random_selector.c

   1 /*
   2  * Copyright (C) 2004-2006 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 "db.h"
  25 #include "error.h"
  26 #include "net.h"
  27 #include "string.h"
  28
  29 static int com_random_info(int, int, char **);
  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                 return -E_FILE_COUNT;
  45         audio_file_list[audio_file_count] = make_message("%s/%s", dir, name);
  46         audio_file_count++;
  47         return 1;
  48 }
  49
  50 /* array of commands that are supported by this selector */
  51 static struct server_command cmds[] = {
  52 {
  53 .name = "random_info",
  54 .handler = com_random_info,
  55 .perms = 0,
  56 .description = "about the random audio file selector",
  57 .synopsis = "random_info",
  58 .help =
  59
  60 "Select a random file under the given directory"
  61 }, {
  62 .name = NULL,
  63 }
  64 };
  65
  66 static int com_random_info(int fd, __a_unused int argc, __a_unused char *argv[])
  67 {
  68         return send_buffer(fd, "Don't use for huge directories as it is "
  69                 "very inefficient in this case.\n");
  70 }
  71
  72 /*
  73  * Load a list of all audio files into memory and chose num of them randomly.
  74  * Called by server to determine next audio file to be streamed.
  75  */
  76 static char **random_get_audio_file_list(unsigned int num)
  77 {
  78         int i, ret;
  79         unsigned int len;
  80         char **ret_list = NULL; /* what we are going to return */
  81
  82         audio_file_list = NULL;
  83         num_audio_files = 0;
  84         /* first run, just count all audio files. dopey */
  85         ret = find_audio_files(conf.random_dir_arg, count_audio_files);
  86         if (ret < 0)
  87                 goto out;
  88         ret = -E_NOTHING_FOUND;
  89         if (!num_audio_files)
  90                 goto out;
  91         /* yeah, that doesn't scale, also dopey */
  92         audio_file_list = para_malloc(num_audio_files * sizeof(char *));
  93         audio_file_count = 0;
  94         /* second run (hot dentry cache, hopefully), fill audio_file_list */
  95         ret = find_audio_files(conf.random_dir_arg, remember_file);
  96         if (ret < 0)
  97                 goto out;
  98         /* careful, files might got deleted underneath */
  99         num_audio_files = audio_file_count; /* can only decrease */
 100         len = PARA_MIN(num, num_audio_files);
 101         ret = -E_NOTHING_FOUND;
 102         if (!len) /* nothing found, return NULL */
 103                 goto out;
 104         /* success, return NULL-terminated list */
 105         ret_list = para_calloc((len + 1) * sizeof(char *));
 106         for (i = 0; i < len; i++) { /* choose randomly */
 107                 int r = (int) ((num_audio_files + 0.0) * (rand()
 108                         / (RAND_MAX + 1.0)));
 109                 ret_list[i] = para_strdup(audio_file_list[r]);
 110         }
 111         ret = 1;
 112 out:
 113         if (audio_file_list) {
 114                 for (i = 0; i < num_audio_files; i++)
 115                         free(audio_file_list[i]);
 116                 free(audio_file_list);
 117         }
 118         if (ret > 0) {
 119         } else
 120                 sprintf(mmd->selector_info, "dbinfo1:%s\n", PARA_STRERROR(-ret));
 121         return ret_list;
 122 }
 123
 124 void random_update_audio_file(char *audio_file)
 125 {
 126         char *dn = para_dirname(audio_file);
 127         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 128                 "dbinfo1:current dir: %s\n"
 129                 "dbinfo2:random_dir: %s\n"
 130                 "dbinfo3:%d files available\n",
 131                 dn, conf.random_dir_arg, num_audio_files);
 132         free(dn);
 133         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 134 }
 135 static void random_shutdown(void)
 136 {
 137 }
 138
 139 /**
 140  *  the init function for the random audio file selector
 141  *
 142  * Init all function pointers of \a s, init the info text and seed the
 143  * PRNG.
 144  *
 145  * \sa struct audio_file_selector, misc_meta_data::selector_info, mysql.c
 146  */
 147 int random_selector_init(struct audio_file_selector *s)
 148 {
 149         struct timeval now;
 150
 151         PARA_INFO_LOG("%s", "registering random handlers ;)\n");
 152         gettimeofday(&now, NULL);
 153         srand(now.tv_usec);
 154         s->cmd_list = cmds;
 155         s->get_audio_file_list = random_get_audio_file_list;
 156         s->shutdown = random_shutdown;
 157         s->update_audio_file = random_update_audio_file;
 158         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 159                 "dbinfo1: Welcome to the random selector\n"
 160                 "dbinfo2: random_dir: %s\n", conf.random_dir_arg);
 161         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 162         return 1;
 163 }