326 lines
11 KiB
C++
326 lines
11 KiB
C++
// Copyright 2009-2021 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#pragma once
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#include "../common/default.h"
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/* force a complete cache invalidation when running out of allocation space */
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#define FORCE_SIMPLE_FLUSH 0
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#define THREAD_BLOCK_ATOMIC_ADD 4
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#if defined(DEBUG)
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#define CACHE_STATS(x)
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#else
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#define CACHE_STATS(x)
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#endif
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namespace embree
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{
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class SharedTessellationCacheStats
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{
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public:
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/* stats */
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static std::atomic<size_t> cache_accesses;
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static std::atomic<size_t> cache_hits;
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static std::atomic<size_t> cache_misses;
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static std::atomic<size_t> cache_flushes;
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static size_t cache_num_patches;
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__aligned(64) static SpinLock mtx;
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/* print stats for debugging */
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static void printStats();
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static void clearStats();
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};
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void resizeTessellationCache(size_t new_size);
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void resetTessellationCache();
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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struct __aligned(64) ThreadWorkState
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{
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ALIGNED_STRUCT_(64);
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std::atomic<size_t> counter;
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ThreadWorkState* next;
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bool allocated;
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__forceinline ThreadWorkState(bool allocated = false)
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: counter(0), next(nullptr), allocated(allocated)
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{
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assert( ((size_t)this % 64) == 0 );
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}
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};
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class __aligned(64) SharedLazyTessellationCache
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{
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public:
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static const size_t NUM_CACHE_SEGMENTS = 8;
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static const size_t NUM_PREALLOC_THREAD_WORK_STATES = 512;
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static const size_t COMMIT_INDEX_SHIFT = 32+8;
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#if defined(__64BIT__)
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static const size_t REF_TAG_MASK = 0xffffffffff;
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#else
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static const size_t REF_TAG_MASK = 0x7FFFFFFF;
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#endif
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static const size_t MAX_TESSELLATION_CACHE_SIZE = REF_TAG_MASK+1;
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static const size_t BLOCK_SIZE = 64;
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/*! Per thread tessellation ref cache */
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static __thread ThreadWorkState* init_t_state;
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static ThreadWorkState* current_t_state;
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static __forceinline ThreadWorkState *threadState()
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{
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if (unlikely(!init_t_state))
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/* sets init_t_state, can't return pointer due to macosx icc bug*/
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SharedLazyTessellationCache::sharedLazyTessellationCache.getNextRenderThreadWorkState();
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return init_t_state;
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}
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struct Tag
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{
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__forceinline Tag() : data(0) {}
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__forceinline Tag(void* ptr, size_t combinedTime) {
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init(ptr,combinedTime);
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}
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__forceinline Tag(size_t ptr, size_t combinedTime) {
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init((void*)ptr,combinedTime);
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}
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__forceinline void init(void* ptr, size_t combinedTime)
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{
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if (ptr == nullptr) {
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data = 0;
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return;
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}
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int64_t new_root_ref = (int64_t) ptr;
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new_root_ref -= (int64_t)SharedLazyTessellationCache::sharedLazyTessellationCache.getDataPtr();
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assert( new_root_ref <= (int64_t)REF_TAG_MASK );
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new_root_ref |= (int64_t)combinedTime << COMMIT_INDEX_SHIFT;
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data = new_root_ref;
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}
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__forceinline int64_t get() const { return data.load(); }
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__forceinline void set( int64_t v ) { data.store(v); }
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__forceinline void reset() { data.store(0); }
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private:
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atomic<int64_t> data;
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};
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static __forceinline size_t extractCommitIndex(const int64_t v) { return v >> SharedLazyTessellationCache::COMMIT_INDEX_SHIFT; }
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struct CacheEntry
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{
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Tag tag;
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SpinLock mutex;
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};
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private:
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float *data;
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bool hugepages;
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size_t size;
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size_t maxBlocks;
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ThreadWorkState *threadWorkState;
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__aligned(64) std::atomic<size_t> localTime;
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__aligned(64) std::atomic<size_t> next_block;
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__aligned(64) SpinLock reset_state;
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__aligned(64) SpinLock linkedlist_mtx;
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__aligned(64) std::atomic<size_t> switch_block_threshold;
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__aligned(64) std::atomic<size_t> numRenderThreads;
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public:
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SharedLazyTessellationCache();
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~SharedLazyTessellationCache();
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void getNextRenderThreadWorkState();
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__forceinline size_t maxAllocSize() const {
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return switch_block_threshold;
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}
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__forceinline size_t getCurrentIndex() { return localTime.load(); }
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__forceinline void addCurrentIndex(const size_t i=1) { localTime.fetch_add(i); }
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__forceinline size_t getTime(const size_t globalTime) {
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return localTime.load()+NUM_CACHE_SEGMENTS*globalTime;
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}
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__forceinline size_t lockThread (ThreadWorkState *const t_state, const ssize_t plus=1) { return t_state->counter.fetch_add(plus); }
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__forceinline size_t unlockThread(ThreadWorkState *const t_state, const ssize_t plus=-1) { assert(isLocked(t_state)); return t_state->counter.fetch_add(plus); }
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__forceinline bool isLocked(ThreadWorkState *const t_state) { return t_state->counter.load() != 0; }
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static __forceinline void lock () { sharedLazyTessellationCache.lockThread(threadState()); }
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static __forceinline void unlock() { sharedLazyTessellationCache.unlockThread(threadState()); }
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static __forceinline bool isLocked() { return sharedLazyTessellationCache.isLocked(threadState()); }
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static __forceinline size_t getState() { return threadState()->counter.load(); }
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static __forceinline void lockThreadLoop() { sharedLazyTessellationCache.lockThreadLoop(threadState()); }
