Add SkRacy

SkRacy<T> is a zero-overhead wrapper for a T, except it also
silences race warnings when TSAN is running.

Here we apply in several classes.  In SkMatrix and SkPathRef,
we use it to opportunistically cache some idempotent work.

In SkPixelRef, we wrap the genIDs.  We think the worst that
can happen here is we'll increment the global next-genID a
few times instead of once when we go to get another ID.

BUG=skia:
R=reed@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/371363004

1 files changed, 10 insertions, 12 deletions

diff --git a/src/core/SkPathRef.cpp b/src/core/SkPathRef.cpp
index de7a8f56ae..e60f618b4f 100644
--- a/src/core/SkPathRef.cpp
+++ b/src/core/SkPathRef.cpp
@@ -30,9 +30,7 @@ SkPathRef::Editor::Editor(SkAutoTUnref<SkPathRef>* pathRef,
 //////////////////////////////////////////////////////////////////////////////
 
 SkPathRef* SkPathRef::CreateEmptyImpl() {
-    SkPathRef* p = SkNEW(SkPathRef);
-    p->computeBounds();   // Preemptively avoid a race to clear fBoundsIsDirty.
-    return p;
+    return SkNEW(SkPathRef);
 }
 
 SkPathRef* SkPathRef::CreateEmpty() {
@@ -85,13 +83,13 @@ void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
     if (canXformBounds) {
         (*dst)->fBoundsIsDirty = false;
         if (src.fIsFinite) {
-            matrix.mapRect(&(*dst)->fBounds, src.fBounds);
-            if (!((*dst)->fIsFinite = (*dst)->fBounds.isFinite())) {
-                (*dst)->fBounds.setEmpty();
+            matrix.mapRect((*dst)->fBounds.get(), src.fBounds);
+            if (!((*dst)->fIsFinite = (*dst)->fBounds->isFinite())) {
+                (*dst)->fBounds->setEmpty();
             }
         } else {
             (*dst)->fIsFinite = false;
-            (*dst)->fBounds.setEmpty();
+            (*dst)->fBounds->setEmpty();
         }
     } else {
         (*dst)->fBoundsIsDirty = true;
@@ -441,14 +439,14 @@ void SkPathRef::validate() const {
     SkASSERT(this->currSize() ==
                 fFreeSpace + sizeof(SkPoint) * fPointCnt + sizeof(uint8_t) * fVerbCnt);
 
-    if (!fBoundsIsDirty && !fBounds.isEmpty()) {
+    if (!fBoundsIsDirty && !fBounds->isEmpty()) {
         bool isFinite = true;
         for (int i = 0; i < fPointCnt; ++i) {
             SkASSERT(!fPoints[i].isFinite() || (
-                     fBounds.fLeft - fPoints[i].fX   < SK_ScalarNearlyZero &&
-                     fPoints[i].fX - fBounds.fRight  < SK_ScalarNearlyZero &&
-                     fBounds.fTop  - fPoints[i].fY   < SK_ScalarNearlyZero &&
-                     fPoints[i].fY - fBounds.fBottom < SK_ScalarNearlyZero));
+                     fBounds->fLeft - fPoints[i].fX   < SK_ScalarNearlyZero &&
+                     fPoints[i].fX - fBounds->fRight  < SK_ScalarNearlyZero &&
+                     fBounds->fTop  - fPoints[i].fY   < SK_ScalarNearlyZero &&
+                     fPoints[i].fY - fBounds->fBottom < SK_ScalarNearlyZero));
             if (!fPoints[i].isFinite()) {
                 isFinite = false;
             }