C 线程同步-何时终止线程？

我正在写一个程序，需要一些输入；目录、文件名和一些标志。该程序的目的是在给定目录中搜索给定文件。在搜索时，如果它找到另一个目录，它将打开该目录并继续在那里搜索。其中一个标志允许用户选择程序用于搜索文件的线程数

目录存储在堆栈中，我遇到的问题是线程之间的同步。我目前正在使用一个带有定时等待条件的互斥锁。这意味着，如果线程等待了一定时间，并且存储目录的堆栈为空，则线程将结束。问题是，当只运行2个线程时，1个线程可能会完成所有工作，即打开400个目录，而另一个线程打开0个目录

所以我的问题是。。。如何以更好的方式同步线程？可能不使用定时等待条件？线程何时终止

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <getopt.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <pthread.h>

void search_func(char *path, char *name, int d, int f, int l);
void *thread_func(void *arg);
void push(char *data);
char* pop();
#define MAXLENGTH 1000
#define MAXSIZE 10000
#define WAIT_TIME_SECONDS 0.1
pthread_mutex_t lock;
pthread_cond_t count_threshold_cv;
struct stack
{
    char stk[MAXSIZE][MAXLENGTH];
    int top;
};
typedef struct stack STACK;
STACK s;

struct arg_keeper {
    char **argv;
    int argc;
    int d;
    int f;
    int l;
};

int main(int argc, char **argv) {
    if(argc < 3) {
        fprintf(stderr, "Not enough arguments\n");
        return 1;
    }
    char *xValue = NULL;
    int x;
    int d = 0;
    int f = 0;
    int l = 0;
    int nrthr = 0;
    opterr = 0;
    int thread_count = 0;
    int directory_exist = 0;
    pthread_t tid[1024];

    while ((x = getopt(argc, argv, "t:p:")) != -1) {
        switch (x) {
        case 't':
            xValue = optarg;
            if (*xValue == 'd') {
                d = 1;
            } else if (*xValue == 'f') {
                f = 1;
            } else if (*xValue == 'l') {
                l = 1;
            }
            break;
        case 'p':
            nrthr = atoi(optarg);
            if(nrthr == 0) {
                fprintf(stderr, "Invalid thread count\n");
                return 1;
            }
            break;
        case '?':
            if (isprint (optopt))
                fprintf(stderr, "Unknown option '-%c'.\n",
                                optopt);
            return 1;
        default:
            abort();
        }
    }

    if (argc >= 3) {
        int i;
        for (i = optind; i < argc - 1; i++) {
            directory_exist = 1;
            push(argv[i]);
        }
    }
    if(directory_exist == 0) {
        fprintf(stderr, "No directories entered\n");
        return 1;
    }

    struct arg_keeper * arg_struct = malloc(sizeof(*arg_struct));
    arg_struct->argv = argv;
    arg_struct->argc = argc;
    arg_struct->d = d;
    arg_struct->f = f;
    arg_struct->l = l;

    if(pthread_mutex_init(&lock, NULL) != 0) {
        fprintf(stderr, "Mutex initialisation failed\n");
        return 1;
    }
    if(pthread_cond_init(&count_threshold_cv, NULL) != 0) {
        fprintf(stderr, "Condition variable initialisation failed\n");
        return 1;
    }

    while(thread_count < nrthr - 1) {
        if(pthread_create(&(tid[thread_count++]), NULL, thread_func,
                            arg_struct) != 0)
            fprintf(stderr, "Can't create thread\n");
    }

    if(nrthr!=0)
        thread_func(arg_struct);
    else
        thread_func(arg_struct);

    int c;
    for(c = 0; c < nrthr; c++) {
        pthread_join(tid[c], NULL);
    }
    pthread_mutex_destroy(&lock);
    free(arg_struct);
    return 0;
}

void *thread_func(void *arg) {
    int dirOpened = 0;
    struct arg_keeper arg_struct = *(struct arg_keeper *)arg;
    char *data;

    pthread_mutex_lock(&lock);
    struct timespec ts;
    struct timeval tp;
    while(1) {
        gettimeofday(&tp, NULL);
        ts.tv_sec  = tp.tv_sec;
        ts.tv_nsec = tp.tv_usec * 1000;
        ts.tv_sec += WAIT_TIME_SECONDS;

        if (pthread_cond_timedwait(&count_threshold_cv, &lock, &ts) == ETIMEDOUT) {
            if (s.top) {
                data = pop();
                pthread_cond_signal(&count_threshold_cv);
                dirOpened++;
                search_func(data, arg_struct.argv[arg_struct.argc - 1], arg_struct.d,
                        arg_struct.f, arg_struct.l);
            }
            else
                break;
        }
    }
    pthread_mutex_unlock(&lock);
    fprintf(stdout, "Thread with id %lu opened %d directories\n",
                pthread_self(), dirOpened);
    return NULL;
}

