GrGpuResource.h

/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef GrGpuResource_DEFINED
#define GrGpuResource_DEFINED

#include "GrResourceKey.h"
#include "GrTypesPriv.h"

class GrContext;
class GrGpu;
class GrResourceCache;
class SkTraceMemoryDump;

template <typename DERIVED> class GrIORef : public SkNoncopyable {
public:
    // Some of the signatures are written to mirror SkRefCnt so that GrGpuResource can work with
    // templated helper classes (e.g. sk_sp). However, we have different categories of
    // refs (e.g. pending reads). We also don't require thread safety as GrCacheable objects are
    // not intended to cross thread boundaries.
    void ref() const {
        this->validate();
        ++fRefCnt;
    }

    void unref() const {
        this->validate();

        if (!(--fRefCnt)) {
            if (!static_cast<const DERIVED*>(this)->notifyRefCountIsZero()) {
                return;
            }
        }

        this->didRemoveRefOrPendingIO(kRef_CntType);
    }

    void validate() const {
#ifdef SK_DEBUG
        SkASSERT(fRefCnt >= 0);
        SkASSERT(fPendingReads >= 0);
        SkASSERT(fPendingWrites >= 0);
        SkASSERT(fRefCnt + fPendingReads + fPendingWrites >= 0);
#endif
    }

protected:
    GrIORef() : fRefCnt(1), fPendingReads(0), fPendingWrites(0) { }

    enum CntType {
        kRef_CntType,
        kPendingRead_CntType,
        kPendingWrite_CntType,
    };

    bool isPurgeable() const { return !this->internalHasRef() && !this->internalHasPendingIO(); }

    bool internalHasPendingRead() const { return SkToBool(fPendingReads); }
    bool internalHasPendingWrite() const { return SkToBool(fPendingWrites); }
    bool internalHasPendingIO() const { return SkToBool(fPendingWrites | fPendingReads); }

    bool internalHasRef() const { return SkToBool(fRefCnt); }

private:
    friend class GrIORefProxy; // needs to forward on wrapped IO calls
    // This is for a unit test.
    template <typename T>
    friend void testingOnly_getIORefCnts(const T*, int* refCnt, int* readCnt, int* writeCnt);

    void addPendingRead() const {
        this->validate();
        ++fPendingReads;
    }

    void completedRead() const {
        this->validate();
        --fPendingReads;
        this->didRemoveRefOrPendingIO(kPendingRead_CntType);
    }

    void addPendingWrite() const {
        this->validate();
        ++fPendingWrites;
    }

    void completedWrite() const {
        this->validate();
        --fPendingWrites;
        this->didRemoveRefOrPendingIO(kPendingWrite_CntType);
    }

private:
    void didRemoveRefOrPendingIO(CntType cntTypeRemoved) const {
        if (0 == fPendingReads && 0 == fPendingWrites && 0 == fRefCnt) {
            static_cast<const DERIVED*>(this)->notifyAllCntsAreZero(cntTypeRemoved);
        }
    }

    mutable int32_t fRefCnt;
    mutable int32_t fPendingReads;
    mutable int32_t fPendingWrites;

    // This class is used to manage conversion of refs to pending reads/writes.
    friend class GrGpuResourceRef;
    friend class GrResourceCache; // to check IO ref counts.

    template <typename, GrIOType> friend class GrPendingIOResource;
};

class SK_API GrGpuResource : public GrIORef<GrGpuResource> {
public:

    bool wasDestroyed() const { return NULL == fGpu; }

    const GrContext* getContext() const;
    GrContext* getContext();

    size_t gpuMemorySize() const {
        if (kInvalidGpuMemorySize == fGpuMemorySize) {
            fGpuMemorySize = this->onGpuMemorySize();
            SkASSERT(kInvalidGpuMemorySize != fGpuMemorySize);
        }
        return fGpuMemorySize;
    }

    class UniqueID {
    public:
        static UniqueID InvalidID() {
            return UniqueID(uint32_t(SK_InvalidUniqueID));
        }

        UniqueID() {}

        explicit UniqueID(uint32_t id) : fID(id) {}

        uint32_t asUInt() const { return fID; }

        bool operator==(const UniqueID& other) const {
            return fID == other.fID;
        }
        bool operator!=(const UniqueID& other) const {
            return !(*this == other);
        }

        void makeInvalid() { fID = SK_InvalidUniqueID; }
        bool isInvalid() const { return SK_InvalidUniqueID == fID; }

    protected:
        uint32_t fID;
    };

    UniqueID uniqueID() const { return fUniqueID; }

    const GrUniqueKey& getUniqueKey() const { return fUniqueKey; }

    class CacheAccess;
    inline CacheAccess cacheAccess();
    inline const CacheAccess cacheAccess() const;

    class ResourcePriv;
    inline ResourcePriv resourcePriv();
    inline const ResourcePriv resourcePriv() const;

    void abandon();

    virtual void dumpMemoryStatistics(SkTraceMemoryDump* traceMemoryDump) const;

    static uint32_t CreateUniqueID();

protected:
    // This must be called by every non-wrapped GrGpuObject. It should be called once the object is
    // fully initialized (i.e. only from the constructors of the final class).
    void registerWithCache(SkBudgeted);

    // This must be called by every GrGpuObject that references any wrapped backend objects. It
    // should be called once the object is fully initialized (i.e. only from the constructors of the
    // final class).
    void registerWithCacheWrapped();

    GrGpuResource(GrGpu*);
    virtual ~GrGpuResource();

    GrGpu* getGpu() const { return fGpu; }

    virtual void onRelease() { }
    virtual void onAbandon() { }

    void didChangeGpuMemorySize() const;

    virtual void setMemoryBacking(SkTraceMemoryDump*, const SkString&) const {}

private:
    virtual void computeScratchKey(GrScratchKey*) const { }

    void release();

    virtual size_t onGpuMemorySize() const = 0;

    // See comments in CacheAccess and ResourcePriv.
    void setUniqueKey(const GrUniqueKey&);
    void removeUniqueKey();
    void notifyAllCntsAreZero(CntType) const;
    bool notifyRefCountIsZero() const;
    void removeScratchKey();
    void makeBudgeted();
    void makeUnbudgeted();

#ifdef SK_DEBUG
    friend class GrGpu;  // for assert in GrGpu to access getGpu
#endif

    // An index into a heap when this resource is purgeable or an array when not. This is maintained
    // by the cache.
    int fCacheArrayIndex;
    // This value reflects how recently this resource was accessed in the cache. This is maintained
    // by the cache.
    uint32_t fTimestamp;
    uint32_t fExternalFlushCntWhenBecamePurgeable;
    GrStdSteadyClock::time_point fTimeWhenBecamePurgeable;

    static const size_t kInvalidGpuMemorySize = ~static_cast<size_t>(0);
    GrScratchKey fScratchKey;
    GrUniqueKey fUniqueKey;

    // This is not ref'ed but abandon() or release() will be called before the GrGpu object
    // is destroyed. Those calls set will this to NULL.
    GrGpu* fGpu;
    mutable size_t fGpuMemorySize;

    SkBudgeted fBudgeted;
    bool fRefsWrappedObjects;
    const UniqueID fUniqueID;

    typedef GrIORef<GrGpuResource> INHERITED;
    friend class GrIORef<GrGpuResource>; // to access notifyAllCntsAreZero and notifyRefCntIsZero.
};

#endif