Unslab announcer record + use unslabEncode helper (#192)

* Unslab announcer record

* Use encodeUnslab helper

lib/announcer.js

@@ -1,6 +1,7 @@
 const safetyCatch = require('safety-catch')
 const c = require('compact-encoding')
 const Signal = require('signal-promise')
+const { encodeUnslab } = require('./encode')
 const Sleeper = require('./sleeper')
 const m = require('./messages')
 const Persistent = require('./persistent')
@@ -17,7 +18,7 @@ module.exports = class Announcer {
     this.relayAddresses = []
     this.stopped = false
     this.suspended = false
-    this.record = c.encode(m.peer, { publicKey: keyPair.publicKey, relayAddresses: [] })
+    this.record = encodeUnslab(m.peer, { publicKey: keyPair.publicKey, relayAddresses: [] })
     this.online = new Signal()
 
     this._refreshing = false

lib/encode.js

@@ -0,0 +1,16 @@
+const b4a = require('b4a')
+const cenc = require('compact-encoding')
+
+function encodeUnslab (enc, m) {
+  // Faster than unslab(c.encode(enc, data)) because it avoids the mem copy.
+  // Makes sense to put in compact-encoding when we need it in other modules too
+  const state = cenc.state()
+  enc.preencode(state, m)
+  state.buffer = b4a.allocUnsafeSlow(state.end)
+  enc.encode(state, m)
+  return state.buffer
+}
+
+module.exports = {
+  encodeUnslab
+}

lib/persistent.js

@@ -5,6 +5,7 @@ const Cache = require('xache')
 const b4a = require('b4a')
 const unslab = require('unslab')
 
+const { encodeUnslab } = require('./encode')
 const m = require('./messages')
 const { NS, ERROR } = require('./constants')
 
@@ -124,7 +125,7 @@ module.exports = class Persistent {
 
     const k = b4a.toString(req.target, 'hex')
     const announceSelf = b4a.equals(TMP, req.target)
-    const record = unslab(c.encode(m.peer, peer))
+    const record = encodeUnslab(m.peer, peer)
 
     if (announceSelf) {
       this.dht._router.set(k, {
@@ -196,8 +197,7 @@ module.exports = class Persistent {
       }
     }
 
-    const entry = c.encode(m.mutableGetResponse, { seq, value, signature })
-    this.mutables.set(k, unslab(entry))
+    this.mutables.set(k, encodeUnslab(m.mutableGetResponse, { seq, value, signature }))
     req.reply(null)
   }