void search_func(char *inPath, char *testName, int d, int f, int l) {
    char path[PATH_MAX];
    strcpy(path, inPath);
    struct dirent *pDirent;
    DIR *pDir;
    struct stat file_info;

    if ((pDir = opendir(path)) == NULL) {
        fprintf(stderr, "Error:'%s': %s\n", path, strerror(errno));
    } else {
        int v1;
        int v2;
        char *str1 = ".";
        char *str2 = "..";

        char name[PATH_MAX];
        strcpy(name, testName);

        char testPath[PATH_MAX];
        strcpy(testPath, path);

        char testPathLast[PATH_MAX];
        strcpy(testPathLast, path);

        while ((pDirent = readdir(pDir)) != NULL) {
            if (strcmp(pDirent->d_name, name) == 0 && d == 0 &&
                    f == 0 && l == 0) {
                if (path[strlen(path) - 1] != '/')
                    strcat(testPathLast, "/");

                strcat(testPathLast, pDirent->d_name);
                fprintf(stdout, "%s\n", testPathLast);
            }

            char testPath2[PATH_MAX];
            strcpy(testPath2, testPath);
            strcat(testPath2, "/");
            strcat(testPath2, pDirent->d_name);

            if (lstat(testPath2, &file_info) != 0)
                fprintf(stderr, "lstat error2: %s\n",
                            strerror(errno));

            if (d == 1) {
                if (strcmp(pDirent->d_name, name)
                    == 0 && S_ISDIR(file_info.st_mode)) {
                    if (path[strlen(path) - 1] != '/')
                        strcat(testPathLast, "/");

                    strcat(testPathLast, pDirent->d_name);
                    fprintf(stdout, "%s\n", testPathLast);
                }
            }

            if (f == 1) {
                if (strcmp(pDirent->d_name, name)
                    == 0 && S_ISREG(file_info.st_mode)) {
                    if (path[strlen(path) - 1] != '/')
                        strcat(testPathLast, "/");

                    strcat(testPathLast, pDirent->d_name);
                    fprintf(stdout, "%s\n", testPathLast);
                }
            }

            if (l == 1) {
                if (strcmp(pDirent->d_name, name)
                    == 0 && S_ISLNK(file_info.st_mode)) {
                    if (path[strlen(path) - 1] != '/')
                        strcat(testPathLast, "/");

                    strcat(testPathLast, pDirent->d_name);
                    fprintf(stdout, "%s\n", testPathLast);
                }
            }

            v1 = strcmp(pDirent->d_name, str1);
            v2 = strcmp(pDirent->d_name, str2);

            if ((v1 != 0 && v2 != 0) && S_ISDIR(file_info.st_mode)) {
                strcpy(path, testPath);
                strcpy(path, testPath);
                if (path[strlen(path) - 1] != '/')
                    strcat(path, "/");
                strcat(path, pDirent->d_name);
                push(path);
            }
        }
        closedir(pDir);
    }
}

void push(char *data)
{
    if(s.top == (MAXSIZE - 1)) {
        fprintf(stderr, "Stack is full\n");
        return;
    }
    else {
        s.top = s.top + 1;
        strcpy(&(s.stk[s.top][0]), data);
    }
    return;
}

char* pop()
{
    char *data;
    if(s.top == -1) {
        fprintf(stderr, "Stack is empty\n");
        return NULL;
    }
    else {
        data = s.stk[s.top];
        s.top = s.top - 1;
    }
    return data;
}

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无效搜索函数（字符*路径，字符*名称，int d，int f，int l）；
void*thread_func（void*arg）；
无效推送（字符*数据）；
char*pop（）；
#定义MAXLENGTH 1000
#定义MAXSIZE 10000
#定义等待时间秒0.1
pthread_mutex_t lock；
pthread_cond_t count_threshold_cv；
结构堆栈
{
字符stk[MAXSIZE][MAXLENGTH]；
int top；
};
typedef结构堆栈；
堆栈s；
结构参数{
字符**argv；
int-argc；
int d；
int f；
int l；
};
int main（int argc，字符**argv）{
如果（argc<3）{
fprintf（stderr，“参数不足”\n）；
返回1；
}
char*xValue=NULL；
int x；
int d=0；
int f=0；
int l=0；
int nrthr=0；
opterr=0；
int线程计数=0；
int目录_exist=0；
pthread_t tid[1024]；
而（（x=getopt（argc，argv，t:p:）！=-1）{
开关（x）{
案例“t”：
xValue=optarg；
如果（*xValue=='d'）{
d=1；
}else if（*xValue=='f'）{
f=1；
}如果（*xValue=='l'），则为else{
l=1；
}
打破
案例“p”：
nrthr=atoi（optarg）；
如果（nrthr==0）{
fprintf（stderr，“无效线程计数\n”）；
返回1；
}
打破
案例“？”：
如果（iPrint（optopt））
fprintf（标准，“未知选项”-%c.\n“，
光电转换）；
返回1；
违约：
中止（）；
}
}
如果（argc>=3）{
int i；
对于（i=optind；iargv=argv；
arg_struct->argc=argc；
arg_struct->d=d；
参数结构->f=f；
参数结构->l=l；
if（pthread\u mutex\u init（&lock，NULL）！=0）{
fprintf（stderr，“互斥体初始化失败\n”）；
返回1；
}
if（pthread\u cond\u init（&count\u threshold\u cv，NULL）！=0）{
fprintf（stderr，“条件变量初始化失败\n”）；
返回1；
}
while（线程计数d_name，name）==0&&d==0&&
f==0&&l==0）{
if（路径[strlen（路径）-1]！='/'））
strcat（testPathLast，“/”；
strcat（testPathLast，pDirent->d_name）；
fprintf（stdout，“%s\n”，testPathLast）；
}
char testPath2[PATH_MAX]；
strcpy（testPath2，testPath）；
strcat（测试路径2，“/
struct work_item {
    struct work_item *next;
    char              path[];
};

