contrib/llvm/tools/lldb/include/lldb/Host/ProcessRunLock.h

   1 //===-- ProcessRunLock.h ----------------------------------------*- 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 #ifndef liblldb_ProcessRunLock_h_
  10 #define liblldb_ProcessRunLock_h_
  11
  12 #include <stdint.h>
  13 #include <time.h>
  14
  15 #include "lldb/lldb-defines.h"
  16
  17 /// Enumerations for broadcasting.
  18 namespace lldb_private {
  19
  20 /// \class ProcessRunLock ProcessRunLock.h "lldb/Host/ProcessRunLock.h"
  21 /// A class used to prevent the process from starting while other
  22 /// threads are accessing its data, and prevent access to its data while it is
  23 /// running.
  24
  25 class ProcessRunLock {
  26 public:
  27   ProcessRunLock();
  28   ~ProcessRunLock();
  29
  30   bool ReadTryLock();
  31   bool ReadUnlock();
  32   bool SetRunning();
  33   bool TrySetRunning();
  34   bool SetStopped();
  35
  36   class ProcessRunLocker {
  37   public:
  38     ProcessRunLocker() : m_lock(nullptr) {}
  39
  40     ~ProcessRunLocker() { Unlock(); }
  41
  42     // Try to lock the read lock, but only do so if there are no writers.
  43     bool TryLock(ProcessRunLock *lock) {
  44       if (m_lock) {
  45         if (m_lock == lock)
  46           return true; // We already have this lock locked
  47         else
  48           Unlock();
  49       }
  50       if (lock) {
  51         if (lock->ReadTryLock()) {
  52           m_lock = lock;
  53           return true;
  54         }
  55       }
  56       return false;
  57     }
  58
  59   protected:
  60     void Unlock() {
  61       if (m_lock) {
  62         m_lock->ReadUnlock();
  63         m_lock = nullptr;
  64       }
  65     }
  66
  67     ProcessRunLock *m_lock;
  68
  69   private:
  70     DISALLOW_COPY_AND_ASSIGN(ProcessRunLocker);
  71   };
  72
  73 protected:
  74   lldb::rwlock_t m_rwlock;
  75   bool m_running;
  76
  77 private:
  78   DISALLOW_COPY_AND_ASSIGN(ProcessRunLock);
  79 };
  80
  81 } // namespace lldb_private
  82
  83 #endif // liblldb_ProcessRunLock_h_