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 LLDB_HOST_PROCESSRUNLOCK_H
10 #define LLDB_HOST_PROCESSRUNLOCK_H
11 
12 #include <cstdint>
13 #include <ctime>
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() = default;
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 = nullptr;
68 
69   private:
70     ProcessRunLocker(const ProcessRunLocker &) = delete;
71     const ProcessRunLocker &operator=(const ProcessRunLocker &) = delete;
72   };
73 
74 protected:
75   lldb::rwlock_t m_rwlock;
76   bool m_running = false;
77 
78 private:
79   ProcessRunLock(const ProcessRunLock &) = delete;
80   const ProcessRunLock &operator=(const ProcessRunLock &) = delete;
81 };
82 
83 } // namespace lldb_private
84 
85 #endif // LLDB_HOST_PROCESSRUNLOCK_H
86