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      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 
     15 class GrResourceCacheEntry;
     16 class GrResourceCache2;
     17 class GrGpu;
     18 class 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  */
     36 class GrIORef : public SkNoncopyable {
     37 public:
     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 
     84 protected:
     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 
     91 private:
     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 
    118 private:
    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  */
    131 class GrGpuResource : public GrIORef {
    132 public:
    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 
    193 protected:
    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 
    226 private:
    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