Port most uses of SkOnce to SkLazyPtr.

BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=15006

Committed: http://code.google.com/p/skia/source/detail?r=15014

R=reed@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/304383005

include/core/SkPathRef.h

@@ -418,7 +418,7 @@ private:
     /**
      * Called the first time someone calls CreateEmpty to actually create the singleton.
      */
-    static void CreateEmptyImpl(int/*unused*/);
+    static SkPathRef* CreateEmptyImpl();
 
     void setIsOval(bool isOval) { fIsOval = isOval; }
 

include/core/SkTypeface.h

@@ -339,7 +339,8 @@ private:
                           uint32_t glyphIDsCount = 0) const;
 
 private:
-    static void create_default_typeface(Style style);
+    static SkTypeface* CreateDefault(int style);  // SkLazyPtr requires an int, not a Style.
+    static void        DeleteDefault(SkTypeface*);
 
     SkFontID    fUniqueID;
     Style       fStyle;

include/ports/SkFontMgr.h

@@ -131,7 +131,7 @@ protected:
                                                unsigned styleBits) const = 0;
 private:
     static SkFontMgr* Factory();    // implemented by porting layer
-    friend void set_up_default(SkFontMgr** singleton);
+    static SkFontMgr* CreateDefault();
 
     typedef SkRefCnt INHERITED;
 };

include/ports/SkFontMgr_indirect.h

@@ -11,7 +11,6 @@
 #include "SkDataTable.h"
 #include "SkFontMgr.h"
 #include "SkFontStyle.h"
-#include "SkOnce.h"
 #include "SkRemotableFontMgr.h"
 #include "SkTArray.h"
 #include "SkTypeface.h"

include/ports/SkRemotableFontMgr.h

@@ -46,7 +46,7 @@ public:
 
 private:
     SkRemotableFontIdentitySet() : fCount(0), fData() { }
-    static void NewEmptyImpl(int);
+    static SkRemotableFontIdentitySet* NewEmptyImpl();
 
     int fCount;
     SkAutoTMalloc<SkFontIdentity> fData;

src/core/SkFontHost.cpp

@@ -6,7 +6,7 @@
  */
 
 #include "SkFontLCDConfig.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 
 static SkFontLCDConfig::LCDOrientation gLCDOrientation = SkFontLCDConfig::kHorizontal_LCDOrientation;
 static SkFontLCDConfig::LCDOrder gLCDOrder = SkFontLCDConfig::kRGB_LCDOrder;
@@ -198,19 +198,14 @@ SkTypeface* SkFontMgr::legacyCreateTypeface(const char familyName[],
     return this->onLegacyCreateTypeface(familyName, styleBits);
 }
 
-void set_up_default(SkFontMgr** singleton) {
-  *singleton = SkFontMgr::Factory();
-  // we never want to return NULL
-  if (NULL == *singleton) {
-      *singleton = SkNEW(SkEmptyFontMgr);
-  }
+SkFontMgr* SkFontMgr::CreateDefault() {
+    SkFontMgr* fm = SkFontMgr::Factory();
+    return fm ? fm : SkNEW(SkEmptyFontMgr);
 }
 
 SkFontMgr* SkFontMgr::RefDefault() {
-    static SkFontMgr* gFM = NULL;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, set_up_default, &gFM);
-    return SkRef(gFM);
+    SK_DECLARE_STATIC_LAZY_PTR(SkFontMgr, singleton, CreateDefault);
+    return SkRef(singleton.get());
 }
 
 //////////////////////////////////////////////////////////////////////////

src/core/SkGlyphCache.cpp

@@ -11,7 +11,7 @@
 #include "SkGlyphCache_Globals.h"
 #include "SkDistanceFieldGen.h"
 #include "SkGraphics.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkPaint.h"
 #include "SkPath.h"
 #include "SkTemplates.h"
@@ -21,18 +21,18 @@
 //#define SPEW_PURGE_STATUS
 //#define RECORD_HASH_EFFICIENCY
 
-static void create_globals(SkGlyphCache_Globals** globals) {
-    *globals = SkNEW_ARGS(SkGlyphCache_Globals, (SkGlyphCache_Globals::kYes_UseMutex));
+namespace {
+
+SkGlyphCache_Globals* create_globals() {
+    return SkNEW_ARGS(SkGlyphCache_Globals, (SkGlyphCache_Globals::kYes_UseMutex));
 }
 
+}  // namespace
+
 // Returns the shared globals
 static SkGlyphCache_Globals& getSharedGlobals() {
-    // we leak this, so we don't incur any shutdown cost of the destructor
-    static SkGlyphCache_Globals* gGlobals = NULL;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, create_globals, &gGlobals);
-    SkASSERT(NULL != gGlobals);
-    return *gGlobals;
+    SK_DECLARE_STATIC_LAZY_PTR(SkGlyphCache_Globals, globals, create_globals);
+    return *globals.get();
 }
 
