src/dynamic_configuration.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/timeb.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/file.h>
#ifdef TEST
#define FUSE_KAFKA_DYNAMIC_CONFIGURATION_PATH "/tmp/fuse_kafka.args"
#else
#define FUSE_KAFKA_DYNAMIC_CONFIGURATION_PATH "/var/run/fuse_kafka.args"
#endif
typedef struct
{
    int argc;
    char** argv;
    char* line;
    int loaded;
    void* context;
    char* path;
    pthread_t thread;
} dynamic_configuration;
static dynamic_configuration* dynamic_configuration_get()
{
    static dynamic_configuration conf;
    return &conf;
}
static char* dynamic_configuration_get_path()
{
    dynamic_configuration* conf = dynamic_configuration_get();
    if(conf->path == NULL)
        return FUSE_KAFKA_DYNAMIC_CONFIGURATION_PATH;
    return conf->path;
}
int parse_line_from_file_nolock(FILE *f, char** linep, int* sizep)
{
    fseek(f, 0, SEEK_END);
    (*sizep) = ftell(f);
    (*linep) = (char*) malloc((*sizep) + 1);
    if((*linep) == NULL) return 2;
    fseek(f, 0, SEEK_SET);
    int read = fread((*linep), 1, (*sizep), f);
    if(read < (*sizep)) { free((*linep)); return 3; }
    (*linep)[*sizep] = 0;
    return 0;
}
int parse_line_from_file(char* path, char** linep, int* sizep)
{
    int result;
    FILE* f = fopen(path, "r");
    if(f == NULL) return 1;
#ifndef LOCK_SH
#define LOCK_SH 1
#endif
    flock(fileno(f), LOCK_SH);
    result = parse_line_from_file_nolock(f, linep, sizep);
    fclose(f);
    return result;
}
int parse_args_from_file(char* path, int* argcp, char*** argvp, char** linep)
{
    int i = *argcp = 0, k = 0, size = 0, l;
    if((i = parse_line_from_file(path, linep, &size)) != 0) return i;
    for(i = 0; i < size; i++)
        if((i == 0 || (*linep)[i-1]  == ' ') && (*linep)[i] != ' ') (*argcp)++;
    (*argvp) = calloc((*argcp), sizeof(char*));
    if((*argvp) == NULL) { free((*linep)); return 4; }
    for(i = 0; i <= size; i++)
    {
        if((i == 0 || !(*linep)[i-1] || (*linep)[i-1]  == ' ') && ((*linep)[i] != ' ' || k == *argcp))
        {
            if(k < *argcp) (*argvp)[k++] = (*linep) + i;
            if(i > 0)
            {
                (*linep)[i - 1] = 0;
                for(l = i - 2; l > 0; l--)
                {
                    if((*linep)[l] != ' ') break;
                    else (*linep)[l] = 0;
                }
            }
        }
    }
    return 0;
}
unsigned long long millisecond(struct stat* info)
{
    return info->st_mtime * 1000
#ifndef _WIN32
        + info->st_mtim.tv_nsec / 1000000
#endif
        ;
}
unsigned long long millisecond_clock()
{
    struct timeb t;
    ftime(&t);
    return t.time * 1000 + t.millitm;
}
long long* dynamic_configuration_get_last_change()
{
    static long long last_change = 0;
    return &last_change;
}
int dynamic_configuration_changed()
{
    long long * last_change = dynamic_configuration_get_last_change();
    long long new_change;
    struct stat stats;
    if(*last_change == 0) *last_change = millisecond_clock();
    if(stat(dynamic_configuration_get_path(), &stats) != 0)
        return 0;
    new_change = millisecond(&stats);
    if(new_change <= *last_change) return 0;
    *last_change = new_change;
    return 1;
}
void dynamic_configuration_free()
{
    dynamic_configuration* conf = dynamic_configuration_get();
    if(conf == NULL) return;
    free(conf->line);
    free(conf->argv);
}
int dynamic_configuration_load()
{
    char* line;
    char** argv;
    int argc;
    dynamic_configuration* conf = dynamic_configuration_get();
    if(parse_args_from_file(dynamic_configuration_get_path(),
                &argc, &argv, &line) == 0)
    {
        if(conf->loaded) dynamic_configuration_free();
        conf->argc = argc;
        conf->line = line;
        conf->argv = argv;
        conf->loaded = 1;
        return 0;
    }
    return 1;
}
int* dynamic_configuration_watch_routine_running()
{
    static int running = 1;
    return &running;
}
void* dynamic_configuration_watch_routine(void(*f)(int argc, char** argv, void* context))
{
    while(*dynamic_configuration_watch_routine_running())
    {
        if(dynamic_configuration_get()->context && 
                dynamic_configuration_changed() &&
                dynamic_configuration_load() == 0)
        {
            dynamic_configuration* conf = dynamic_configuration_get();
            f(conf->argc, conf->argv, conf->context);
        }
        fk_sleep(5);
    }
    return NULL;
}
void dynamic_configuration_watch(void(*f)(int argc, char** argv, void* context))
{
    pthread_create(&(dynamic_configuration_get()->thread), NULL, 
            (void * (*)(void *))
            dynamic_configuration_watch_routine, (void*) f);
}
void dynamic_configuration_watch_stop()
{
    *dynamic_configuration_watch_routine_running() = 0;
    dynamic_configuration* conf = dynamic_configuration_get();
    if(conf != NULL && conf->thread != 0)
    {
        pthread_cancel(conf->thread);
        pthread_join(conf->thread, NULL);
    }
    *dynamic_configuration_watch_routine_running() = 1;
}