refactor out Transaction.applySamplingStrategy

Author: amychisholm03

lib/samplers/adaptive-sampler.js

@@ -106,8 +106,16 @@ class AdaptiveSampler extends Sampler {
     return false
   }
 
-  applySamplingDecision(transaction) {
+  applySamplingDecision({ transaction, tracestate = null }) {
     if (!transaction) return
+    if (tracestate) {
+      // Explicitly set sampled and priority from tracestate intrinsics if available
+      transaction.sampled = tracestate?.intrinsics ? tracestate.isSampled : null
+      transaction.priority = tracestate?.intrinsics ? tracestate.priority : null
+      return
+    }
+
+    // If a tracestate is not defined, then do our normal priority calculation.
     // eslint-disable-next-line sonarjs/pseudo-random
     const initPriority = Math.random()
     transaction.sampled = this.shouldSample(initPriority)

lib/samplers/always-off-sampler.js

@@ -6,7 +6,7 @@
 const Sampler = require('./sampler')
 
 class AlwaysOffSampler extends Sampler {
-  applySamplingDecision(transaction) {
+  applySamplingDecision({ transaction }) {
     if (!transaction) return
     transaction.priority = 0
     transaction.sampled = false

lib/samplers/always-on-sampler.js

@@ -6,7 +6,7 @@
 const Sampler = require('./sampler')
 
 class AlwaysOnSampler extends Sampler {
-  applySamplingDecision(transaction) {
+  applySamplingDecision({ transaction }) {
     if (!transaction) return
     transaction.priority = 2.0
     transaction.sampled = true

lib/samplers/ratio-based-sampler.js

@@ -25,7 +25,7 @@ class TraceIdRatioBasedSampler extends Sampler {
     this._upperBound = Math.floor(this._ratio * 0xffffffff)
   }
 
-  applySamplingDecision(transaction) {
+  applySamplingDecision({ transaction }) {
     if (!transaction) return
     // eslint-disable-next-line sonarjs/pseudo-random
     const initPriority = Math.random()

lib/samplers/sampler.js

@@ -11,9 +11,10 @@ class Sampler {
   /**
    * Sets `priority` and `sampled` on the transaction
    * in respect to this sampler's decision.
-   * @param {Transaction} transaction the transaction to update
+   * @param {object} params to make the sampling decision with
+   * @param {Transaction} params.transaction the transaction to update
    */
-  applySamplingDecision(transaction) {
+  applySamplingDecision({ transaction }) {
     throw new Error('must implement applySamplingDecision for %s', transaction)
   }
 }

lib/transaction/index.js

@@ -1029,35 +1029,13 @@ function acceptTraceContextPayload(traceparentHeader, tracestateHeader, transpor
   }
 
   // Decide sampling from w3c data
+  let sampler = null
   if (traceparent.isSampled === true) {
-    applySamplingStrategy({ transaction: this, tracestate, sampler: this.agent.remoteParentSampledSampler })
+    sampler = this.agent.remoteParentSampledSampler
+    sampler.applySamplingDecision({ transaction: this, tracestate })
   } else if (traceparent.isSampled === false) {
-    applySamplingStrategy({ transaction: this, tracestate, sampler: this.agent.remoteParentNotSampledSampler })
-  }
-}
-
-/**
- * Updates the transaction's `sampled` and `priority` properties
- * based on the given sampling configuration.
- *
- * @param {*} params Function parameters.
- * @param {Transaction} params.transaction The transaction to update.
- * @param {Tracestate} [params.tracestate] A tracestate object with embedded New Relic intrinsics.
- * @param {object} params.sampler The sampler to use, e.g. AdaptiveSampler or TraceIdRatioBasedSampler.
- */
-function applySamplingStrategy({ transaction, tracestate = null, sampler }) {
-  if (sampler?.toString() !== 'AdaptiveSampler') {
-    sampler.applySamplingDecision(transaction)
-  } else {
-    // This case is if we're coming from the deprecated newrelic header logic
-    // and we don't want to override the sampled and priority values
-    if (!tracestate) {
-      return
-    }
-
-    // Explicitly set sampled and priority from tracestate intrinsics if available
-    transaction.sampled = tracestate?.intrinsics ? tracestate.isSampled : null
-    transaction.priority = tracestate?.intrinsics ? tracestate.priority : null
+    sampler = this.agent.remoteParentNotSampledSampler
+    sampler.applySamplingDecision({ transaction: this, tracestate })
   }
 }
 
@@ -1164,10 +1142,16 @@ const _dtDefineAttrsFromTraceData = function _dtDefineAttrsFromTraceData(data, t
     // Even though New Relic headers are deprecated,
     // we still have to apply our sampling decision on top
     // of the priority and sampled values we receive.
+    // However, this only applies if the sampler is NOT
+    // the default sampler (adaptive). In that case,
+    // we leave it alone.
+    let sampler
     if (data?.sa) {
-      applySamplingStrategy({ transaction: this, sampler: this.agent.remoteParentSampledSampler })
+      sampler = this.agent.remoteParentSampledSampler
+      if (sampler.toString() !== 'AdaptiveSampler') sampler.applySamplingDecision({ transaction: this })
     } else {
-      applySamplingStrategy({ transaction: this, sampler: this.agent.remoteParentNotSampledSampler })
+      sampler = this.agent.remoteParentNotSampledSampler
+      if (sampler.toString() !== 'AdaptiveSampler') sampler.applySamplingDecision({ transaction: this })
     }
   }
 
@@ -1384,7 +1368,7 @@ Transaction.prototype.isSampled = function isSampled() {
 Transaction.prototype._calculatePriority = function _calculatePriority() {
   if (this.priority === null) {
     const sampler = this.agent.transactionSampler
-    sampler.applySamplingDecision(this)
+    sampler.applySamplingDecision({ transaction: this })
   }
 }