SimpleLibraryViews plugin update increases library build time by a factor of 10

[mherger]

One question, to go through all the libraries I'm iterating over the result of 'Slim::Utils::Misc::getAudioDirs()'. Is that the right thing to do?

I'm not sure I understand. Yes, you'll have to can all of getAudioDirs(). But no, you don't have to do this for all libraries. You could do it once, and collect a list of all library name files you find. Keep this around in a (module) global variable:

{
   library1 => [ dir1, dir2, .. ],
   library2 => [ dir2, dirx, .. ],
   ...
}

So for the next library you'd only have to evaluate the folders in respective hash entry instead of crawling the filesystem once again.

Any suggestions on how to do this filtering? Perl is far from my first
language!

Sort the $dirs before processing them. Keep track of the previous value. If your current folder is a sub-folder of the previous, skip its processing

	my $previousDir;
	foreach my $dir ( sort { $a cmp $b } @includeDirs ) {
		next if $previousDir && $dir =~ /^\Q$previousDir\E/;
		$previousDir = $dir;

		my $pathSearch = Slim::Utils::Misc::fileURLFromPath($dir) . '/%';
		$log->debug("$libName: Including '$dir', pathSearch: '$pathSearch'");
		$sth_insert->execute($id, $pathSearch);
	}

You might notice I've modified the $pathSearch, too: using catfile() for the URL is wrong. That function would concatenate paths and file names following the operating system's conventions (eg. "/" vs. "" on Windows). But the URL used for the $pathSearch would always have a forward slash (to be confirmed - haven't tested this code!).

Also, I've had a request to make the recursive behaviour configurable.
Given the way the scanning code works, is there any way I could achieve
this? The SQL SELECT statement that finds the tracks would need to only
accept ones that are in a directory that has a matching file.

Yeah, that's trickier. Hmm... You'd probably have to use a different SQL query using REGEXP instead of LIKE for non-recursive. Then create a regex which would match the path, but no more slash after that.

if ($nonRecursive) {
   $pathSearch = '^\Q' . Slim::Utils::Misc::fileURLFromPath($dir) . '/\E[^\/]*$';
}

Again: I haven't tested this. I'm not sure it would work. Please give it a try. I'd have to check what regexes SQL supports.

[adhawkins]

Thanks for the info, will go back and take a look at applying it to the code.

Regarding the 'non-recursive', I've managed to implement this and it seems to be fairly efficient. What I do is:

Iterate over all the directories I found the file in.
Run a query on the database to select all the files that match this directory (which will also include the ones below it)
For each result, get the directory its in.
If this directory is the same as the directory I searched for, add it in.

Perhaps not the most efficient way of doing it, but it basically mirrors what the original code does. It seems to work correctly.

The code is below:

	my $sth_recursive_insert;
	my $sth_select;
	my $sth_insert;

	if ($recursive) {
		$sth_recursive_insert = $dbh->prepare('
			INSERT OR IGNORE INTO library_track (library, track)
			SELECT ?, tracks.id
			FROM tracks
			WHERE url like ?
			AND content_type NOT IN ("cpl", "src", "ssp", "dir")
		');
	} else {
		$sth_select = $dbh->prepare('
			SELECT id, url FROM tracks
				WHERE url like ? AND content_type NOT IN ("cpl", "src", "ssp", "dir")
				ORDER BY url
		');

		$sth_insert = $dbh->prepare('
			INSERT OR IGNORE INTO library_track (library, track) values (?, ?)
		');
	}

	foreach my $dir ( @includeDirs ) {
		my $pathSearch = Slim::Utils::Misc::fileURLFromPath($dir) . File::Spec->catfile('', '') . "%";
		main::DEBUGLOG && $log->is_debug && $log->debug("$libName: Including '$dir', pathSearch: '$pathSearch'");

		if ($recursive) {
			main::DEBUGLOG && $log->is_debug && $log->debug("Doing recursive");

			$sth_recursive_insert->execute($id, $pathSearch);
		} else {
			$sth_select->execute($pathSearch);

			while ( my ($trackid, $url) = $sth_select->fetchrow_array ) {
				my $trackDir = dirname(Slim::Utils::Misc::pathFromFileURL($url));

				main::DEBUGLOG && $log->is_debug && $log->debug("dir for '$url' is '$trackDir'");

				if ( $trackDir eq $dir ) {
					main::DEBUGLOG && $log->is_debug && $log->debug("Inserting");

					$sth_insert->execute($id, $trackid);
				}
			}
		}
	}

How does that look?

