Make GrResourceCache use a priority queue of purgeable resources.

Review URL: https://codereview.chromium.org/921323002

include/gpu/GrGpuResource.h

@@ -269,7 +269,7 @@ private:
 
     virtual size_t onGpuMemorySize() const = 0;
 
-    // See comments in CacheAccess.
+    // See comments in CacheAccess and ResourcePriv.
     bool setContentKey(const GrContentKey& contentKey);
     void removeContentKey();
     void notifyIsPurgeable() const;
@@ -283,9 +283,15 @@ private:
 
     static uint32_t CreateUniqueID();
 
-    // We're in an internal doubly linked list owned by GrResourceCache
+    // We're in an internal doubly linked list owned by GrResourceCache. TODO: Replace this with an
+    // array of unpurgeable resources in the cache.
     SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrGpuResource);
 
+    // An index into a heap when this resource is purgeable. 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;
 
     static const size_t kInvalidGpuMemorySize = ~static_cast<size_t>(0);
     GrScratchKey                fScratchKey;

src/core/SkTDPQueue.h

@@ -92,6 +92,10 @@ public:
         this->validate();
     }
 
+#ifdef SK_DEBUG
+    T at(int i) const { return fArray[i]; }
+#endif
+
 private:
     static int LeftOf(int x) { SkASSERT(x >= 0); return 2 * x + 1; }
     static int ParentOf(int x) { SkASSERT(x > 0); return (x - 1) >> 1; }

src/gpu/GrGpuResource.cpp

@@ -23,6 +23,7 @@ GrGpuResource::GrGpuResource(GrGpu* gpu, LifeCycle lifeCycle)
     , fGpuMemorySize(kInvalidGpuMemorySize)
     , fLifeCycle(lifeCycle)
     , fUniqueID(CreateUniqueID()) {
+    SkDEBUGCODE(fCacheArrayIndex = -1);
 }
 
 void GrGpuResource::registerWithCache() {

src/gpu/GrGpuResourceCacheAccess.h

@@ -55,6 +55,11 @@ private:
         }
     }
 
+    uint32_t timestamp() const { return fResource->fTimestamp; }
+    void setTimestamp(uint32_t ts) { fResource->fTimestamp = ts; }
+
+    int* accessCacheIndex() const { return &fResource->fCacheArrayIndex; }
+
     CacheAccess(GrGpuResource* resource) : fResource(resource) {}
     CacheAccess(const CacheAccess& that) : fResource(that.fResource) {}
     CacheAccess& operator=(const CacheAccess&); // unimpl

src/gpu/GrResourceCache.cpp

@@ -58,7 +58,8 @@ static const int kDefaultMaxCount = 2 * (1 << 10);
 static const size_t kDefaultMaxSize = 96 * (1 << 20);
 
 GrResourceCache::GrResourceCache()
-    : fMaxCount(kDefaultMaxCount)
+    : fTimestamp(0)
+    , fMaxCount(kDefaultMaxCount)
     , fMaxBytes(kDefaultMaxSize)
 #if GR_CACHE_STATS
     , fHighWaterCount(0)
@@ -70,8 +71,6 @@ GrResourceCache::GrResourceCache()
     , fBytes(0)
     , fBudgetedCount(0)
     , fBudgetedBytes(0)
-    , fPurging(false)
-    , fNewlyPurgeableResourceWhilePurging(false)
     , fOverBudgetCB(NULL)
     , fOverBudgetData(NULL) {
 }
@@ -90,7 +89,6 @@ void GrResourceCache::insertResource(GrGpuResource* resource) {
     SkASSERT(resource);
     SkASSERT(!resource->wasDestroyed());
     SkASSERT(!this->isInCache(resource));
-    SkASSERT(!fPurging);
     fResources.addToHead(resource);
 
     size_t size = resource->gpuMemorySize();
@@ -112,13 +110,20 @@ void GrResourceCache::insertResource(GrGpuResource* resource) {
         SkASSERT(!resource->cacheAccess().isWrapped());
         fScratchMap.insert(resource->resourcePriv().getScratchKey(), resource);
     }
-    
+
+    resource->cacheAccess().setTimestamp(fTimestamp++);
+
     this->purgeAsNeeded();
 }
 
 void GrResourceCache::removeResource(GrGpuResource* resource) {
+    this->validate();
     SkASSERT(this->isInCache(resource));
 
+    if (resource->isPurgeable()) {
+        fPurgeableQueue.remove(resource);
+    }
+
     size_t size = resource->gpuMemorySize();
     --fCount;
     fBytes -= size;
@@ -140,7 +145,6 @@ void GrResourceCache::removeResource(GrGpuResource* resource) {
 void GrResourceCache::abandonAll() {
     AutoValidate av(this);
 
