| Index: include/core/SkOnce.h
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| diff --git a/include/core/SkOnce.h b/include/core/SkOnce.h
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| deleted file mode 100644
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| index 43e7353d4dd9240fde565a8a115a1344318672da..0000000000000000000000000000000000000000
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| --- a/include/core/SkOnce.h
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| +++ /dev/null
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| @@ -1,139 +0,0 @@
|
| -/*
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| - * Copyright 2013 Google Inc.
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| - *
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| - * Use of this source code is governed by a BSD-style license that can be
|
| - * found in the LICENSE file.
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| - */
|
| -
|
| -#ifndef SkOnce_DEFINED
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| -#define SkOnce_DEFINED
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| -
|
| -// Before trying SkOnce, see if SkLazyPtr or SkLazyFnPtr will work for you.
|
| -// They're smaller and faster, if slightly less versatile.
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| -
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| -
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| -// SkOnce.h defines SK_DECLARE_STATIC_ONCE and SkOnce(), which you can use
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| -// together to create a threadsafe way to call a function just once. E.g.
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| -//
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| -// static void register_my_stuff(GlobalRegistry* registry) {
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| -// registry->register(...);
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| -// }
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| -// ...
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| -// void EnsureRegistered() {
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| -// SK_DECLARE_STATIC_ONCE(once);
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| -// SkOnce(&once, register_my_stuff, GetGlobalRegistry());
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| -// }
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| -//
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| -// No matter how many times you call EnsureRegistered(), register_my_stuff will be called just once.
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| -// OnceTest.cpp also should serve as a few other simple examples.
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| -
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| -#include "../private/SkAtomics.h"
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| -#include "SkSpinlock.h"
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| -
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| -// This must be used in a global scope, not in function scope or as a class member.
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| -#define SK_DECLARE_STATIC_ONCE(name) namespace {} static SkOnceFlag name
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| -
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| -class SkOnceFlag;
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| -
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| -inline void SkOnce(SkOnceFlag* once, void (*f)());
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| -
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| -template <typename Arg>
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| -inline void SkOnce(SkOnceFlag* once, void (*f)(Arg), Arg arg);
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| -
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| -// If you've already got a lock and a flag to use, this variant lets you avoid an extra SkOnceFlag.
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| -template <typename Lock>
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| -inline void SkOnce(bool* done, Lock* lock, void (*f)());
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| -
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| -template <typename Lock, typename Arg>
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| -inline void SkOnce(bool* done, Lock* lock, void (*f)(Arg), Arg arg);
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| -
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| -// ---------------------- Implementation details below here. -----------------------------
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| -
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| -// This class has no constructor and must be zero-initialized (the macro above does this).
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| -class SkOnceFlag {
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| -public:
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| - bool* mutableDone() { return &fDone; }
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| -
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| - void acquire() { fSpinlock.acquire(); }
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| - void release() { fSpinlock.release(); }
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| -
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| -private:
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| - bool fDone;
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| - SkPODSpinlock fSpinlock;
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| -};
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| -
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| -// We've pulled a pretty standard double-checked locking implementation apart
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| -// into its main fast path and a slow path that's called when we suspect the
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| -// one-time code hasn't run yet.
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| -
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| -// This is the guts of the code, called when we suspect the one-time code hasn't been run yet.
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| -// This should be rarely called, so we separate it from SkOnce and don't mark it as inline.
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| -// (We don't mind if this is an actual function call, but odds are it'll be inlined anyway.)
|
| -template <typename Lock, typename Arg>
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| -static void sk_once_slow(bool* done, Lock* lock, void (*f)(Arg), Arg arg) {
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| - lock->acquire();
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| - if (!sk_atomic_load(done, sk_memory_order_relaxed)) {
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| - f(arg);
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| - // Also known as a store-store/load-store barrier, this makes sure that the writes
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| - // done before here---in particular, those done by calling f(arg)---are observable
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| - // before the writes after the line, *done = true.
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| - //
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| - // In version control terms this is like saying, "check in the work up
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| - // to and including f(arg), then check in *done=true as a subsequent change".
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| - //
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| - // We'll use this in the fast path to make sure f(arg)'s effects are
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| - // observable whenever we observe *done == true.
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| - sk_release_store(done, true);
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| - }
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| - lock->release();
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| -}
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| -
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| -// This is our fast path, called all the time. We do really want it to be inlined.
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| -template <typename Lock, typename Arg>
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| -inline void SkOnce(bool* done, Lock* lock, void (*f)(Arg), Arg arg) {
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| - // When *done == true:
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| - // Also known as a load-load/load-store barrier, this acquire barrier makes
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| - // sure that anything we read from memory---in particular, memory written by
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| - // calling f(arg)---is at least as current as the value we read from done.
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| - //
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| - // In version control terms, this is a lot like saying "sync up to the
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| - // commit where we wrote done = true".
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| - //
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| - // The release barrier in sk_once_slow guaranteed that done = true
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| - // happens after f(arg), so by syncing to done = true here we're
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| - // forcing ourselves to also wait until the effects of f(arg) are readble.
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| - //
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| - // When *done == false:
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| - // We'll try to call f(arg) in sk_once_slow.
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| - // If we get the lock, great, we call f(arg), release true into done, and drop the lock.
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| - // If we race and don't get the lock first, we'll wait for the first guy to finish.
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| - // Then lock acquire() will give us at least an acquire memory barrier to get the same
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| - // effect as the acquire load in the *done == true fast case. We'll see *done is true,
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| - // then just drop the lock and return.
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| - if (!sk_atomic_load(done, sk_memory_order_acquire)) {
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| - sk_once_slow(done, lock, f, arg);
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| - }
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| -}
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| -
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| -template <typename Arg>
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| -inline void SkOnce(SkOnceFlag* once, void (*f)(Arg), Arg arg) {
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| - return SkOnce(once->mutableDone(), once, f, arg);
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| -}
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| -
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| -// Calls its argument.
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| -// This lets us use functions that take no arguments with SkOnce methods above.
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| -// (We pass _this_ as the function and the no-arg function as its argument. Cute eh?)
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| -static void sk_once_no_arg_adaptor(void (*f)()) {
|
| - f();
|
| -}
|
| -
|
| -inline void SkOnce(SkOnceFlag* once, void (*func)()) {
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| - return SkOnce(once, sk_once_no_arg_adaptor, func);
|
| -}
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| -
|
| -template <typename Lock>
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| -inline void SkOnce(bool* done, Lock* lock, void (*func)()) {
|
| - return SkOnce(done, lock, sk_once_no_arg_adaptor, func);
|
| -}
|
| -
|
| -#endif // SkOnce_DEFINED
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|
|