fix(/api/diff): chunk large lists of objects (#1737)

* Revert "fix(/api/diff): return 400 if greater than max objects (#1736)"
This reverts commit 783e785.

* fix(/api/diff): chunk long object lists to remain within maximum length

packages/server/modules/core/rest/diffUpload.js

@@ -6,7 +6,7 @@ const { validatePermissionsWriteStream } = require('./authUtils')
 
 const { hasObjects } = require('../services/objects')
 
-const MAXIMUM_OBJECTS = 65536
+const { chunk } = require('lodash')
 
 module.exports = (app) => {
   app.options('/api/diff/:streamId', corsMiddleware())
@@ -25,19 +25,22 @@ module.exports = (app) => {
     }
 
     const objectList = JSON.parse(req.body.objects)
-    if (objectList.length > MAXIMUM_OBJECTS) {
-      req.log.warn(
-        `User ${req.context.userId} tried to diff ${objectList.length} objects, which is greater than the maximum of ${MAXIMUM_OBJECTS}.`
-      )
-      return res.status(400).end(`Too many objects. Maximum ${MAXIMUM_OBJECTS}.`)
-    }
 
     req.log.info(`Diffing ${objectList.length} objects.`)
 
-    const response = await hasObjects({
-      streamId: req.params.streamId,
-      objectIds: objectList
-    })
+    const chunkSize = 1000
+    const objectListChunks = chunk(objectList, chunkSize)
+    const mappedObjects = await Promise.all(
+      objectListChunks.map((objectListChunk) =>
+        hasObjects({
+          streamId: req.params.streamId,
+          objectIds: objectListChunk
+        })
+      )
+    )
+    const response = {}
+    Object.assign(response, ...mappedObjects)
+
     req.log.debug(response)
     res.writeHead(200, {
       'Content-Encoding': 'gzip',