src/gpu/GrLayerCache.cpp - skia - Git at Google

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

 #include "GrAtlas.h"
 #include "GrGpu.h"
 #include "GrLayerCache.h"

 DECLARE_SKMESSAGEBUS_MESSAGE(GrPictureDeletedMessage);

 #ifdef SK_DEBUG
 void GrCachedLayer::validate(const GrTexture* backingTexture) const {
     SkASSERT(SK_InvalidGenID != fKey.pictureID());
     SkASSERT(fKey.start() > 0 && fKey.stop() > 0);


     if (NULL != fTexture) {
         // If the layer is in some texture then it must occupy some rectangle
         SkASSERT(!fRect.isEmpty());
         if (!this->isAtlased()) {
             // If it isn't atlased then the rectangle should start at the origin
             SkASSERT(0.0f == fRect.fLeft && 0.0f == fRect.fTop);
         }
     } else {
         SkASSERT(fRect.isEmpty());
         SkASSERT(NULL == fPlot);
         SkASSERT(!fLocked);     // layers without a texture cannot be locked
     }

     if (NULL != fPlot) {
         // If a layer has a plot (i.e., is atlased) then it must point to
         // the backing texture. Additionally, its rect should be non-empty.
         SkASSERT(NULL != fTexture && backingTexture == fTexture);
         SkASSERT(!fRect.isEmpty());
     }

     if (fLocked) {
         // If a layer is locked it must have a texture (though it need not be
         // the atlas-backing texture) and occupy some space.
         SkASSERT(NULL != fTexture);
         SkASSERT(!fRect.isEmpty());
     }
 }

 class GrAutoValidateLayer : ::SkNoncopyable {
 public:
     GrAutoValidateLayer(GrTexture* backingTexture, const GrCachedLayer* layer)
         : fBackingTexture(backingTexture)
         , fLayer(layer) {
         if (NULL != fLayer) {
             fLayer->validate(backingTexture);
         }
     }
     ~GrAutoValidateLayer() {
         if (NULL != fLayer) {
             fLayer->validate(fBackingTexture);
         }
     }
     void setBackingTexture(GrTexture* backingTexture) {
         SkASSERT(NULL == fBackingTexture || fBackingTexture == backingTexture);
         fBackingTexture = backingTexture;
     }

 private:
     const GrTexture* fBackingTexture;
     const GrCachedLayer* fLayer;
 };
 #endif

 GrLayerCache::GrLayerCache(GrContext* context)
     : fContext(context) {
     this->initAtlas();
     memset(fPlotLocks, 0, sizeof(fPlotLocks));
 }

 GrLayerCache::~GrLayerCache() {

     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         GrCachedLayer* layer = &(*iter);
         this->unlock(layer);
         SkDELETE(layer);
     }

     // The atlas only lets go of its texture when the atlas is deleted.
     fAtlas.free();
 }

 void GrLayerCache::initAtlas() {
     SkASSERT(NULL == fAtlas.get());

     SkISize textureSize = SkISize::Make(kAtlasTextureWidth, kAtlasTextureHeight);
     fAtlas.reset(SkNEW_ARGS(GrAtlas, (fContext->getGpu(), kSkia8888_GrPixelConfig,
                                       kRenderTarget_GrTextureFlagBit,
                                       textureSize, kNumPlotsX, kNumPlotsY, false)));
 }

 void GrLayerCache::freeAll() {

     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         GrCachedLayer* layer = &(*iter);
         this->unlock(layer);
         SkDELETE(layer);
     }
     fLayerHash.rewind();

     // The atlas only lets go of its texture when the atlas is deleted.
     fAtlas.free();
     // GrLayerCache always assumes an atlas exists so recreate it. The atlas
     // lazily allocates a replacement texture so reallocating a new
     // atlas here won't disrupt a GrContext::abandonContext or freeGpuResources.
     // TODO: Make GrLayerCache lazily allocate the atlas manager?
     this->initAtlas();
 }

 GrCachedLayer* GrLayerCache::createLayer(uint32_t pictureID,
                                          int start, int stop,
                                          const SkMatrix& ctm) {
     SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);