-    SkASSERT(!fPurging);
     while (GrGpuResource* head = fResources.head()) {
         SkASSERT(!head->wasDestroyed());
         head->cacheAccess().abandon();
@@ -158,7 +162,6 @@ void GrResourceCache::abandonAll() {
 void GrResourceCache::releaseAll() {
     AutoValidate av(this);
 
-    SkASSERT(!fPurging);
     while (GrGpuResource* head = fResources.head()) {
         SkASSERT(!head->wasDestroyed());
         head->cacheAccess().release();
@@ -188,16 +191,14 @@ private:
 };
 
 GrGpuResource* GrResourceCache::findAndRefScratchResource(const GrScratchKey& scratchKey,
-                                                           uint32_t flags) {
+                                                          uint32_t flags) {
-    SkASSERT(!fPurging);
     SkASSERT(scratchKey.isValid());
 
     GrGpuResource* resource;
     if (flags & (kPreferNoPendingIO_ScratchFlag | kRequireNoPendingIO_ScratchFlag)) {
         resource = fScratchMap.find(scratchKey, AvailableForScratchUse(true));
         if (resource) {
-            resource->ref();
+            this->refAndMakeResourceMRU(resource);
-            this->makeResourceMRU(resource);
             this->validate();
             return resource;
         } else if (flags & kRequireNoPendingIO_ScratchFlag) {
@@ -208,8 +209,7 @@ GrGpuResource* GrResourceCache::findAndRefScratchResource(const GrScratchKey& sc
     }
     resource = fScratchMap.find(scratchKey, AvailableForScratchUse(false));
     if (resource) {
-        resource->ref();
+        this->refAndMakeResourceMRU(resource);
-        this->makeResourceMRU(resource);
         this->validate();
     }
     return resource;
@@ -228,7 +228,6 @@ void GrResourceCache::willRemoveContentKey(const GrGpuResource* resource) {
 }
 
 bool GrResourceCache::didSetContentKey(GrGpuResource* resource) {
-    SkASSERT(!fPurging);
     SkASSERT(resource);
     SkASSERT(this->isInCache(resource));
     SkASSERT(resource->getContentKey().isValid());
@@ -243,12 +242,16 @@ bool GrResourceCache::didSetContentKey(GrGpuResource* resource) {
     return true;
 }
 
-void GrResourceCache::makeResourceMRU(GrGpuResource* resource) {
+void GrResourceCache::refAndMakeResourceMRU(GrGpuResource* resource) {
-    SkASSERT(!fPurging);
     SkASSERT(resource);
     SkASSERT(this->isInCache(resource));
-    fResources.remove(resource);    
+    if (resource->isPurgeable()) {
-    fResources.addToHead(resource);
+        // It's about to become unpurgeable.
+        fPurgeableQueue.remove(resource);
+    }
+    resource->ref();
+    resource->cacheAccess().setTimestamp(fTimestamp++);
+    SkASSERT(!resource->isPurgeable());
 }
 
 void GrResourceCache::notifyPurgeable(GrGpuResource* resource) {
@@ -256,49 +259,37 @@ void GrResourceCache::notifyPurgeable(GrGpuResource* resource) {
     SkASSERT(this->isInCache(resource));
     SkASSERT(resource->isPurgeable());
 
-    // We can't purge if in the middle of purging because purge is iterating. Instead record
+    SkASSERT(-1 == *resource->cacheAccess().accessCacheIndex());
-    // that additional resources became purgeable.
+    fPurgeableQueue.insert(resource);
-    if (fPurging) {
-        fNewlyPurgeableResourceWhilePurging = true;
-        return;
-    }
 
-    bool release = false;
+    if (!resource->resourcePriv().isBudgeted()) {
-
-    if (resource->cacheAccess().isWrapped()) {
-        release = true;
-    } else if (!resource->resourcePriv().isBudgeted()) {
         // Check whether this resource could still be used as a scratch resource.
-        if (resource->resourcePriv().getScratchKey().isValid()) {
+        if (!resource->cacheAccess().isWrapped() &&
+            resource->resourcePriv().getScratchKey().isValid()) {
             // We won't purge an existing resource to make room for this one.
             bool underBudget = fBudgetedCount < fMaxCount &&
                                fBudgetedBytes + resource->gpuMemorySize() <= fMaxBytes;
             if (underBudget) {
                 resource->resourcePriv().makeBudgeted();
-            } else {
+                return;
-                release = true;
             }
-        } else {
-            release = true;
         }
     } else {
-        // Purge the resource if we're over budget
+        // Purge the resource immediately if we're over budget
         bool overBudget = fBudgetedCount > fMaxCount || fBudgetedBytes > fMaxBytes;
 
