使用线程的几种方式（2）工作组

在工作组模式中，数据由一组线程分别独立的处理。

以下例子来自于《POSIX多线程编程》，显示了一个简单的工作组。使用两个参数运行程序，一个字符串和一个搜索路径，结果类似于命令“find argv[2] -name * | xargs grep argv[1]". 程序使用一个crew来管理工作组，工作组将搜素路径排队为单链表，如果该路劲是文件，则打开搜素是否包含。

/* * crew.c * make:gcc -g -o crew -Wall -lpthread crew.c * 没有在程序异常情况下，对申请的资源work_t 链表释放。 */#include <pthread.h>#include <sys/types.h>#include <sys/stat.h>#include <dirent.h>#include "errors.h"#define CREW_SIZE 4/* work_t组成单链表，其中，表头为crew->first * 表尾为crew->last，crew->last->nest = crew->last */typedef struct work_tag {    struct work_tag *next;    char            *path;    char            *string;} work_t, *work_p;typedef struct worter_tag {    int             index;    pthread_t       pthread;        struct crew_tag *crew;} worker_t, *worker_p;typedef struct crew_tag {    int             crew_size;    worker_t        crew[CREW_SIZE];    long            work_count;    work_t          *first, *last;    pthread_mutex_t mutex;    pthread_cond_t  done;    pthread_cond_t  go;} crew_t, *crew_p;size_t path_max;size_t name_max;void* worker_routine(void *arg){    worker_p mine = (worker_t*)arg;    crew_p crew = mine->crew;    work_p work, new_work;    struct stat filestat;    struct dirent *entry;    int status;    entry = (struct dirent*)malloc(sizeof(struct dirent) + name_max);    if(entry ==  NULL) errno_abort("malloc error");    status = pthread_mutex_lock(&crew->mutex);    if(status != 0) err_abort(status, "pthread_mutex_lock failed");    while(crew->work_count == 0) {        status = pthread_cond_wait(&crew->go, &crew->mutex);        if(status != 0) err_abort(status, "pthread_cond_wait failed");    }    status = pthread_mutex_unlock(&crew->mutex);    if(status != 0) err_abort(status, "pthread_mutex_unlock failed");    //printf("Crew %d starting\n", mine->index);     while(1)    {        status = pthread_mutex_lock(&crew->mutex);        if (status != 0) err_abort(status, "pthread_mutex_lock failed");        //printf("Crew %d top: first is %#lx, count is %d\n", mine->index, crew->first, crew->work_count);        while(crew->first == NULL){            status = pthread_cond_wait(&crew->go, &crew->mutex);            if (status != 0) err_abort(status, "pthread_cond_wait  failed");             }                work = crew->first;        crew->first = crew->first->next;        if(crew->first == NULL) {            crew->last= NULL;        }        status = pthread_mutex_unlock(&crew->mutex);        if(status != 0) err_abort(status, "pthread_mutex_unlock failed");        status = lstat(work->path, &filestat);        if(S_ISLNK(filestat.st_mode))            printf("Thread %d :%s is a link, skipping. \n", mine->index, work->path);        else if(S_ISDIR(filestat.st_mode)) {            DIR *directory;            struct dirent *result;            directory = opendir(work->path);            if(directory == NULL) {                fprintf(stderr, "unable to open directory %s: %d (%s)\n", work->path, errno, strerror(errno));                continue;            }            while(1) {                /* readdir_r 可重入函数，线程安全 */                status = readdir_r(directory, entry, &result);                if(status != 0){                    fprintf(stderr, "unable to open directory %s: %d (%s)\n", work->path, status, strerror(status));                                break;                }                if(result == NULL) break;                if(strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;                new_work = (work_p)malloc(sizeof(work_t));                if(new_work == NULL) errno_abort("unable to allocate request");                new_work->path = (char*)malloc(path_max);                if(new_work->path == NULL) errno_abort("unable to allocate path");                strcpy(new_work->path, work->path);                strcat(new_work->path, "/");                strcat(new_work->path, entry->d_name);                new_work->string = work->string;                new_work->next = NULL;                status = pthread_mutex_lock(&crew->mutex);                if(status != 0) err_abort(status, "pthread_mutex_lock failed");                if(crew->first == NULL) {                    crew->first = new_work;                    crew->last = new_work;                } else {                    crew->last->next = new_work;                    crew->last = new_work;                }                crew->work_count++;                status = pthread_cond_signal(&crew->go);                status = pthread_mutex_unlock(&crew->mutex);                if(status != 0) err_abort(status, "pthread_mutex_unlock failed");            }            closedir(directory);       } else if(S_ISREG(filestat.st_mode)) {           FILE *search;           char buffer[256], *buf_ptr, *search_ptr;           if((search = fopen(work->path, "r")) == NULL)               fprintf(stderr, "unable to open file %s: %d (%s)\n", work->path, status, strerror(status));                       else {               while((buf_ptr = fgets(buffer, sizeof(buffer), search)) != NULL) {                   search_ptr = strstr(buffer, work->string);                   if(search_ptr != NULL){                       printf("thread %d found \"%s\" in %s \n", mine->index, work->string, work->path);                       break;                   }               }           }            fclose(search);        } else {           fprintf(stderr, "thred %d : %s is type %o (%s) \n", mine->index, work->path, filestat.st_mode & S_IFMT,                           S_ISFIFO(filestat.st_mode) ? "FIFO" :(S_ISCHR(filestat.st_mode) ? "CHR":                           ((S_ISBLK(filestat.st_mode) ? "BLK":((S_ISSOCK(filestat.st_mode) ? "SOCK":"UNKNOWN"))))));       }       free(work->path);       free(work);       status = pthread_mutex_lock(&crew->mutex);       if(status != 0) err_abort(status, "pthread_mutex_lock failed");       crew->work_count--;       if(crew->work_count <= 0) {           status = pthread_cond_broadcast(&crew->done);           if(status != 0) err_abort(status, "pthread_cond_broadcast failed");            status = pthread_mutex_unlock(&crew->mutex);           if(status != 0) err_abort(status, "pthread_mutex_unlock failed");           break;            }       status = pthread_mutex_unlock(&crew->mutex);       if(status != 0) err_abort(status, "pthread_mutex_unlock failed");    }    free(entry);    return (void*)0;}int crew_start(crew_p crew, char *filepath, char *search){    work_p request;    int status;    status = pthread_mutex_lock(&crew->mutex);    if (status != 0) return status;        /*等待crew完成*/    while(crew->work_count >0){        pthread_cond_wait(&crew->done, &crew->mutex);        if(status != 0) {            pthread_mutex_unlock(&crew->mutex);            return status;        }    }    errno = 0;    path_max = pathconf(filepath, _PC_PATH_MAX);    if(path_max == -1){        if(errno == 0) path_max = 256;        else errno_abort("unable to get path_max");    }      errno = 0;    name_max = pathconf(filepath, _PC_NAME_MAX);    if(name_max == -1){        if(errno == 0) name_max = 256;        else errno_abort("unable to get name_max");    }          //printf("PATH_MAX for %s is %ld, NAME_MAX is %ld", filepath, path_max, name_max);     path_max++;    name_max++;    request = (work_p)malloc(sizeof(work_t));    if(request == NULL) errno_abort("unable to allocate request");        request->path = (char*)malloc(path_max);    if(request->path == NULL) errno_abort("unable to allocate path");    strcpy(request->path, filepath);    request->string = search;    request->next = NULL;        if(crew->first == NULL) {        crew->first = request;        crew->last = request;    } else {        crew->last->next = request;        crew->last = request;    }        crew->work_count++;    status = pthread_cond_signal(&crew->go);    if(status != 0) {        free(crew->first);        crew->first = NULL;        crew->work_count = 0;        pthread_mutex_unlock(&crew->mutex);        return status;    }    while(crew->work_count > 0) {        status = pthread_cond_wait(&crew->done, &crew->mutex);         if(status != 0) err_abort(status, "pthread_cond_wait failed");    }    status = pthread_mutex_unlock(&crew->mutex);    if(status != 0) err_abort(status, "pthread_mutex_unlock failed");    return 0;}int crew_create(crew_t *crew, int crew_size){    int status;    int crew_index;    if(crew_size > CREW_SIZE)        return EINVAL;    crew->crew_size = crew_size;    crew->work_count = 0;    crew->first = NULL;    crew->last = NULL;    status = pthread_mutex_init(&crew->mutex, NULL);    if (status != 0) return status;     status = pthread_cond_init(&crew->go, NULL);    if (status != 0) return status;     status = pthread_cond_init(&crew->done, NULL);    if (status != 0) return status;    for(crew_index = 0; crew_index < crew_size; crew_index++) {        crew->crew[crew_index].index = crew_index;        crew->crew[crew_index].crew = crew;        status = pthread_create(&crew->crew[crew_index].pthread, NULL,                                 worker_routine, (void*)&crew->crew[crew_index]);        if(status != 0) err_abort(status, "pthread_create failed");     }    return 0;}int main(int argc, char *argv[]){    crew_t my_crew;    int status;    if(argc < 3) {        fprintf(stderr, "Usage:%s string path\n", argv[0]);        exit(-1);    }    status = crew_create(&my_crew, CREW_SIZE);    if(status != 0) err_abort(status, "create crew.");    status = crew_start(&my_crew, argv[2], argv[1]);    if(status != 0) err_abort(status, "start crew.");    return 0;}