     GrCachedLayer* layer = SkNEW_ARGS(GrCachedLayer, (pictureID, start, stop, ctm));
     fLayerHash.add(layer);
     return layer;
 }

 GrCachedLayer* GrLayerCache::findLayer(uint32_t pictureID,
                                        int start, int stop,
                                        const SkMatrix& ctm) {
     SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);
     return fLayerHash.find(GrCachedLayer::Key(pictureID, start, stop, ctm));
 }

 GrCachedLayer* GrLayerCache::findLayerOrCreate(uint32_t pictureID,
                                                int start, int stop,
                                                const SkMatrix& ctm) {
     SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);
     GrCachedLayer* layer = fLayerHash.find(GrCachedLayer::Key(pictureID, start, stop, ctm));
     if (NULL == layer) {
         layer = this->createLayer(pictureID, start, stop, ctm);
     }

     return layer;
 }

 bool GrLayerCache::lock(GrCachedLayer* layer, const GrTextureDesc& desc, bool dontAtlas) {
     SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)

     if (layer->locked()) {
         // This layer is already locked
 #ifdef SK_DEBUG
         if (layer->isAtlased()) {
             // It claims to be atlased
             SkASSERT(!dontAtlas);
             SkASSERT(layer->rect().width() == desc.fWidth);
             SkASSERT(layer->rect().height() == desc.fHeight);
         }
 #endif
         return false;
     }

     if (layer->isAtlased()) {
         // Hooray it is still in the atlas - make sure it stays there
         SkASSERT(!dontAtlas);
         layer->setLocked(true);
         fPlotLocks[layer->plot()->id()]++;
         return false;
     } else if (!dontAtlas && PlausiblyAtlasable(desc.fWidth, desc.fHeight)) {
         // Not in the atlas - will it fit?
         GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
         if (NULL == pictInfo) {
             pictInfo = SkNEW_ARGS(GrPictureInfo, (layer->pictureID()));
             fPictureHash.add(pictInfo);
         }

         SkIPoint16 loc;
         for (int i = 0; i < 2; ++i) { // extra pass in case we fail to add but are able to purge
             GrPlot* plot = fAtlas->addToAtlas(&pictInfo->fPlotUsage,
                                               desc.fWidth, desc.fHeight,
                                               NULL, &loc);
             // addToAtlas can allocate the backing texture
             SkDEBUGCODE(avl.setBackingTexture(fAtlas->getTexture()));
             if (NULL != plot) {
                 // The layer was successfully added to the atlas
                 GrIRect16 bounds = GrIRect16::MakeXYWH(loc.fX, loc.fY,
                                                        SkToS16(desc.fWidth),
                                                        SkToS16(desc.fHeight));
                 layer->setTexture(fAtlas->getTexture(), bounds);
                 layer->setPlot(plot);
                 layer->setLocked(true);
                 fPlotLocks[layer->plot()->id()]++;
                 return true;
             }

             // The layer was rejected by the atlas (even though we know it is
             // plausibly atlas-able). See if a plot can be purged and try again.
             if (!this->purgePlot()) {
                 break;  // We weren't able to purge any plots
             }
         }
     }

     // The texture wouldn't fit in the cache - give it it's own texture.
     // This path always uses a new scratch texture and (thus) doesn't cache anything.
     // This can yield a lot of re-rendering
     SkAutoTUnref<GrTexture> tex(fContext->lockAndRefScratchTexture(desc,
                                                         GrContext::kApprox_ScratchTexMatch));

     layer->setTexture(tex, GrIRect16::MakeWH(SkToS16(desc.fWidth), SkToS16(desc.fHeight)));
     layer->setLocked(true);
     return true;
 }

 void GrLayerCache::unlock(GrCachedLayer* layer) {
     SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)

     if (NULL == layer || !layer->locked()) {
         // invalid or not locked
         return;
     }

     if (layer->isAtlased()) {
         const int plotID = layer->plot()->id();

         SkASSERT(fPlotLocks[plotID] > 0);
         fPlotLocks[plotID]--;
         // At this point we could aggressively clear out un-locked plots but
         // by delaying we may be able to reuse some of the atlased layers later.
 #if DISABLE_CACHING
         // This testing code aggressively removes the atlased layers. This
         // can be used to separate the performance contribution of less
         // render target pingponging from that due to the re-use of cached layers
         GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
         SkASSERT(NULL != pictInfo);

