add express-session instrumentation

packages/datadog-instrumentations/src/express-session.js

@@ -0,0 +1,52 @@
+'use strict'
+
+const { addHook } = require('./helpers/instrument')
+const shimmer = require('../../datadog-shimmer')
+const { channel } = require('./helpers/instrument')
+
+const sessionMiddlewareFinishCh = channel('datadog:express-session:middleware:finish')
+
+function wrapSessionMiddleware (sessionMiddleware) {
+  return function wrappedSessionMiddleware (req, res, next) {
+    shimmer.wrap(arguments, 2, function wrapNext (next) {
+      return function wrappedNext () {
+        if (sessionMiddlewareFinishCh.hasSubscribers) {
+          const abortController = new AbortController()
+
+          sessionMiddlewareFinishCh.publish({ req, res, sessionId: req.sessionID, abortController })
+
+          if (abortController.signal.aborted) return
+        }
+
+        return next.apply(this, arguments)
+      }
+    })
+
+    return sessionMiddleware.apply(this, arguments)
+  }
+}
+
+function wrapSession (session) {
+  return function wrappedSession () {
+    const sessionMiddleware = session.apply(this, arguments)
+
+    return shimmer.wrapFunction(sessionMiddleware, wrapSessionMiddleware)
+  }
+}
+
+addHook({
+  name: 'express-session',
+  versions: ['>=0.3.0'] // TODO
+}, session => {
+  return shimmer.wrapFunction(session, wrapSession)
+})
+
+
+  return shimmer.wrapFunction(session, function wrapSession {
+      const queryMiddleware = query.apply(this, arguments)
+
+      return shimmer.wrapFunction(queryMiddleware, queryMiddleware => function (req, res, next) {
+      arguments[2] = publishQueryParsedAndNext(req, res, next)
+      return queryMiddleware.apply(this, arguments)
+    })
+  })