diff options
| -rw-r--r-- | server/media.erl | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/server/media.erl b/server/media.erl index 165338b..5eea592 100644 --- a/server/media.erl +++ b/server/media.erl @@ -3,6 +3,10 @@ -define(TESTPATTERN, "../ac/*.mp3"). -define(TIMEOUT, 100000000). +%This module is responsible for the management of the music database. +%It keeps track of playlist items with their current voting and locked/unlocked status +%and automatically selects the next song with the highest vote count to play back. + % Since we are not willing to calculate and deliver all the id3 tags everytime they are requested, % we try to get something persistent with mnesia. % Concerning the parsing of id3tags we use the library id3v2 by Brendon Hogger. For detailed information take a @@ -13,9 +17,9 @@ -record(track, {title, artist, votes, locked, filepath }). % Before this module becomes usable, we must initialize it with the following steps: -% 1. Initialize the mnesiadatabase and create the table within it. +% 1. Initialize the mnesia database and create the table within it. % 2. Parse the mp3s in the working directory and add them to the database -% 3. Get into a loop so the database can be actually queried and files can be played. +% 3. Get into a loop so the database can be queried and files can be played. init() -> mnesia:create_schema([node()]), @@ -40,14 +44,14 @@ read_files([FN|Rest],Total,Fail) -> end; read_files([],Total,Fail) -> io:format("Total: ~w, Failed: ~w~n", [Total, Fail]). -% Our Runloop to play music all the time, play waits on exit_status +% Our loop to play music all the time, play waits on exit_status start_playing() -> {Artist, Title} = search_best(media:all(), 0,0), play(Artist, Title). -% Basic insertion of entrys into the database. Some entries are left out because they are 0 or false. +% Basic insertion of entries into the database. Some entries are left out because they are 0 or false. insert(Artist, Title, Filepath) -> F = fun() -> @@ -70,7 +74,7 @@ search_best([Head|Rest], Max_Votes, Track) -> search_best([], 0, 0) -> reset_all(all()); search_best([], _, Track) -> {Track#track.artist, Track#track.title}. -% if nothing is playable anymore just reset them and start playing again... +% if nothing is playable anymore (because all songs are locked) just reset all songs and start playing again... reset_all([Head|Rest]) -> unlock(Head#track.artist, Head#track.title), @@ -86,7 +90,7 @@ ask(Artist, Title) -> {atomic, Results} = mnesia:transaction(F), Results. -% Just in case the client is interested in everything we got. +% Just in case the client is interested in everything we have. all() -> F = fun() -> @@ -95,7 +99,7 @@ all() -> {atomic, Results} = mnesia:transaction(F), Results. -% We want to play mp3s from our database. After we play them they will become locked. +% We want to play mp3s from our database. After we play them they will be locked. % In practice we are going to set their locked variable to true and spawn a process which will unlock them after a certain time. % Well this could be considered abuse. @@ -111,8 +115,13 @@ play(Artist, Title) -> {Port, {exit_status, 0}} -> start_playing(); {Port, {exit_status, S}} -> throw({commandfailed, S}) end. -%Increase the vote in the database so it will hopefully be played in the future + +% Of course we need a query to find out what the highest voted track is. +% We accomplish this by requesting all the records from the database and then iterate over them, just taking a look at the vote +% variable, so it is like a list of integers. In case no tracks were voted for we just take the first track we found and play it. Of course this song is locked afterwards so a different one will be chosen. + +%votes for a track, i.e. increases its vote count by one. vote(Artist, Title) -> F = fun() -> [Head|_] = ask(Artist, Title), @@ -122,8 +131,7 @@ vote(Artist, Title) -> end, mnesia:transaction(F). -% decrease votes in database - +%votes against a track, i.e. decreases its vote count by one. devote(Artist, Title) -> F = fun() -> [Head|_] = ask(Artist, Title), @@ -133,8 +141,7 @@ devote(Artist, Title) -> end, mnesia:transaction(F). -% Reset votes to zero in database - +%resets the vote count of selected track to 0 (this is called when the song is played). reset_votes(Artist, Title) -> F = fun() -> [Head|_] = ask(Artist, Title), @@ -143,8 +150,7 @@ reset_votes(Artist, Title) -> end, mnesia:transaction(F). -% Lock a song - +%locks a song so it can't be played again or voted for for that time. lock(Artist, Title) -> F = fun() -> [Head|_] = ask(Artist, Title), @@ -153,8 +159,7 @@ lock(Artist, Title) -> end, mnesia:transaction(F). -% Unlock a song... - +%unlocks a song so it can be played and voted for again. unlock(Artist, Title) -> F = fun() -> [Head|_] = ask(Artist, Title), @@ -165,7 +170,6 @@ unlock(Artist, Title) -> % Lock a song if it was just played, after a Timeout it will be unlocked automaticly % If all songs are locked, all will be unlocked. - lock_process(Artist, Title) -> lock(Artist, Title), receive |