         GrAtlas::RemovePlot(&pictInfo->fPlotUsage, layer->plot());

         layer->setPlot(NULL);
         layer->setTexture(NULL, GrIRect16::MakeEmpty());
 #endif

     } else {
         fContext->unlockScratchTexture(layer->texture());
         layer->setTexture(NULL, GrIRect16::MakeEmpty());
     }

     layer->setLocked(false);
 }

 #ifdef SK_DEBUG
 void GrLayerCache::validate() const {
     int plotLocks[kNumPlotsX * kNumPlotsY];
     memset(plotLocks, 0, sizeof(plotLocks));

     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::ConstIter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         const GrCachedLayer* layer = &(*iter);

         layer->validate(fAtlas->getTexture());

         const GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
         if (NULL != pictInfo) {
             // In aggressive cleanup mode a picture info should only exist if
             // it has some atlased layers
 #if !DISABLE_CACHING
             SkASSERT(!pictInfo->fPlotUsage.isEmpty());
 #endif
         } else {
             // If there is no picture info for this layer then all of its
             // layers should be non-atlased.
             SkASSERT(!layer->isAtlased());
         }

         if (NULL != layer->plot()) {
             SkASSERT(NULL != pictInfo);
             SkASSERT(pictInfo->fPictureID == layer->pictureID());

             SkASSERT(pictInfo->fPlotUsage.contains(layer->plot()));

             if (layer->locked()) {
                 plotLocks[layer->plot()->id()]++;
             }
         }
     }

     for (int i = 0; i < kNumPlotsX*kNumPlotsY; ++i) {
         SkASSERT(plotLocks[i] == fPlotLocks[i]);
     }
 }

 class GrAutoValidateCache : ::SkNoncopyable {
 public:
     explicit GrAutoValidateCache(GrLayerCache* cache)
         : fCache(cache) {
         fCache->validate();
     }
     ~GrAutoValidateCache() {
         fCache->validate();
     }
 private:
     GrLayerCache* fCache;
 };
 #endif

 void GrLayerCache::purge(uint32_t pictureID) {

     SkDEBUGCODE(GrAutoValidateCache avc(this);)

     // We need to find all the layers associated with 'picture' and remove them.
     SkTDArray<GrCachedLayer*> toBeRemoved;

     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         if (pictureID == (*iter).pictureID()) {
             *toBeRemoved.append() = &(*iter);
         }
     }

     for (int i = 0; i < toBeRemoved.count(); ++i) {
         this->unlock(toBeRemoved[i]);
         fLayerHash.remove(GrCachedLayer::GetKey(*toBeRemoved[i]));
         SkDELETE(toBeRemoved[i]);
     }

     GrPictureInfo* pictInfo = fPictureHash.find(pictureID);
     if (NULL != pictInfo) {
         fPictureHash.remove(pictureID);
         SkDELETE(pictInfo);
     }
 }

 bool GrLayerCache::purgePlot() {
     SkDEBUGCODE(GrAutoValidateCache avc(this);)

     GrAtlas::PlotIter iter;
     GrPlot* plot;
     for (plot = fAtlas->iterInit(&iter, GrAtlas::kLRUFirst_IterOrder);
          NULL != plot;
          plot = iter.prev()) {
         if (fPlotLocks[plot->id()] > 0) {
             continue;
         }

         this->purgePlot(plot);
         return true;
     }

     return false;
 }

 void GrLayerCache::purgePlot(GrPlot* plot) {
     SkASSERT(0 == fPlotLocks[plot->id()]);

     // We need to find all the layers in 'plot' and remove them.
     SkTDArray<GrCachedLayer*> toBeRemoved;

     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
     for (; !iter.done(); ++iter) {
         if (plot == (*iter).plot()) {
             *toBeRemoved.append() = &(*iter);
         }
     }

     for (int i = 0; i < toBeRemoved.count(); ++i) {
         SkASSERT(!toBeRemoved[i]->locked());

