feat!: Removed legacy context manager (#2404)

documentation/feature-flags.md

@@ -33,12 +33,6 @@ Any prerelease flags can be enabled or disabled in your agent config by adding a
 * Description: Now that `new_promise_tracking` is the default async context tracking behavior in the agent, `unresolved_promise_cleanup` is enabled by default. Disabling it can help with performance of agent when an application creates many promises. 
 * **WARNING**: If you set `unresolved_promise_cleanup` to `false`, failure to resolve all promises in your application will result in memory leaks even if those promises are garbage collected.
 
-#### legacy_context_manager
-* Enabled by default: `false`
-* Configuration: `{ feature_flag: { legacy_context_manager: true|false }}`
-* Environment Variable: `NEW_RELIC_FEATURE_FLAG_LEGACY_CONTEXT_MANAGER`
-* Description: The legacy context manager was replaced by AsyncLocalContextManager for async context propagation. If your application is not recording certain spans or creating orphaned data, you may want to enable this older context manager. Enabling this feature flag may increase the agent's use of memory and CPU.
-
 #### kakfajs_instrumentation
 * Enabled by default: `false`
 * Configuration: `{ feature_flag: { kafkajs_instrumentation: true|false }}`

lib/context-manager/create-context-manager.js

@@ -16,10 +16,6 @@ const logger = require('../logger')
  * the current configuration.
  */
 function createContextManager(config) {
-  if (config.feature_flag.legacy_context_manager) {
-    return createLegacyContextManager(config)
-  }
-
   return createAsyncLocalContextManager(config)
 }
 
@@ -30,11 +26,4 @@ function createAsyncLocalContextManager(config) {
   return new AsyncLocalContextManager(config)
 }
 
-function createLegacyContextManager(config) {
-  logger.info('Using LegacyContextManager')
-
-  const LegacyContextManager = require('./legacy-context-manager')
-  return new LegacyContextManager(config)
-}
-
 module.exports = createContextManager

lib/feature_flags.js

@@ -15,7 +15,6 @@ exports.prerelease = {
   reverse_naming_rules: false,
   undici_async_tracking: true,
   unresolved_promise_cleanup: true,
-  legacy_context_manager: false,
   kafkajs_instrumentation: false
 }
 
@@ -43,4 +42,4 @@ exports.released = [
 ]
 
 // flags that are no longer used for unreleased features
-exports.unreleased = ['unreleased']
+exports.unreleased = ['unreleased', 'legacy_context_manager']

lib/instrumentation/core/globals.js

@@ -5,7 +5,6 @@
 
 'use strict'
 
-const asyncHooks = require('./async-hooks')
 const symbols = require('../../symbols')
 
 module.exports = initialize
@@ -63,8 +62,4 @@ function initialize(agent, nodule, name, shim) {
       return original.apply(this, arguments)
     }
   }
-
-  // This will initialize the most optimal native-promise instrumentation that
-  // we have available.
-  asyncHooks(agent, shim)
 }

lib/instrumentation/core/timers.js

@@ -11,50 +11,10 @@ const Timers = require('timers')
 
 module.exports = initialize
 
-function initialize(agent, timers, _moduleName, shim) {
-  const isLegacyContext = agent.config.feature_flag.legacy_context_manager
-
-  if (isLegacyContext) {
-    instrumentProcessMethods(shim, process)
-    instrumentSetImmediate(shim, [timers, global])
-  }
-
+function initialize(_agent, timers, _moduleName, shim) {
   instrumentTimerMethods(shim, [timers, global])
 }
 
-/**
- * Sets up instrumentation for setImmediate on both timers and global.
- *
- * We do not want to create segments for setImmediate calls,
- * as the object allocation may incur too much overhead in some situations
- *
- * @param {Shim} shim instance of shim
- * @param {Array<Timers,global>} pkgs array with references to timers and global
- */
-function instrumentSetImmediate(shim, pkgs) {
-  pkgs.forEach((nodule) => {
-    if (shim.isWrapped(nodule.setImmediate)) {
-      return
-    }
-
-    shim.wrap(nodule, 'setImmediate', function wrapSetImmediate(shim, fn) {
-      return function wrappedSetImmediate() {
-        const segment = shim.getActiveSegment()
-        if (!segment) {
-          return fn.apply(this, arguments)
-        }
-
-        const args = shim.argsToArray.apply(shim, arguments, segment)
-        shim.bindSegment(args, shim.FIRST)
-
-        return fn.apply(this, args)
-      }
-    })
-
-    copySymbols(shim, nodule, 'setImmediate')
-  })
-}
-
 /**
  * Sets up instrumentation for setTimeout, setInterval and clearTimeout
  * on timers and global.
@@ -107,37 +67,6 @@ function recordAsynchronizers(shim, _fn, name) {
   return new RecorderSpec({ name: 'timers.' + name, callback: shim.FIRST })
 }
 
-/**
- * Instruments core process methods: nextTick, _nextDomainTick, _tickDomainCallback
- * Note: This does not get registered when the context manager is async local
- *
- * @param {Shim} shim instance of shim
- * @param {process} process global process object
- */
-function instrumentProcessMethods(shim, process) {
-  const processMethods = ['nextTick', '_nextDomainTick', '_tickDomainCallback']
-
-  shim.wrap(process, processMethods, function wrapProcess(shim, fn) {
-    return function wrappedProcess() {
-      const segment = shim.getActiveSegment()
-      if (!segment) {
-        return fn.apply(this, arguments)
-      }
-
-      // Manual copy because helper methods add significant overhead in some usages
-      const len = arguments.length
-      const args = new Array(len)
-      for (let i = 0; i < len; ++i) {
-        args[i] = arguments[i]
-      }
-
-      shim.bindSegment(args, shim.FIRST, segment)
-
-      return fn.apply(this, args)
-    }
-  })
-}
-
 /**
  * Copies the symbols from original setTimeout and setInterval onto the wrapped functions
  *