random_selector.c

   1 /*
   2  * Copyright (C) 2004-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file random_selector.c An audio file selector which chooses files by random */
  20
  21 #include <sys/time.h> /* gettimeofday */
  22 #include "server.cmdline.h"
  23 #include "server.h"
  24 #include "afs.h"
  25 #include "error.h"
  26 #include "net.h"
  27 #include "string.h"
  28 #include "random_selector_command_list.h"
  29
  30 extern struct misc_meta_data *mmd;
  31
  32 static unsigned int num_audio_files, audio_file_count;
  33 static char **audio_file_list;
  34
  35 static int count_audio_files(__a_unused const char *dir, __a_unused const char *name)
  36 {
  37         num_audio_files++;
  38         return 1;
  39 }
  40
  41 static int remember_file(const char *dir, const char *name)
  42 {
  43         if (audio_file_count < num_audio_files) {
  44                 audio_file_list[audio_file_count] =
  45                         make_message("%s/%s", dir, name);
  46                 audio_file_count++;
  47         }
  48         return 1;
  49 }
  50
  51 int com_random_info(int fd, __a_unused int argc, __a_unused char *argv[])
  52 {
  53         return send_buffer(fd, "Don't use for huge directories as it is "
  54                 "very inefficient in this case.\n");
  55 }
  56
  57 /*
  58  * Load a list of all audio files into memory and chose num of them randomly.
  59  * Called by server to determine next audio file to be streamed.
  60  */
  61 static char **random_get_audio_file_list(unsigned int num)
  62 {
  63         int i, ret;
  64         unsigned int len;
  65         char **ret_list = NULL; /* what we are going to return */
  66
  67         audio_file_list = NULL;
  68         num_audio_files = 0;
  69         /* first run, just count all audio files. dopey */
  70         ret = find_audio_files(conf.random_dir_arg, count_audio_files);
  71         if (ret < 0)
  72                 goto out;
  73         ret = -E_NOTHING_FOUND;
  74         if (!num_audio_files)
  75                 goto out;
  76         /* yeah, that doesn't scale, also dopey */
  77         audio_file_list = para_malloc(num_audio_files * sizeof(char *));
  78         audio_file_count = 0;
  79         /* second run (hot dentry cache, hopefully), fill audio_file_list */
  80         ret = find_audio_files(conf.random_dir_arg, remember_file);
  81         if (ret < 0)
  82                 goto out;
  83         /* careful, files might got deleted underneath */
  84         num_audio_files = audio_file_count; /* can only decrease */
  85         len = PARA_MIN(num, num_audio_files);
  86         ret = -E_NOTHING_FOUND;
  87         if (!len) /* nothing found, return NULL */
  88                 goto out;
  89         /* success, return NULL-terminated list */
  90         ret_list = para_calloc((len + 1) * sizeof(char *));
  91         for (i = 0; i < len; i++) { /* choose randomly */
  92                 int r = (int) ((num_audio_files + 0.0) * (rand()
  93                         / (RAND_MAX + 1.0)));
  94                 ret_list[i] = para_strdup(audio_file_list[r]);
  95         }
  96         ret = 1;
  97 out:
  98         if (audio_file_list) {
  99                 for (i = 0; i < num_audio_files; i++)
 100                         free(audio_file_list[i]);
 101                 free(audio_file_list);
 102         }
 103         if (ret > 0) {
 104         } else
 105                 sprintf(mmd->selector_info, "dbinfo1:%s\n", PARA_STRERROR(-ret));
 106         return ret_list;
 107 }
 108
 109 static void random_update_audio_file(char *audio_file)
 110 {
 111         char *dn = para_dirname(audio_file);
 112         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 113                 "dbinfo1:current dir: %s\n"
 114                 "dbinfo2:random_dir: %s\n"
 115                 "dbinfo3:%d files available\n",
 116                 dn, conf.random_dir_arg, num_audio_files);
 117         free(dn);
 118         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 119 }
 120 static void random_shutdown(void)
 121 {
 122 }
 123
 124 /**
 125  * the init function for the random audio file selector
 126  *
 127  * \param s pointer ro the struct to iniitalize
 128  *
 129  * Init all function pointers of \a s, init the info text and seed the PRNG.
 130  *
 131  * \sa struct audio_file_selector, misc_meta_data::selector_info, mysql.c
 132  */
 133 int random_selector_init(struct audio_file_selector *s)
 134 {
 135         struct timeval now;
 136         unsigned int seed;
 137
 138         PARA_INFO_LOG("%s", "registering random handlers ;)\n");
 139         gettimeofday(&now, NULL);
 140         seed = now.tv_usec;
 141         srand(seed);
 142         s->cmd_list = random_selector_cmds;
 143         s->get_audio_file_list = random_get_audio_file_list;
 144         s->shutdown = random_shutdown;
 145         s->update_audio_file = random_update_audio_file;
 146         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 147                 "dbinfo1: Welcome to the random selector\n"
 148                 "dbinfo2: random_dir: %s\n", conf.random_dir_arg);
 149         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 150         return 1;
 151 }