struct work {
    pthread_mutex_t   mutex;
    pthread_cond_t    cond;
    long              active;
    struct work_item *item;
};
#define WORK_INITIALIZER {     \
    PTHREAD_MUTEX_INITIALIZER, \
    PTHREAD_COND_INITIALIZER,  \
    0L, NULL }

void *worker_thread(void *work_ptr)
{
    struct work *const work = (struct work *)word_ptr;
    struct work_item  *item;

    pthread_mutex_lock(&(work->mutex));

    while (1) {

        /* If there are no active workers,
           nor any work items, we're done. */
        if (!work->item && !work->active) {
            /* Ensure threads waiting on the condition
               variable are woken up, so they quit too. */
            pthread_cond_broadcast(&(work->cond));
            pthread_mutex_unlock(&(work->mutex));
            return NULL;
        }

        /* No work items left? */
        if (!work->item) {
            /* Wait for a new one to be produced,
               or a worker to notice we're done. */
            pthread_cond_wait(&(work->cond), &(work->mutex));
            continue;
        }

        /* Increment active worker count, grab an item,
           and work on it. */
        work->active++;
        item = work->item;
        work->item = work->item->next;
        item->next = NULL;

        /* Unlock mutex while working. */
        pthread_mutex_unlock(&(work->mutex));

        /*
         * TODO: Work on item
        */

        pthread_mutex_lock(&(work->mutex));
        work->active--;
    }
}

        struct work_item *temp;

        /* TODO: Allocate and initialize temp */

        pthread_mutex_lock(&(work->mutex));
        temp->next = work->item;
        work->item = temp;
        pthread_cond_signal(&(work->cond));
        pthread_mutex_unlock(&(work->mutex));

#include <sys/sem.h>
int semid;

void push(char *data)
{
    pthread_mutex_lock(&lock);
    if (s.top == MAXSIZE-1)
        fprintf(stderr, "Stack is full\n");
    else
        strcpy(s.stk[++s.top], data),
        semop(semid, &(struct sembuf){0, 1}, 1);    // add 1 to "dirs on stack"
    pthread_mutex_unlock(&lock);
    return;
}

char *pop()
{
    char *data;
    pthread_mutex_lock(&lock);
    if (s.top == -1)
        fprintf(stderr, "Stack is empty\n"),
        data = NULL;
    else
        data = strdup(s.stk[s.top--]);  // Don't return freed stack slot!
    pthread_mutex_unlock(&lock);
    return data;
}

    // create semaphore set of 2 sems: [0] dirs on stack, [1] threads at work
    semid = semget(IPC_PRIVATE, 2, S_IRWXU);
    semctl(semid, 0, SETALL, (unsigned short [2]){});   // zero the sem values

    while (thread_count < nrthr)
        if (pthread_create(&tid[thread_count++], NULL, thread_func, arg_struct))
            fprintf(stderr, "Can't create thread\n");

    // wait until no more dirs on stack and no more threads at work
    semop(semid, (struct sembuf []){{0, 0}, {1, 0}}, 2);
    semctl(semid, 0, IPC_RMID); // remove the semaphores, make threads finish

void *thread_func(void *arg)
{
    int dirOpened = 0;
    struct arg_keeper arg_struct = *(struct arg_keeper *)arg;
    char *data;
    // wait for work, subtract 1 from dirs on stack and add 1 to threads at work
    while (semop(semid, (struct sembuf []){{0, -1}, {1, 1}}, 2) == 0)
    {   // this loop ends when semid is removed
        data = pop();
        dirOpened++;
        search_func(data, arg_struct.argv[arg_struct.argc-1],
                    arg_struct.d, arg_struct.f, arg_struct.l);
        free(data);
        semop(semid, &(struct sembuf){1, -1}, 1);   // "threads at work" -= 1
    }
    fprintf(stdout, "Thread with id %lu opened %d directories\n",
            pthread_self(), dirOpened);
    return (void *)dirOpened;
}