Optimize. This brings the ALL_COURSES sort time down. I didn't check the time

spent in this code in release, but in debug this brings the time spent building
musicwheel items in ALL_COURSES sort mode from 30 seconds with my 1600+
songs in about 80 groups down to 12 seconds. Release is down to 6 seconds,
but I don't know where it was to start. This time would increase nearly
exponentially with the number of songs and groups.

stepmania/src/Course.cpp

@@ -512,6 +512,33 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 	/* Set to true if CourseDifficulty is able to change something. */
 	bool bCourseDifficultyIsSignificant = (cd == DIFFICULTY_MEDIUM);
 
+	// get a list of all songs that are 1 stage long
+	vector<Song*> vpAllPossibleSongs;
+	SONGMAN->GetSongs(vpAllPossibleSongs, 1);
+
+	// remove locked and tutorial songs from the list
+	FOREACH( Song*, vpAllPossibleSongs, song )
+	{
+		// Ignore locked songs when choosing randomly
+		// TODO: Move Course initialization after UNLOCKMAN is created
+		if( UNLOCKMAN  &&  UNLOCKMAN->SongIsLocked(*song) )
+		{
+			vector<Song*>::iterator eraseme = song;
+			song--;
+			vpAllPossibleSongs.erase( eraseme );
+			continue;
+		}
+
+		// Ignore boring tutorial songs
+		if( (*song)->IsTutorial() )
+		{
+			vector<Song*>::iterator eraseme = song;
+			song--;
+			vpAllPossibleSongs.erase( eraseme );
+			continue;
+		}
+	}
+
 	// Resolve each entry to a Song and Steps.
 	FOREACH_CONST( CourseEntry, entries, e )
 	{
@@ -524,77 +551,41 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 
 		// Start with all songs
 		vector<Song*> vpPossibleSongs;
+		vector<Steps*> vpPossibleSteps;
 
 		if( e->pSong )
 		{
-			// Choose an exact song
+			// Choose an exact song, if we have matching steps and all
-			vpPossibleSongs.push_back( e->pSong );
+			e->pSong->GetSteps( vpPossibleSteps, st, e->baseDifficulty, e->iLowMeter, e->iHighMeter );
+			if( ( !e->sSongGroup.empty() && (*song)->m_sGroupName == e->sSongGroup ) && !vpPossibleSteps.empty() )
+			{
+				pResolvedSong = e->pSong;
 			}
 			else
 			{
-			vpPossibleSongs = SONGMAN->GetAllSongs();
-
-			FOREACH( Song*, vpPossibleSongs, song )
-			{
-				// Ignore locked songs when choosing randomly
-				// TODO: Move Course initialization after UNLOCKMAN is created
-				if( UNLOCKMAN  &&  UNLOCKMAN->SongIsLocked(*song) )
-				{
-					vector<Song*>::iterator eraseme = song;
-					song--;
-					vpPossibleSongs.erase( eraseme );
-					continue;
-				}
-
-				// Ignore boring tutorial songs
-				if( (*song)->IsTutorial() )
-				{
-					vector<Song*>::iterator eraseme = song;
-					song--;
-					vpPossibleSongs.erase( eraseme );
-					continue;
-				}
-
-				// Don't allow long songs
-				if( SONGMAN->GetNumStagesForSong(*song) > 1 )
-				{
-					vector<Song*>::iterator eraseme = song;
-					song--;
-					vpPossibleSongs.erase( eraseme );
 				continue;
 			}
 		}
-		}
+		else
-
+		{
-
+			// copy over any songs that match our group filter, if one is set, and match our
-		// Filter out all songs that don't have matching steps
+			// steps filter.
-		// At the same time, create a list of matching song/steps.
+			FOREACH( Song*, vpAllPossibleSongs, song )
-		typedef vector<Steps*> StepsVector;
-		map<Song*,StepsVector> mapSongToSteps;
-		FOREACH( Song*, vpPossibleSongs, song )
 			{
-			// Apply song group filter
 				if( !e->sSongGroup.empty() && (*song)->m_sGroupName != e->sSongGroup )
-			{
-				vector<Song*>::iterator eraseme = song;
-				song--;
-				vpPossibleSongs.erase( eraseme );
 					continue;
-			}
 
 				vector<Steps*> vpMatchingSteps;
 				(*song)->GetSteps( vpMatchingSteps, st, e->baseDifficulty, e->iLowMeter, e->iHighMeter );
 				if( vpMatchingSteps.empty() )
-			{
-				vector<Song*>::iterator eraseme = song;
-				song--;
-				vpPossibleSongs.erase( eraseme );
 					continue;
+
+				vpPossibleSongs.push_back( *song );
 			}
 
-			mapSongToSteps[*song] = vpMatchingSteps;
+			// if there are no songs to choose from, abort now
-		}
+			if( vpPossibleSongs.empty() )
-
+				continue;
 
 			// TODO: Move Course initialization after PROFILEMAN is created
 			switch( e->songSort )
@@ -623,12 +614,18 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 			if( e->iChooseIndex < int(vpPossibleSongs.size()) )
 			{
 				pResolvedSong = vpPossibleSongs[e->iChooseIndex];
-			vector<Steps*> &vpPossibleSteps = mapSongToSteps[pResolvedSong];
+				pResolvedSong->GetSteps( vpPossibleSteps, st, e->baseDifficulty, e->iLowMeter, e->iHighMeter );
-			ASSERT( !vpPossibleSteps.empty() );	// if no steps are playable, this shouldn't be a possible song
+			}
-			random_shuffle( vpPossibleSteps.begin(), vpPossibleSteps.end(), rnd );
+			else
-			pResolvedSteps = vpPossibleSteps[0];
+			{
+				continue;
+			}
 		}
 
+		ASSERT( !vpPossibleSteps.empty() );	// if no steps are playable, this shouldn't be a possible song
+		if( vpPossibleSteps.size() > 1 )	// no reason to randomize if there's only one set of possible steps
+			random_shuffle( vpPossibleSteps.begin(), vpPossibleSteps.end(), rnd );
+		pResolvedSteps = vpPossibleSteps[0];
 
 		if( pResolvedSong == NULL || pResolvedSteps == NULL )
 			continue;	// this song entry isn't playable.  Skip.