SkLazyPtr.h revision 6059f16fd98421ef1add03f708f3fd2c21cfc4f5
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* GetSingletonFoo() { 166059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton); // Created with SkNEW, destroyed with SkDELETE. 1797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return singleton.get(); 1897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 1997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 206059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * These macros take an optional T* (*Create)() and void (*Destroy)(T*) at the end. 216059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * If not given, we'll use SkNEW and SkDELETE. 226059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * These options are most useful when T doesn't have a public constructor or destructor. 236059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * Create comes first, so you may use a custom Create with a default Destroy, but not vice versa. 2497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 256059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * Foo* CustomCreate() { return ...; } 266059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * void CustomDestroy(Foo* ptr) { ... } 2797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* GetSingletonFooWithCustomCleanup() { 286059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CustomCreate, CustomDestroy); 2997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return singleton.get(); 3097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 3197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 3297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * If you have a bunch of related static pointers of the same type, you can 336059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein * declare an array of lazy pointers together, and we'll pass the index to Create(). 3497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 3597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* CreateFoo(int i) { return ...; } 3697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * Foo* GetCachedFoo(Foo::Enum enumVal) { 3797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SK_DECLARE_STATIC_LAZY_PTR_ARRAY(Foo, Foo::kEnumCount, cachedFoos, CreateFoo); 3897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * return cachedFoos[enumVal]; 3997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * } 4097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * You can think of SK_DECLARE_STATIC_LAZY_PTR as a cheaper specialization of 4397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * SkOnce. There is no mutex or extra storage used past the pointer itself. 4497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * In debug mode, each lazy pointer will be cleaned up at process exit so we 4597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * can check that we've not leaked or freed them early. 4697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 4797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * We may call Create more than once, but all threads will see the same pointer 4897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * returned from get(). Any extra calls to Create will be cleaned up. 4997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * 5097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org * These macros must be used in a global or function scope, not as a class member. 5197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org */ 5297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 536059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein#define SK_DECLARE_STATIC_LAZY_PTR(T, name, ...) \ 546059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein static Private::SkLazyPtr<T, ##__VA_ARGS__> name 5597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 566059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein#define SK_DECLARE_STATIC_LAZY_PTR_ARRAY(T, name, N, ...) \ 576059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein static Private::SkLazyPtrArray<T, N, ##__VA_ARGS__> name 5897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 5997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 6097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 6197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Everything below here is private implementation details. Don't touch, don't even look. 6297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 6397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkDynamicAnnotations.h" 6497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkThread.h" 6597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#include "SkThreadPriv.h" 6697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 67f6351a071810b3a848a5002a0c0ba7e1490fd0dbcommit-bot@chromium.org// See FIXME below. 686059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleinclass SkFontConfigInterfaceDirect; 6997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgnamespace Private { 7197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Set *dst to ptr if *dst is NULL. Returns value of *dst, destroying ptr if not swapped in. 7397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// Issues the same memory barriers as sk_atomic_cas: acquire on failure, release on success. 7497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgtemplate <typename P, void (*Destroy)(P)> 7597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgstatic P try_cas(void** dst, P ptr) { 7697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org P prev = (P)sk_atomic_cas(dst, NULL, ptr); 7797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 7897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org if (prev) { 7997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // We need an acquire barrier before returning prev, which sk_atomic_cas provided. 8097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org Destroy(ptr); 8197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return prev; 8297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } else { 8397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // We need a release barrier before returning ptr, which sk_atomic_cas provided. 8497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr; 8597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 8697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org} 8797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 886059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleintemplate <typename T> T* sk_new() { return SkNEW(T); } 896059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleintemplate <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); } 906059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein 9197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// This has no constructor and must be zero-initalized (the macro above does this). 926059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleintemplate <typename T, T* (*Create)() = sk_new<T>, void (*Destroy)(T*) = sk_delete<T> > 9397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkLazyPtr { 9497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgpublic: 9597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* get() { 9697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If fPtr has already been filled, we need an acquire barrier when loading it. 9797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If not, we need a release barrier when setting it. try_cas will do that. 9897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* ptr = (T*)sk_acquire_load(&fPtr); 9997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create()); 10097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 10197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 1020d03db7446126be6ccce744be9b37ef475142e16mtklein#ifdef SK_DEVELOPER 10397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // FIXME: We know we leak refs on some classes. For now, let them leak. 1046059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein void cleanup(SkFontConfigInterfaceDirect*) {} 10597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org template <typename U> void cleanup(U* ptr) { Destroy(ptr); } 10697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 10797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org ~SkLazyPtr() { 10897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org this->cleanup((T*)fPtr); 10997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org fPtr = NULL; 11097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 11197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif 11297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 11397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgprivate: 11497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org void* fPtr; 11597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org}; 11697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 1176059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleintemplate <typename T> T* sk_new_arg(int i) { return SkNEW_ARGS(T, (i)); } 1186059f16fd98421ef1add03f708f3fd2c21cfc4f5mtklein 11997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org// This has no constructor and must be zero-initalized (the macro above does this). 1206059f16fd98421ef1add03f708f3fd2c21cfc4f5mtkleintemplate <typename T, int N, T* (*Create)(int) = sk_new_arg<T>, void (*Destroy)(T*) = sk_delete<T> > 12197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgclass SkLazyPtrArray { 12297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgpublic: 12397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* operator[](int i) { 12497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org SkASSERT(i >= 0 && i < N); 12597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If fPtr has already been filled, we need an acquire barrier when loading it. 12697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org // If not, we need a release barrier when setting it. try_cas will do that. 12797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org T* ptr = (T*)sk_acquire_load(&fArray[i]); 12897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org return ptr ? ptr : try_cas<T*, Destroy>(&fArray[i], Create(i)); 12997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 13097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 1310d03db7446126be6ccce744be9b37ef475142e16mtklein#ifdef SK_DEVELOPER 13297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org ~SkLazyPtrArray() { 13397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org for (int i = 0; i < N; i++) { 134f6351a071810b3a848a5002a0c0ba7e1490fd0dbcommit-bot@chromium.org Destroy((T*)fArray[i]); 13597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org fArray[i] = NULL; 13697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 13797de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org } 13897de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif 13997de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 14097de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.orgprivate: 14197de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org void* fArray[N]; 14297de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org}; 14397de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 14497de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org} // namespace Private 14597de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org 14697de357270e54be53acb17e1cb4b4d5e25bacc01commit-bot@chromium.org#endif//SkLazyPtr_DEFINED 147