pass transaction context in sampling context

Author: lobsterkatie

packages/tracing/src/hubextensions.ts

@@ -29,15 +29,15 @@ function traceHeaders(this: Hub): { [key: string]: string } {
 }
 
 /**
- * Implements sampling inheritance and falls back to user-provided static rate if no parent decision is available.
+ * Uses existing sampling decision if available; falls back to user-provided static rate.
  *
- * @param parentSampled: The parent transaction's sampling decision, if any.
+ * @param existingDecision: The transaction's existing sampling decision, if any (likely inherited).
  * @param givenRate: The rate to use if no parental decision is available.
  *
- * @returns The parent's sampling decision (if one exists), or the provided static rate
+ * @returns The existing sampling decision (if one exists), or the provided static rate
  */
-function _inheritOrUseGivenRate(parentSampled: boolean | undefined, givenRate: unknown): boolean | unknown {
-  return parentSampled !== undefined ? parentSampled : givenRate;
+function _useExistingDecisionOrGivenRate(existingDecision: boolean | undefined, givenRate: unknown): boolean | unknown {
+  return existingDecision !== undefined ? existingDecision : givenRate;
 }
 
 /**
@@ -52,7 +52,7 @@ function _inheritOrUseGivenRate(parentSampled: boolean | undefined, givenRate: u
  *
  * @returns The given transaction with its `sampled` value set
  */
-function sample<T extends Transaction>(hub: Hub, transaction: T, samplingContext: SamplingContext = {}): T {
+function sample<T extends Transaction>(hub: Hub, transaction: T, samplingContext: SamplingContext): T {
   const client = hub.getClient();
   const options = (client && client.getOptions()) || {};
 
@@ -67,7 +67,7 @@ function sample<T extends Transaction>(hub: Hub, transaction: T, samplingContext
   const sampleRate =
     typeof options.tracesSampler === 'function'
       ? options.tracesSampler(samplingContext)
-      : _inheritOrUseGivenRate(samplingContext.parentSampled, options.tracesSampleRate);
+      : _useExistingDecisionOrGivenRate(samplingContext.transactionContext.sampled, options.tracesSampleRate);
 
   // Since this is coming from the user (or from a function provided by the user), who knows what we might get. (The
   // only valid values are booleans or numbers between 0 and 1.)
@@ -116,13 +116,8 @@ function sample<T extends Transaction>(hub: Hub, transaction: T, samplingContext
  *
  * @returns The default sample context
  */
-function getDefaultSamplingContext<T extends Transaction>(transaction: T): SamplingContext {
-  const defaultSamplingContext: SamplingContext = {};
-
-  // include parent's sampling decision, if there is one
-  if (transaction.parentSpanId && transaction.sampled !== undefined) {
-    defaultSamplingContext.parentSampled = transaction.sampled;
-  }
+function getDefaultSamplingContext(transactionContext: TransactionContext): SamplingContext {
+  const defaultSamplingContext: SamplingContext = { transactionContext };
 
   if (isNodeEnv()) {
     const domain = getActiveDomain();
@@ -196,24 +191,27 @@ function isValidSampleRate(rate: unknown): boolean {
  */
 function _startTransaction(
   this: Hub,
-  context: TransactionContext,
+  transactionContext: TransactionContext,
   customSamplingContext?: CustomSamplingContext,
 ): Transaction {
-  const transaction = new Transaction(context, this);
-  return sample(this, transaction, { ...getDefaultSamplingContext(transaction), ...customSamplingContext });
+  const transaction = new Transaction(transactionContext, this);
+  return sample(this, transaction, {
+    ...getDefaultSamplingContext(transactionContext),
+    ...customSamplingContext,
+  });
 }
 
 /**
  * Create new idle transaction.
  */
 export function startIdleTransaction(
   hub: Hub,
-  context: TransactionContext,
+  transactionContext: TransactionContext,
   idleTimeout?: number,
   onScope?: boolean,
 ): IdleTransaction {
-  const transaction = new IdleTransaction(context, hub, idleTimeout, onScope);
-  return sample(hub, transaction, getDefaultSamplingContext(transaction));
+  const transaction = new IdleTransaction(transactionContext, hub, idleTimeout, onScope);
+  return sample(hub, transaction, getDefaultSamplingContext(transactionContext));
 }
 
 /**

packages/tracing/test/hub.test.ts

@@ -143,20 +143,18 @@ describe('Hub', () => {
         expect(tracesSampler).toHaveBeenCalledWith(expect.objectContaining({ location: dogParkLocation }));
       });
 
-      it("should add parent's sampling decision to default sample context", () => {
+      it('should add transaction context data to default sample context', () => {
         const tracesSampler = jest.fn();
         const hub = new Hub(new BrowserClient({ tracesSampler }));
-        const parentSamplingDecsion = false;
-
-        hub.startTransaction({
+        const transactionContext = {
           name: 'dogpark',
           parentSpanId: '12312012',
-          sampled: parentSamplingDecsion,
-        });
+          sampled: true,
+        };
 
-        expect(tracesSampler).toHaveBeenLastCalledWith(
-          expect.objectContaining({ parentSampled: parentSamplingDecsion }),
-        );
+        hub.startTransaction(transactionContext);
+
+        expect(tracesSampler).toHaveBeenLastCalledWith(expect.objectContaining({ transactionContext }));
       });
     });
 

packages/types/src/transaction.ts

@@ -63,6 +63,11 @@ export interface CustomSamplingContext {
  * Adds default data to data provided by the user. See {@link Hub.startTransaction}
  */
 export interface SamplingContext extends CustomSamplingContext {
+  /**
+   * Context data with which transaction being sampled was created
+   */
+  transactionContext: TransactionContext;
+
   /**
    * Object representing the URL of the current page or worker script. Passed by default in a browser or service worker
    * context.
@@ -73,9 +78,4 @@ export interface SamplingContext extends CustomSamplingContext {
    * Object representing the incoming request to a node server. Passed by default when using the TracingHandler.
    */
   request?: ExtractedNodeRequestData;
-
-  /**
-   * Sampling decision from the parent transaction, if any.
-   */
-  parentSampled?: boolean;
 }