测试字符串比较函数的性能

strcmp_bench.c

#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <time.h>

#include "sds.h"

/**
 * 高效地比较两个字符串的大小
 */
static inline int sdscmp4(const sds s1, const sds s2) {
    size_t l1, l2;
    int d;

    l1 = sdslen(s1);
    l2 = sdslen(s2);
    d = l1 - l2;
    
    /// 长度更短的字符串更小
    if (d < 0) {
        return -1;
    }
    else if (d > 0) {
        return 1;
    }
    
    /// 如果长度相同，则进行常规比较
    char *ss1, *ss2;
    ss1 = s1;
    ss2 = s2;
    
    
    while (l1 > 0) {
        if (*(uint64_t*)ss1 > *(uint64_t*)ss2) {
            return 1;
        }
        else if (*(uint64_t*)ss1 < *(uint64_t*)ss2) {
            return -1;
        }
        else {
            ss1 += 8;
            ss2 += 8;
            l1 -= 8;
        }
    }
    
    
    return 0;
    
}


/**
 * @param int   字符串长度（不含末尾 \0）
 * @param int   循环次数，单位是千次
 */
void strcmp_bench(int len, int kloops) {
    char **s1, **s2;
    sds *sd1, *sd2;
    clock_t t_nop, t1, t2;
    int i, k, ret;
    
    s1 = malloc(kloops * sizeof(char*));
    s2 = malloc(kloops * sizeof(char*));
    sd1 = malloc(kloops * sizeof(sds));
    sd2 = malloc(kloops * sizeof(sds));
   
   
    for (i = 0; i < kloops; i++) {
        s1[i] = malloc(len + 1);
        memset(s1[i], 'a', len);
        s1[i][len] = 0x00;
        
        s2[i] = strdup(s1[i]);
        s2[i][len - 1] = 0x00;
        
        
        sd1[i] = sdsnew(s1[i]);
        sd2[i] = sdsnew(s2[i]);
    }
    
    
    ret = 0;
    t1 = clock();
    for (k = 0; k < 1000; k++) {
        for (i = 0; i < kloops; i++) {
            ret += len;
        }
    }
    t_nop = clock() - t1;
    
    printf("ret=%d\n", ret);
    printf("空循环耗时 %0.3lf 秒\n", t_nop / (double)CLOCKS_PER_SEC);
    
    
    
    ret = 0;
    t1 = clock();
    for (k = 0; k < 1000; k++) {
        for (i = 0; i < kloops; i++) {
            ret += strcmp(s1[i], s2[i]);
        }
    }
    t2 = clock() - t1;
    
    printf("ret=%d\n", ret);
    printf("strcmp 循环耗时 %0.3lf 秒\n", t2 / (double)CLOCKS_PER_SEC);
    
    
    
    ret = 0;
    t1 = clock();
    for (k = 0; k < 1000; k++) {
        for (i = 0; i < kloops; i++) {
            ret += sdscmp(sd1[i], sd2[i]);
        }
    }
    t2 = clock() - t1;
    
    printf("ret=%d\n", ret);
    printf("sdscmp 循环耗时 %0.3lf 秒\n", t2 / (double)CLOCKS_PER_SEC);
    
    
    
    
    ret = 0;
    t1 = clock();
    for (k = 0; k < 1000; k++) {
        for (i = 0; i < kloops; i++) {
            ret += sdscmp4(sd1[i], sd2[i]);
        }
    }
    t2 = clock() - t1;
    
    printf("ret=%d\n", ret);
    printf("sdscmp4 循环耗时 %0.3lf 秒\n", t2 / (double)CLOCKS_PER_SEC);
    
    
    
    
}


int main() {
    strcmp_bench(3200, 1000);
    return 0;
}