多线程查询数据

超、凢脫俗 2022-09-25 07:23 159阅读 0赞

多线程查询数据：

此处主要是对内存与数据的联系的理解，如使用到的地二级指针

#define _CRT_SECURE_NO_WARNINGS
    #include<stdio.h>
    #include<stdlib.h>
    #include<Windows.h>
    #include<string.h>
    #include<process.h>
    
    #define N 2027358
    
    char **g_bh;
    
    
    void init(char *path)
    {
    	//初始化
    	printf("init start...\n");
    	g_bh = malloc(sizeof(char *)*N);	//分配内存
    	//初始化时这儿不小心把 '\0' 写成了 "\0",结果造成了意想不到的程序崩溃...	
    	//memset(g_bh, "\0", sizeof(char *)*N);	
    	memset(g_bh, '\0', sizeof(char *)*N);		//初始化
    	FILE *pfr = fopen(path, "r");
    	if (pfr == NULL)
    	{
    		return;
    	}
    	else
    	{
    		for (int i = 0; i < N; i++)
    		{
    			char str[1024] = { 0 };
    			fgets(str, 1024, pfr);
    			int length = strlen(str);
    			if (length >= 1)
    			{
    				g_bh[i] = malloc(sizeof(char)*length + 1);
    				memset(g_bh[i], '\0', length + 1);		//初始化
    				if (g_bh[i] != NULL)	//如果内存分配成功则拷贝数据
    				{
    					strcpy(g_bh[i], str);
    				}
    			}
    
    		}
    	}
    
    	fclose(pfr);
    	printf("init end\n");
    
    }
    
    typedef struct threadBH
    {
    	char **ppstart;		//记录数据的开始地址
    	char *findstr;	//保存查询的数据
    	int id;			//记录线程的编号
    	int length;		//每个线程查询的数据长度
    } bh,*Pbh;
    
    void searchthread(void *p)
    {
    	//转换数据类型
    	Pbh pbh = p;
    	//利用传递的参数进行数据查询	
    	for (int i = 0; i < pbh->length; i++)
    	{
    		if (pbh->ppstart[i])
    		{
    			char *res = strstr(pbh->ppstart[i], pbh->findstr);
    			if (res)
    			{
    				printf("线程：%d 查询到，%s\n", pbh->id, pbh->ppstart[i]);
    			}
    		}
    	}
    }
    
    
    使用多线程查询数据
    void searchwiththread(char *str)
    {
    	int sum = 23;	//设置有 23 个线程，设置线程最好是CPU的倍数
    	//因为这儿要把
    	Pbh pbh= malloc(sizeof(bh)*sum);
    	memset(pbh, '\0', sizeof(bh)*sum);
    	HANDLE *phd = malloc(sizeof(HANDLE)* 23);	//这个相当于 int ** 
    	if (N%sum == 0)
    	{
    		for (int i = 0; i < sum; i++)
    		{
    			pbh[i].findstr = str;
    			pbh[i].id = i;
    			pbh[i].length = N / sum;
    			pbh[i].ppstart = g_bh + i*(N / sum);
    			phd[i] = _beginthread(searchthread, 0, &pbh[i]);
    		}
    	}
    	else
    	{
    		for (int i = 0; i < sum-1; i++)
    		{
    			pbh[i].findstr = str;
    			pbh[i].id = i;
    			pbh[i].length = N / (sum-1);
    			pbh[i].ppstart = g_bh + i*(N / (sum - 1));
    			phd[i] = _beginthread(searchthread, 0, &pbh[i]);
    		}
    		{
    			int i = sum - 1;
    			pbh[i].findstr = str;
    			pbh[i].id = i;
    			pbh[i].length = N % (sum - 1);
    			pbh[i].ppstart = g_bh + i*(N / (sum - 1));
    			phd[i] = _beginthread(searchthread, 0, &pbh[i]);		
    		}
    		
    	}
    	WaitForMultipleObjects(sum, phd, TRUE, INFINITE);
    }
    
    //void  searchwiththread(char*str)
    //{
    //	int num = 23;//线程是CPU核心的倍数
    //	Pbh pbh = malloc(sizeof(bh)* 23);//堆上开辟
    //	memset(pbh, '\0', sizeof(bh)* 23);
    //	HANDLE *phd = malloc(sizeof(HANDLE) * 23);
    //
    //	if (N%num==0)
    //	{
    //		for (int i = 0; i < num;i++)
    //		{
    //			pbh[i].id = i;
    //			pbh[i].findstr = str;
    //			pbh[i].length = N / num;//100  5  
    //			pbh[i].ppstart = g_bh + i*(N / num);//起始地址
    //			phd[i] = _beginthread(searchthread, 0, &pbh[i]);//创建线程
    //
    //		}
    //
    //	} 
    //	else
    //	{
    //		//100 9  8×12+4
    //		for (int i = 0; i < num-1; i++)
    //		{
    //			pbh[i].id = i;
    //			pbh[i].findstr = str;
    //			pbh[i].length = N / (num - 1);//100  5  
    //			pbh[i].ppstart = g_bh + i*(N / (num - 1));//起始地址
    //			phd[i] = _beginthread(searchthread, 0, &pbh[i]);//创建线程
    //
    //		}
    //		{
    //			int i = num - 1;
    //			pbh[i].id = i;
    //			pbh[i].findstr = str;
    //			pbh[i].length = N % (num - 1);//100  5  
    //			pbh[i].ppstart = g_bh + i*(N / (num - 1));//起始地址
    //			phd[i] = _beginthread(searchthread, 0, &pbh[i]);//创建线程
    //			//0 8*12
    //		}
    //
    //	}
    //
    //	WaitForMultipleObjects(23, phd, TRUE, INFINITE);//等待所有线程退出
    //	
    //}
    
    
    
    char *path = "E:\\baihe.txt";
    
    void main()
    {
    	//Sleep(5000);
    	init(path);
    
    	while (1)
    	{
    		printf("请输入要查询的名字：");
    		char name[30];
    		scanf("%s", name);	
    		searchwiththread(name);
    	}
    
    
    
    	system("pause");
    }