-
Linux 原子操作CAS与锁实现
1、互斥锁（mutex）
#include#include #include #define __USE_GNU #include #include #include #include #define THREAD_COUNT 30 pthread_mutex_t mutex; pthread_spinlock_t spinlock; void* callback(void* data){ int* pdata = (int*)data; for(int i=0;i<100000;i++){ #if 1 pthread_mutex_lock(&mutex); (*pdata)++; pthread_mutex_unlock(&mutex); #else pthread_spin_lock(&spinlock); (*pdata)++; pthread_spin_unlock(&spinlock); #endif } return NULL; } int main() { pthread_mutex_init(&mutex,NULL); pthread_spin_init(&spinlock,PTHREAD_PROCESS_SHARED); pthread_t tid[THREAD_COUNT] = {0}; int ptcount = 0; for(int i=0;i<THREAD_COUNT;i++){ pthread_create(&tid[i],NULL,callback,(void*)&ptcount); } for(int i=0;i<100;i++){ printf("ptcount:%d\n",ptcount); sleep(1); } return 0; } - 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
2、自旋锁（spinlock）
#include#include #include #define __USE_GNU #include #include #include #include #define THREAD_COUNT 30 pthread_mutex_t mutex; pthread_spinlock_t spinlock; void* callback(void* data){ int* pdata = (int*)data; for(int i=0;i<100000;i++){ #if 0 pthread_mutex_lock(&mutex); (*pdata)++; pthread_mutex_unlock(&mutex); #else pthread_spin_lock(&spinlock); (*pdata)++; pthread_spin_unlock(&spinlock); #endif } return NULL; } int main() { pthread_mutex_init(&mutex,NULL); pthread_spin_init(&spinlock,PTHREAD_PROCESS_SHARED); pthread_t tid[THREAD_COUNT] = {0}; int ptcount = 0; for(int i=0;i<THREAD_COUNT;i++){ pthread_create(&tid[i],NULL,callback,(void*)&ptcount); } for(int i=0;i<100;i++){ printf("ptcount:%d\n",ptcount); sleep(1); } return 0; } - 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
3、原子操作
int inc(int *value, int add) { int old; __asm__ volatile ( "lock; xaddl %2, %1;" : "=a" (old) : "m" (*value), "a" (add) : "cc", "memory" ); return old; } void *callback(void *data){ int* pdata = (int*)data; for(int i=0;i<100000;i++){ inc(pdata,1); #if 0 pthread_mutex_lock(&mutex); (*pdata)++; pthread_mutex_unlock(&mutex); #elif 0 pthread_spin_lock(&spinlock); (*pdata)++; pthread_spin_unlock(&spinlock); #endif } return NULL; }- 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
4、线程私有空间（pthread_key）
1、pthread_key_create() 用来创建线程私有数据。该函数从 TSD 池中分配一项，将其地址值赋给 key 供以后访问使用，第2个参数，是指定销毁函数，可以设置为NULL，设置为NULL的情况下，系统使用默认的销毁函数对数据进行销毁，不为空的时候，当线程退出时（pthread_exit()），将key对应的数据调出来，去释放。
2、不论哪个线程调用了 pthread_key_create()，所创建的 key 都是所有线程可以访问的，但各个线程可以根据自己的需要往 key 中填入不同的值，相当于提供了一个同名而不同值的全局变量(这个全局变量相对于拥有这个变量的线程来说)。
3、注销一个 TSD 使用 pthread_key_delete() 函数。该函数并不检查当前是否有线程正在使用该 TSD，也不会调用清理函数(destructor function)，而只是将 TSD 释放以供下一次调用 pthread_key_create() 使用。在 LinuxThread 中，它还会将与之相关的线程数据项设置为 NULL。key被创建之后，因为是全局变量，所以所有的线程都可以访问。各个线程可以根据需求往key中，填入不同的值，这就相当于提供了一个同名而值不同的全局变量，即一键多值。一键多值依靠的一个结构体数组，即
static struct pthread_key_struct pthread_keys[PTHREAD_KEYS_MAX] ={{0,NULL}}; // 定义 struct pthread_key_struct { /* Sequence numbers. Even numbers indicated vacant entries. Note that zero is even. We use uintptr_t to not require padding on 32- and 64-bit machines. On 64-bit machines it helps to avoid wrapping, too. */ uintptr_t seq; /* Destructor for the data. */ void (*destr) (void *); };- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
#include#include #include #define __USE_GNU #include #include #include #include #define THREAD_COUNT 3 pthread_key_t key; typedef void* (*thread_cb)(void*); void *func1(void *data){ int i = 9; pthread_setspecific(key,&i); int *p = pthread_getspecific(key); printf("p=%d\n",*p); return NULL; } void *func2(void *data){ char *str = "hello world"; pthread_setspecific(key,str); char *ptr = pthread_getspecific(key); printf("ptr=%s\n",ptr); return NULL; } struct pair { int x; int y; }; void *func3(void *data){ struct pair p1 = {1, 2}; pthread_setspecific(key, &p1); struct pair *p = (struct pair *)pthread_getspecific(key); printf("pair x=%d,y=%d\n",p->x,p->y); return NULL; } int main() { thread_cb callback_cb[THREAD_COUNT] = { func1, func2, func3 }; pthread_key_create(&key,NULL); pthread_t tid[THREAD_COUNT] = {0}; int count = 0; for(int i=0;i<THREAD_COUNT;i++){ pthread_create(&tid[i],NULL,callback_cb[i],&count); } for(int i=0;i<THREAD_COUNT;i++){ pthread_join(tid[i],NULL); } pthread_key_delete ( key ); return 0; } - 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
