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

   1 //===-- ProcessRunLock.h ----------------------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef liblldb_ProcessRunLock_h_
  11 #define liblldb_ProcessRunLock_h_
  12
  13 // C Includes
  14 #include <stdint.h>
  15 #include <time.h>
  16
  17 // C++ Includes
  18 // Other libraries and framework includes
  19 // Project includes
  20 #include "lldb/lldb-defines.h"
  21
  22 //----------------------------------------------------------------------
  23 /// Enumerations for broadcasting.
  24 //----------------------------------------------------------------------
  25 namespace lldb_private {
  26
  27 //----------------------------------------------------------------------
  28 /// @class ProcessRunLock ProcessRunLock.h "lldb/Host/ProcessRunLock.h"
  29 /// A class used to prevent the process from starting while other
  30 /// threads are accessing its data, and prevent access to its data while it is
  31 /// running.
  32 //----------------------------------------------------------------------
  33
  34 class ProcessRunLock {
  35 public:
  36   ProcessRunLock();
  37   ~ProcessRunLock();
  38
  39   bool ReadTryLock();
  40   bool ReadUnlock();
  41   bool SetRunning();
  42   bool TrySetRunning();
  43   bool SetStopped();
  44
  45   class ProcessRunLocker {
  46   public:
  47     ProcessRunLocker() : m_lock(nullptr) {}
  48
  49     ~ProcessRunLocker() { Unlock(); }
  50
  51     // Try to lock the read lock, but only do so if there are no writers.
  52     bool TryLock(ProcessRunLock *lock) {
  53       if (m_lock) {
  54         if (m_lock == lock)
  55           return true; // We already have this lock locked
  56         else
  57           Unlock();
  58       }
  59       if (lock) {
  60         if (lock->ReadTryLock()) {
  61           m_lock = lock;
  62           return true;
  63         }
  64       }
  65       return false;
  66     }
  67
  68   protected:
  69     void Unlock() {
  70       if (m_lock) {
  71         m_lock->ReadUnlock();
  72         m_lock = nullptr;
  73       }
  74     }
  75
  76     ProcessRunLock *m_lock;
  77
  78   private:
  79     DISALLOW_COPY_AND_ASSIGN(ProcessRunLocker);
  80   };
  81
  82 protected:
  83   lldb::rwlock_t m_rwlock;
  84   bool m_running;
  85
  86 private:
  87   DISALLOW_COPY_AND_ASSIGN(ProcessRunLock);
  88 };
  89
  90 } // namespace lldb_private
  91
  92 #endif // liblldb_ProcessRunLock_h_