 // Returns the TLS globals (if set), or the shared globals

src/core/SkLazyPtr.h

@@ -64,7 +64,6 @@
 
 // See FIXME below.
 class SkFontConfigInterface;
-class SkTypeface;
 
 namespace Private {
 
@@ -100,7 +99,6 @@ public:
 #ifdef SK_DEVELOPER
     // FIXME: We know we leak refs on some classes.  For now, let them leak.
     void cleanup(SkFontConfigInterface*) {}
-    void cleanup(SkTypeface*) {}
     template <typename U> void cleanup(U* ptr) { Destroy(ptr); }
 
     ~SkLazyPtr() {

src/core/SkMatrix.cpp

@@ -7,7 +7,7 @@
 
 #include "SkMatrix.h"
 #include "SkFloatBits.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkString.h"
 
 // In a few places, we performed the following
@@ -1558,29 +1558,33 @@ bool SkMatrix::getMinMaxScales(SkScalar scaleFactors[2]) const {
     return get_scale_factor<kBoth_MinMaxOrBoth>(this->getType(), fMat, scaleFactors);
 }
 
-static void reset_identity_matrix(SkMatrix* identity) {
-    identity->reset();
+namespace {
+
+SkMatrix* create_identity() {
+    SkMatrix* m = SkNEW(SkMatrix);
+    m->reset();
+    return m;
 }
 
+SkMatrix* create_invalid() {
+    SkMatrix* m = SkNEW(SkMatrix);
+    m->setAll(SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
+              SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
+              SK_ScalarMax, SK_ScalarMax, SK_ScalarMax);
+    m->getType();  // Force the type to be computed.
+    return m;
+}
+
+}  // namespace
+
 const SkMatrix& SkMatrix::I() {
-    // If you can use C++11 now, you might consider replacing this with a constexpr constructor.
-    static SkMatrix gIdentity;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, reset_identity_matrix, &gIdentity);
-    return gIdentity;
+    SK_DECLARE_STATIC_LAZY_PTR(SkMatrix, identity, create_identity);
+    return *identity.get();
 }
 
 const SkMatrix& SkMatrix::InvalidMatrix() {
-    static SkMatrix gInvalid;
-    static bool gOnce;
-    if (!gOnce) {
-        gInvalid.setAll(SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
-                        SK_ScalarMax, SK_ScalarMax, SK_ScalarMax,
-                        SK_ScalarMax, SK_ScalarMax, SK_ScalarMax);
-        gInvalid.getType(); // force the type to be computed
-        gOnce = true;
-    }
-    return gInvalid;
+    SK_DECLARE_STATIC_LAZY_PTR(SkMatrix, invalid, create_invalid);
+    return *invalid.get();
 }
 
 ///////////////////////////////////////////////////////////////////////////////

src/core/SkMessageBus.h

@@ -8,7 +8,7 @@
 #ifndef SkMessageBus_DEFINED
 #define SkMessageBus_DEFINED
 
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkTDArray.h"
 #include "SkThread.h"
 #include "SkTypes.h"
@@ -38,7 +38,7 @@ public:
 private:
     SkMessageBus();
     static SkMessageBus* Get();
-    static void New(SkMessageBus**);
+    static SkMessageBus* New();
 
     SkTDArray<Inbox*> fInboxes;
     SkMutex           fInboxesMutex;
@@ -49,11 +49,8 @@ private:
 #define DECLARE_SKMESSAGEBUS_MESSAGE(Message)                        \
     template <>                                                      \
     SkMessageBus<Message>* SkMessageBus<Message>::Get() {            \
-        static SkMessageBus<Message>* bus = NULL;         \
-        SK_DECLARE_STATIC_ONCE(once);                     \
-        SkOnce(&once, &New, &bus);                        \
-        SkASSERT(bus != NULL);                            \
-        return bus;                                       \
+        SK_DECLARE_STATIC_LAZY_PTR(SkMessageBus<Message>, bus, New); \
+        return bus.get();                                            \
     }
 
 //   ----------------------- Implementation of SkMessageBus::Inbox -----------------------
@@ -100,8 +97,8 @@ template <typename Message>
 SkMessageBus<Message>::SkMessageBus() {}
 
 template <typename Message>
-/*static*/ void SkMessageBus<Message>::New(SkMessageBus<Message>** bus) {
-    *bus = new SkMessageBus<Message>();
+/*static*/ SkMessageBus<Message>* SkMessageBus<Message>::New() {
+    return SkNEW(SkMessageBus<Message>);
 }
 
 template <typename Message>

src/core/SkPathRef.cpp

@@ -6,7 +6,7 @@
  */
 
 #include "SkBuffer.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkPath.h"
 #include "SkPathRef.h"
 
