From 2e58f2cdde7c4c053407fc48c0815b1edc420e4f Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Tue, 19 Dec 2023 18:20:13 +0000
Subject: [PATCH] Add traces to track running arbitrary JS.

---
 packages/backend-core/src/timers/timers.ts |  6 ++-
 packages/server/src/jsRunner.ts            | 53 +++++++++++++---------
 2 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/packages/backend-core/src/timers/timers.ts b/packages/backend-core/src/timers/timers.ts
index 3bb556703f..9de57af7f1 100644
--- a/packages/backend-core/src/timers/timers.ts
+++ b/packages/backend-core/src/timers/timers.ts
@@ -30,7 +30,7 @@ export class ExecutionTimeTracker {
     return new ExecutionTimeTracker(limitMs)
   }
 
-  constructor(private limitMs: number) {}
+  constructor(readonly limitMs: number) {}
 
   private totalTimeMs = 0
 
@@ -46,6 +46,10 @@ export class ExecutionTimeTracker {
     }
   }
 
+  get elapsedMS() {
+    return this.totalTimeMs
+  }
+
   private checkLimit() {
     if (this.totalTimeMs > this.limitMs) {
       throw new ExecutionTimeoutError(
diff --git a/packages/server/src/jsRunner.ts b/packages/server/src/jsRunner.ts
index a9301feb60..ab0381a399 100644
--- a/packages/server/src/jsRunner.ts
+++ b/packages/server/src/jsRunner.ts
@@ -2,35 +2,44 @@ import vm from "vm"
 import env from "./environment"
 import { setJSRunner } from "@budibase/string-templates"
 import { context, timers } from "@budibase/backend-core"
+import tracer from "dd-trace"
 
 type TrackerFn = <T>(f: () => T) => T
 
 export function init() {
   setJSRunner((js: string, ctx: vm.Context) => {
-    const perRequestLimit = env.JS_PER_REQUEST_TIME_LIMIT_MS
-    let track: TrackerFn = f => f()
-    if (perRequestLimit) {
-      const bbCtx = context.getCurrentContext()
-      if (bbCtx) {
-        if (!bbCtx.jsExecutionTracker) {
-          bbCtx.jsExecutionTracker =
-            timers.ExecutionTimeTracker.withLimit(perRequestLimit)
+    return tracer.trace("runJS", {}, span => {
+      const perRequestLimit = env.JS_PER_REQUEST_TIME_LIMIT_MS
+      let track: TrackerFn = f => f()
+      if (perRequestLimit) {
+        const bbCtx = context.getCurrentContext()
+        if (bbCtx) {
+          if (!bbCtx.jsExecutionTracker) {
+            bbCtx.jsExecutionTracker =
+              timers.ExecutionTimeTracker.withLimit(perRequestLimit)
+          }
+          track = bbCtx.jsExecutionTracker.track.bind(bbCtx.jsExecutionTracker)
+          span?.addTags({
+            js: {
+              limitMS: bbCtx.jsExecutionTracker.limitMs,
+              elapsedMS: bbCtx.jsExecutionTracker.elapsedMS,
+            },
+          })
         }
-        track = bbCtx.jsExecutionTracker.track.bind(bbCtx.jsExecutionTracker)
       }
-    }
 
-    ctx = {
-      ...ctx,
-      alert: undefined,
-      setInterval: undefined,
-      setTimeout: undefined,
-    }
-    vm.createContext(ctx)
-    return track(() =>
-      vm.runInNewContext(js, ctx, {
-        timeout: env.JS_PER_EXECUTION_TIME_LIMIT_MS,
-      })
-    )
+      ctx = {
+        ...ctx,
+        alert: undefined,
+        setInterval: undefined,
+        setTimeout: undefined,
+      }
+      vm.createContext(ctx)
+      return track(() =>
+        vm.runInNewContext(js, ctx, {
+          timeout: env.JS_PER_EXECUTION_TIME_LIMIT_MS,
+        })
+      )
+    })
   })
 }