feat: Removed children from segments. (#2689)

lib/instrumentation/nextjs/utils.js

@@ -56,16 +56,3 @@ utils.isMiddlewareInstrumentationSupported = function isMiddlewareInstrumentatio
     semver.gte(version, MIN_MW_SUPPORTED_VERSION) && semver.lte(version, MAX_MW_SUPPORTED_VERSION)
   )
 }
-
-/**
- * Depending on the Next.js version the segment tree varies as it adds setTimeout segments.
- * This util will find the segment that has `getServerSideProps` in the name
- *
- * @param {object} rootSegment trace root
- * @returns {object} getServerSideProps segment
- */
-utils.getServerSidePropsSegment = function getServerSidePropsSegment(rootSegment) {
-  return rootSegment.children[0].children.find((segment) =>
-    segment.name.includes('getServerSideProps')
-  )
-}

lib/metrics/recorders/custom.js

@@ -9,7 +9,7 @@ const NAMES = require('../names')
 
 function record(segment, scope, transaction) {
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
   const name = NAMES.CUSTOM + NAMES.ACTION_DELIMITER + segment.name
 
   if (scope) {

lib/metrics/recorders/database-operation.js

@@ -22,7 +22,7 @@ const metrics = require('../names')
  */
 function recordOperationMetrics(segment, scope, transaction) {
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
   const type = transaction.isWeb() ? 'allWeb' : 'allOther'
   const operation = segment.name
 

lib/metrics/recorders/database.js

@@ -15,9 +15,8 @@ const { DESTINATIONS } = require('../../config/attribute-filter')
  */
 
 function recordQueryMetrics(segment, scope, transaction) {
-  debugger
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
   const type = transaction.isWeb() ? DB.WEB : DB.OTHER
   const thisTypeSlash = this.type + '/'
   const operation = DB.OPERATION + '/' + thisTypeSlash + this.operation

lib/metrics/recorders/generic.js

@@ -7,7 +7,7 @@
 
 function record(segment, scope, transaction) {
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
 
   if (scope) {
     transaction.measure(segment.name, scope, duration, exclusive)

lib/metrics/recorders/http.js

@@ -23,7 +23,7 @@ function recordWeb(segment, scope, tx) {
 
   const duration = segment.getDurationInMillis()
   const totalTime = tx.trace.getTotalTimeDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(tx.trace)
   const partial = segment.partialName
   const config = tx.agent.config
   // named / key transaction support requires per-name apdexT

lib/metrics/recorders/http_external.js

@@ -10,7 +10,7 @@ const EXTERNAL = require('../../metrics/names').EXTERNAL
 function recordExternal(host, library) {
   return function externalRecorder(segment, scope, transaction) {
     const duration = segment.getDurationInMillis()
-    const exclusive = segment.getExclusiveDurationInMillis()
+    const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
     const metricName = EXTERNAL.PREFIX + host + '/' + library
     const rollupType = transaction.isWeb() ? EXTERNAL.WEB : EXTERNAL.OTHER
     const rollupHost = EXTERNAL.PREFIX + host + '/all'

lib/metrics/recorders/message-transaction.js

@@ -13,7 +13,7 @@ function recordMessageTransaction(segment, scope, tx) {
   }
 
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(tx.trace)
   const totalTime = tx.trace.getTotalTimeDurationInMillis()
 
   if (scope) {

lib/metrics/recorders/middleware.js

@@ -16,7 +16,7 @@
 function makeMiddlewareRecorder(_shim, metricName) {
   return function middlewareMetricRecorder(segment, scope, transaction) {
     const duration = segment.getDurationInMillis()
-    const exclusive = segment.getExclusiveDurationInMillis()
+    const exclusive = segment.getExclusiveDurationInMillis(transaction.trace)
 
     if (scope) {
       transaction.measure(metricName, scope, duration, exclusive)

lib/metrics/recorders/other.js

@@ -15,7 +15,7 @@ function recordBackground(segment, scope, tx) {
   }
 
   const duration = segment.getDurationInMillis()
-  const exclusive = segment.getExclusiveDurationInMillis()
+  const exclusive = segment.getExclusiveDurationInMillis(tx.trace)
   const totalTime = tx.trace.getTotalTimeDurationInMillis()
   const name = segment.partialName
 

lib/shim/shim.js

@@ -1325,8 +1325,7 @@ function createSegment(name, recorder, parent) {
  * @param {Shim} params.shim instance of shim
  * @param {Transaction} params.transaction active transaction
  * @param {TraceSegment} params.parent the segment that will be the parent of the newly created segment
- * @param params.spec
- * @param {string|specs.SegmentSpec} spec options for creating segment
+ * @param {string|specs.SegmentSpec} params.spec options for creating segment
  * @returns {?TraceSegment} A new trace segment if a transaction is active, else
  *  `null` is returned.
  */

