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1 /*
2  * Copyright (C) 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef INCLUDE_PERFETTO_TRACING_LOCKED_HANDLE_H_
18 #define INCLUDE_PERFETTO_TRACING_LOCKED_HANDLE_H_
19 
20 #include <mutex>
21 
22 namespace perfetto {
23 
24 // This is used for GetDataSourceLocked(), in the (rare) case where the
25 // tracing code wants to access the state of its data source from the Trace()
26 // method.
27 template <typename T>
28 class LockedHandle {
29  public:
LockedHandle(std::recursive_mutex * mtx,T * obj)30   LockedHandle(std::recursive_mutex* mtx, T* obj) : lock_(*mtx), obj_(obj) {}
31   LockedHandle() = default;  // For the invalid case.
32   LockedHandle(LockedHandle&&) = default;
33   LockedHandle& operator=(LockedHandle&&) = default;
34 
valid()35   bool valid() const { return obj_; }
36   explicit operator bool() const { return valid(); }
37 
38   T* operator->() {
39     assert(valid());
40     return obj_;
41   }
42 
43   T& operator*() { return *(this->operator->()); }
44 
45  private:
46   std::unique_lock<std::recursive_mutex> lock_;
47   T* obj_ = nullptr;
48 };
49 
50 }  // namespace perfetto
51 
52 #endif  // INCLUDE_PERFETTO_TRACING_LOCKED_HANDLE_H_
53