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 = 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 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 //              PARA_ERROR_LOG("%s\n", PARA_STRERROR(-ret));
 120         return ret_list;
 121 }
 122
 123 static void random_shutdown(void)
 124 {
 125 }
 126
 127 /**
 128  *  the init function for the random audio file selector
 129  *
 130  * Init all function pointers of \a db, init the info text and seed the
 131  * PRNG.
 132  *
 133  * \sa struct audio_file_selector, misc_meta_data::selector_info, mysql.c
 134  */
 135 int random_selector_init(struct audio_file_selector *db)
 136 {
 137         struct timeval now;
 138
 139         PARA_INFO_LOG("%s", "registering random handlers ;)\n");
 140         sprintf(mmd->selector_info, "dbinfo1:database info? You're kidding. "
 141                 "I'm still dopey!\ndbinfo2:\ndbinfo3:\n");
 142         gettimeofday(&now, NULL);
 143         srand(now.tv_usec);
 144         db->cmd_list = cmds;
 145         db->get_audio_file_list = random_get_audio_file_list;
 146         db->shutdown = random_shutdown;
 147         return 1;
 148 }