lib/transaction/trace/exclusive-time-calculator.js

@@ -6,7 +6,9 @@
 'use strict'
 
 class ExclusiveCalculator {
-  constructor(root) {
+  constructor(root, trace) {
+    this.trace = trace
+    this.id = root.id
     this.toProcess = [root]
     // use a second stack to do a post-order traversal
     this.parentStack = []
@@ -19,7 +21,7 @@ class ExclusiveCalculator {
   process() {
     while (this.toProcess.length) {
       const segment = this.toProcess.pop()
-      const children = segment.getChildren()
+      const children = this.trace.getChildren(segment.id)
       // when we hit a leaf, calc the exclusive time and report the time
       // range to the parent
       if (children.length === 0) {

lib/transaction/trace/index.js

@@ -41,7 +41,7 @@ function Trace(transaction) {
   this.root.start()
 
   this.intrinsics = Object.create(null)
-  this.segmentsSeen = 0
+  this.segments = []
   this.totalTimeCache = null
 
   this.custom = new Attributes(ATTRIBUTE_SCOPE, MAXIMUM_CUSTOM_ATTRIBUTES)
@@ -63,16 +63,11 @@ function Trace(transaction) {
  * segments that support recording.
  */
 Trace.prototype.end = function end() {
-  const segments = [this.root]
+  this.root.finalize(this)
+  const segments = this.segments
 
-  while (segments.length) {
-    const segment = segments.pop()
-    segment.finalize()
-
-    const children = segment.getChildren()
-    for (let i = 0; i < children.length; ++i) {
-      segments.push(children[i])
-    }
+  for (let i = 0; i < segments.length; i++) {
+    segments[i].finalize(this)
   }
 }
 
@@ -85,14 +80,13 @@ Trace.prototype.generateSpanEvents = function generateSpanEvents() {
   if (!shouldGenerateSpanEvents(config, this.transaction)) {
     return
   }
-  const toProcess = []
 
   // Root segment does not become a span, so we need to process it separately.
   const spanAggregator = this.transaction.agent.spanEventAggregator
 
-  const children = this.root.getChildren()
+  const segments = this.segments
 
-  if (children.length > 0) {
+  if (segments.length > 0) {
     // At the point where these attributes are available, we only have a
     // root span. Adding attributes to first non-root span here.
     const attributeMap = {
@@ -106,54 +100,35 @@ Trace.prototype.generateSpanEvents = function generateSpanEvents() {
 
     for (const [key, value] of Object.entries(attributeMap)) {
       if (value !== null) {
-        children[0].addSpanAttribute(key, value)
+        segments[0].addSpanAttribute(key, value)
       }
     }
   }
 
-  for (let i = 0; i < children.length; ++i) {
-    toProcess.push(new DTTraceNode(children[i], this.transaction.parentSpanId, true))
-  }
-
-  while (toProcess.length) {
-    const segmentInfo = toProcess.pop()
-    const segment = segmentInfo.segment
-
+  for (let i = 0; i < segments.length; ++i) {
+    const segment = segments[i]
+    const isRoot = segment.parentId === this.root.id
+    const parentId = isRoot ? this.transaction.parentSpanId : segment.parentId
     // Even though at some point we might want to stop adding events because all the priorities
     // should be the same, we need to count the spans as seen.
     spanAggregator.addSegment({
       segment,
       transaction: this.transaction,
-      parentId: segmentInfo.parentId,
-      isRoot: segmentInfo.isRoot
+      parentId,
+      isRoot
     })
-
-    const nodes = segment.getChildren()
-    for (let i = 0; i < nodes.length; ++i) {
-      const node = new DTTraceNode(nodes[i], segment.id)
-      toProcess.push(node)
-    }
   }
 }
 
 function shouldGenerateSpanEvents(config, txn) {
-  if (!config.distributed_tracing.enabled) {
-    return false
-  }
-  if (!config.span_events.enabled) {
+  if (!(config.distributed_tracing.enabled && config.span_events.enabled)) {
     return false
   }
 
   const infiniteTracingConfigured = Boolean(config.infinite_tracing.trace_observer.host)
   return infiniteTracingConfigured || txn.sampled
 }
 
-function DTTraceNode(segment, parentId, isRoot = false) {
-  this.segment = segment
-  this.parentId = parentId
-  this.isRoot = isRoot
-}
-
 /**
  * Add a child to the list of segments.
  *
@@ -220,7 +195,7 @@ Trace.prototype.addCustomAttribute = function addCustomAttribute(key, value) {
  *                   traces, in milliseconds.
  */
 Trace.prototype.getExclusiveDurationInMillis = function getExclusiveDurationInMillis() {
-  return this.root.getExclusiveDurationInMillis()
+  return this.root.getExclusiveDurationInMillis(this)
 }
 
