// Copyright (C) 2014 The Android Open Source Project // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include "emugl/common/lazy_instance.h" #ifdef _WIN32 # define WIN32_LEAN_AND_MEAN 1 # include #else # include #endif namespace emugl { namespace internal { typedef LazyInstanceState::AtomicType AtomicType; #if defined(__GNUC__) static inline void compilerBarrier() { __asm__ __volatile__ ("" : : : "memory"); } #else #error "Your compiler is not supported" #endif #if defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) # define acquireBarrier() compilerBarrier() # define releaseBarrier() compilerBarrier() #else # error "Your CPU is not supported" #endif static inline AtomicType loadAcquire(AtomicType volatile* ptr) { AtomicType ret = *ptr; acquireBarrier(); return ret; } static inline void storeRelease(AtomicType volatile* ptr, AtomicType value) { releaseBarrier(); *ptr = value; } static int atomicCompareAndSwap(AtomicType volatile* ptr, int expected, int value) { #ifdef _WIN32 return InterlockedCompareExchange(ptr, value, expected); #elif defined(__GNUC__) return __sync_val_compare_and_swap(ptr, expected, value); #else #error "Your compiler is not supported" #endif } static void yieldThread() { #ifdef _WIN32 ::Sleep(0); #else sched_yield(); #endif } bool LazyInstanceState::inInitState() { return loadAcquire(&mState) == STATE_INIT; } bool LazyInstanceState::needConstruction() { AtomicType state = loadAcquire(&mState); if (mState == STATE_DONE) return false; state = atomicCompareAndSwap(&mState, STATE_INIT, STATE_CONSTRUCTING); if (state == STATE_INIT) return true; do { yieldThread(); state = loadAcquire(&mState); } while (state != STATE_DONE); return false; } void LazyInstanceState::doneConstructing() { storeRelease(&mState, STATE_DONE); } } // namespace internal } // namespace emugl