feat(functions): add Cloud Functions support for Windows desktop by akshaynexus · Pull Request #18471 · firebase/flutterfire

akshaynexus · 2026-07-21T18:48:20Z

Description

Implements Cloud Functions for Windows desktop over the Firebase C++ SDK, filling in the CloudFunctionsHostApi pigeon interface whose Windows codegen (windows/messages.g.*) already existed in the repo but had no host implementation.

This mirrors the Linux implementation from #18461 (tested working there against the emulator on real hardware); the two are structurally parallel so a later shared-core extraction can cover both.

What's included

httpsCallable / httpsCallableFromUrl with full firebase::Variant <-> EncodableValue conversion (including typed-data lists)
Canonical error-code mapping, with code/message in the error details map as Dart's platformExceptionToFirebaseFunctionsException expects
Per-call timeout enforced in the plugin via a deadline thread (the C++ SDK has no deadline API); responds deadline-exceeded while the SDK completion only cleans up
Emulator support via the origin argument
Streaming callables (.stream()) report unimplemented — the C++ SDK has no streaming API

e2e

cloud_functions is added to the Windows case of the tests-app e2e suite. Skips are limited to genuine C++ SDK gaps (streaming callables, exception details payload), and the timeout test drains its uncancellable request afterwards so the next test isn't queued behind it.

Related Issues

Companion to #18461 (Linux desktop support).

Checklist

I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
My PR includes e2e test coverage for the new feature.
All existing and new tests are passing.

Implements the CloudFunctionsHostApi pigeon interface (already generated into windows/messages.g.*) over the Firebase C++ SDK, mirroring the Linux implementation from firebase#18461: - httpsCallable / httpsCallableFromUrl calls with full Variant <-> EncodableValue conversion (including typed-data lists) - canonical error code mapping with code/message details for Dart's exception mapping - per-call timeout enforced by the plugin via a deadline thread, since the C++ SDK has no deadline API (responds deadline-exceeded; the SDK completion then only cleans up) - emulator origin support - streaming callables report 'unimplemented' (no C++ SDK support) Adds cloud_functions to the Windows e2e suite with skips limited to genuine C++ SDK gaps (streaming, error details payload) and a drain after the timeout test because the timed-out request cannot be cancelled.

gemini-code-assist · 2026-07-21T18:48:24Z

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize the Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counterproductive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

akshaynexus · 2026-07-21T19:06:30Z

/gemini review

gemini-code-assist

Code Review

This pull request adds Windows platform support to the cloud_functions plugin using the Firebase C++ SDK, along with corresponding integration test updates. The code review highlights several critical issues in the C++ implementation, including a potential use-after-free vulnerability when converting blob data, thread-safety concerns from invoking the Pigeon callback on background threads, and redundant caching of raw Functions pointers that could lead to dangling pointers if Firebase apps are destroyed. Suggestions are provided to safely manage blob lifetimes, dispatch callbacks to the main thread, and track emulator configurations using a std::set.

The C++ SDK already caches instances per (app, region) inside Functions::GetInstance; a plugin-side raw-pointer cache could dangle if an app were deleted and recreated. Addresses review feedback.

akshaynexus · 2026-07-21T19:21:20Z

/gemini review

gemini-code-assist

Code Review

This pull request adds Windows support to the cloud_functions plugin using the Firebase C++ SDK, and updates the integration tests to handle desktop-specific limitations. The review feedback suggests two important improvements: first, avoiding manual heap allocation of HttpsCallableReference by capturing it by value in the completion lambda to leverage automatic lifetime management; second, ensuring that the platform channel result callbacks are dispatched back to the main thread to prevent thread-safety issues with the Flutter Windows engine.

akshaynexus · 2026-07-21T19:30:36Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces Windows support for the cloud_functions package by implementing a C++ plugin backed by the Firebase C++ SDK, along with corresponding build configurations and integration test updates. The feedback focuses on improving the C++ implementation's robustness and resource management. Key recommendations include avoiding manual heap allocation of HttpsCallableReference by capturing it by value in the completion lambda, refactoring the timeout thread to use a std::condition_variable instead of std::this_thread::sleep_for to release resources immediately upon completion, and correcting a compiler definition syntax in CMakeLists.txt to prevent double-prefixing.

