There's something very inefficient about link lists in build-json

[peterbe]

The function itemFromDirectory is called, as of today, 21 times. For each directory. In total, that function gets called 1,630 times when it should be 1,630/21 times.

[peterbe]

Perhaps @wbamberg can see the whole picture better but I'd rather not memoize this function but take a step back and be aware of calling it instead. The itemFromDirectory is actually a "private" (not exported) function that is used by the exported functions linkListFromChapterList, linkListFromDirectory, and linkListFromFilePaths I think. So those functions might be better aware of what it's calling. But perhaps it goes deeper than that. Actually, I think linkListFromChapterList is called 21 times with /content/learn/html/Introduction_to_HTML.yaml and 21 times with /content/html/guides/Guides.yaml.

[peterbe]

So, perhaps one needs to zoom out even further and eventually do something like this:

+  const list = {};
    stuff.forEach(thing => {
-     const relatedLinks = doSomething(thing.directory);  
+    if (!list[thing.directory]) {
+       list[thing.directory] = doSomething(thing.directory); 
+   }
+     const relatedLinks = list[thing.directory]

[peterbe]

Note, this is not urgent because npm run build-json only takes about 3-4 seconds. But that'll potentially be exponentially worse when the number of files increases.

[wbamberg]

Yes, build-json is very inefficient, and when (not if) it becomes enough of a problem we should rewrite it, in particular (I expect) to minimise the number of file reads we do.