feat: wrap client if @dynatrace/oneagent-sdk is present (#777)

todos:
- [x] remove unused code (if streaming extension is not needed)
- [ ] document on capire?

it works (the yellow span):
<img width="1328" alt="Screenshot 2024-08-12 at 21 56 28"
src="https://github.com/user-attachments/assets/879f149a-fdda-4817-8339-011ed6266c54">

---------

Co-authored-by: Johannes Vogel <31311694+johannes-vogel@users.noreply.github.com>

hana/lib/drivers/dynatrace.js

@@ -0,0 +1,91 @@
+// COPIED AS IS (excluding unused code) FROM @sap/cds
+
+const dynatrace = {}
+try {
+  dynatrace.sdk = require('@dynatrace/oneagent-sdk')
+  dynatrace.api = dynatrace.sdk.createInstance()
+} catch {
+  // If module was not required, do not do anything
+}
+
+const isDynatraceEnabled = () => {
+  return dynatrace.sdk !== undefined && !process.env.CDS_SKIP_DYNATRACE
+}
+
+const _dynatraceResultCallback = function (tracer, cb) {
+  return function (err, ...args) {
+    const results = args.shift()
+    if (err) {
+      tracer.error(err)
+    } else {
+      tracer.setResultData({
+        rowsReturned: (results && results.length) || results
+      })
+    }
+    tracer.end(cb, err, results, ...args)
+  }
+}
+
+const _execUsingDynatrace = (client, execFn, dbInfo) => {
+  // args = [sql, options, callback] --> options is optional
+  return function (...args) {
+    const cb = args[args.length - 1]
+
+    const tracer = dynatrace.api.traceSQLDatabaseRequest(dbInfo, {
+      statement: args[0]
+    })
+
+    tracer.startWithContext(execFn, client, ...args.slice(0, args.length - 1), _dynatraceResultCallback(tracer, cb))
+  }
+}
+
+const _preparedStmtUsingDynatrace = function (client, prepareFn, dbInfo) {
+  // args = [sql, options, callback] --> options is optional
+  return function (...args) {
+    const cb = args[args.length - 1]
+
+    const tracer = dynatrace.api.traceSQLDatabaseRequest(dbInfo, {
+      statement: args[0]
+    })
+
+    tracer.startWithContext(prepareFn, client, ...args.slice(0, args.length - 1), (err, stmt) => {
+      if (err) {
+        tracer.error(err)
+        tracer.end(cb, err)
+      } else {
+        // same here. hana-client does not like decorating
+        const originalExecFn = stmt.exec
+        stmt.exec = function (...args) {
+          const stmtCb = args[args.length - 1]
+          originalExecFn.call(stmt, ...args.slice(0, args.length - 1), _dynatraceResultCallback(tracer, stmtCb))
+        }
+        cb(null, stmt)
+      }
+    })
+  }
+}
+
+const dynatraceClient = (client, credentials, tenant) => {
+  const dbInfo = {
+    name: `SAPHANA${tenant ? `-${tenant}` : ''}`,
+    vendor: dynatrace.sdk.DatabaseVendor.HANADB,
+    host: credentials.host,
+    port: Number(credentials.port)
+  }
+
+  // hana-client does not like decorating.
+  // because of that, we need to override the fn and pass the original fn for execution
+  const originalExecFn = client.exec
+  client.exec = _execUsingDynatrace(client, originalExecFn, dbInfo)
+  const originalPrepareFn = client.prepare
+  if (client.name === '@sap/hana-client') {
+    // client.prepare = ... doesn't work for hana-client
+    Object.defineProperty(client, 'prepare', { value: _preparedStmtUsingDynatrace(client, originalPrepareFn, dbInfo) })
+  } else {
+    client.prepare = _preparedStmtUsingDynatrace(client, originalPrepareFn, dbInfo)
+  }
+
+  return client
+}
+
+module.exports = { dynatraceClient, isDynatraceEnabled }

hana/lib/drivers/hana-client.js

@@ -3,6 +3,7 @@ const { Readable, Stream } = require('stream')
 const cds = require('@sap/cds')
 const hdb = require('@sap/hana-client')
 const { driver, prom, handleLevel } = require('./base')
+const { isDynatraceEnabled: dt_sdk_is_present, dynatraceClient: wrap_client } = require('./dynatrace')
 const LOG = cds.log('@sap/hana-client')
 if (process.env.NODE_ENV === 'production' && !process.env.HDB_NODEJS_THREADPOOL_SIZE && !process.env.UV_THREADPOOL_SIZE) LOG.warn("When using @sap/hana-client, it's strongly recommended to adjust its thread pool size with environment variable `HDB_NODEJS_THREADPOOL_SIZE`, otherwise it might lead to performance issues.\nLearn more: https://help.sap.com/docs/SAP_HANA_CLIENT/f1b440ded6144a54ada97ff95dac7adf/31a8c93a574b4f8fb6a8366d2c758f21.html")
 
@@ -43,6 +44,7 @@ class HANAClientDriver extends driver {
 
     super(creds)
     this._native = hdb.createConnection(creds)
+    if (dt_sdk_is_present()) this._native = wrap_client(this._native, creds, creds.tenant)
     this._native.setAutoCommit(false)
   }
 

hana/lib/drivers/hdb.js

@@ -6,6 +6,7 @@ const hdb = require('hdb')
 const iconv = require('iconv-lite')
 
 const { driver, prom, handleLevel } = require('./base')
+const { isDynatraceEnabled: dt_sdk_is_present, dynatraceClient: wrap_client } = require('./dynatrace')
 
 const credentialMappings = [
   { old: 'certificate', new: 'ca' },
@@ -33,6 +34,7 @@ class HDBDriver extends driver {
 
     super(creds)
     this._native = hdb.createClient(creds)
+    if (dt_sdk_is_present()) this._native = wrap_client(this._native, creds, creds.tenant)
     this._native.setAutoCommit(false)
     this._native.on('close', () => this.destroy?.())