Fix race condition in trigger disable

[samtstern]

Description

Fixes #2857

We give all background triggers a "generation number" which allows us to disable triggers inside the functions emulator and then when incoming calls try to run those triggers, even after a large delay, we can ignore it.

Scenarios Tested

functions/index.js

const functions = require('firebase-functions');

exports.httpFunction = functions.https.onRequest((request, response) => {
  console.log("httpFunction");
  response.send("Hello from Firebase!");
});

exports.rtdbFunction = functions.database.ref('/foo/{bar}').onWrite((change, ctx) => {
  console.log("rtdbFunction: ", ctx.params.bar);
  return true;
});

exports.firestoreFunctions = functions.firestore.document('/foo/{bar}').onWrite((change, ctx) => {
  console.log("firestoreFunction: ", ctx.params.bar);
  return true;
});

functions/test.js

const firebase = require("@firebase/rules-unit-testing");

async function addDoc(fs, id) {
  await fs.collection('foo').doc(id).set({
    date: new Date().getTime()
  });
  console.log("Added: ", id);
}

async function main() {
  const app = firebase.initializeAdminApp({
    projectId: 'fir-dumpster'
  });
  const fs = app.firestore();

  await addDoc(fs, 'should-trigger-1');
  await firebase.withFunctionTriggersDisabled(async () => {
    await addDoc(fs, 'should-not-trigger');
  });
  await addDoc(fs, 'should-trigger-2');
}

main();

Logs:

$ firebase emulators:exec "node test.js"                      
i  emulators: Starting emulators: functions, firestore, database
⚠  hub: emulator hub unable to start on port 4400, starting on 4401 instead.
⚠  functions: The following emulators are not running, calls to these services from the Functions emulator will affect production: auth, hosting, pubsub
⚠  Your requested "node" version "12" doesn't match your global version "10"
⚠  firestore: Did not find a Cloud Firestore rules file specified in a firebase.json config file.
⚠  firestore: The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration.
i  firestore: Firestore Emulator logging to firestore-debug.log
⚠  database: Did not find a Realtime Database rules file specified in a firebase.json config file. The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration.
i  database: Database Emulator logging to database-debug.log
i  functions: Watching "/private/var/folders/xl/6lkrzp7j07581mw8_4dlt3b000643s/T/tmp.EtFy933F/functions" for Cloud Functions...
✔  functions[httpFunction]: http function initialized (http://localhost:5001/fir-dumpster/us-central1/httpFunction).
✔  functions[rtdbFunction]: database function initialized.
✔  functions[firestoreFunctions]: firestore function initialized.
i  Running script: node test.js
Added:  should-trigger-1
i  emulators: Disabling Cloud Functions triggers, non-HTTP functions will not execute.
i  functions[rtdbFunction]: function temporarily disabled.
i  functions[firestoreFunctions]: function temporarily disabled.
Added:  should-not-trigger
i  emulators: Enabling Cloud Functions triggers, non-HTTP functions will execute.
i  functions: Beginning execution of "firestoreFunctions"
✔  functions[rtdbFunction]: database function initialized.
✔  functions[firestoreFunctions]: firestore function initialized.
Added:  should-trigger-2
>  firestoreFunction:  should-trigger-1
i  functions: Finished "firestoreFunctions" in ~1s
i  functions: Beginning execution of "firestoreFunctions"
>  firestoreFunction:  should-trigger-2
i  functions: Finished "firestoreFunctions" in ~1s
✔  Script exited successfully (code 0)
i  emulators: Shutting down emulators.
i  functions: Stopping Functions Emulator
i  database: Stopping Database Emulator
i  firestore: Stopping Firestore Emulator
i  hub: Stopping emulator hub

Sample Commands

N/A

[samtstern]

@yuchenshi this one is ready to go now.

[yuchenshi]

LGTM! One question: What happens if the functions code is hot-reloaded while trigger is disabled? Would it cause a race condition somehow and re-enable the functions early?

[samtstern]

@yuchenshi hot reload would not re-enable existing functions because the generation number won't be increased.