refactor: export traced channels as self-contained objects

Consumers import { queryChannel } or { cursorNextChannel } and use
.trace() or .channel directly. Adding a new channel is a single line
in tracing.js with no export changes needed.

Author: logaretm

lib/aggregate.js

@@ -15,7 +15,7 @@ const { buildMiddlewareFilter } = require('./helpers/buildMiddlewareFilter');
 const stringifyFunctionOperators = require('./helpers/aggregate/stringifyFunctionOperators');
 const utils = require('./utils');
 const { modelSymbol } = require('./helpers/symbols');
-const { trace } = require('./tracing');
+const { queryChannel } = require('./tracing');
 const read = Query.prototype.read;
 const readConcern = Query.prototype.readConcern;
 
@@ -1073,7 +1073,7 @@ Aggregate.prototype.exec = async function exec() {
     this._optionsForExec();
 
     const _this = this;
-    return trace(async function maybeTracedConnectionAggregate() {
+    return queryChannel.trace(async function maybeTracedConnectionAggregate() {
       const cursor = await _this._connection.client.db().aggregate(_this._pipeline, _this.options);
       return await cursor.toArray();
     }, () => ({
@@ -1104,7 +1104,7 @@ Aggregate.prototype.exec = async function exec() {
   stringifyFunctionOperators(this._pipeline);
 
   const _this = this;
-  return trace(async function maybeTracedAggregateExec() {
+  return queryChannel.trace(async function maybeTracedAggregateExec() {
     const preFilter = buildMiddlewareFilter(_this.options, 'pre');
     const postFilter = buildMiddlewareFilter(_this.options, 'post');
 

lib/cursor/aggregationCursor.js

@@ -10,7 +10,7 @@ const eachAsync = require('../helpers/cursor/eachAsync');
 const immediate = require('../helpers/immediate');
 const kareem = require('kareem');
 const util = require('util');
-const { traceCursorNext } = require('../tracing');
+const { cursorNextChannel } = require('../tracing');
 
 /**
  * An AggregationCursor is a concurrency primitive for processing aggregation
@@ -280,7 +280,7 @@ AggregationCursor.prototype.next = async function next() {
   }
   const _this = this;
   const model = this.agg._model;
-  return traceCursorNext(function maybeTracedAggCursorNext() {
+  return cursorNextChannel.trace(function maybeTracedAggCursorNext() {
     return new Promise((resolve, reject) => {
       _next(_this, (err, res) => {
         if (err != null) {

lib/cursor/queryCursor.js

@@ -12,7 +12,7 @@ const kareem = require('kareem');
 const immediate = require('../helpers/immediate');
 const { once } = require('events');
 const util = require('util');
-const { traceCursorNext } = require('../tracing');
+const { cursorNextChannel } = require('../tracing');
 
 /**
  * A QueryCursor is a concurrency primitive for processing query results
@@ -312,7 +312,7 @@ QueryCursor.prototype.next = async function next() {
     throw new MongooseError('Cannot call `next()` on a closed cursor');
   }
   const _this = this;
-  return traceCursorNext(function maybeTracedQueryCursorNext() {
+  return cursorNextChannel.trace(function maybeTracedQueryCursorNext() {
     return new Promise((resolve, reject) => {
       _next(_this, function(error, doc) {
         if (error) {

lib/model.js

@@ -7,7 +7,7 @@
 const Aggregate = require('./aggregate');
 const ChangeStream = require('./cursor/changeStream');
 const Document = require('./document');
-const { trace } = require('./tracing');
+const { queryChannel } = require('./tracing');
 const DocumentNotFoundError = require('./error/notFound');
 const EventEmitter = require('events').EventEmitter;
 const Kareem = require('kareem');
@@ -665,7 +665,7 @@ Model.prototype.save = async function save(options) {
   this.$__.saveOptions = options;
 
   const _this = this;
-  return trace(async function maybeTracedSave() {
+  return queryChannel.trace(async function maybeTracedSave() {
     try {
       await _this.$__save(options);
     } catch (error) {
@@ -3027,7 +3027,7 @@ Model.insertMany = function insertMany(arr, options) {
   }
 
   const ThisModel = this;
-  return trace(function maybeTracedInsertMany() { return _insertMany.call(ThisModel, arr, options); }, () => ({
+  return queryChannel.trace(function maybeTracedInsertMany() { return _insertMany.call(ThisModel, arr, options); }, () => ({
     operation: 'insertMany',
     collection: ThisModel.collection.name,
     database: ThisModel.db?.name,
@@ -3403,7 +3403,7 @@ Model.bulkWrite = function bulkWrite(ops, options) {
   }
 
   const ThisModel = this;
-  return trace(function maybeTracedBulkWrite() { return _bulkWrite.call(ThisModel, ops, options); }, () => ({
+  return queryChannel.trace(function maybeTracedBulkWrite() { return _bulkWrite.call(ThisModel, ops, options); }, () => ({
     operation: 'bulkWrite',
     collection: ThisModel.collection.name,
     database: ThisModel.db?.name,

lib/query.js

@@ -42,7 +42,7 @@ const updateValidators = require('./helpers/updateValidators');
 const util = require('util');
 const utils = require('./utils');
 const queryMiddlewareFunctions = require('./constants').queryMiddlewareFunctions;
-const { trace } = require('./tracing');
+const { queryChannel } = require('./tracing');
 
 const queryOptionMethods = new Set([
   'allowDiskUse',
@@ -4780,7 +4780,7 @@ Query.prototype.exec = async function exec(op) {
   this._execCount++;
 
   const _this = this;
-  return trace(async function maybeTracedQueryExec() {
+  return queryChannel.trace(async function maybeTracedQueryExec() {
     let skipWrappedFunction = null;
     try {
       await _this._hooks.execPre('exec', _this, []);

lib/tracing.js

@@ -35,13 +35,7 @@ function createTracedChannel(name) {
   return { channel: ch, trace };
 }
 
-const query = createTracedChannel('mongoose:query');
-const cursorNext = createTracedChannel('mongoose:cursor:next');
-
 module.exports = {
-  channel: query.channel,
-  cursorNextChannel: cursorNext.channel,
-  trace: query.trace,
-  traceCursorNext: cursorNext.trace,
-  shouldTrace
+  queryChannel: createTracedChannel('mongoose:query'),
+  cursorNextChannel: createTracedChannel('mongoose:cursor:next')
 };