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 #include <stdint.h>
  14 #include <time.h>
  15
  16 #include "lldb/lldb-defines.h"
  17
  18 //----------------------------------------------------------------------
  19 /// Enumerations for broadcasting.
  20 //----------------------------------------------------------------------
  21 namespace lldb_private {
  22
  23 //----------------------------------------------------------------------
  24 /// @class ProcessRunLock ProcessRunLock.h "lldb/Host/ProcessRunLock.h"
  25 /// A class used to prevent the process from starting while other
  26 /// threads are accessing its data, and prevent access to its data while it is
  27 /// running.
  28 //----------------------------------------------------------------------
  29
  30 class ProcessRunLock {
  31 public:
  32   ProcessRunLock();
  33   ~ProcessRunLock();
  34
  35   bool ReadTryLock();
  36   bool ReadUnlock();
  37   bool SetRunning();
  38   bool TrySetRunning();
  39   bool SetStopped();
  40
  41   class ProcessRunLocker {
  42   public:
  43     ProcessRunLocker() : m_lock(nullptr) {}
  44
  45     ~ProcessRunLocker() { Unlock(); }
  46
  47     // Try to lock the read lock, but only do so if there are no writers.
  48     bool TryLock(ProcessRunLock *lock) {
  49       if (m_lock) {
  50         if (m_lock == lock)
  51           return true; // We already have this lock locked
  52         else
  53           Unlock();
  54       }
  55       if (lock) {
  56         if (lock->ReadTryLock()) {
  57           m_lock = lock;
  58           return true;
  59         }
  60       }
  61       return false;
  62     }
  63
  64   protected:
  65     void Unlock() {
  66       if (m_lock) {
  67         m_lock->ReadUnlock();
  68         m_lock = nullptr;
  69       }
  70     }
  71
  72     ProcessRunLock *m_lock;
  73
  74   private:
  75     DISALLOW_COPY_AND_ASSIGN(ProcessRunLocker);
  76   };
  77
  78 protected:
  79   lldb::rwlock_t m_rwlock;
  80   bool m_running;
  81
  82 private:
  83   DISALLOW_COPY_AND_ASSIGN(ProcessRunLock);
  84 };
  85
  86 } // namespace lldb_private
  87
  88 #endif // liblldb_ProcessRunLock_h_