         GrPictureInfo* pictInfo = fPictureHash.find(toBeRemoved[i]->pictureID());
         SkASSERT(NULL != pictInfo);

         GrAtlas::RemovePlot(&pictInfo->fPlotUsage, plot);

         // Aggressively remove layers and, if now totally uncached, picture info
         fLayerHash.remove(GrCachedLayer::GetKey(*toBeRemoved[i]));
         SkDELETE(toBeRemoved[i]);

         if (pictInfo->fPlotUsage.isEmpty()) {
             fPictureHash.remove(pictInfo->fPictureID);
             SkDELETE(pictInfo);
         }
     }

     plot->resetRects();
 }

 void GrLayerCache::purgeAll() {
     GrAtlas::PlotIter iter;
     GrPlot* plot;
     for (plot = fAtlas->iterInit(&iter, GrAtlas::kLRUFirst_IterOrder);
          NULL != plot;
          plot = iter.prev()) {
         SkASSERT(0 == fPlotLocks[plot->id()]);

         this->purgePlot(plot);
     }
 }

 class GrPictureDeletionListener : public SkPicture::DeletionListener {
     virtual void onDeletion(uint32_t pictureID) SK_OVERRIDE{
         const GrPictureDeletedMessage message = { pictureID };
         SkMessageBus<GrPictureDeletedMessage>::Post(message);
     }
 };

 void GrLayerCache::trackPicture(const SkPicture* picture) {
     if (NULL == fDeletionListener) {
         fDeletionListener.reset(SkNEW(GrPictureDeletionListener));
     }

     picture->addDeletionListener(fDeletionListener);
 }

 void GrLayerCache::processDeletedPictures() {
     SkTDArray<GrPictureDeletedMessage> deletedPictures;
     fPictDeletionInbox.poll(&deletedPictures);

     for (int i = 0; i < deletedPictures.count(); i++) {
         this->purge(deletedPictures[i].pictureID);
     }
 }
	/*
	* Copyright 2014 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "GrAtlas.h"
	#include "GrGpu.h"
	#include "GrLayerCache.h"

	DECLARE_SKMESSAGEBUS_MESSAGE(GrPictureDeletedMessage);

	#ifdef SK_DEBUG
	void GrCachedLayer::validate(const GrTexture* backingTexture) const {
	SkASSERT(SK_InvalidGenID != fKey.pictureID());
	SkASSERT(fKey.start() > 0 && fKey.stop() > 0);


	if (NULL != fTexture) {
	// If the layer is in some texture then it must occupy some rectangle
	SkASSERT(!fRect.isEmpty());
	if (!this->isAtlased()) {
	// If it isn't atlased then the rectangle should start at the origin
	SkASSERT(0.0f == fRect.fLeft && 0.0f == fRect.fTop);
	}
	} else {
	SkASSERT(fRect.isEmpty());
	SkASSERT(NULL == fPlot);
	SkASSERT(!fLocked); // layers without a texture cannot be locked
	}

	if (NULL != fPlot) {
	// If a layer has a plot (i.e., is atlased) then it must point to
	// the backing texture. Additionally, its rect should be non-empty.
	SkASSERT(NULL != fTexture && backingTexture == fTexture);
	SkASSERT(!fRect.isEmpty());
	}

	if (fLocked) {
	// If a layer is locked it must have a texture (though it need not be
	// the atlas-backing texture) and occupy some space.
	SkASSERT(NULL != fTexture);
	SkASSERT(!fRect.isEmpty());
	}
	}

	class GrAutoValidateLayer : ::SkNoncopyable {
	public:
	GrAutoValidateLayer(GrTexture* backingTexture, const GrCachedLayer* layer)
	: fBackingTexture(backingTexture)
	, fLayer(layer) {
	if (NULL != fLayer) {
	fLayer->validate(backingTexture);
	}
	}
	~GrAutoValidateLayer() {
	if (NULL != fLayer) {
	fLayer->validate(fBackingTexture);
	}
	}
	void setBackingTexture(GrTexture* backingTexture) {
	SkASSERT(NULL == fBackingTexture \|\| fBackingTexture == backingTexture);
	fBackingTexture = backingTexture;
	}

	private:
	const GrTexture* fBackingTexture;
	const GrCachedLayer* fLayer;
	};
	#endif

