feat: make TraceParent a local class module

CHANGELOG.asciidoc

@@ -36,6 +36,8 @@ Notes:
 [float]
 ===== Features
 
+- Pulled `traceparent` NPM module into local class file.
+
 - Add a `parent` option to `agent.captureError(err[, options][, cb])` to allow
   passing in a Transaction or Span to use as the parent for the error. Before
   this change the *current* span or transaction, if any, was always used.

lib/tracecontext/index.js

@@ -1,5 +1,5 @@
 'use strict'
-const TraceParent = require('traceparent')
+const { TraceParent } = require('./traceparent')
 const TraceState = require('./tracestate')
 
 class TraceContext {

lib/tracecontext/traceparent.js

@@ -0,0 +1,156 @@
+'use strict'
+
+const { randomFillSync } = require('random-poly-fill') // TODO: Remove when Node.js 6 is no longer supported
+
+const SIZES = {
+  version: 1,
+  traceId: 16,
+  id: 8,
+  flags: 1,
+  parentId: 8,
+
+  // Aggregate sizes
+  ids: 24, // traceId + id
+  all: 34
+}
+
+const OFFSETS = {
+  version: 0,
+  traceId: SIZES.version,
+  id: SIZES.version + SIZES.traceId,
+  flags: SIZES.version + SIZES.ids,
+
+  // Additional parentId is stored after the header content
+  parentId: SIZES.version + SIZES.ids + SIZES.flags
+}
+
+const FLAGS = {
+  recorded: 0b00000001
+}
+
+function defineLazyProp (obj, prop, fn) {
+  Object.defineProperty(obj, prop, {
+    configurable: true,
+    enumerable: true,
+    get () {
+      const value = fn()
+      if (value !== undefined) {
+        Object.defineProperty(obj, prop, {
+          configurable: true,
+          enumerable: true,
+          value
+        })
+      }
+      return value
+    }
+  })
+}
+
+function hexSliceFn (buffer, offset, length) {
+  return () => buffer.slice(offset, length).toString('hex')
+}
+
+function maybeHexSliceFn (buffer, offset, length) {
+  const fn = hexSliceFn(buffer, offset, length)
+  return () => {
+    const value = fn()
+    // Check for any non-zero characters to identify a valid ID
+    if (/[1-9a-f]/.test(value)) {
+      return value
+    }
+  }
+}
+
+function makeChild (buffer) {
+  // Move current id into parentId region
+  buffer.copy(buffer, OFFSETS.parentId, OFFSETS.id, OFFSETS.flags)
+
+  // Generate new id
+  randomFillSync(buffer, OFFSETS.id, SIZES.id)
+
+  return new TraceParent(buffer)
+}
+
+function isValidHeader (header) {
+  return /^[\da-f]{2}-[\da-f]{32}-[\da-f]{16}-[\da-f]{2}$/.test(header)
+}
+
+// NOTE: The version byte is not fully supported yet, but is not important until
+// we use the official header name rather than elastic-apm-traceparent.
+// https://w3c.github.io/distributed-tracing/report-trace-context.html#versioning-of-traceparent
+function headerToBuffer (header) {
+  const buffer = Buffer.alloc(SIZES.all)
+  buffer.write(header.replace(/-/g, ''), 'hex')
+  return buffer
+}
+
+function resume (header) {
+  return makeChild(headerToBuffer(header))
+}
+
+function start (sampled = false) {
+  const buffer = Buffer.alloc(SIZES.all)
+
+  // Generate new ids
+  randomFillSync(buffer, OFFSETS.traceId, SIZES.ids)
+
+  if (sampled) {
+    buffer[OFFSETS.flags] |= FLAGS.recorded
+  }
+
+  return new TraceParent(buffer)
+}
+
+const bufferSymbol = Symbol('trace-context-buffer')
+
+class TraceParent {
+  constructor (buffer) {
+    this[bufferSymbol] = buffer
+    Object.defineProperty(this, 'recorded', {
+      value: !!(buffer[OFFSETS.flags] & FLAGS.recorded),
+      enumerable: true
+    })
+
+    defineLazyProp(this, 'version', hexSliceFn(buffer, OFFSETS.version, OFFSETS.traceId))
+    defineLazyProp(this, 'traceId', hexSliceFn(buffer, OFFSETS.traceId, OFFSETS.id))
+    defineLazyProp(this, 'id', hexSliceFn(buffer, OFFSETS.id, OFFSETS.flags))
+    defineLazyProp(this, 'flags', hexSliceFn(buffer, OFFSETS.flags, OFFSETS.parentId))
+    defineLazyProp(this, 'parentId', maybeHexSliceFn(buffer, OFFSETS.parentId))
+  }
+
+  static startOrResume (childOf, conf) {
+    if (childOf instanceof TraceParent) return childOf.child()
+    if (childOf && childOf._context instanceof TraceParent) return childOf._context.child()
+
+    return isValidHeader(childOf)
+      ? resume(childOf)
+      : start(Math.random() <= conf.transactionSampleRate)
+  }
+
+  static fromString (header) {
+    return new TraceParent(headerToBuffer(header))
+  }
+
+  ensureParentId () {
+    let id = this.parentId
+    if (!id) {
+      randomFillSync(this[bufferSymbol], OFFSETS.parentId, SIZES.id)
+      id = this.parentId
+    }
+    return id
+  }
+
+  child () {
+    return makeChild(Buffer.from(this[bufferSymbol]))
+  }
+
+  toString () {
+    return `${this.version}-${this.traceId}-${this.id}-${this.flags}`
+  }
+}
+
+TraceParent.FLAGS = FLAGS
+
+module.exports = {
+  TraceParent
+}

