpu; }
204
205    // Derived classes should always call their parent class' onRelease
206    // and onAbandon methods in their overrides.
207    virtual void onRelease() {};
208    virtual void onAbandon() {};
209
210    bool isWrapped() const { return kWrapped_FlagBit & fFlags; }
211
212    /**
213     * This entry point should be called whenever gpuMemorySize() begins
214     * reporting a different size. If the object is in the cache, it will call
215     * gpuMemorySize() immediately and pass the new size on to the resource
216     * cache.
217     */
218    void didChangeGpuMemorySize() const;
219
220    /**
221     * Optionally called by the GrGpuResource subclass if the resource can be used as scratch.
222     * By default resources are not usable as scratch. This should only be called once.
223     **/
224    void setScratchKey(const GrResourceKey& scratchKey);
225
226private:
227#ifdef SK_DEBUG
228    friend class GrGpu; // for assert in GrGpu to access getGpu
229#endif
230
231    static uint32_t CreateUniqueID();
232
233    // We're in an internal doubly linked list owned by GrResourceCache2
234    SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrGpuResource);
235
236    // This is not ref'ed but abandon() or release() will be called before the GrGpu object
237    // is destroyed. Those calls set will this to NULL.
238    GrGpu* fGpu;
239
240    enum Flags {
241        /**
242         * This object wraps a GPU object given to us by the user.
243         * Lifetime management is left up to the user (i.e., we will not
244         * free it).
245         */
246        kWrapped_FlagBit         = 0x1,
247    };
248
249    uint32_t                fFlags;
250
251    GrResourceCacheEntry*   fCacheEntry;  // NULL if not in cache
252    const uint32_t          fUniqueID;
253
254    GrResourceKey           fScratchKey;
255
256    typedef GrIORef INHERITED;
257};
258
259#endif
260