fix(perf): Close MongoDB cursors after calling forEach2() (#405)

* fix(perf): Close cursor after calls to mongodb.forEach2()

* fix

* 🧹 /api/track

* fix "TypeError: Cannot read property 's' of undefined"

* recognize errors

* models/notif.js: also jump over errors

* close cursor and skip errors in snapshotTrackScores()

* same in refreshTrackCollection()

* 🧹 updateAndPopulateMetadata() and populateTrackMetadata() + callers

app/controllers/admin/db.js

@@ -59,12 +59,6 @@ function listMissingUsers(uids, cb) {
 }
 
 var fileGenerators = {
-  populateTrackMetadata: function (p, cb) {
-    trackModel.populateTrackMetadata(function (r) {
-      console.log('populateTrackMetadata => ', r || { ok: 'done' });
-    });
-    cb('populating track metadata...');
-  },
   refreshTrackCollection: function (p, cb) {
     trackModel.refreshTrackCollection(function (r) {
       console.log('refreshTrackCollection => ', r || { ok: 'done' });

app/models/deezer.js

@@ -73,44 +73,5 @@ exports.fetchTrackMetadata = function (_trackId, cb, raw) {
   );
 };
 
-/*
-var METADATA_MAPPING = {
-	"art": "artistName",
-	"tit": "trackTitle"
-};
-
-exports.getDeezerId = function(p, cb){
-	console.log("getting deezer track id", p.eId);
-	function returnMetaOr(orCb){
-		return function(tr) {
-			var meta = tr.meta || {};
-			if (meta.dz) {
-				console.log("found dz meta");
-				cb(tr);
-			}
-			else if (meta.art && meta.tit) {
-				var q = snip.filterFields(meta, METADATA_MAPPING);
-				console.log("querying dz...", q);
-				deezerApi.searchTracks(q, function(dzRes){
-					console.log("dz response => dzRes");
-					tr.dzRes = dzRes;
-					cb(tr);
-				});
-			}
-			else if (orCb)
-				orCb(tr);
-			else
-				cb(tr);
-		};
-	}
-	trackModel.fetchTrackByEid(p.eId, returnMetaOr(function(tr){
-		console.log("missing metadata => update metadata...");
-		trackModel.updateAndPopulateMetadata(p.eId, returnMetaOr(), true);
-	}));
-},
-*/
-// searchTracks({trackTitle:"the monster", artistName:"eminem"}, console.log); // =>
-// fetchTrackInfo(17782324, console.log);
-
 exports.searchTracks = searchTracks;
 exports.fetchTrackInfo = fetchTrackInfo;

app/models/mongodb.js

@@ -135,8 +135,11 @@ exports.forEach2 = function (colName, params, handler) {
       cursor.next(function (err, item) {
         if (err) {
           console.error('mongodb.forEach2 ERROR', err);
-          handler({ error: err });
-        } else handler(item, item ? next : undefined);
+          handler({ error: err }, undefined, cursor.close.bind(cursor));
+          cursor.close();
+        } else {
+          handler(item, item ? next : undefined, cursor.close.bind(cursor));
+        }
       });
     })();
   });

app/models/notif.js

@@ -368,9 +368,13 @@ exports.post = function (post) {
     projection: { uId: true },
   };
   mongodb.forEach2('post', query, function (sameTrack, next) {
-    var author = sameTrack && mongodb.usernames[sameTrack.uId];
-    if (author) notifEmails.sendPostedSameTrack(author, next);
-    else if (next) next();
+    var author =
+      sameTrack && !sameTrack.error && mongodb.usernames[sameTrack.uId];
+    if (author) {
+      notifEmails.sendPostedSameTrack(author, next);
+    } else if (next) {
+      next();
+    }
   });
 };
 

app/models/post.js

@@ -137,30 +137,17 @@ exports.fetchByAuthors = function (uidList, options, cb) {
   var limit = params.limit;
   params.limit = undefined; // prevent forEach2 from limiting cursor
   params.q = query;
-  mongodb.forEach2('post', params, function (post, next) {
-    if (post && !uidSet[(post.repost || {}).uId]) posts.push(post);
+  mongodb.forEach2('post', params, function (post, next, closeCursor) {
+    if (post && !post.error && !uidSet[(post.repost || {}).uId]) {
+      posts.push(post);
+    }
     if (!post || !next || posts.length == limit) {
       //console.timeEnd("post.fetchByAuthors2...");
-      cb(processPosts(posts)); // TODO: close cursor
-    } else next();
-  });
-};
-
-var MAX_OTHER_AUTHORS = 3;
-
-exports.fetchByOtherAuthors = function (uidList, options, cb) {
-  //console.time("post.fetchByOtherAuthors...");
-  var posts = [],
-    uidSet = snip.arrayToSet(uidList);
-  mongodb.forEach2('post', { q: {}, sort: [['_id', 'desc']] }, function (
-    post,
-    next
-  ) {
-    if (post && !uidSet[post.uId]) posts.push(post);
-    if (!post || !next || posts.length == MAX_OTHER_AUTHORS) {
-      //console.timeEnd("post.fetchByOtherAuthors...");
-      cb(processPosts(posts)); // TODO: close cursor
-    } else next();
+      cb(processPosts(posts));
+      closeCursor();
+    } else {
+      next();
+    }
   });
 };
 
@@ -279,7 +266,6 @@ exports.savePost = function (postObj, handler) {
     if (result) {
       if (Array.isArray(result)) result = result[0];
       searchModel.indexTyped('post', result);
-      //trackModel.updateAndPopulateMetadata(result.eId); // Notice: Cross platform player metadata extraction was shut down on 7/1/2015
       result.isNew = !pId;
       if (result.isNew) notif.post(result);
       /*
@@ -361,7 +347,6 @@ exports.rePost = function (pId, repostObj, handler) {
         //searchModel.indexPost(result);
         result = result[0];
         searchModel.indexTyped('post', result);
-        //trackModel.updateAndPopulateMetadata(result.eId); // Notice: Cross platform player metadata extraction was shut down on 7/1/2015
         /*
 				recomModel.matchingEngine.addPost(result, function() {
 					console.log("=> added post to matching engine index");