	GrLayerCache::GrLayerCache(GrContext* context)
	: fContext(context) {
	this->initAtlas();
	memset(fPlotLocks, 0, sizeof(fPlotLocks));
	}

	GrLayerCache::~GrLayerCache() {

	SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
	for (; !iter.done(); ++iter) {
	GrCachedLayer* layer = &(*iter);
	this->unlock(layer);
	SkDELETE(layer);
	}

	// The atlas only lets go of its texture when the atlas is deleted.
	fAtlas.free();
	}

	void GrLayerCache::initAtlas() {
	SkASSERT(NULL == fAtlas.get());

	SkISize textureSize = SkISize::Make(kAtlasTextureWidth, kAtlasTextureHeight);
	fAtlas.reset(SkNEW_ARGS(GrAtlas, (fContext->getGpu(), kSkia8888_GrPixelConfig,
	kRenderTarget_GrTextureFlagBit,
	textureSize, kNumPlotsX, kNumPlotsY, false)));
	}

	void GrLayerCache::freeAll() {

	SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
	for (; !iter.done(); ++iter) {
	GrCachedLayer* layer = &(*iter);
	this->unlock(layer);
	SkDELETE(layer);
	}
	fLayerHash.rewind();

	// The atlas only lets go of its texture when the atlas is deleted.
	fAtlas.free();
	// GrLayerCache always assumes an atlas exists so recreate it. The atlas
	// lazily allocates a replacement texture so reallocating a new
	// atlas here won't disrupt a GrContext::abandonContext or freeGpuResources.
	// TODO: Make GrLayerCache lazily allocate the atlas manager?
	this->initAtlas();
	}

	GrCachedLayer* GrLayerCache::createLayer(uint32_t pictureID,
	int start, int stop,
	const SkMatrix& ctm) {
	SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);

	GrCachedLayer* layer = SkNEW_ARGS(GrCachedLayer, (pictureID, start, stop, ctm));
	fLayerHash.add(layer);
	return layer;
	}

	GrCachedLayer* GrLayerCache::findLayer(uint32_t pictureID,
	int start, int stop,
	const SkMatrix& ctm) {
	SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);
	return fLayerHash.find(GrCachedLayer::Key(pictureID, start, stop, ctm));
	}

	GrCachedLayer* GrLayerCache::findLayerOrCreate(uint32_t pictureID,
	int start, int stop,
	const SkMatrix& ctm) {
	SkASSERT(pictureID != SK_InvalidGenID && start > 0 && stop > 0);
	GrCachedLayer* layer = fLayerHash.find(GrCachedLayer::Key(pictureID, start, stop, ctm));
	if (NULL == layer) {
	layer = this->createLayer(pictureID, start, stop, ctm);
	}

	return layer;
	}

	bool GrLayerCache::lock(GrCachedLayer* layer, const GrTextureDesc& desc, bool dontAtlas) {
	SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)

	if (layer->locked()) {
	// This layer is already locked
	#ifdef SK_DEBUG
	if (layer->isAtlased()) {
	// It claims to be atlased
	SkASSERT(!dontAtlas);
	SkASSERT(layer->rect().width() == desc.fWidth);
	SkASSERT(layer->rect().height() == desc.fHeight);
	}
	#endif
	return false;
	}

	if (layer->isAtlased()) {
	// Hooray it is still in the atlas - make sure it stays there
	SkASSERT(!dontAtlas);
	layer->setLocked(true);
	fPlotLocks[layer->plot()->id()]++;
	return false;
	} else if (!dontAtlas && PlausiblyAtlasable(desc.fWidth, desc.fHeight)) {
	// Not in the atlas - will it fit?
	GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
	if (NULL == pictInfo) {
	pictInfo = SkNEW_ARGS(GrPictureInfo, (layer->pictureID()));
	fPictureHash.add(pictInfo);
	}