5、共享内存
待续6、cpu的亲缘性（affinity）
#include#include #include #define __USE_GNU #include #include #include #include #define THREAD_COUNT 3 void process_affinity(int num) { //gettid(); pid_t selfid = syscall(__NR_gettid); printf("pid=%d\n",selfid); cpu_set_t mask; CPU_ZERO(&mask); // cpu编号从0开始 CPU_SET(num, &mask); // 也可以填入selfid sched_setaffinity(0, sizeof(mask), &mask); while(1) ; } int main() { int num = sysconf(_SC_NPROCESSORS_CONF); int i = 0; pid_t pid = 0; for(int i=0;i<num/2;i++){ pid = fork(); if(pid<0) break; } if(pid == 0){ printf("main pid=%d\n",pid); process_affinity(num); } while (1) usleep(1); return 0; } - 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
7、setjmp/longjmp
int setjmp(jmp_buf env);
调用setjmp将堆栈上下文保存在jmp_buf结构体中(入栈),供longjmp稍后使用（出栈）。如果直接调用返回0，如果使用保存的上下文从longjmp返回，则返回保存值非零。
void longjmp(jmp_buf env, int val);
调用longjmp程序跳转到最后一次使用相应env参数调用setjmp处，调用longjmp后setjmp不能返回0，如果longjmp第二个参数设置0，则将返回1#include#include int main(int argc, char *argv[]) { int idx = 0; jmp_buf env; int count = 0; count = setjmp(env); if (count == 0) { printf("count:%d\n", count); longjmp(env, ++idx); } else if (count == 1) { printf("count:%d\n", count); longjmp(env, ++idx); } else if (count == 2) { printf("count:%d\n", count); longjmp(env, ++idx); } else { printf("other count:%d\n",count); } return 0; } - 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
#include#include #include #include #include #include #define ntyThreadData pthread_key_t #define ntyThreadDataSet(key, value) pthread_setspecific((key), (value)) #define ntyThreadDataGet(key) pthread_getspecific((key)) #define ntyThreadDataCreate(key) pthread_key_create(&(key), NULL) #define EXCEPTIN_MESSAGE_LENGTH 512 typedef struct _ntyException { const char *name; } ntyException; ntyException SQLException = {"SQLException"}; ntyException TimeoutException = {"TimeoutException"}; ntyThreadData ExceptionStack; typedef struct _ntyExceptionFrame { jmp_buf env; int line; const char *func; const char *file; ntyException *exception; struct _ntyExceptionFrame *prev; char message[EXCEPTIN_MESSAGE_LENGTH+1]; } ntyExceptionFrame; #define ntyExceptionPopStack \ ntyThreadDataSet(ExceptionStack, ((ntyExceptionFrame*)ntyThreadDataGet(ExceptionStack))->prev) #define ReThrow ntyExceptionThrow(frame.exception, frame.func, frame.file, frame.line, NULL) #define Throw(e, cause, ...) ntyExceptionThrow(&(e), __func__, __FILE__, __LINE__, cause, ##__VA_ARGS__, NULL) enum { ExceptionEntered = 0, ExceptionThrown, ExceptionHandled, ExceptionFinalized }; #define Try do { \ volatile int Exception_flag; \ ntyExceptionFrame frame; \ frame.message[0] = 0; \ frame.prev = (ntyExceptionFrame*)ntyThreadDataGet(ExceptionStack); \ ntyThreadDataSet(ExceptionStack, &frame); \ Exception_flag = setjmp(frame.env); \ if (Exception_flag == ExceptionEntered) { #define Catch(e) \ if (Exception_flag == ExceptionEntered) ntyExceptionPopStack; \ } else if (frame.exception == &(e)) { \ Exception_flag = ExceptionHandled; #define Finally \ if (Exception_flag == ExceptionEntered) ntyExceptionPopStack; \ } { \ if (Exception_flag == ExceptionEntered) \ Exception_flag = ExceptionFinalized; #define EndTry \ if (Exception_flag == ExceptionEntered) ntyExceptionPopStack; \ } if (Exception_flag == ExceptionThrown) ReThrow; \ } while (0) static pthread_once_t once_control = PTHREAD_ONCE_INIT; static void init_once(void) { ntyThreadDataCreate(ExceptionStack); } void ntyExceptionInit(void) { pthread_once(&once_control, init_once); } void ntyExceptionThrow(ntyException *excep, const char *func, const char *file, int line, const char *cause, ...) { va_list ap; ntyExceptionFrame *frame = (ntyExceptionFrame*)ntyThreadDataGet(ExceptionStack); if (frame) { frame->exception = excep; frame->func = func; frame->file = file; frame->line = line; if (cause) { va_start(ap, cause); vsnprintf(frame->message, EXCEPTIN_MESSAGE_LENGTH, cause, ap); va_end(ap); } ntyExceptionPopStack; longjmp(frame->env, ExceptionThrown); } else if (cause) { char message[EXCEPTIN_MESSAGE_LENGTH+1]; va_start(ap, cause); vsnprintf(message, EXCEPTIN_MESSAGE_LENGTH, cause, ap); va_end(ap); printf("%s: %s\n raised in %s at %s:%d\n", excep->name, message, func ? func : "?", file ? file : "?", line); } else { printf("%s: %p\n raised in %s at %s:%d\n", excep->name, excep, func ? func : "?", file ? file : "?", line); } } /* ** **** ******** **************** debug **************** ******** **** ** */ ntyException A = {"AException"}; ntyException B = {"BException"}; ntyException C = {"CException"}; ntyException D = {"DException"}; void *thread(void *args) { pthread_t selfid = pthread_self(); Try { Throw(A, "A"); } Catch (A) { printf("catch A : %ld\n", selfid); } EndTry; Try { Throw(B, "B"); } Catch (B) { printf("catch B : %ld\n", selfid); } EndTry; Try { Throw(C, "C"); } Catch (C) { printf("catch C : %ld\n", selfid); } EndTry; Try { Throw(D, "D"); } Catch (D) { printf("catch D : %ld\n", selfid); } EndTry; Try { Throw(A, "A Again"); Throw(B, "B Again"); Throw(C, "C Again"); Throw(D, "D Again"); } Catch (A) { printf("catch A again : %ld\n", selfid); } Catch (B) { printf("catch B again : %ld\n", selfid); } Catch (C) { printf("catch C again : %ld\n", selfid); } Catch (D) { printf("catch B again : %ld\n", selfid); } EndTry; } #define THREADS 50 int main(void) { ntyExceptionInit(); Throw(D, NULL); Throw(C, "null C"); printf("\n\n=> Test1: Try-Catch\n"); Try { Try { Throw(B, "recall B"); } Catch (B) { printf("recall B \n"); } EndTry; Throw(A, NULL); } Catch(A) { printf("\tResult: Ok\n"); } EndTry; printf("=> Test1: Ok\n\n"); printf("=> Test2: Test Thread-safeness\n"); #if 1 int i = 0; pthread_t threads[THREADS]; for (i = 0;i < THREADS;i ++) { pthread_create(&threads[i], NULL, thread, NULL); } for (i = 0;i < THREADS;i ++) { pthread_join(threads[i], NULL); } #endif printf("=> Test2: Ok\n\n"); } - 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
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151
- 152
- 153
- 154
- 155
- 156
- 157
- 158
- 159
- 160
- 161
- 162
- 163
- 164
- 165
- 166
- 167
- 168
- 169
- 170
- 171
- 172
- 173
- 174
- 175
- 176
- 177
- 178
- 179
- 180
- 181
- 182
- 183
- 184
- 185
- 186
- 187
- 188
- 189
- 190
- 191
- 192
- 193
- 194
- 195
- 196
- 197
- 198
- 199
- 200
- 201
- 202
- 203
- 204
- 205
- 206
- 207
- 208
- 209
- 210
- 211
- 212
- 213
- 214
- 215
- 216
- 217
- 218
- 219
- 220
- 221
- 222
- 223
- 224
- 225
- 226
- 227
- 228
- 229
- 230
- 231
- 232
- 233
- 234
- 235
- 236
- 237
- 238
- 239
- 240
- 241
- 242
- 243
- 244
- 245
- 246
- 247
- 248
- 249
- 250
- 251
- 252
- 253
- 254
- 255
- 256
- 257
- 258
- 259
- 260
- 261
- 262
- 263
- 264
- 265
- 266
- 267
- 268
- 269
-
相关阅读:
PTA天梯赛训练 7-8 查验身份证 （15分）
[附源码]Python计算机毕业设计Djangospringboot作业管理系统
【论文阅读】SPARK：针对视觉跟踪的空间感知在线增量攻击
tiny4412编译出来的zImage不能开机
c51定时器
【jackson解析复杂对象】
【Vue】环境搭建
解决No Feign Client for loadBalancing defined，修改Maven依赖
【java筑基】IO流基础之文件的常见操作
Mysql 事物与存储引擎
- 原文地址：https://blog.csdn.net/weixin_45715405/article/details/133690623