package.json

@@ -101,6 +101,7 @@
     "object-identity-map": "^1.0.2",
     "original-url": "^1.2.3",
     "pino": "^6.11.2",
+    "random-poly-fill": "^1.0.1",
     "read-pkg-up": "^7.0.1",
     "relative-microtime": "^2.0.0",
     "require-in-the-middle": "^5.0.3",
@@ -109,7 +110,6 @@
     "shallow-clone-shim": "^2.0.0",
     "source-map": "^0.8.0-beta.0",
     "sql-summary": "^1.0.1",
-    "traceparent": "^1.0.0",
     "traverse": "^0.6.6",
     "unicode-byte-truncate": "^1.0.0"
   },

test/instrumentation/modules/@elastic/elasticsearch.test.js

@@ -37,7 +37,7 @@ const es = require(esClientPkgName)
 
 const { Readable } = require('stream')
 const test = require('tape')
-const TraceParent = require('traceparent')
+const { TraceParent } = require('../../../../lib/tracecontext/traceparent')
 
 const findObjInArray = require('../../../_utils').findObjInArray
 const mockClient = require('../../../_mock_http_client')

test/instrumentation/modules/http/basic.test.js

@@ -16,7 +16,7 @@ var test = require('tape')
 
 var assert = require('./_assert')
 var mockClient = require('../../../_mock_http_client')
-var TraceParent = require('traceparent')
+var { TraceParent } = require('../../../../lib/tracecontext/traceparent')
 
 test('http.createServer', function (t) {
   t.test('direct callback', function (t) {

test/instrumentation/modules/http/outgoing.test.js

@@ -20,7 +20,7 @@ var test = require('tape')
 
 var echoServer = require('./_echo_server_util').echoServer
 var mockClient = require('../../../_mock_http_client')
-var TraceParent = require('traceparent')
+var { TraceParent } = require('../../../../lib/tracecontext/traceparent')
 
 var methods = ['request', 'get']
 

test/tracecontext/tracecontext.test.js

@@ -12,7 +12,7 @@ const agent = require('../..').start({
 const tape = require('tape')
 const TraceContext = require('../../lib/tracecontext')
 const TraceState = require('../../lib/tracecontext/tracestate')
-const TraceParent = require('traceparent')
+const { TraceParent } = require('../../lib/tracecontext/traceparent')
 
 tape.test('propagateTraceContextHeaders tests', function (suite) {
   suite.test('Span test', function (t) {