platform_thread_ref.h (2071B)
1 // Copyright 2021 The Chromium Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // WARNING: *DO NOT* use this class directly. base::PlatformThreadRef is a 6 // low-level platform-specific abstraction to the OS's threading interface. 7 // Instead, consider using a message-loop driven base::Thread, see 8 // base/threading/thread.h. 9 10 #ifndef BASE_THREADING_PLATFORM_THREAD_REF_H_ 11 #define BASE_THREADING_PLATFORM_THREAD_REF_H_ 12 13 #include <iosfwd> 14 15 #include "base/base_export.h" 16 #include "build/build_config.h" 17 18 #if BUILDFLAG(IS_WIN) 19 #include "base/win/windows_types.h" 20 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) 21 #include <pthread.h> 22 #endif 23 24 namespace base { 25 26 // Used for thread checking and debugging. 27 // Meant to be as fast as possible. 28 // These are produced by PlatformThread::CurrentRef(), and used to later 29 // check if we are on the same thread or not by using ==. These are safe 30 // to copy between threads, but can't be copied to another process as they 31 // have no meaning there. Also, the internal identifier can be re-used 32 // after a thread dies, so a PlatformThreadRef cannot be reliably used 33 // to distinguish a new thread from an old, dead thread. 34 class PlatformThreadRef { 35 public: 36 #if BUILDFLAG(IS_WIN) 37 using RefType = DWORD; 38 #elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA) 39 using RefType = pthread_t; 40 #endif 41 42 constexpr PlatformThreadRef() = default; 43 explicit constexpr PlatformThreadRef(RefType id) : id_(id) {} 44 45 bool operator==(PlatformThreadRef other) const { return id_ == other.id_; } 46 bool operator!=(PlatformThreadRef other) const { return id_ != other.id_; } 47 48 bool is_null() const { return id_ == 0; } 49 50 private: 51 friend BASE_EXPORT std::ostream& operator<<(std::ostream& os, 52 const PlatformThreadRef& ref); 53 54 RefType id_ = 0; 55 }; 56 57 BASE_EXPORT std::ostream& operator<<(std::ostream& os, 58 const PlatformThreadRef& ref); 59 60 } // namespace base 61 62 #endif // BASE_THREADING_PLATFORM_THREAD_REF_H_