catchup should be mutexed and fix related bugs

lib/batch.js

@@ -76,7 +76,6 @@ module.exports = class HypercoreBatch extends EventEmitter {
   async update (opts) {
     if (this.opened === false) await this.ready()
     await this.session.update(opts)
-    await this._catchup()
   }
 
   setUserData (key, value, opts) {
@@ -275,7 +274,7 @@ module.exports = class HypercoreBatch extends EventEmitter {
     const offset = this.core.tree.length - this._sessionLength
     for (let i = 0; i < offset; i++) this._byteLength -= this._appends[i].byteLength
 
-    await this.core.insertValuesUnsafe(this._appends.slice(0, offset), this._sessionLength, this._sessionByteLength, b.nodes)
+    await this.core.insertValuesUnsafe(this._appends.slice(0, offset), this._sessionLength, this._sessionByteLength, b.nodes.slice(0))
 
     this._sessionLength = this.session.length
     this._sessionByteLength = this.session.byteLength
@@ -287,11 +286,12 @@ module.exports = class HypercoreBatch extends EventEmitter {
 
   async _flush (length, keyPair, signature) { // TODO: make this safe to interact with a parallel truncate...
     if (this._appends.length === 0) return true
-    if (!(await this._catchup())) return false
 
     await this.core._mutex.lock()
 
     try {
+      if (!(await this._catchup())) return false
+
       const flushingLength = Math.min(length - this._sessionLength, this._appends.length)
       if (flushingLength <= 0) return true
 

lib/core.js

@@ -439,18 +439,18 @@ module.exports = class Core {
     const bitfield = {
       drop: false,
       start: offset,
-      end: offset + values.length
+      length: values.length
     }
 
     await this.blocks.putBatch(offset, values, byteOffset)
-    await this.oplog.append({
+    await this.oplog.append([{
       userData: null,
       treeNodes,
       treeUpgrade: null,
       bitfield
-    }, false)
+    }], false)
 
-    this.bitfield.setRange(bitfield.start, values.length, true)
+    this.bitfield.setRange(bitfield.start, bitfield.length, true)
     for (const node of treeNodes) this.tree.unflushed.set(node.index, node)
 
     const status = updateContig(this.header, bitfield, this.bitfield)