blob: f684e087711970719f13640f81d1aac799711ed0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#ifdef __serenity__
# include <AK/Assertions.h>
# include <AK/Atomic.h>
# include <AK/Types.h>
# include <unistd.h>
namespace LibThread {
class Lock {
public:
Lock() { }
~Lock() { }
void lock();
void unlock();
private:
Atomic<pid_t> m_holder { 0 };
u32 m_level { 0 };
};
class Locker {
public:
ALWAYS_INLINE explicit Locker(Lock& l)
: m_lock(l)
{
lock();
}
ALWAYS_INLINE ~Locker() { unlock(); }
ALWAYS_INLINE void unlock() { m_lock.unlock(); }
ALWAYS_INLINE void lock() { m_lock.lock(); }
private:
Lock& m_lock;
};
ALWAYS_INLINE void Lock::lock()
{
pid_t tid = gettid();
if (m_holder == tid) {
++m_level;
return;
}
for (;;) {
int expected = 0;
if (m_holder.compare_exchange_strong(expected, tid, AK::memory_order_acq_rel)) {
m_level = 1;
return;
}
donate(expected);
}
}
inline void Lock::unlock()
{
VERIFY(m_holder == gettid());
VERIFY(m_level);
if (m_level == 1)
m_holder.store(0, AK::memory_order_release);
else
--m_level;
}
template<typename T>
class Lockable {
public:
Lockable() { }
template<typename... Args>
Lockable(Args&&... args)
: m_resource(forward(args)...)
{
}
Lockable(T&& resource)
: m_resource(move(resource))
{
}
Lock& lock() { return m_lock; }
T& resource() { return m_resource; }
T lock_and_copy()
{
Locker locker(m_lock);
return m_resource;
}
private:
T m_resource;
Lock m_lock;
};
}
#else
namespace LibThread {
class Lock {
public:
Lock() { }
~Lock() { }
};
class Locker {
public:
explicit Locker(Lock&) { }
~Locker() { }
};
}
#endif
|
