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 gengetopt_args_info conf;
  31 extern struct misc_meta_data *mmd;
  32
  33 static unsigned int num_audio_files, audio_file_count;
  34 static char **audio_file_list;
  35
  36 static int count_audio_files(__a_unused const char *dir, __a_unused const char *name)
  37 {
  38         num_audio_files++;
  39         return 1;
  40 }
  41
  42 static int remember_file(const char *dir, const char *name)
  43 {
  44         if (audio_file_count >= num_audio_files)
  45                 return -E_FILE_COUNT;
  46         audio_file_list[audio_file_count] = make_message("%s/%s", dir, name);
  47         audio_file_count++;
  48         return 1;
  49 }
  50
  51 /* array of commands that are supported by this selector */
  52 static struct server_command cmds[] = {
  53 {
  54 .name = "random_info",
  55 .handler = com_random_info,
  56 .perms = 0,
  57 .description = "about the random audio file selector",
  58 .synopsis = "random_info",
  59 .help =
  60
  61 "Select a random file under the given directory"
  62 }, {
  63 .name = NULL,
  64 }
  65 };
  66
  67 static int com_random_info(int fd, __a_unused int argc, __a_unused char *argv[])
  68 {
  69         return send_buffer(fd, "Don't use for huge directories as it is "
  70                 "very inefficient in this case.\n");
  71 }
  72
  73 /*
  74  * Load a list of all audio files into memory and chose num of them randomly.
  75  * Called by server to determine next audio file to be streamed.
  76  */
  77 static char **random_get_audio_file_list(unsigned int num)
  78 {
  79         int i, ret;
  80         unsigned int len;
  81         char **ret_list = NULL; /* what we are going to return */
  82
  83         audio_file_list = NULL;
  84         num_audio_files = 0;
  85         /* first run, just count all audio files. dopey */
  86         ret = find_audio_files(conf.random_dir_arg, count_audio_files);
  87         if (ret < 0)
  88                 goto out;
  89         ret = -E_NOTHING_FOUND;
  90         if (!num_audio_files)
  91                 goto out;
  92         /* yeah, that doesn't scale, also dopey */
  93         audio_file_list = para_malloc(num_audio_files * sizeof(char *));
  94         audio_file_count = 0;
  95         /* second run (hot dentry cache, hopefully), fill audio_file_list */
  96         ret = find_audio_files(conf.random_dir_arg, remember_file);
  97         if (ret < 0)
  98                 goto out;
  99         /* careful, files might got deleted underneath */
 100         num_audio_files = audio_file_count; /* can only decrease */
 101         len = PARA_MIN(num, num_audio_files);
 102         ret = -E_NOTHING_FOUND;
 103         if (!len) /* nothing found, return NULL */
 104                 goto out;
 105         /* success, return NULL-terminated list */
 106         ret_list = para_calloc((len + 1) * sizeof(char *));
 107         for (i = 0; i < len; i++) { /* choose randomly */
 108                 int r = (int) ((num_audio_files + 0.0) * (rand()
 109                         / (RAND_MAX + 1.0)));
 110                 ret_list[i] = para_strdup(audio_file_list[r]);
 111         }
 112         ret = 1;
 113 out:
 114         if (audio_file_list) {
 115                 for (i = 0; i < num_audio_files; i++)
 116                         free(audio_file_list[i]);
 117                 free(audio_file_list);
 118         }
 119         if (ret > 0) {
 120         } else
 121                 sprintf(mmd->selector_info, "dbinfo1:%s\n", PARA_STRERROR(-ret));
 122         return ret_list;
 123 }
 124
 125 void random_update_audio_file(char *audio_file)
 126 {
 127         char *dn = para_dirname(audio_file);
 128         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 129                 "dbinfo1:current dir: %s\n"
 130                 "dbinfo2:random_dir: %s\n"
 131                 "dbinfo3:%d files available\n",
 132                 dn, conf.random_dir_arg, num_audio_files);
 133         free(dn);
 134         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 135 }
 136 static void random_shutdown(void)
 137 {
 138 }
 139
 140 /**
 141  *  the init function for the random audio file selector
 142  *
 143  * Init all function pointers of \a s, init the info text and seed the
 144  * PRNG.
 145  *
 146  * \sa struct audio_file_selector, misc_meta_data::selector_info, mysql.c
 147  */
 148 int random_selector_init(struct audio_file_selector *s)
 149 {
 150         struct timeval now;
 151
 152         PARA_INFO_LOG("%s", "registering random handlers ;)\n");
 153         gettimeofday(&now, NULL);
 154         srand(now.tv_usec);
 155         s->cmd_list = cmds;
 156         s->get_audio_file_list = random_get_audio_file_list;
 157         s->shutdown = random_shutdown;
 158         s->update_audio_file = random_update_audio_file;
 159         snprintf(mmd->selector_info, MMD_INFO_SIZE - 1,
 160                 "dbinfo1: Welcome to the random selector\n"
 161                 "dbinfo2: random_dir: %s\n", conf.random_dir_arg);
 162         mmd->selector_info[MMD_INFO_SIZE - 1] = '\0';
 163         return 1;
 164 }