Andy

[mherger]

> Perhaps not the most efficient way of doing it, but it basically mirrors
> what the original code does. It seems to work correctly.

Whatever works! Sometimes optimizations aren't worth the hassle. If
you're happy with the result then it's better to keep the code you
understand and know how to maintain.

> my $pathSearch = Slim::Utils::Misc::fileURLFromPath($dir) . File::Spec->catfile('', '') . "%";

I still believe this could fail on Windows. Would you have any Windows
testers? catfile() should not be used with a URL. Just use the forward
slash "/" instead.

[adhawkins]

Yeah, that's trickier. Hmm... You'd probably have to use a different SQL query using REGEXP instead of LIKE for non-recursive. Then create a regex which would match the path, but no more slash after that.

if ($nonRecursive) {
   $pathSearch = '^\Q' . Slim::Utils::Misc::fileURLFromPath($dir) . '/\E[^\/]*';
}

Again: I haven't tested this. I'm not sure it would work. Please give it a try. I'd have to check what regexes SQL supports.

Looks like the DBD::SQLite module registers a 'regexp' function that just uses Perl regexps. So as long as that is a valid Perl RE it should be Ok.

Was going to try it in the command line client, but looks like that might not work. A bit of googling suggested there was an extension to sqlite that handled Perl REs, so will have a look at that.

Thanks as ever.

Andy

[adhawkins]

> my $pathSearch = Slim::Utils::Misc::fileURLFromPath($dir) . File::Spec->catfile('', '') . "%";

I still believe this could fail on Windows. Would you have any Windows
testers? catfile() should not be used with a URL. Just use the forward
slash "/" instead.

Yes, I've replaced that. I deliberately used catfile because I wanted to make sure I used the correct separator under Windows. You are of course correct though, the URI format that's actually used in the database should only use the '/' as a separator, so I've changed that.

Cheers

Andy

[mherger]

> Looks like the DBD::SQLite module registers a 'regexp' function that
> just uses Perl regexps. So as long as that is a valid Perl RE it should
> be Ok.
>
> Was going to try it in the command line client, but looks like that
> might not work. A bit of googling suggested there was an extension to
> sqlite that handled Perl REs, so will have a look at that.

SQLiteStudio has built-in support for regexp (https://sqlitestudio.pl).
And my regex almost did work. I'm going to edit it (needs a '$' matcher
at the end). SQLiteStudio didn't need to escape the slash ("[^\/]"). I'm not sure
about DBI. Give it a try, and change to just "[^/]" if it doesn't work.

[adhawkins]

SQLiteStudio has built-in support for regexp (https://sqlitestudio.pl).
And my regex almost did work. I'm going to edit it (needs a '$' matcher
at the end). SQLiteStudio didn't need to escape the slash ("[^\/]"). I'm not sure
about DBI. Give it a try, and change to just "[^/]" if it doesn't work.

To be honest, I think I'll take your advice and stick with code I understand. Regular expressions have always been something I've been a bit uncomfortable with, so keeping the code simple is a good idea I think. My new version does seem relatively performant which is good.

I've also taken your advice and rewritten the plugin so it does a single search of the filesystem per scan. That code is now pushed to GitHub in the 'recurse' branch if you wanted to take a look at what I believe is the final version.

Just rewriting your 'build' script from several years ago, as in its current state it didn't seem to handle versions with letters in them.

Once again, thanks so much for all your assistance in getting this far. Perl is not a language I use regularly, so there's been a lot of re-learning required in this work!

Andy