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 #include "lldb/Host/Mutex.h"
  22 #include "lldb/Host/Condition.h"
  23
  24 //----------------------------------------------------------------------
  25 /// Enumerations for broadcasting.
  26 //----------------------------------------------------------------------
  27 namespace lldb_private {
  28
  29 //----------------------------------------------------------------------
  30 /// @class ProcessRunLock ProcessRunLock.h "lldb/Host/ProcessRunLock.h"
  31 /// @brief A class used to prevent the process from starting while other
  32 /// threads are accessing its data, and prevent access to its data while
  33 /// it is running.
  34 //----------------------------------------------------------------------
  35
  36 class ProcessRunLock
  37 {
  38 public:
  39     ProcessRunLock();
  40     ~ProcessRunLock();
  41
  42     bool ReadTryLock ();
  43     bool ReadUnlock ();
  44     bool SetRunning ();
  45     bool TrySetRunning ();
  46     bool SetStopped ();
  47
  48     class ProcessRunLocker
  49     {
  50     public:
  51         ProcessRunLocker () :
  52             m_lock (nullptr)
  53         {
  54         }
  55
  56         ~ProcessRunLocker()
  57         {
  58             Unlock();
  59         }
  60
  61         // Try to lock the read lock, but only do so if there are no writers.
  62         bool
  63         TryLock (ProcessRunLock *lock)
  64         {
  65             if (m_lock)
  66             {
  67                 if (m_lock == lock)
  68                     return true; // We already have this lock locked
  69                 else
  70                     Unlock();
  71             }
  72             if (lock)
  73             {
  74                 if (lock->ReadTryLock())
  75                 {
  76                     m_lock = lock;
  77                     return true;
  78                 }
  79             }
  80             return false;
  81         }
  82
  83     protected:
  84         void
  85         Unlock ()
  86         {
  87             if (m_lock)
  88             {
  89                 m_lock->ReadUnlock();
  90                 m_lock = nullptr;
  91             }
  92         }
  93
  94         ProcessRunLock *m_lock;
  95
  96     private:
  97         DISALLOW_COPY_AND_ASSIGN(ProcessRunLocker);
  98     };
  99
 100 protected:
 101     lldb::rwlock_t m_rwlock;
 102     bool m_running;
 103
 104 private:
 105     DISALLOW_COPY_AND_ASSIGN(ProcessRunLock);
 106 };
 107
 108 } // namespace lldb_private
 109
 110 #endif // liblldb_ProcessRunLock_h_