Add abliity to set textblob cache budget to GrContext

src/gpu/GrTextBlobCache.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextBlobCache_DEFINED
 #define GrTextBlobCache_DEFINED
 
 #include "GrAtlasTextContext.h"
 #include "SkTDynamicHash.h"
 #include "SkTextBlob.h"
 
 class GrTextBlobCache {
 public:
     /**
      * The callback function used by the cache when it is still over budget after a purge. The
      * passed in 'data' is the same 'data' handed to setOverbudgetCallback.
      */
     typedef void (*PFOverBudgetCB)(void* data);
 
     GrTextBlobCache(PFOverBudgetCB cb, void* data)
         : fPool(kPreAllocSize, kMinGrowthSize)
         , fCallback(cb)
-        , fData(data) {
+        , fData(data)
+        , fBudget(kDefaultBudget) {
         SkASSERT(cb && data);
     }
     ~GrTextBlobCache();
 
     // creates an uncached blob
     GrAtlasTextBlob* createBlob(int glyphCount, int runCount, size_t maxVASize);
     GrAtlasTextBlob* createBlob(const SkTextBlob* blob, size_t maxVAStride) {
         int glyphCount = 0;
         int runCount = 0;
         BlobGlyphCount(&glyphCount, &runCount, blob);
@@ skipping 37 matching lines @@
     void remove(GrAtlasTextBlob* blob) {
         fCache.remove(blob->fKey);
         fBlobList.remove(blob);
         blob->unref();
     }
 
     void add(GrAtlasTextBlob* blob) {
         fCache.add(blob);
         fBlobList.addToHead(blob);
 
+        this->checkPurge(blob);
+    }
+
+    void makeMRU(GrAtlasTextBlob* blob) {
+        if (fBlobList.head() == blob) {
+            return;
+        }
+
+        fBlobList.remove(blob);
+        fBlobList.addToHead(blob);
+    }
+
+    void freeAll();
+
+    // TODO move to SkTextBlob
+    static void BlobGlyphCount(int* glyphCount, int* runCount, const SkTextBlob* blob) {
+        SkTextBlob::RunIterator itCounter(blob);
+        for (; !itCounter.done(); itCounter.next(), (*runCount)++) {
+            *glyphCount += itCounter.glyphCount();
+        }
+    }
+
+    void setBudget(size_t budget) {
+        fBudget = budget;
+        this->checkPurge();
+    }
+
+private:
+    typedef SkTInternalLList<GrAtlasTextBlob> BitmapBlobList;
+
+    void checkPurge(GrAtlasTextBlob* blob = NULL) {
         // If we are overbudget, then unref until we are below budget again
-        if (fPool.size() > kBudget) {
+        if (fPool.size() > fBudget) {
             BitmapBlobList::Iter iter;
             iter.init(fBlobList, BitmapBlobList::Iter::kTail_IterStart);
             GrAtlasTextBlob* lruBlob = iter.get();
             SkASSERT(lruBlob);
-            while (fPool.size() > kBudget && (lruBlob = iter.get()) && lruBlob != blob) {
+            while (fPool.size() > fBudget && (lruBlob = iter.get()) && lruBlob != blob) {
                 fCache.remove(lruBlob->fKey);
 
                 // Backup the iterator before removing and unrefing the blob
                 iter.prev();
                 fBlobList.remove(lruBlob);
                 lruBlob->unref();
             }
 
             // If we break out of the loop with lruBlob == blob, then we haven't purged enough
             // use the call back and try to free some more.  If we are still overbudget after this,
             // then this single textblob is over our budget
-            if (lruBlob == blob) {
+            if (blob && lruBlob == blob) {
                 (*fCallback)(fData);
             }
 
-#ifdef SK_DEBUG
-            if (fPool.size() > kBudget) {
+#ifdef SPEW_BUDGET_MESSAGE
+            if (fPool.size() > fBudget) {
                 SkDebugf("Single textblob is larger than our whole budget");
             }
 #endif
         }
     }
 
-    void makeMRU(GrAtlasTextBlob* blob) {
-        if (fBlobList.head() == blob) {
-            return;
-        }
-
-        fBlobList.remove(blob);
-        fBlobList.addToHead(blob);
-    }
-
-    void freeAll();
-
-    // TODO move to SkTextBlob
-    static void BlobGlyphCount(int* glyphCount, int* runCount, const SkTextBlob* blob) {
-        SkTextBlob::RunIterator itCounter(blob);
-        for (; !itCounter.done(); itCounter.next(), (*runCount)++) {
-            *glyphCount += itCounter.glyphCount();
-        }
-    }
-
-private:
-    typedef SkTInternalLList<GrAtlasTextBlob> BitmapBlobList;
-
     // Budget was chosen to be ~4 megabytes.  The min alloc and pre alloc sizes in the pool are
     // based off of the largest cached textblob I have seen in the skps(a couple of kilobytes).
     static const int kPreAllocSize = 1 << 17;
     static const int kMinGrowthSize = 1 << 17;
-    static const int kBudget = 1 << 22;
+    static const int kDefaultBudget = 1 << 22;
     BitmapBlobList fBlobList;
     SkTDynamicHash<GrAtlasTextBlob, GrAtlasTextBlob::Key> fCache;
     GrMemoryPool fPool;
     PFOverBudgetCB fCallback;
     void* fData;
+    size_t fBudget;
 };
 
 #endif