一種簡單的跨平臺使用者態自旋鎖
阿新 • • 發佈：2018-12-27
自旋鎖作為一種併發同步的手段，特別適用於競爭少和鎖時間短的情況，在驅動及核心程式碼中經常被用到，本文講述一種適合使用者態程式的自旋鎖，支援Windows和Linux（GCC>=4.1.2）平臺，並提供了C語言的介面和實現。
介面
spin_trylock如果獲取成功返回1，否則返回0；spin_is_lock如果已加鎖，返回1，否則返回0。 1
typedef struct 2
{
3
volatilelong flag_;
4 volatilelong* spin_;
5
}spin_lock_t;
6
7void spin_init(spin_lock_t*lock,long* flag);
8
9void spin_lock(spin_lock_t*lock);
10
11int spin_trylock(spin_lock_t*lock);
12
13
14
15int spin_is_lock(spin_lock_t*lock);
實現 1#ifdef _MSC_VER
2#include <windows.h> 3#elif defined(__GNUC__) 4#if __GNUC__<4 || (__GNUC__==4 && __GNUC_MINOR__<1) 5#error GCC version must be greater or equal than 4.1.2 6#endif 7#include
12void spin_init(spin_lock_t*lock,long* flag)
13{
14#ifdef _MSC_VER
15 InterlockedExchange((volatilelong*)&lock->flag_,0);
16 InterlockedExchange((volatilelong*)&lock->spin_,flag?(long)flag:(
17#elif defined(__GNUC__)18 __sync_and_and_fetch((long*)&lock->flag_,0);
19 __sync_lock_test_and_set((long*)&lock->spin_,flag?(long)flag:(long)&lock->flag_);
20#endif21}22
23void spin_lock(spin_lock_t*lock)
24{
25#ifdef _MSC_VER
26 for (;0!=InterlockedExchange((volatilelong*)lock->spin_,1);)
27
{
28 Sleep(1);
29
}30#elif defined(__GNUC__)31 for (;0!=__sync_fetch_and_or(lock->spin_,1);)
32 {
33 sched_yield();
34 }35#endif36}37
38int spin_trylock(spin_lock_t*lock)
39{
40#ifdef _MSC_VER
41 return!InterlockedExchange((volatilelong*)lock->spin_,1);
42#elif defined(__GNUC__)43 return!__sync_fetch_and_or(lock->spin_,1);
44#endif45}46
47void spin_unlock(spin_lock_t*lock)
48{
49#ifdef _MSC_VER
50 InterlockedExchange((volatilelong*)lock->spin_,0);
51#elif defined(__GNUC__)52 __sync_and_and_fetch(lock->spin_,0);
53#endif54}55
56int spin_is_lock(spin_lock_t*lock)
57{
58#ifdef _MSC_VER
59 return InterlockedExchangeAdd((volatilelong*)lock->spin_,0);
60#elif defined(__GNUC__)61 return __sync_add_and_fetch(lock->spin_,0);
62#endif63}
介面
spin_trylock如果獲取成功返回1，否則返回0；spin_is_lock如果已加鎖，返回1，否則返回0。 1
typedef struct 2{
3
volatilelong flag_;4
volatilelong* spin_;5
}spin_lock_t;6
7
void spin_init(spin_lock_t*lock,long* flag);8
9
void spin_lock(spin_lock_t*lock);10
11
int spin_trylock(spin_lock_t*lock);12
13
void spin_unlock(spin_lock_t*lock);14
15
int spin_is_lock(spin_lock_t*lock);
實現 1
#ifdef _MSC_VER2
#include <windows.h> 3#elif defined(__GNUC__) 4#if __GNUC__<4 || (__GNUC__==4 && __GNUC_MINOR__<1) 5#error GCC version must be greater or equal than 4.1.2 6#endif 7#include #else 9#error Currently only windows and linux os are supported10#endif1112
void spin_init(spin_lock_t*lock,long* flag)13
{14
#ifdef _MSC_VER15
InterlockedExchange((volatilelong*)&lock->flag_,0);16
InterlockedExchange((volatilelong*)&lock->spin_,flag?(long)flag:(17
#elif defined(__GNUC__)18 __sync_and_and_fetch((long*)&lock->flag_,0);19
__sync_lock_test_and_set((long*)&lock->spin_,flag?(long)flag:(long)&lock->flag_);20
#endif21}2223
void spin_lock(spin_lock_t*lock)24
{25
#ifdef _MSC_VER26
for (;0!=InterlockedExchange((volatilelong*)lock->spin_,1);)27
{
28
Sleep(1);29
}30#elif defined(__GNUC__)31 for (;0!=__sync_fetch_and_or(lock->spin_,1);)32
{33
sched_yield();34
}35#endif36}3738
int spin_trylock(spin_lock_t*lock)39
{40
#ifdef _MSC_VER41
return!InterlockedExchange((volatilelong*)lock->spin_,1);42
#elif defined(__GNUC__)43 return!__sync_fetch_and_or(lock->spin_,1);44
#endif45}4647
void spin_unlock(spin_lock_t*lock)48
{49
#ifdef _MSC_VER50
InterlockedExchange((volatilelong*)lock->spin_,0);51
#elif defined(__GNUC__)52 __sync_and_and_fetch(lock->spin_,0);53
#endif54}5556
int spin_is_lock(spin_lock_t*lock)57
{58
#ifdef _MSC_VER59
return InterlockedExchangeAdd((volatilelong*)lock->spin_,0);60
#elif defined(__GNUC__)61 return __sync_add_and_fetch(lock->spin_,0);62
#endif63}