1 | // Copyright 2009-2021 Intel Corporation |
---|---|
2 | // SPDX-License-Identifier: Apache-2.0 |
3 | |
4 | #pragma once |
5 | |
6 | #include "platform.h" |
7 | #include "intrinsics.h" |
8 | #include "atomic.h" |
9 | |
10 | #define CPU_CACHELINE_SIZE 64 |
11 | namespace embree |
12 | { |
13 | /*! system mutex */ |
14 | class MutexSys { |
15 | friend struct ConditionImplementation; |
16 | public: |
17 | MutexSys(); |
18 | ~MutexSys(); |
19 | |
20 | private: |
21 | MutexSys (const MutexSys& other) DELETED; // do not implement |
22 | MutexSys& operator= (const MutexSys& other) DELETED; // do not implement |
23 | |
24 | public: |
25 | void lock(); |
26 | bool try_lock(); |
27 | void unlock(); |
28 | |
29 | protected: |
30 | void* mutex; |
31 | }; |
32 | |
33 | /*! spinning mutex */ |
34 | class SpinLock |
35 | { |
36 | public: |
37 | |
38 | SpinLock () |
39 | : flag(false) {} |
40 | |
41 | __forceinline bool isLocked() { |
42 | return flag.load(); |
43 | } |
44 | |
45 | __forceinline void lock() |
46 | { |
47 | while (true) |
48 | { |
49 | while (flag.load()) |
50 | { |
51 | _mm_pause(); |
52 | _mm_pause(); |
53 | } |
54 | |
55 | bool expected = false; |
56 | if (flag.compare_exchange_strong(expected,true,std::memory_order_acquire)) |
57 | break; |
58 | } |
59 | } |
60 | |
61 | __forceinline bool try_lock() |
62 | { |
63 | bool expected = false; |
64 | if (flag.load() != expected) { |
65 | return false; |
66 | } |
67 | return flag.compare_exchange_strong(expected,true,std::memory_order_acquire); |
68 | } |
69 | |
70 | __forceinline void unlock() { |
71 | flag.store(false,std::memory_order_release); |
72 | } |
73 | |
74 | __forceinline void wait_until_unlocked() |
75 | { |
76 | while(flag.load()) |
77 | { |
78 | _mm_pause(); |
79 | _mm_pause(); |
80 | } |
81 | } |
82 | |
83 | public: |
84 | atomic<bool> flag; |
85 | }; |
86 | |
87 | class PaddedSpinLock : public SpinLock |
88 | { |
89 | private: |
90 | char padding[CPU_CACHELINE_SIZE - sizeof(SpinLock)]; |
91 | }; |
92 | /*! safe mutex lock and unlock helper */ |
93 | template<typename Mutex> class Lock { |
94 | public: |
95 | Lock (Mutex& mutex) : mutex(mutex), locked(true) { mutex.lock(); } |
96 | Lock (Mutex& mutex, bool locked) : mutex(mutex), locked(locked) {} |
97 | ~Lock() { if (locked) mutex.unlock(); } |
98 | __forceinline void lock() { assert(!locked); locked = true; mutex.lock(); } |
99 | __forceinline bool isLocked() const { return locked; } |
100 | protected: |
101 | Mutex& mutex; |
102 | bool locked; |
103 | }; |
104 | } |
105 |