@@ -28,18 +28,16 @@ SkPathRef::Editor::Editor(SkAutoTUnref<SkPathRef>* pathRef,
 }
 
 //////////////////////////////////////////////////////////////////////////////
-static SkPathRef* gEmptyPathRef = NULL;
-static void cleanup_gEmptyPathRef() { gEmptyPathRef->unref(); }
 
-void SkPathRef::CreateEmptyImpl(int) {
-    gEmptyPathRef = SkNEW(SkPathRef);
-    gEmptyPathRef->computeBounds();  // Preemptively avoid a race to clear fBoundsIsDirty.
+SkPathRef* SkPathRef::CreateEmptyImpl() {
+    SkPathRef* p = SkNEW(SkPathRef);
+    p->computeBounds();   // Preemptively avoid a race to clear fBoundsIsDirty.
+    return p;
 }
 
 SkPathRef* SkPathRef::CreateEmpty() {
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, SkPathRef::CreateEmptyImpl, 0, cleanup_gEmptyPathRef);
-    return SkRef(gEmptyPathRef);
+    SK_DECLARE_STATIC_LAZY_PTR(SkPathRef, empty, CreateEmptyImpl);
+    return SkRef(empty.get());
 }
 
 void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,

src/core/SkTypeface.cpp

@@ -8,7 +8,7 @@
 #include "SkAdvancedTypefaceMetrics.h"
 #include "SkFontDescriptor.h"
 #include "SkFontHost.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkStream.h"
 #include "SkTypeface.h"
 
@@ -74,34 +74,30 @@ protected:
     }
 };
 
-static SkTypeface* gDefaultTypefaces[] = { NULL, NULL, NULL, NULL };
-static const size_t FONT_STYLE_COUNT = SK_ARRAY_COUNT(gDefaultTypefaces);
-static SkOnceFlag gDefaultTypefaceOnce[FONT_STYLE_COUNT] = {
-    SK_ONCE_INIT, SK_ONCE_INIT, SK_ONCE_INIT, SK_ONCE_INIT
-};
-template <uintmax_t N> struct SkTIsPow2 {
-    static const bool value = (N & (N - 1)) == 0;
-};
-SK_COMPILE_ASSERT(SkTIsPow2<FONT_STYLE_COUNT>::value, FONT_STYLE_COUNT_not_power_of_2);
+SkTypeface* SkTypeface::CreateDefault(int style) {
+    // If backed by fontconfig, it's not safe to call SkFontHost::CreateTypeface concurrently.
+    // To be safe, we serialize here with a mutex so only one call to
+    // CreateTypeface is happening at any given time.
+    // TODO(bungeman, mtklein): This is sad.  Make our fontconfig code safe?
+    SK_DECLARE_STATIC_MUTEX(mutex);
+    SkAutoMutexAcquire lock(&mutex);
 
-void SkTypeface::create_default_typeface(Style style) {
-    if (NULL == gDefaultTypefaces[style]) {
-        gDefaultTypefaces[style] = SkFontHost::CreateTypeface(NULL, NULL, style);
-    }
-    if (NULL == gDefaultTypefaces[style]) {
-        // FIXME: Use a singleton for SkEmptyTypeface.
-        gDefaultTypefaces[style] = SkEmptyTypeface::Create();
+    SkTypeface* t = SkFontHost::CreateTypeface(NULL, NULL, (Style)style);
+    return t ? t : SkEmptyTypeface::Create();
 }
+
+void SkTypeface::DeleteDefault(SkTypeface* t) {
+    // The SkTypeface returned by SkFontHost::CreateTypeface may _itself_ be a
+    // cleverly-shared singleton.  This is less than ideal.  This means we
+    // cannot just assert our ownership and SkDELETE(t) like we'd want to.
+    SkSafeUnref(t);
 }
 
 SkTypeface* SkTypeface::GetDefaultTypeface(Style style) {
-    SkASSERT((size_t)style < FONT_STYLE_COUNT);
+    SK_DECLARE_STATIC_LAZY_PTR_ARRAY(SkTypeface, defaults, 4, CreateDefault, DeleteDefault);
 
-    // mask off any other bits to avoid a crash in SK_RELEASE
-    style = (Style)(style & (FONT_STYLE_COUNT - 1));
-
-    SkOnce(&gDefaultTypefaceOnce[style], SkTypeface::create_default_typeface, style);
-    return gDefaultTypefaces[style];
+    SkASSERT((int)style < 4);
+    return defaults[style];
 }
 