Dart sends a 70s default timeout, so every call parked its deadline thread (holding the reply callback) for the full duration. A condition variable notified from the completion handler lets the thread exit as soon as the request finishes. Addresses review feedback.

akshaynexus · 2026-07-21T19:36:47Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces Windows support for the cloud_functions Flutter plugin, implementing the platform channel in C++ using the Firebase C++ SDK and updating integration tests accordingly. The review feedback highlights several critical issues in the C++ implementation, including a potential deadlock risk from invoking external callbacks while holding a mutex, potential undefined behavior when handling empty blobs or byte vectors with null pointers, and a potential linker error due to a non-inline function definition in a header file.

…x; guard zero-size blobs

akshaynexus · 2026-07-21T19:49:30Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces Windows support for the cloud_functions plugin, implementing the native C++ plugin code and updating the integration tests to run on Windows while skipping unsupported desktop C++ SDK features (such as streaming callables and exception details propagation). Feedback on the implementation suggests refactoring the Call function in cloud_functions_plugin.cpp to comply with the repository style guide's 20-line limit, initializing HttpsCallableReference directly using the copy constructor, and capturing state by value instead of by reference in the predicate lambda to avoid lifetime issues.

gemini-code-assist · 2026-07-21T19:51:35Z

+void CloudFunctionsPlugin::Call(
+    const flutter::EncodableMap& arguments,
+    std::function<void(ErrorOr<std::optional<flutter::EncodableValue>> reply)>
+        result) {


The Call function is currently around 130 lines long, which violates the repository style guide rule of keeping functions under 20 lines to maintain conciseness and readability. Consider refactoring this function by extracting logical parts (such as argument parsing, callable reference initialization, and timeout thread setup) into smaller helper functions.

References

Functions should be kept under 20 lines to avoid verbosity and improve maintainability. ^(link)

gemini-code-assist · 2026-07-21T19:51:35Z

+  auto* ref = new HttpsCallableReference();
+  if (!function_name.empty()) {
+    *ref = functions->GetHttpsCallable(function_name.c_str());
+  } else if (!function_uri.empty()) {
+    *ref = functions->GetHttpsCallableFromURL(function_uri.c_str());
+  } else {
+    delete ref;
+    result(MakeFunctionsError(
+        "invalid-argument",
+        "Either functionName or functionUri must be provided"));
+    return;
+  }


Instead of default-constructing HttpsCallableReference and then assigning to it, you can initialize it directly using the copy constructor. This is cleaner and avoids unnecessary default construction.

HttpsCallableReference* ref = nullptr; if (!function_name.empty()) { ref = new HttpsCallableReference(functions->GetHttpsCallable(function_name.c_str())); } else if (!function_uri.empty()) { ref = new HttpsCallableReference(functions->GetHttpsCallableFromURL(function_uri.c_str())); } else { result(MakeFunctionsError( "invalid-argument", "Either functionName or functionUri must be provided")); return; }

gemini-code-assist · 2026-07-21T19:51:35Z

+      if (!state->cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),
+                              [&state] { return state->responded; })) {


Capture state by value ([state]) instead of by reference ([&state]) in the predicate lambda. Since state is a std::shared_ptr, capturing it by value is cheap, safe, and avoids any potential compiler warnings or lifetime concerns with the outer lambda's stack frame.

Suggested change

if (!state->cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),

[&state] { return state->responded; })) {

if (!state->cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),

[state] { return state->responded; })) {

SelaseKay · 2026-07-22T10:15:20Z

Hi @akshaynexus, thanks for the contribution. It looks like a few CI checks are failing. Could you kindly take a look when you have a chance?

…art tests

luccasclezar · 2026-09-01T17:04:22Z

+            result(MakeFunctionsError(code, message));
+          }
+        }
+        delete state->ref;


I tried merging this PR into a fork to use cloud functions in Windows, and this line crashed the app after any cloud function call. What ended up fixing the issue is wrapping the delete in a short-lived thread:

std::thread([ref = state->ref]() { delete ref; }).detach();

I honestly don't know much about native Windows code, but I just wanted to point this out as it crashes the app every single time in my tests.