         // Also purge if the resource has neither a valid scratch key nor a content key.
         bool noKey = !resource->resourcePriv().getScratchKey().isValid() &&
-                     !resource->getContentKey().isValid();
+                        !resource->getContentKey().isValid();
-        if (overBudget || noKey) {
+        if (!overBudget && !noKey) {
-            release = true;
+            return;
         }
     }
 
-    if (release) {
+    SkDEBUGCODE(int beforeCount = fCount;)
-        SkDEBUGCODE(int beforeCount = fCount;)
+    resource->cacheAccess().release();
-        resource->cacheAccess().release();
+    // We should at least free this resource, perhaps dependent resources as well.
-        // We should at least free this resource, perhaps dependent resources as well.
+    SkASSERT(fCount < beforeCount);
-        SkASSERT(fCount < beforeCount);
-    }
     this->validate();
 }
 
@@ -325,7 +316,6 @@ void GrResourceCache::didChangeGpuMemorySize(const GrGpuResource* resource, size
 }
 
 void GrResourceCache::didChangeBudgetStatus(GrGpuResource* resource) {
-    SkASSERT(!fPurging);
     SkASSERT(resource);
     SkASSERT(this->isInCache(resource));
 
@@ -348,67 +338,38 @@ void GrResourceCache::didChangeBudgetStatus(GrGpuResource* resource) {
 }
 
 void GrResourceCache::internalPurgeAsNeeded() {
-    SkASSERT(!fPurging);
-    SkASSERT(!fNewlyPurgeableResourceWhilePurging);
     SkASSERT(fBudgetedCount > fMaxCount || fBudgetedBytes > fMaxBytes);
 
-    fPurging = true;
+    bool stillOverbudget = true;
-
+    while (fPurgeableQueue.count()) {
-    bool overBudget = true;
+        GrGpuResource* resource = fPurgeableQueue.peek();
-    do {
+        SkASSERT(resource->isPurgeable());
-        fNewlyPurgeableResourceWhilePurging = false;
+        resource->cacheAccess().release();
-        ResourceList::Iter resourceIter;
+        if (fBudgetedCount <= fMaxCount && fBudgetedBytes <= fMaxBytes) {
-        GrGpuResource* resource = resourceIter.init(fResources,
+            stillOverbudget = false;
-                                                    ResourceList::Iter::kTail_IterStart);
+            break;
-
-        while (resource) {
-            GrGpuResource* prev = resourceIter.prev();
-            if (resource->isPurgeable()) {
-                resource->cacheAccess().release();
-            }
-            resource = prev;
-            if (fBudgetedCount <= fMaxCount && fBudgetedBytes <= fMaxBytes) {
-                overBudget = false;
-                resource = NULL;
-            }
         }
+    }
 
-        if (!fNewlyPurgeableResourceWhilePurging && overBudget && fOverBudgetCB) {
-            // Despite the purge we're still over budget. Call our over budget callback.
-            (*fOverBudgetCB)(fOverBudgetData);
-        }
-    } while (overBudget && fNewlyPurgeableResourceWhilePurging);
-
-    fNewlyPurgeableResourceWhilePurging = false;
-    fPurging = false;
     this->validate();
+
+    if (stillOverbudget) {
+        // Despite the purge we're still over budget. Call our over budget callback. If this frees
+        // any resources then we'll get notifyPurgeable() calls and take appropriate action.
+        (*fOverBudgetCB)(fOverBudgetData);
+        this->validate();
+    }
 }
 
 void GrResourceCache::purgeAllUnlocked() {
-    SkASSERT(!fPurging);
+    // We could disable maintaining the heap property here, but it would add a lot of complexity.
-    SkASSERT(!fNewlyPurgeableResourceWhilePurging);
+    // Moreover, this is rarely called.
+    while (fPurgeableQueue.count()) {
+        GrGpuResource* resource = fPurgeableQueue.peek();
+        SkASSERT(resource->isPurgeable());
+        resource->cacheAccess().release();
+    }
 
-    fPurging = true;
-
-    do {
-        fNewlyPurgeableResourceWhilePurging = false;
-        ResourceList::Iter resourceIter;
-        GrGpuResource* resource =
-            resourceIter.init(fResources, ResourceList::Iter::kTail_IterStart);
-
-        while (resource) {
-            GrGpuResource* prev = resourceIter.prev();
-            if (resource->isPurgeable()) {
-                resource->cacheAccess().release();
-            }
-            resource = prev;
-        }
-
-        if (!fNewlyPurgeableResourceWhilePurging && fCount && fOverBudgetCB) {
-            (*fOverBudgetCB)(fOverBudgetData);
-        }
-    } while (fNewlyPurgeableResourceWhilePurging);
-    fPurging = false;
     this->validate();
 }
 
