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Unified Diff: src/core/SkLazyFnPtr.h

Issue 300843012: Revert of Spin off just SkLazyFnPtr from 305513002. (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Created 6 years, 7 months ago
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Index: src/core/SkLazyFnPtr.h
diff --git a/src/core/SkLazyFnPtr.h b/src/core/SkLazyFnPtr.h
deleted file mode 100644
index cb7832d4c51140433f4e70fd397b34422506073d..0000000000000000000000000000000000000000
--- a/src/core/SkLazyFnPtr.h
+++ /dev/null
@@ -1,58 +0,0 @@
-#ifndef SkLazyFnPtr_DEFINED
-#define SkLazyFnPtr_DEFINED
-
-/** Declare a lazily-chosen static function pointer of type F.
- *
- * Example usage:
- *
- * typedef int (*FooImpl)(int, int);
- *
- * static FooImpl choose_foo() { return ... };
- *
- * int Foo(int a, int b) {
- * SK_DECLARE_STATIC_LAZY_FN_PTR(FooImpl, choice);
- * return choice.get(choose_foo)(a, b);
- * }
- *
- * You can think of SK_DECLARE_STATIC_LAZY_FN_PTR as a cheaper specialization of SkOnce.
- * There is no mutex, and in the fast path, no memory barriers are issued.
- *
- * This must be used in a global or function scope, not as a class member.
- */
-#define SK_DECLARE_STATIC_LAZY_FN_PTR(F, name) static Private::SkLazyFnPtr<F> name = { NULL }
-
-
-// Everything below here is private implementation details. Don't touch, don't even look.
-
-#include "SkDynamicAnnotations.h"
-#include "SkThread.h"
-
-namespace Private {
-
-// This has no constructor and is link-time initialized, so its members must be public.
-template <typename F>
-struct SkLazyFnPtr {
- F get(F (*choose)()) {
- // First, try reading to see if it's already set.
- F fn = (F)SK_ANNOTATE_UNPROTECTED_READ(fPtr);
- if (fn != NULL) {
- return fn;
- }
-
- // We think it's not already set.
- fn = choose();
-
- // No particular memory barriers needed; we're not guarding anything but the pointer itself.
- F prev = (F)sk_atomic_cas(&fPtr, NULL, (void*)fn);
-
- // If prev != NULL, someone snuck in and set fPtr concurrently.
- // If prev == NULL, we did write fn to fPtr.
- return prev != NULL ? prev : fn;
- }
-
- void* fPtr;
-};
-
-} // namespace Private
-
-#endif//SkLazyFnPtr_DEFINED
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