Use MATH to figure out cursor window

ROADMAP.md

@@ -1,9 +1,5 @@
 # Current
 
-- [ ] Fix pagination
-
-# Next
-
 - [ ] Relay detail page, with more information about the relay + tabbed feeds (notes, more?)
 - [ ] Add customize icon and route with editable custom view cards using "lists" nip
   - nevent1qqspjcqw2hu5gfcpkrjhs0aqvxuzjgtp50l375mcqjfpmk48cg5hevgpr3mhxue69uhkummnw3ez6un9d3shjtnhd3m8xtnnwpskxegpzamhxue69uhkummnw3ezuendwsh8w6t69e3xj7spramhxue69uhkummnw3ez6un9d3shjtnwdahxxefwv93kzer9d4usz9rhwden5te0wfjkccte9ejxzmt4wvhxjmcpr9mhxue69uhkummnw3ezuer9d3hjuum0ve68wctjv5n8hwfg

src/partials/Channel.svelte

@@ -72,12 +72,11 @@
     const scroller = createScroller(
       async () => {
         await loadMessages(cursor, newMessages => {
-          cursor.onChunk(newMessages)
-
           stickToBottom('auto', () => {
             loading = sleep(30_000)
             messages = sortBy(e => -e.created_at, newMessages.concat(messages))
             network.loadPeople(pluck('pubkey', newMessages))
+            cursor.update(messages)
           })
         })
       },

src/util/misc.ts

@@ -1,5 +1,5 @@
 import {debounce, throttle} from 'throttle-debounce'
-import {path as getPath, allPass, pipe, isNil, complement, equals, is, pluck, sum, identity, sortBy} from "ramda"
+import {aperture, path as getPath, allPass, pipe, isNil, complement, equals, is, pluck, sum, identity, sortBy} from "ramda"
 import Fuse from "fuse.js/dist/fuse.min.js"
 import {writable} from 'svelte/store'
 import {isObject} from 'hurdak/lib/hurdak'
@@ -152,14 +152,19 @@ export class Cursor {
     this.until = now()
     this.limit = limit
   }
-  onChunk(events) {
+  update(events) {
-    const minDelta = timedelta(1, 'minutes')
+    // update takes all events in a feed and figures out the best place to set `until`
-    const maxDelta = timedelta(1, 'hours')
+    // in order to find older events without re-fetching events that we've already seen.
-    const delta = pluck('created_at', events).reduce(Math.min, 0) || 0
+    // There are various edge cases:
+    // - When we have zero events, there's nothing we can do, presumably we have everything.
+    // - Sometimes relays send us extremely old events. Use median to avoid too-large gaps
+    if (events.length > 1) {
+      const timestamps = sortBy(identity, pluck('created_at', events))
+      const gaps = aperture(2, timestamps).map(([a, b]) => b - a)
+      const gap = quantile(gaps, 0.5)
 
-    // If the delta is very large, size it down. Relays with sparse data
+      this.until -= Math.round(gap * events.length)
-    // can slide the window very quickly, skipping a lot of events on more dense relays
+    }
-    this.until -= Math.max(minDelta, Math.min(maxDelta, delta))
   }
 }
 
@@ -262,3 +267,14 @@ export const union = (...sets) =>
 
 export const difference = (a, b) =>
   new Set(Array.from(a).filter(x => !b.has(x)))
+
+export const quantile = (a, q) => {
+    const sorted = sortBy(identity, a)
+    const pos = (sorted.length - 1) * q
+    const base = Math.floor(pos)
+    const rest = pos - base
+
+    return isNil(sorted[base + 1])
+      ? sorted[base]
+      : sorted[base] + rest * (sorted[base + 1] - sorted[base])
+}

src/views/Toast.svelte

@@ -12,7 +12,7 @@
   transition:fly={{y: -50, duration: 300}}>
   <div
     class={cx(
-      "rounded shadow-xl mx-24 sm:mx-32 mt-2 p-3 text-center border pointer-events-auto",
+      "rounded shadow-xl m-2 ml-16 sm:ml-2 p-3 text-center border pointer-events-auto",
       "max-w-xl flex-grow transition-all",
       {
         'bg-dark border-medium text-white': $toast.type === 'info',

src/views/notes/Feed.svelte

@@ -68,8 +68,7 @@
     notes = uniqBy(prop('id'), notes.concat(bottom))
     notesBuffer = top.concat(notesBuffer).slice(0, maxNotes)
 
-    // Check all notes every time to stay very conservative with moving the window
+    cursor.update(notes)
-    cursor.onChunk(notes)
   }
 
   onMount(() => {