Add a function to update the job timestamp

lib/messages.js

@@ -87,3 +87,13 @@ function parseSubmitResult(buffer){
         succeed: succeed
     };
 }
+
+exports.updateJobTimestamp = function(job, updater) {
+    var headerBlob = job.headerBlob
+    var encodedTsLength = 8
+    var encodedTargetLength = 4
+    var tsOffset = job.headerBlob.length - (encodedTsLength + encodedTargetLength)
+    var jobTs = Number(headerBlob.readBigUInt64BE(tsOffset))
+    var newJobTs = updater(jobTs)
+    headerBlob.writeBigUInt64BE(BigInt(newJobTs), tsOffset)
+}

test/messagesTest.js

@@ -0,0 +1,38 @@
+const { expect } = require('chai');
+const { randomBytes } = require('crypto');
+const constants = require('../lib/constants');
+const { updateJobTimestamp } = require("../lib/messages")
+
+it('should update the job timestamp', function(){
+  function randomHeaderBlob(ts) {
+    var encodedTs = Buffer.alloc(8)
+    encodedTs.writeBigUInt64BE(BigInt(ts))
+    return Buffer.concat([
+      randomBytes(24), // nonce
+      randomBytes(1), // version
+      randomBytes(1 + (2 * constants.GroupSize - 1) * 32), // block deps
+      randomBytes(32), // state hash
+      randomBytes(32), // txs hash
+      encodedTs,
+      randomBytes(4), // target
+    ])
+  }
+
+  for (var i = 1; i <= 10; i += 1) {
+    var jobTs = Date.now() + (i * 60 * 1000)
+    var job = { headerBlob: randomHeaderBlob(jobTs) }
+    var prevHeaderBlob = Buffer.from(job.headerBlob)
+
+    updateJobTimestamp(job, _ => jobTs)
+    expect(job.headerBlob).to.deep.equal(prevHeaderBlob)
+
+    var delta = i * 60 * 1000
+    updateJobTimestamp(job, ts => ts + delta)
+    expect(job.headerBlob).to.not.deep.equal(prevHeaderBlob)
+
+    var tsOffset = job.headerBlob.length - 12
+    prevHeaderBlob.writeBigUInt64BE(BigInt(jobTs + delta), tsOffset)
+    expect(job.headerBlob).to.deep.equal(prevHeaderBlob)
+    expect(Number(job.headerBlob.readBigUInt64BE(tsOffset))).to.equal(jobTs + delta)
+  }
+})