	SkIPoint16 loc;
	for (int i = 0; i < 2; ++i) { // extra pass in case we fail to add but are able to purge
	GrPlot* plot = fAtlas->addToAtlas(&pictInfo->fPlotUsage,
	desc.fWidth, desc.fHeight,
	NULL, &loc);
	// addToAtlas can allocate the backing texture
	SkDEBUGCODE(avl.setBackingTexture(fAtlas->getTexture()));
	if (NULL != plot) {
	// The layer was successfully added to the atlas
	GrIRect16 bounds = GrIRect16::MakeXYWH(loc.fX, loc.fY,
	SkToS16(desc.fWidth),
	SkToS16(desc.fHeight));
	layer->setTexture(fAtlas->getTexture(), bounds);
	layer->setPlot(plot);
	layer->setLocked(true);
	fPlotLocks[layer->plot()->id()]++;
	return true;
	}

	// The layer was rejected by the atlas (even though we know it is
	// plausibly atlas-able). See if a plot can be purged and try again.
	if (!this->purgePlot()) {
	break; // We weren't able to purge any plots
	}
	}
	}

	// The texture wouldn't fit in the cache - give it it's own texture.
	// This path always uses a new scratch texture and (thus) doesn't cache anything.
	// This can yield a lot of re-rendering
	SkAutoTUnref<GrTexture> tex(fContext->lockAndRefScratchTexture(desc,
	GrContext::kApprox_ScratchTexMatch));

	layer->setTexture(tex, GrIRect16::MakeWH(SkToS16(desc.fWidth), SkToS16(desc.fHeight)));
	layer->setLocked(true);
	return true;
	}

	void GrLayerCache::unlock(GrCachedLayer* layer) {
	SkDEBUGCODE(GrAutoValidateLayer avl(fAtlas->getTexture(), layer);)

	if (NULL == layer \|\| !layer->locked()) {
	// invalid or not locked
	return;
	}

	if (layer->isAtlased()) {
	const int plotID = layer->plot()->id();

	SkASSERT(fPlotLocks[plotID] > 0);
	fPlotLocks[plotID]--;
	// At this point we could aggressively clear out un-locked plots but
	// by delaying we may be able to reuse some of the atlased layers later.
	#if DISABLE_CACHING
	// This testing code aggressively removes the atlased layers. This
	// can be used to separate the performance contribution of less
	// render target pingponging from that due to the re-use of cached layers
	GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
	SkASSERT(NULL != pictInfo);

	GrAtlas::RemovePlot(&pictInfo->fPlotUsage, layer->plot());

	layer->setPlot(NULL);
	layer->setTexture(NULL, GrIRect16::MakeEmpty());
	#endif

	} else {
	fContext->unlockScratchTexture(layer->texture());
	layer->setTexture(NULL, GrIRect16::MakeEmpty());
	}

	layer->setLocked(false);
	}

	#ifdef SK_DEBUG
	void GrLayerCache::validate() const {
	int plotLocks[kNumPlotsX * kNumPlotsY];
	memset(plotLocks, 0, sizeof(plotLocks));

	SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::ConstIter iter(&fLayerHash);
	for (; !iter.done(); ++iter) {
	const GrCachedLayer* layer = &(*iter);

	layer->validate(fAtlas->getTexture());

	const GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
	if (NULL != pictInfo) {
	// In aggressive cleanup mode a picture info should only exist if
	// it has some atlased layers
	#if !DISABLE_CACHING
	SkASSERT(!pictInfo->fPlotUsage.isEmpty());
	#endif
	} else {
	// If there is no picture info for this layer then all of its
	// layers should be non-atlased.
	SkASSERT(!layer->isAtlased());
	}

	if (NULL != layer->plot()) {
	SkASSERT(NULL != pictInfo);
	SkASSERT(pictInfo->fPictureID == layer->pictureID());

	SkASSERT(pictInfo->fPlotUsage.contains(layer->plot()));

	if (layer->locked()) {
	plotLocks[layer->plot()->id()]++;
	}
	}
	}

	for (int i = 0; i < kNumPlotsX*kNumPlotsY; ++i) {
	SkASSERT(plotLocks[i] == fPlotLocks[i]);
	}
	}

	class GrAutoValidateCache : ::SkNoncopyable {
	public:
	explicit GrAutoValidateCache(GrLayerCache* cache)
	: fCache(cache) {
	fCache->validate();
	}
	~GrAutoValidateCache() {
	fCache->validate();
	}
	private:
	GrLayerCache* fCache;
	};
	#endif

	void GrLayerCache::purge(uint32_t pictureID) {

	SkDEBUGCODE(GrAutoValidateCache avc(this);)