 /**
@@ -234,16 +209,14 @@ Trace.prototype.getTotalTimeDurationInMillis = function getTotalTimeDurationInMi
   if (this.totalTimeCache !== null) {
     return this.totalTimeCache
   }
-  if (this.root.children.length === 0) {
+  const segments = this.segments
+  if (segments.length === 0) {
     return 0
   }
-  const segments = this.root.getChildren()
-  let totalTimeInMillis = 0
 
-  while (segments.length !== 0) {
-    const segment = segments.pop()
-    totalTimeInMillis += segment.getExclusiveDurationInMillis()
-    segment.getChildren().forEach((childSegment) => segments.push(childSegment))
+  let totalTimeInMillis = 0
+  for (let i = 0; i < segments.length; i++) {
+    totalTimeInMillis += segments[i].getExclusiveDurationInMillis(this)
   }
 
   if (!this.transaction.isActive()) {
@@ -366,6 +339,104 @@ Trace.prototype._getRequestUri = function _getRequestUri() {
   return requestUri
 }
 
+/**
+ * Gets all children of a segment.
+ *
+ * @param {number} id of segment
+ * @returns {Array.<TraceSegment>} list of all segments that have the parentId of the segment
+ */
+Trace.prototype.getChildren = function getChildren(id) {
+  return this.segments.filter((segment) => segment.parentId === id)
+}
+
+/**
+ * Gets all children of a segment that should be collected and not ignored.
+ *
+ * @param {number} id of segment
+ * @returns {Array.<TraceSegment>} list of all segments that have the parentId of the segment
+ */
+Trace.prototype.getCollectedChildren = function getCollectedChildren(id) {
+  return this.segments.filter(
+    (segment) => segment.parentId === id && segment._collect && !segment.ignore
+  )
+}
+
+/**
+ * Gets the parent segment from list of segments on trace by passing in the `parentId`
+ * and matching on the `segment.id`
+ *
+ * @param {number} parentId id of parent segment you want to retrieve
+ * @returns {TraceSegment} parent segment
+ */
+Trace.prototype.getParent = function getParent(parentId) {
+  return this.segments.filter((segment) => segment.id === parentId)[0]
+}
+
+/**
+ * This is perhaps the most poorly-documented element of transaction traces:
+ * what do each of the segment representations look like prior to encoding?
+ * Spelunking in the code for the other agents has revealed that each child
+ * node is an array with the following field in the following order:
+ *
+ * 0: entry timestamp relative to transaction start time
+ * 1: exit timestamp
+ * 2: metric name
+ * 3: parameters as a name -> value JSON dictionary
+ * 4: any child segments
+ *
+ * Other agents include further fields in this. I haven't gotten to the bottom
+ * of all of them (and Ruby, of course, sends marshalled Ruby object), but
+ * here's what I know so far:
+ *
+ * in Java:
+ * 5: class name
+ * 6: method name
+ *
+ * in Python:
+ * 5: a "label"
+ *
+ * FIXME: I don't know if it makes sense to add custom fields for Node. TBD
+ */
+Trace.prototype.toJSON = function toJSON() {
+  // use depth-first search on the segment tree using stack
+  const resultDest = []
+  // array of objects relating a segment and the destination for its
+  // serialized data.
+  const segmentsToProcess = [
+    {
+      segment: this.root,
+      destination: resultDest
+    }
+  ]
+
+  while (segmentsToProcess.length !== 0) {
+    const { segment, destination } = segmentsToProcess.pop()
+    const start = segment.timer.startedRelativeTo(this.root.timer)
+    const duration = segment.getDurationInMillis()
+
+    const segmentChildren = this.getCollectedChildren(segment.id)
+    const childArray = []
+
+    // push serialized data into the specified destination
+    destination.push([start, start + duration, segment.name, segment.getAttributes(), childArray])
+
+    if (segmentChildren.length) {
+      // push the children and the parent's children array into the stack.
+      // to preserve the chronological order of the children, push them
+      // onto the stack backwards (so the first one created is on top).
+      for (let i = segmentChildren.length - 1; i >= 0; --i) {
+        segmentsToProcess.push({
+          segment: segmentChildren[i],
+          destination: childArray
+        })
+      }
+    }
+  }
+
+  // pull the result out of the array we serialized it into
+  return resultDest[0]
+}
+
 /**
  * Serializes the trace into the expected JSON format to be sent.
  *
@@ -379,17 +450,21 @@ Trace.prototype._serializeTrace = function _serializeTrace() {
     intrinsics: this.intrinsics
   }
 
-  return [
+  const trace = [
     this.root.timer.start * FROM_MILLIS,
     {}, // moved to agentAttributes
     {
       // hint to RPM for how to display this trace's segments
       nr_flatten_leading: false
     }, // moved to userAttributes
-    this.root.toJSON(),
+    this.toJSON(),
     attributes,
     [] // FIXME: parameter groups
   ]
+
+  // clear out segments
+  this.segments = []
+  return trace
 }
 
 module.exports = Trace