SkLazyPtr.h revision f6351a071810b3a848a5002a0c0ba7e1490fd0db
197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org/* 297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Copyright 2014 Google Inc. 397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Use of this source code is governed by a BSD-style license that can be 597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * found in the LICENSE file. 697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org */ 797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#ifndef SkLazyPtr_DEFINED 997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#define SkLazyPtr_DEFINED 1097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 1197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org/** Declare a lazily-chosen static pointer (or array of pointers) of type F. 1297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 1397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Example usage: 1497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 1597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* CreateFoo() { return SkNEW(Foo); } 1697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* GetSingletonFoo() { 1797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CreateFoo); // Clean up with SkDELETE. 1897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return singleton.get(); 1997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 2097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 2197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * These macros take an optional void (*Destroy)(T*) at the end. If not given, we'll use SkDELETE. 2297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * This option is most useful when T doesn't have a public destructor. 2397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 2497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * void CustomCleanup(Foo* ptr) { ... } 2597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* GetSingletonFooWithCustomCleanup() { 2697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CreateFoo, CustomCleanup); 2797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return singleton.get(); 2897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 2997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 3097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * If you have a bunch of related static pointers of the same type, you can 3197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * declare an array of lazy pointers together: 3297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 3397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* CreateFoo(int i) { return ...; } 3497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* GetCachedFoo(Foo::Enum enumVal) { 3597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SK_DECLARE_STATIC_LAZY_PTR_ARRAY(Foo, Foo::kEnumCount, cachedFoos, CreateFoo); 3697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return cachedFoos[enumVal]; 3797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 3897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 3997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * You can think of SK_DECLARE_STATIC_LAZY_PTR as a cheaper specialization of 4197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SkOnce. There is no mutex or extra storage used past the pointer itself. 4297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * In debug mode, each lazy pointer will be cleaned up at process exit so we 4397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * can check that we've not leaked or freed them early. 4497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * We may call Create more than once, but all threads will see the same pointer 4697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * returned from get(). Any extra calls to Create will be cleaned up. 4797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * These macros must be used in a global or function scope, not as a class member. 4997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org */ 5097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#define SK_DECLARE_STATIC_LAZY_PTR(T, name, Create, ...) \ 5297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org static Private::SkLazyPtr<T, Create, ##__VA_ARGS__> name 5397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#define SK_DECLARE_STATIC_LAZY_PTR_ARRAY(T, name, N, Create, ...) \ 5597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org static Private::SkLazyPtrArray<T, N, Create, ##__VA_ARGS__> name 5697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Everything below here is private implementation details. Don't touch, don't even look. 6097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 6197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkDynamicAnnotations.h" 6297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkThread.h" 6397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkThreadPriv.h" 6497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 65f6351a071810b3a848a5002a0c0ba7e1490fd0dbcommit-bot@chromium.org// See FIXME below. 6697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkFontConfigInterface; 6797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkTypeface; 6897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 6997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgnamespace Private { 7097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgtemplate <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); } 7297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Set *dst to ptr if *dst is NULL. Returns value of *dst, destroying ptr if not swapped in. 7497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Issues the same memory barriers as sk_atomic_cas: acquire on failure, release on success. 7597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgtemplate <typename P, void (*Destroy)(P)> 7697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgstatic P try_cas(void** dst, P ptr) { 7797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org P prev = (P)sk_atomic_cas(dst, NULL, ptr); 7897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org if (prev) { 8097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // We need an acquire barrier before returning prev, which sk_atomic_cas provided. 8197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org Destroy(ptr); 8297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return prev; 8397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } else { 8497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // We need a release barrier before returning ptr, which sk_atomic_cas provided. 8597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr; 8697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 8797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org} 8897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 8997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// This has no constructor and must be zero-initalized (the macro above does this). 9097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgtemplate <typename T, T* (*Create)(), void (*Destroy)(T*) = sk_delete<T> > 9197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkLazyPtr { 9297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgpublic: 9397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* get() { 9497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If fPtr has already been filled, we need an acquire barrier when loading it. 9597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If not, we need a release barrier when setting it. try_cas will do that. 9697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* ptr = (T*)sk_acquire_load(&fPtr); 9797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create()); 9897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 9997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 10097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#ifdef SK_DEBUG 10197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // FIXME: We know we leak refs on some classes. For now, let them leak. 10297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org void cleanup(SkFontConfigInterface*) {} 103f6351a071810b3a848a5002a0c0ba7e1490fd0dbcommit-bot@chromium.org void cleanup(SkTypeface*) {} 10497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org template <typename U> void cleanup(U* ptr) { Destroy(ptr); } 10597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 10697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org ~SkLazyPtr() { 10797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org this->cleanup((T*)fPtr); 10897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org fPtr = NULL; 10997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 11097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif 11197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 11297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgprivate: 11397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org void* fPtr; 11497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org}; 11597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 11697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// This has no constructor and must be zero-initalized (the macro above does this). 11797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgtemplate <typename T, int N, T* (*Create)(int), void (*Destroy)(T*) = sk_delete<T> > 11897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkLazyPtrArray { 11997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgpublic: 12097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* operator[](int i) { 12197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org SkASSERT(i >= 0 && i < N); 12297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If fPtr has already been filled, we need an acquire barrier when loading it. 12397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If not, we need a release barrier when setting it. try_cas will do that. 12497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* ptr = (T*)sk_acquire_load(&fArray[i]); 12597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr ? ptr : try_cas<T*, Destroy>(&fArray[i], Create(i)); 12697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 12797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 12897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#ifdef SK_DEBUG 12997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org ~SkLazyPtrArray() { 13097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org for (int i = 0; i < N; i++) { 131f6351a071810b3a848a5002a0c0ba7e1490fd0dbcommit-bot@chromium.org Destroy((T*)fArray[i]); 13297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org fArray[i] = NULL; 13397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 13497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 13597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif 13697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 13797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgprivate: 13897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org void* fArray[N]; 13997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org}; 14097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 14197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org} // namespace Private 14297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 14397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif//SkLazyPtr_DEFINED 144