	// We need to find all the layers associated with 'picture' and remove them.
	SkTDArray<GrCachedLayer*> toBeRemoved;

	SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
	for (; !iter.done(); ++iter) {
	if (pictureID == (*iter).pictureID()) {
	toBeRemoved.append() = &(iter);
	}
	}

	for (int i = 0; i < toBeRemoved.count(); ++i) {
	this->unlock(toBeRemoved[i]);
	fLayerHash.remove(GrCachedLayer::GetKey(*toBeRemoved[i]));
	SkDELETE(toBeRemoved[i]);
	}

	GrPictureInfo* pictInfo = fPictureHash.find(pictureID);
	if (NULL != pictInfo) {
	fPictureHash.remove(pictureID);
	SkDELETE(pictInfo);
	}
	}

	bool GrLayerCache::purgePlot() {
	SkDEBUGCODE(GrAutoValidateCache avc(this);)

	GrAtlas::PlotIter iter;
	GrPlot* plot;
	for (plot = fAtlas->iterInit(&iter, GrAtlas::kLRUFirst_IterOrder);
	NULL != plot;
	plot = iter.prev()) {
	if (fPlotLocks[plot->id()] > 0) {
	continue;
	}

	this->purgePlot(plot);
	return true;
	}

	return false;
	}

	void GrLayerCache::purgePlot(GrPlot* plot) {
	SkASSERT(0 == fPlotLocks[plot->id()]);

	// We need to find all the layers in 'plot' and remove them.
	SkTDArray<GrCachedLayer*> toBeRemoved;

	SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);
	for (; !iter.done(); ++iter) {
	if (plot == (*iter).plot()) {
	toBeRemoved.append() = &(iter);
	}
	}

	for (int i = 0; i < toBeRemoved.count(); ++i) {
	SkASSERT(!toBeRemoved[i]->locked());

	GrPictureInfo* pictInfo = fPictureHash.find(toBeRemoved[i]->pictureID());
	SkASSERT(NULL != pictInfo);

	GrAtlas::RemovePlot(&pictInfo->fPlotUsage, plot);

	// Aggressively remove layers and, if now totally uncached, picture info
	fLayerHash.remove(GrCachedLayer::GetKey(*toBeRemoved[i]));
	SkDELETE(toBeRemoved[i]);

	if (pictInfo->fPlotUsage.isEmpty()) {
	fPictureHash.remove(pictInfo->fPictureID);
	SkDELETE(pictInfo);
	}
	}

	plot->resetRects();
	}

	void GrLayerCache::purgeAll() {
	GrAtlas::PlotIter iter;
	GrPlot* plot;
	for (plot = fAtlas->iterInit(&iter, GrAtlas::kLRUFirst_IterOrder);
	NULL != plot;
	plot = iter.prev()) {
	SkASSERT(0 == fPlotLocks[plot->id()]);

	this->purgePlot(plot);
	}
	}

	class GrPictureDeletionListener : public SkPicture::DeletionListener {
	virtual void onDeletion(uint32_t pictureID) SK_OVERRIDE{
	const GrPictureDeletedMessage message = { pictureID };
	SkMessageBus<GrPictureDeletedMessage>::Post(message);
	}
	};

	void GrLayerCache::trackPicture(const SkPicture* picture) {
	if (NULL == fDeletionListener) {
	fDeletionListener.reset(SkNEW(GrPictureDeletionListener));
	}

	picture->addDeletionListener(fDeletionListener);
	}

	void GrLayerCache::processDeletedPictures() {
	SkTDArray<GrPictureDeletedMessage> deletedPictures;
	fPictDeletionInbox.poll(&deletedPictures);

	for (int i = 0; i < deletedPictures.count(); i++) {
	this->purge(deletedPictures[i].pictureID);
	}
	}