From 9d85c029f441092fcfdf5466d65a59151b2b63e5 Mon Sep 17 00:00:00 2001
From: fenwick67 <dfharwell@gmail.com>
Date: Fri, 2 Aug 2019 11:10:45 -0400
Subject: [PATCH] make promise chaining more sustainable

---
 lib/convertv2.js | 57 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/lib/convertv2.js b/lib/convertv2.js
index 6388200..4e1ed1b 100644
--- a/lib/convertv2.js
+++ b/lib/convertv2.js
@@ -3,16 +3,25 @@ var fs = require('fs');
 var template = ejs.compile(fs.readFileSync('./lib/template.ejs', 'utf8'));
 var timeAgo = require('timeago.js');
 
-// TODO try https://www.npmjs.com/package/request-promise-cache for the requests
 var request = require('request-promise-cache')
 
 const hour = 3600000;
 
-// get JSON for an AP URL
-// TODO make it reject on HTTP 4xx or 5xx
+// get JSON for an AP URL, by either fetching it or grabbing it from a cache.
+
+// Honestly request-promise-cache should be good enough. Redis would be a nice upgrade but for
+// a single process install it will be fine.
+
+// note: rejects on HTTP 4xx or 5xx
 async function apGet(url,ttl) {
+    
     return new Promise(function(resolve,reject){
 
+        // fail early
+        if (!url){
+            reject(new Error('URL is invalid'));
+        }
+
         request( {
             uri:url,
             cacheKey:url,
@@ -29,13 +38,24 @@ async function apGet(url,ttl) {
     
 }
 
-// never rejects, instead it returns an object with a status, error and/or result.
-async function apGetNoReject(...args){
-    return new Promise(function(resolve,reject){
-        apGet(...args)
-            .then(res=>resolve({status:true,result:res}))
-            .catch(e=>resolve({status:false,error:e}))
-    });
+// like Promise.all except returns null on error instead of failing all the promises
+async function promiseSome(proms){
+
+    function noRejectWrap(prom){
+        return new Promise(function(resolve,reject){
+                
+            prom // it's already been called
+            .then(resolve)
+            .catch(e=>{
+                // console.warn(e);// for debugging
+                resolve(null)
+            })
+
+        })
+    }
+
+    return await Promise.all(proms.map(noRejectWrap))
+
 }
 
 module.exports = async function (opts) {
@@ -97,16 +117,15 @@ async function itemsForFeed(opts,user,feed) {
         var boostData = [];
         var boostUrls = feed.orderedItems.filter(i=>i.type=="Announce").map(i=>i.object);
         // console.log(boostUrls);
-        boostData = await Promise.all(boostUrls.map(apGetNoReject));
-        boostData = boostData.map(d=>d.result||{});
+        boostData = await promiseSome(boostUrls.map(apGet));
 
         // now get user data for each of those
-        let userData = await Promise.all(boostData.map(d=>d.attributedTo||'').map(apGetNoReject));
+        let userData = await promiseSome(boostData.map(d=>d?d.attributedTo||'':null).map(apGet));
 
-        // put a ._userdata key on the item object if this is a boost etc
+        // put a ._userdata key on the item object if this is a boost
         for (var i = 0; i < boostData.length; i ++){
-            if (userData[i].status){
-                boostData[i]._userdata = userData[i].result;
+            if (userData[i] && boostData[i]){
+                boostData[i]._userdata = userData[i];
             }
         }
 
@@ -116,8 +135,8 @@ async function itemsForFeed(opts,user,feed) {
 
         boostData.forEach((boostToot)=>{
 
-            if (!boostToot.id){
-                return;// case where it's a {} b/c the request failed or w/e
+            if (!boostToot){// failed request
+                return;
             }
             
             // inject in-place into items
@@ -142,8 +161,6 @@ async function itemsForFeed(opts,user,feed) {
 
 
     return items.filter((item)=>{
-        // this is temporary, don't handle boosts (TODO)
-        // return item.type == "Create" && item.object && item.object.type=="Note";
         return typeof item.object == 'object';// handle weird cases
     }).map((item)=>{