include/llvm/Support/ThreadLocal.h

   1 //===- llvm/Support/ThreadLocal.h - Thread Local Data ------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file declares the llvm::sys::ThreadLocal class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_SUPPORT_THREADLOCAL_H
  14 #define LLVM_SUPPORT_THREADLOCAL_H
  15
  16 #include "llvm/Support/DataTypes.h"
  17 #include "llvm/Support/Threading.h"
  18 #include <cassert>
  19
  20 namespace llvm {
  21   namespace sys {
  22     // ThreadLocalImpl - Common base class of all ThreadLocal instantiations.
  23     // YOU SHOULD NEVER USE THIS DIRECTLY.
  24     class ThreadLocalImpl {
  25       typedef uint64_t ThreadLocalDataTy;
  26       /// Platform-specific thread local data.
  27       ///
  28       /// This is embedded in the class and we avoid malloc'ing/free'ing it,
  29       /// to make this class more safe for use along with CrashRecoveryContext.
  30       union {
  31         char data[sizeof(ThreadLocalDataTy)];
  32         ThreadLocalDataTy align_data;
  33       };
  34     public:
  35       ThreadLocalImpl();
  36       virtual ~ThreadLocalImpl();
  37       void setInstance(const void* d);
  38       void *getInstance();
  39       void removeInstance();
  40     };
  41
  42     /// ThreadLocal - A class used to abstract thread-local storage.  It holds,
  43     /// for each thread, a pointer a single object of type T.
  44     template<class T>
  45     class ThreadLocal : public ThreadLocalImpl {
  46     public:
  47       ThreadLocal() : ThreadLocalImpl() { }
  48
  49       /// get - Fetches a pointer to the object associated with the current
  50       /// thread.  If no object has yet been associated, it returns NULL;
  51       T* get() { return static_cast<T*>(getInstance()); }
  52
  53       // set - Associates a pointer to an object with the current thread.
  54       void set(T* d) { setInstance(d); }
  55
  56       // erase - Removes the pointer associated with the current thread.
  57       void erase() { removeInstance(); }
  58     };
  59   }
  60 }
  61
  62 #endif