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threadLocalScopedCache.h
1//
2// Copyright 2016 Pixar
3//
4// Licensed under the Apache License, Version 2.0 (the "Apache License")
5// with the following modification; you may not use this file except in
6// compliance with the Apache License and the following modification to it:
7// Section 6. Trademarks. is deleted and replaced with:
8//
9// 6. Trademarks. This License does not grant permission to use the trade
10// names, trademarks, service marks, or product names of the Licensor
11// and its affiliates, except as required to comply with Section 4(c) of
12// the License and to reproduce the content of the NOTICE file.
13//
14// You may obtain a copy of the Apache License at
15//
16// http://www.apache.org/licenses/LICENSE-2.0
17//
18// Unless required by applicable law or agreed to in writing, software
19// distributed under the Apache License with the above modification is
20// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
21// KIND, either express or implied. See the Apache License for the specific
22// language governing permissions and limitations under the Apache License.
23//
24#ifndef PXR_USD_AR_THREAD_LOCAL_SCOPED_CACHE_H
25#define PXR_USD_AR_THREAD_LOCAL_SCOPED_CACHE_H
26
27#include "pxr/pxr.h"
28#include "pxr/usd/ar/api.h"
29
30#include "pxr/base/vt/value.h"
32
33#include <tbb/enumerable_thread_specific.h>
34#include <memory>
35#include <vector>
36
37PXR_NAMESPACE_OPEN_SCOPE
38
65template <class CachedType>
67{
68public:
69 using CachePtr = std::shared_ptr<CachedType>;
70
71 void BeginCacheScope(VtValue* cacheScopeData)
72 {
73 // Since this is intended to be used by ArResolver implementations,
74 // we expect cacheScopeData to never be NULL and to either be empty
75 // or holding a cache pointer that we've filled in previously.
76 if (!cacheScopeData ||
77 (!cacheScopeData->IsEmpty() &&
78 !cacheScopeData->IsHolding<CachePtr>())) {
79 TF_CODING_ERROR("Unexpected cache scope data");
80 return;
81 }
82
83 _CachePtrStack& cacheStack = _threadCacheStack.local();
84 if (cacheScopeData->IsHolding<CachePtr>()) {
85 cacheStack.push_back(cacheScopeData->UncheckedGet<CachePtr>());
86 }
87 else {
88 if (cacheStack.empty()) {
89 cacheStack.push_back(std::make_shared<CachedType>());
90 }
91 else {
92 cacheStack.push_back(cacheStack.back());
93 }
94 }
95 *cacheScopeData = cacheStack.back();
96 }
97
98 void EndCacheScope(VtValue* cacheScopeData)
99 {
100 _CachePtrStack& cacheStack = _threadCacheStack.local();
101 if (TF_VERIFY(!cacheStack.empty())) {
102 cacheStack.pop_back();
103 }
104 }
105
106 CachePtr GetCurrentCache()
107 {
108 _CachePtrStack& cacheStack = _threadCacheStack.local();
109 return (cacheStack.empty() ? CachePtr() : cacheStack.back());
110 }
111
112private:
113 using _CachePtrStack = std::vector<CachePtr>;
114 using _ThreadLocalCachePtrStack =
115 tbb::enumerable_thread_specific<_CachePtrStack>;
116 _ThreadLocalCachePtrStack _threadCacheStack;
117};
118
119PXR_NAMESPACE_CLOSE_SCOPE
120
121#endif // PXR_USD_AR_THREAD_LOCAL_SCOPED_CACHE_H
Low-level utilities for informing users of various internal and external diagnostic conditions.
Utility class for custom resolver implementations.
Provides a container which may hold any type, and provides introspection and iteration over array typ...
Definition: value.h:165
bool IsEmpty() const
Returns true iff this value is empty.
Definition: value.h:1300
bool IsHolding() const
Return true if this value is holding an object of type T, false otherwise.
Definition: value.h:1081
T const & UncheckedGet() const &
Returns a const reference to the held object if the held object is of type T.
Definition: value.h:1121
#define TF_CODING_ERROR(fmt, args)
Issue an internal programming error, but continue execution.
Definition: diagnostic.h:85
#define TF_VERIFY(cond, format,...)
Checks a condition and reports an error if it evaluates false.
Definition: diagnostic.h:283