 SkTypeface* SkTypeface::RefDefault(Style style) {

src/fonts/SkRemotableFontMgr.cpp

@@ -7,7 +7,7 @@
 
 #include "SkRemotableFontMgr.h"
 
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 
 SkRemotableFontIdentitySet::SkRemotableFontIdentitySet(int count, SkFontIdentity** data)
       : fCount(count), fData(count)
@@ -16,17 +16,11 @@ SkRemotableFontIdentitySet::SkRemotableFontIdentitySet(int count, SkFontIdentity
     *data = fData;
 }
 
-static SkRemotableFontIdentitySet* gEmptyRemotableFontIdentitySet = NULL;
-static void cleanup_gEmptyRemotableFontIdentitySet() { gEmptyRemotableFontIdentitySet->unref(); }
-
-void SkRemotableFontIdentitySet::NewEmptyImpl(int) {
-    gEmptyRemotableFontIdentitySet = new SkRemotableFontIdentitySet();
+SkRemotableFontIdentitySet* SkRemotableFontIdentitySet::NewEmptyImpl() {
+    return SkNEW(SkRemotableFontIdentitySet);
 }
 
 SkRemotableFontIdentitySet* SkRemotableFontIdentitySet::NewEmpty() {
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, SkRemotableFontIdentitySet::NewEmptyImpl, 0,
-           cleanup_gEmptyRemotableFontIdentitySet);
-    gEmptyRemotableFontIdentitySet->ref();
-    return gEmptyRemotableFontIdentitySet;
+    SK_DECLARE_STATIC_LAZY_PTR(SkRemotableFontIdentitySet, empty, NewEmptyImpl);
+    return SkRef(empty.get());
 }

src/lazy/SkDiscardableMemoryPool.cpp

@@ -7,7 +7,7 @@
 
 #include "SkDiscardableMemory.h"
 #include "SkDiscardableMemoryPool.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkTInternalLList.h"
 #include "SkThread.h"
 
@@ -248,27 +248,20 @@ void DiscardableMemoryPool::dumpPool() {
 
 ////////////////////////////////////////////////////////////////////////////////
 SK_DECLARE_STATIC_MUTEX(gMutex);
-SkDiscardableMemoryPool* gPool = NULL;
-void create_global_pool(int) {
-    SkASSERT(NULL == gPool);
-    gPool = SkDiscardableMemoryPool::Create(
-            SK_DEFAULT_GLOBAL_DISCARDABLE_MEMORY_POOL_SIZE, &gMutex);
-}
-void cleanup_global_pool() {
-    gPool->unref();
+SkDiscardableMemoryPool* create_global_pool() {
+    return SkDiscardableMemoryPool::Create(SK_DEFAULT_GLOBAL_DISCARDABLE_MEMORY_POOL_SIZE,
+                                           &gMutex);
 }
+
 }  // namespace
 
-SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(
-        size_t size, SkBaseMutex* mutex) {
+SkDiscardableMemoryPool* SkDiscardableMemoryPool::Create(size_t size, SkBaseMutex* mutex) {
     return SkNEW_ARGS(DiscardableMemoryPool, (size, mutex));
 }
 
 SkDiscardableMemoryPool* SkGetGlobalDiscardableMemoryPool() {
-    SK_DECLARE_STATIC_ONCE(create_pool_once);
-    SkOnce(&create_pool_once, create_global_pool, 0, &cleanup_global_pool);
-    SkASSERT(NULL != gPool);
-    return gPool;
+    SK_DECLARE_STATIC_LAZY_PTR(SkDiscardableMemoryPool, global, create_global_pool);
+    return global.get();
 }
 
 // defined in SkImageGenerator.h

src/ports/SkFontConfigInterface_direct.cpp

@@ -15,7 +15,7 @@
 
 #include "SkBuffer.h"
 #include "SkFontConfigInterface.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 #include "SkStream.h"
 
 size_t SkFontConfigInterface::FontIdentity::writeToMemory(void* addr) const {
@@ -124,14 +124,13 @@ private:
     SkMutex mutex_;
 };
 
-static void create_singleton_direct_interface(SkFontConfigInterface** singleton) {
-    *singleton = new SkFontConfigInterfaceDirect;
-}
+namespace {
+SkFontConfigInterface* create_direct() { return SkNEW(SkFontConfigInterfaceDirect); }
+} // namespace
+
 SkFontConfigInterface* SkFontConfigInterface::GetSingletonDirectInterface() {
-    static SkFontConfigInterface* gDirect;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, create_singleton_direct_interface, &gDirect);
-    return gDirect;
+    SK_DECLARE_STATIC_LAZY_PTR(SkFontConfigInterface, direct, create_direct);
+    return direct.get();
 }
 
 ///////////////////////////////////////////////////////////////////////////////