Download available blocks on non-sparse core.update() (#111)

* Download available blocks on non-sparse `core.update()`

* Data -> blocks

* Download until `tree.length`

* Await upgrade promise before reading `tree.length`

Author: kasperisager

index.js

@@ -573,10 +573,19 @@ module.exports = class Hypercore extends EventEmitter {
     const activeRequests = (opts && opts.activeRequests) || this.activeRequests
     const req = this.replicator.addUpgrade(activeRequests)
 
-    if (!this.snapshotted) return req.promise
-    if (!(await req.promise)) return false
+    const upgraded = await req.promise
 
-    return this._updateSnapshot()
+    if (!this.sparse) {
+      // Download all available blocks in non-sparse mode
+      const start = this.length
+      const end = this.core.tree.length
+
+      await this.download({ start, end, ifAvailable: true }).downloaded()
+    }
+
+    if (!upgraded) return false
+    if (this.snapshotted) return this._updateSnapshot()
+    return true
   }
 
   async seek (bytes, opts) {

test/replicate.js

@@ -726,3 +726,15 @@ test('download range resolves immediately if no peers', async function (t) {
 
   t.pass('range resolved')
 })
+
+test('download available blocks on non-sparse update', async function (t) {
+  const a = await create()
+  const b = await create(a.key, { sparse: false })
+
+  replicate(a, b, t)
+
+  await a.append(['a', 'b', 'c', 'd', 'e'])
+  await b.update()
+
+  t.is(b.contiguousLength, 5)
+})