@@ -475,8 +436,17 @@ void GrResourceCache::validate() const {
             ++budgetedCount;
             budgetedBytes += resource->gpuMemorySize();
         }
+
+        if (!resource->isPurgeable()) {
+            SkASSERT(-1 == *resource->cacheAccess().accessCacheIndex());
+        }
     }
 
+    for (int i = 0; i < fPurgeableQueue.count(); ++i) {
+        SkASSERT(fPurgeableQueue.at(i)->isPurgeable());
+    }
+
+    SkASSERT(fCount - locked == fPurgeableQueue.count());
     SkASSERT(fBudgetedCount <= fCount);
     SkASSERT(fBudgetedBytes <= fBudgetedBytes);
     SkASSERT(bytes == fBytes);

src/gpu/GrResourceCache.h

@@ -10,11 +10,13 @@
 #define GrResourceCache_DEFINED
 
 #include "GrGpuResource.h"
+#include "GrGpuResourceCacheAccess.h"
 #include "GrGpuResourcePriv.h"
 #include "GrResourceKey.h"
 #include "SkMessageBus.h"
 #include "SkRefCnt.h"
 #include "SkTArray.h"
+#include "SkTDPQueue.h"
 #include "SkTInternalLList.h"
 #include "SkTMultiMap.h"
 
@@ -117,8 +119,7 @@ public:
     GrGpuResource* findAndRefContentResource(const GrContentKey& contentKey) {
         GrGpuResource* resource = fContentHash.find(contentKey);
         if (resource) {
-            resource->ref();
+            this->refAndMakeResourceMRU(resource);
-            this->makeResourceMRU(resource);
         }
         return resource;
     }
@@ -138,7 +139,7 @@ public:
         if (invalidKeyMsgs.count()) {
             this->processInvalidContentKeys(invalidKeyMsgs);
         }
-        if (fPurging || (fBudgetedCount <= fMaxCount && fBudgetedBytes <= fMaxBytes)) {
+        if (fBudgetedCount <= fMaxCount && fBudgetedBytes <= fMaxBytes) {
             return;
         }
         this->internalPurgeAsNeeded();
@@ -179,7 +180,7 @@ private:
     void willRemoveScratchKey(const GrGpuResource*);
     void willRemoveContentKey(const GrGpuResource*);
     void didChangeBudgetStatus(GrGpuResource*);
-    void makeResourceMRU(GrGpuResource*);
+    void refAndMakeResourceMRU(GrGpuResource*);
     /// @}
 
     void internalPurgeAsNeeded();
@@ -216,9 +217,26 @@ private:
 
     typedef SkTInternalLList<GrGpuResource> ResourceList;
 
-    typedef SkMessageBus<GrContentKeyInvalidatedMessage>::Inbox InvalidContentKeyInbox;
+    static bool CompareTimestamp(GrGpuResource* const& a, GrGpuResource* const& b) {
+        return a->cacheAccess().timestamp() < b->cacheAccess().timestamp();
+    }
 
+    static int* AccessResourceIndex(GrGpuResource* const& res) {
+        return res->cacheAccess().accessCacheIndex();
+    }
+
+    typedef SkMessageBus<GrContentKeyInvalidatedMessage>::Inbox InvalidContentKeyInbox;
+    typedef SkTDPQueue<GrGpuResource*, CompareTimestamp, AccessResourceIndex> PurgeableQueue;
+
+    // Whenever a resource is added to the cache or the result of a cache lookup, fTimestamp is
+    // assigned as the resource's timestamp and then incremented. fPurgeableQueue orders the
+    // purgeable resources by this value, and thus is used to purge resources in LRU order.
+    uint32_t                            fTimestamp;
+    PurgeableQueue                      fPurgeableQueue;
+
+    // TODO: Replace this with an array of nonpurgeable resources
     ResourceList                        fResources;
+
     // This map holds all resources that can be used as scratch resources.
     ScratchMap                          fScratchMap;
     // This holds all resources that have content keys.
@@ -243,15 +261,10 @@ private:
     int                                 fBudgetedCount;
     size_t                              fBudgetedBytes;
 
-    // prevents recursive purging
-    bool                                fPurging;
-    bool                                fNewlyPurgeableResourceWhilePurging;
-
     PFOverBudgetCB                      fOverBudgetCB;
     void*                               fOverBudgetData;
 
     InvalidContentKeyInbox              fInvalidContentKeyInbox;
-
 };
 
 class GrResourceCache::ResourceAccess {