simple findTrackObject opimizations

1 files changed, 11 insertions, 11 deletions

diff --git a/playlist-utils.js b/playlist-utils.js
index 1413fb8..5279177 100644
--- a/playlist-utils.js
+++ b/playlist-utils.js
@@ -782,12 +782,15 @@ function getPathScore(path1, path2) {
   return scores.reduce((a, b) => a < b ? a : b)
 }
 
-function findTrackObject(referenceData, sourcePlaylist) {
+function findTrackObject(referenceData, sourcePlaylist, flattenedSourcePlaylist = null) {
   // Finds the track object in the source playlist which most closely resembles
   // the provided reference data. This is used for maintaining the identity of
   // track objects when reloading a playlist (see serialized-backend.js). It's
   // also usable in synchronizing the identity of tracks across linked clients
   // (see socket.js).
+  //
+  // NB: This function is many times more efficient if you pass a preemptively
+  // flattened version of the source playlist in as well!
 
   // Reference data includes track NAME, track SOURCE (downloaderArg), and
   // track PATH (names of parent groups). Specifics of how existing track
@@ -810,18 +813,15 @@ function findTrackObject(referenceData, sourcePlaylist) {
     return getPathScore(path1, path2)
   }
 
-  function compareName(track) {
-    return track.name === referenceData.name
-  }
-
-  function compareSource(track) {
-    return track.downloaderArg === referenceData.downloaderArg
+  if (!flattenedSourcePlaylist) {
+    flattenedSourcePlaylist = flattenGrouplike(sourcePlaylist)
   }
 
   // The only tracks which will be considered at all are those which match at
   // least one of the reference name/source.
-  const baselineResemble = flattenGrouplike(sourcePlaylist).items.filter(
-    track => compareName(track) || compareSource(track))
+  const baselineResemble = flattenedSourcePlaylist.items.filter(track =>
+    track.name === referenceData.name ||
+    track.downloaderArg === referenceData.downloaderArg)
 
   // If no track matches the baseline conditions for resemblance at all,
   // return null. It's up to the caller to decide what to do in this case,
@@ -835,8 +835,8 @@ function findTrackObject(referenceData, sourcePlaylist) {
   // be used as the factors in calculating which track resembles closest.
   const reasons = baselineResemble.map(track => ({
     track,
-    nameMatches: compareName(track),
-    sourceMatches: compareSource(track),
+    nameMatches: track.name === referenceData.name,
+    sourceMatches: track.downloaderArg === referenceData.downloaderArg,
     pathScore: getTrackPathScore(track)
   }))