Ok will fix that,this implementation was loosely ported from a linux implementation pr for firebase so some issues may have happened on windows that didn't happen on Linux

Thanks for the feedback

Upstream moved the Cloud Functions e2e suite into the package example app and replaced the monolithic Windows workflow with per-product reusable jobs, so the Windows wiring from this branch is ported to that layout: - Drop .github/workflows/windows.yaml (deleted upstream) and add a `windows` job to e2e_tests_functions.yaml via reusable_e2e_windows.yaml. - Scaffold a Windows runner for the cloud_functions example so the reusable job has something to `flutter drive`. - Re-apply the desktop C++ SDK skips (no `details` on exceptions, no streaming callables, drain after timeout) on the moved e2e test and drop tests/integration_test/platform_utils.dart, whose only user moved. - Register cloud_functions in the tests app's committed Windows plugin registrant, which the format check flagged on the PR. Claude-Session: https://claude.ai/code/session_01M7EsbBhVWfzLhM3a9WTVsu

…mpletion thread Deleting the HttpsCallableReference from inside its own OnCompletion callback crashed the app after every call on Windows (reported on firebase#18471): the completion runs inside the reference's Future/transport machinery, so destroying it there tears down a live stack. Hand the delete to a short-lived thread instead. The Windows CI job showed the same thing as a non-zero exit at app teardown with every test green. Also folds in the remaining review nits: construct the reference directly, capture the shared state by value in the wait predicate, give the SDK a non-null pointer for empty blobs, and hoist the per-call state, response claiming, and timeout parsing out of Call() so the completion path no longer duplicates the deliver-under-lock logic. Claude-Session: https://claude.ai/code/session_01M7EsbBhVWfzLhM3a9WTVsu

gemini-code-assist Bot reviewed Jul 21, 2026

View reviewed changes

refactor(functions,windows): drop local Functions instance cache

4bb1b36

The C++ SDK already caches instances per (app, region) inside Functions::GetInstance; a plugin-side raw-pointer cache could dangle if an app were deleted and recreated. Addresses review feedback.

gemini-code-assist Bot reviewed Jul 21, 2026

View reviewed changes

Comment thread packages/cloud_functions/cloud_functions/windows/cloud_functions_plugin.cpp Outdated

Comment thread packages/cloud_functions/cloud_functions/windows/cloud_functions_plugin.cpp

docs: mark Cloud Functions as supported (dev-only) on Windows

513838b

gemini-code-assist Bot reviewed Jul 21, 2026

View reviewed changes

fix(functions,windows): invoke reply callbacks outside the state mute…

2062242

…x; guard zero-size blobs

gemini-code-assist Bot reviewed Jul 21, 2026

View reviewed changes

akshaynexus added 2 commits July 23, 2026 06:03

fix(core,windows): add firebase_functions to FIREBASE_RELEASE_PATH_LIBS

5c7adae

fix(ci,windows): build functions before running emulator and format D…

36bc7e0

…art tests

akshaynexus requested review from Lyokone and russellwheatley as code owners July 24, 2026 01:55

luccasclezar reviewed Sep 1, 2026

View reviewed changes

akshaynexus added 2 commits September 2, 2026 02:41

		if (!state->cv.wait_for(lock, std::chrono::milliseconds(timeout_ms),
		[&state] { return state->responded; })) {

Uh oh!

Conversation

akshaynexus commented Jul 21, 2026

Description

What's included

e2e

Related Issues

Checklist

Uh oh!

gemini-code-assist Bot commented Jul 21, 2026

Uh oh!

akshaynexus commented Jul 21, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

akshaynexus commented Jul 21, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

akshaynexus commented Jul 21, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

akshaynexus commented Jul 21, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

akshaynexus commented Jul 21, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot Jul 21, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot Jul 21, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist Bot Jul 21, 2026

Choose a reason for hiding this comment

Uh oh!

SelaseKay commented Jul 22, 2026

Uh oh!

luccasclezar Sep 1, 2026

Choose a reason for hiding this comment

Uh oh!

akshaynexus Sep 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

akshaynexus Sep 1, 2026 •

edited

Loading