fix dropped range issues and user data being mb strings

lib/tx.js

@@ -91,7 +91,8 @@ class CoreTX {
   }
 
   putUserData (key, value) {
-    this.changes.push([core.userData(this.core.dataPointer, key), value, null])
+    const buffer = typeof value === 'string' ? b4a.from(value) : value
+    this.changes.push([core.userData(this.core.dataPointer, key), buffer, null])
   }
 
   deleteUserData (key) {

lib/view.js

@@ -1,6 +1,8 @@
 const { Readable, getStreamError } = require('streamx')
 const b4a = require('b4a')
 
+const DROPPED = [null, null, null]
+
 class OverlayStream extends Readable {
   constructor (stream, start, end, reverse, changes, ranges) {
     super()
@@ -139,6 +141,10 @@ class Overlay {
     changes.sort(cmp)
     ranges.sort(cmp)
 
+    while (changes.length > 0 && changes[changes.length - 1] === DROPPED) {
+      changes.pop()
+    }
+
     this.indexed = view.indexed
     this.changes = changes
     this.ranges = ranges
@@ -225,10 +231,8 @@ class View {
   _indexAndGet (read, key) {
     this._index()
     const change = this.map.get(b4a.toString(key, 'hex'))
-    if (change !== undefined) return Promise.resolve(ensureBuffer(change[1]))
-    const range = this._findRange(key)
-    if (range) return Promise.resolve(range.value)
-    return read.get(key)
+    if (change === undefined) return read.get(key)
+    return Promise.resolve(change[1])
   }
 
   _attached () {
@@ -265,22 +269,13 @@ class View {
     const e = b4a.toString(range[2], 'hex')
 
     for (const key of this.map.keys()) {
-      if (s <= key && key < e) this.map.delete(key)
+      if (s <= key && key < e) this.map.set(key, DROPPED)
     }
 
     if (this.ranges === null) this.ranges = []
     this.ranges.push(range)
   }
 
-  // unsorted so writes are cheap and reads are expensive
-  _findRange (key) {
-    if (this.ranges === null) return null
-    for (const r of this.ranges) {
-      if (b4a.compare(r[0], key) <= 0 && b4a.compare(r[2], key) > 0) return r
-    }
-    return null
-  }
-
   apply (changes) {
     if (this.snap !== null) throw new Error('Illegal to push changes to a snapshot')
 
@@ -320,6 +315,9 @@ class View {
 module.exports = View
 
 function cmpChange (a, b) {
+  if (a === DROPPED) return b === DROPPED ? 0 : 1
+  if (b === DROPPED) return a === DROPPED ? 0 : -1
+
   const c = b4a.compare(a[0], b[0])
   return c === 0 ? b4a.compare(a[2], b[2]) : c
 }
@@ -335,8 +333,3 @@ function reverseArray (list) {
   for (let i = 0; i < list.length; i++) r[r.length - 1 - i] = list[i]
   return r
 }
-
-function ensureBuffer (value) {
-  if (typeof value === 'string') return b4a.from(value)
-  return value
-}