GPU Font Cache improvements:

src/gpu/GrTextStrike.cpp

Index: src/gpu/GrTextStrike.cpp
diff --git a/src/gpu/GrTextStrike.cpp b/src/gpu/GrTextStrike.cpp
index 071c5d272486eadc77a36200e337e6bc15e19088..c1ee5b40c638f06e45492d63df3116584e098507 100644
--- a/src/gpu/GrTextStrike.cpp
+++ b/src/gpu/GrTextStrike.cpp
@@ -62,19 +62,48 @@ void GrFontCache::freeAll() {
 
 void GrFontCache::purgeExceptFor(GrTextStrike* preserveStrike) {
     GrTextStrike* strike = fTail;
+    bool purge = true;
     while (strike) {
         if (strike == preserveStrike) {
             strike = strike->fPrev;
             continue;
         }
         GrTextStrike* strikeToPurge = strike;
-        // keep going if we won't free up any atlases with this strike.
-        strike = (NULL == strikeToPurge->fAtlas) ? strikeToPurge->fPrev : NULL;
-        int index = fCache.slowFindIndex(strikeToPurge);
-        GrAssert(index >= 0);
-        fCache.removeAt(index, strikeToPurge->fFontScalerKey->getHash());
-        this->detachStrikeFromList(strikeToPurge);
-        delete strikeToPurge;
+        strike = strikeToPurge->fPrev;
+        if (purge) {
+            // keep purging if we won't free up any atlases with this strike.
+            purge = (NULL == strikeToPurge->fAtlas);
+            int index = fCache.slowFindIndex(strikeToPurge);
+            GrAssert(index >= 0);
+            fCache.removeAt(index, strikeToPurge->fFontScalerKey->getHash());
+            this->detachStrikeFromList(strikeToPurge);
+            delete strikeToPurge;
+        } else {
+            // for the remaining strikes, we just mark them unused
+            strikeToPurge->markAtlasesUnused();
+        }
+    }
+}
+
+void GrFontCache::freeAtlasExceptFor(GrTextStrike* preserveStrike) {
+    GrTextStrike* strike = fTail;
+    while (strike) {
+        if (strike == preserveStrike) {
+            strike = strike->fPrev;
+            continue;
+        }
+        GrTextStrike* strikeToPurge = strike;
+        strike = strikeToPurge->fPrev;
+        if (strikeToPurge->removeUnusedAtlas()) {
+            if (NULL == strikeToPurge->fAtlas) {
+                int index = fCache.slowFindIndex(strikeToPurge);
+                GrAssert(index >= 0);
+                fCache.removeAt(index, strikeToPurge->fFontScalerKey->getHash());
+                this->detachStrikeFromList(strikeToPurge);
+                delete strikeToPurge;
+            }
+            break;
+        }
     }
 }
 
@@ -142,6 +171,12 @@ GrTextStrike::GrTextStrike(GrFontCache* cache, const GrKey* key,
 
 static void FreeGlyph(GrGlyph*& glyph) { glyph->free(); }
 

[robertphillips, 2013/08/02 15:23:50]

invalidate_glyph?
GrGlyph*?

[bsalomon, 2013/08/02 15:30:35]

ref to a ptr feels weird to me. We aren't assigning to glyph so does the ref
matter?

[jvanverth1, 2013/08/02 21:49:27]

The ref is needed because this function is used in visitAll(), below.

On 2013/08/02 15:30:35, bsalomon wrote:

[bsalomon, 2013/08/05 13:09:54]

Gotcha, maybe a comment // this is used with SkTDArray::vistAll()
? Otherwise the signature will look odd I to a reader I think.

+static void InvalidateGlyph(GrGlyph*& glyph) { 
+    if (glyph->fAtlas && !glyph->fAtlas->fUsed) {
+        glyph->fAtlas = NULL;
+    }
+}
+
 GrTextStrike::~GrTextStrike() {
     GrAtlas::FreeLList(fAtlas);
     fFontScalerKey->unref();
@@ -166,6 +201,34 @@ GrGlyph* GrTextStrike::generateGlyph(GrGlyph::PackedID packed,
     return glyph;
 }
 
+bool GrTextStrike::removeUnusedAtlas() {

[robertphillips, 2013/08/02 15:23:50]

Why is prev a GrAtlas**?

[jvanverth1, 2013/08/02 21:49:27]

Moved to GrAtlas.cpp, but that's done so I don't have to check whether we're at
the head of the list or not. I renamed it.

+    GrAtlas** prev = &fAtlas;
+    GrAtlas* atlas = fAtlas;
+    while (atlas) {
+        if (!atlas->fUsed) {
+            fCache.getArray().visitAll(InvalidateGlyph);
+            *prev = atlas->fNext;
+            fAtlasMgr->deleteAtlas(atlas);
+            atlas = *prev;
+            return true;
+        } else {
+            prev = &atlas->fNext;
+            atlas = atlas->fNext;
+        }
+    }
+    
+    return false;
+}
+
+void GrTextStrike::markAtlasesUnused() {
+    GrAtlas* atlas = fAtlas;

[robertphillips, 2013/08/02 15:23:50]

NULL !=?

[jvanverth1, 2013/08/02 21:49:27]

Done.

+    while (atlas) {
+        atlas->fUsed = false;
+        atlas = atlas->fNext;
+    }
+}
+
+
 bool GrTextStrike::getGlyphAtlas(GrGlyph* glyph, GrFontScaler* scaler) {
 #if 0   // testing hack to force us to flush our cache often
     static int gCounter;
@@ -176,6 +239,7 @@ bool GrTextStrike::getGlyphAtlas(GrGlyph* glyph, GrFontScaler* scaler) {
     GrAssert(scaler);
     GrAssert(fCache.contains(glyph));
     if (glyph->fAtlas) {
+        glyph->fAtlas->fUsed = true;
         return true;
     }
 
@@ -191,7 +255,7 @@ bool GrTextStrike::getGlyphAtlas(GrGlyph* glyph, GrFontScaler* scaler) {
         return false;
     }
 
-    GrAtlas* atlas = fAtlasMgr->addToAtlas(fAtlas, glyph->width(),
+    GrAtlas* atlas = fAtlasMgr->addToAtlas(&fAtlas, glyph->width(),
                                            glyph->height(), storage.get(),
                                            fMaskFormat,
                                            &glyph->fAtlasLocation);
@@ -199,7 +263,7 @@ bool GrTextStrike::getGlyphAtlas(GrGlyph* glyph, GrFontScaler* scaler) {
         return false;
     }
 
-    // update fAtlas as well, since they may be chained in a linklist
-    glyph->fAtlas = fAtlas = atlas;
+    glyph->fAtlas = atlas;
+    atlas->fUsed = true;
     return true;
 }