All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
singleton.h
Go to the documentation of this file.
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 TF_SINGLETON_H
25 #define TF_SINGLETON_H
26 
104 
105 #include "pxr/pxr.h"
106 #include "pxr/base/arch/hints.h"
107 #include "pxr/base/arch/pragmas.h"
108 #include "pxr/base/tf/diagnosticLite.h"
109 
110 #include <mutex>
111 
112 PXR_NAMESPACE_OPEN_SCOPE
113 
121 template <class T>
122 class TfSingleton {
123 public:
137  inline static T& GetInstance() {
138  ARCH_PRAGMA_PUSH
139  // Suppress warnings from clang. TfSingletons are explicitly
140  // instantiated, so the warning around this usage is a false positive.
141  ARCH_PRAGMA_UNDEFINED_VAR_TEMPLATE
142  return ARCH_LIKELY(_instance) ? *_instance : _CreateInstance();
143  ARCH_PRAGMA_POP
144  }
145 
150  static bool CurrentlyExists() {
151  return _instance ? true : false;
152  }
153 
172  static void SetInstanceConstructed(T& instance) {
173  if (_instance)
174  TF_FATAL_ERROR("this function may not be called after "
175  "GetInstance() has completed");
176  _instance = &instance;
177  }
178 
187  static void DeleteInstance() {
188  if (_instance)
189  _DestroyInstance();
190  }
191 private:
192  static T& _CreateInstance();
193  static void _DestroyInstance();
194  static T* _instance;
195  ARCH_PRAGMA_PUSH
196  ARCH_PRAGMA_NEEDS_EXPORT_INTERFACE
197  static std::mutex* _mutex;
198  ARCH_PRAGMA_POP
199 };
200 
201 PXR_NAMESPACE_CLOSE_SCOPE
202 
203 #endif
Manage a single instance of an object (see.
Definition: singleton.h:122
static void SetInstanceConstructed(T &instance)
Indicate that the sole instance object has already been created.
Definition: singleton.h:172
#define TF_FATAL_ERROR(fmt, args)
Issue a fatal error and end the program.
Definition: diagnostic.h:111
static T & GetInstance()
Return a reference to an object of type T, creating it if necessary.
Definition: singleton.h:137
static bool CurrentlyExists()
Return whether or not the single object of type T is currently in existence.
Definition: singleton.h:150
static void DeleteInstance()
Destroy the sole instance object of type T, if it exists.
Definition: singleton.h:187