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static __forceinline size_t getTCacheTime(const size_t globalTime) {
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return sharedLazyTessellationCache.getTime(globalTime);
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}
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/* per thread lock */
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__forceinline void lockThreadLoop (ThreadWorkState *const t_state)
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{
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while(1)
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{
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size_t lock = SharedLazyTessellationCache::sharedLazyTessellationCache.lockThread(t_state,1);
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if (unlikely(lock >= THREAD_BLOCK_ATOMIC_ADD))
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{
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/* lock failed wait until sync phase is over */
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sharedLazyTessellationCache.unlockThread(t_state,-1);
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sharedLazyTessellationCache.waitForUsersLessEqual(t_state,0);
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}
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else
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break;
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}
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}
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static __forceinline void* lookup(CacheEntry& entry, size_t globalTime)
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{
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const int64_t subdiv_patch_root_ref = entry.tag.get();
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CACHE_STATS(SharedTessellationCacheStats::cache_accesses++);
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if (likely(subdiv_patch_root_ref != 0))
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{
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const size_t subdiv_patch_root = (subdiv_patch_root_ref & REF_TAG_MASK) + (size_t)sharedLazyTessellationCache.getDataPtr();
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const size_t subdiv_patch_cache_index = extractCommitIndex(subdiv_patch_root_ref);
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if (likely( sharedLazyTessellationCache.validCacheIndex(subdiv_patch_cache_index,globalTime) ))
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{
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CACHE_STATS(SharedTessellationCacheStats::cache_hits++);
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return (void*) subdiv_patch_root;
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}
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}
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CACHE_STATS(SharedTessellationCacheStats::cache_misses++);
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return nullptr;
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}
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template<typename Constructor>
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static __forceinline auto lookup (CacheEntry& entry, size_t globalTime, const Constructor constructor, const bool before=false) -> decltype(constructor())
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{
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ThreadWorkState *t_state = SharedLazyTessellationCache::threadState();
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while (true)
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{
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sharedLazyTessellationCache.lockThreadLoop(t_state);
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void* patch = SharedLazyTessellationCache::lookup(entry,globalTime);
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if (patch) return (decltype(constructor())) patch;
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if (entry.mutex.try_lock())
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{
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if (!validTag(entry.tag,globalTime))
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{
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auto timeBefore = sharedLazyTessellationCache.getTime(globalTime);
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auto ret = constructor(); // thread is locked here!
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assert(ret);
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/* this should never return nullptr */
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auto timeAfter = sharedLazyTessellationCache.getTime(globalTime);
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auto time = before ? timeBefore : timeAfter;
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__memory_barrier();
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entry.tag = SharedLazyTessellationCache::Tag(ret,time);
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__memory_barrier();
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entry.mutex.unlock();
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return ret;
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}
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entry.mutex.unlock();
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}
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SharedLazyTessellationCache::sharedLazyTessellationCache.unlockThread(t_state);
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}
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}
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__forceinline bool validCacheIndex(const size_t i, const size_t globalTime)
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{
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#if FORCE_SIMPLE_FLUSH == 1
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return i == getTime(globalTime);
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#else
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return i+(NUM_CACHE_SEGMENTS-1) >= getTime(globalTime);
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#endif
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}
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static __forceinline bool validTime(const size_t oldtime, const size_t newTime)
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{
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return oldtime+(NUM_CACHE_SEGMENTS-1) >= newTime;
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}
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static __forceinline bool validTag(const Tag& tag, size_t globalTime)
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{
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const int64_t subdiv_patch_root_ref = tag.get();
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if (subdiv_patch_root_ref == 0) return false;
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const size_t subdiv_patch_cache_index = extractCommitIndex(subdiv_patch_root_ref);
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return sharedLazyTessellationCache.validCacheIndex(subdiv_patch_cache_index,globalTime);
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}
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void waitForUsersLessEqual(ThreadWorkState *const t_state,
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const unsigned int users);
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__forceinline size_t alloc(const size_t blocks)
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{
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if (unlikely(blocks >= switch_block_threshold))
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throw_RTCError(RTC_ERROR_INVALID_OPERATION,"allocation exceeds size of tessellation cache segment");
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assert(blocks < switch_block_threshold);
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size_t index = next_block.fetch_add(blocks);
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if (unlikely(index + blocks >= switch_block_threshold)) return (size_t)-1;
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return index;
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}
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static __forceinline void* malloc(const size_t bytes)
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{
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size_t block_index = -1;
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ThreadWorkState *const t_state = threadState();
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while (true)
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{
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block_index = sharedLazyTessellationCache.alloc((bytes+BLOCK_SIZE-1)/BLOCK_SIZE);
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if (block_index == (size_t)-1)
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{
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sharedLazyTessellationCache.unlockThread(t_state);
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sharedLazyTessellationCache.allocNextSegment();
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sharedLazyTessellationCache.lockThread(t_state);
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continue;
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}
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break;
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}
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return sharedLazyTessellationCache.getBlockPtr(block_index);
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}
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__forceinline void *getBlockPtr(const size_t block_index)
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{
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assert(block_index < maxBlocks);
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assert(data);
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assert(block_index*16 <= size);
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return (void*)&data[block_index*16];
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}
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__forceinline void* getDataPtr() { return data; }
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__forceinline size_t getNumUsedBytes() { return next_block * BLOCK_SIZE; }
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__forceinline size_t getMaxBlocks() { return maxBlocks; }
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__forceinline size_t getSize() { return size; }
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void allocNextSegment();
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void realloc(const size_t newSize);
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void reset();
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static SharedLazyTessellationCache sharedLazyTessellationCache;
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};
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}
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