From 88dbafc62809f9df639dd4e2cffbfb38897259ec Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Thu, 12 Mar 2026 15:17:30 -0700
Subject: [PATCH] Add some testing of the emscripten_condvar API. NFC

---
 test/test_browser.py               |  4 ++
 test/test_core.py                  |  5 ++
 test/wasm_worker/condvar_waitinf.c | 99 ++++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+)
 create mode 100644 test/wasm_worker/condvar_waitinf.c

diff --git a/test/test_browser.py b/test/test_browser.py
index 234d24b305287..9f601dd8a4355 100644
--- a/test/test_browser.py
+++ b/test/test_browser.py
@@ -5224,6 +5224,10 @@ def test_wasm_worker_semaphore_waitinf_acquire(self):
   def test_wasm_worker_semaphore_try_acquire(self):
     self.btest_exit('wasm_worker/semaphore_try_acquire.c', cflags=['-sWASM_WORKERS'])
 
+  @also_with_minimal_runtime
+  def test_wasm_worker_condvar_waitinf(self):
+    self.btest_exit('wasm_worker/condvar_waitinf.c', cflags=['-sWASM_WORKERS'])
+
   # Tests that calling any proxied function in a Wasm Worker will abort at runtime when ASSERTIONS are enabled.
   def test_wasm_worker_proxied_function(self):
     error_msg = "abort:Assertion failed: Attempted to call proxied function '_proxied_js_function' in a Wasm Worker, but in Wasm Worker enabled builds, proxied function architecture is not available!"
diff --git a/test/test_core.py b/test/test_core.py
index c517d88fb4552..9e03c39a10f08 100644
--- a/test/test_core.py
+++ b/test/test_core.py
@@ -2794,6 +2794,11 @@ def test_emscripten_semaphore_waitinf_acquire(self):
   def test_emscripten_semaphore_try_acquire(self):
     self.do_runf('wasm_worker/semaphore_try_acquire.c', 'done\n', cflags=['-pthread'])
 
+  @requires_pthreads
+  @also_with_wasm_workers
+  def test_emscripten_condvar_waitinf(self):
+    self.do_runf('wasm_worker/condvar_waitinf.c', 'done\n', cflags=['-pthread'])
+
   def test_tcgetattr(self):
     self.do_runf('termios/test_tcgetattr.c', 'success')
 
diff --git a/test/wasm_worker/condvar_waitinf.c b/test/wasm_worker/condvar_waitinf.c
new file mode 100644
index 0000000000000..2d6e8004f0fb8
--- /dev/null
+++ b/test/wasm_worker/condvar_waitinf.c
@@ -0,0 +1,99 @@
+#include <assert.h>
+#include <emscripten/console.h>
+#include <emscripten/threading.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#ifdef __EMSCRIPTEN_PTHREADS__
+#include <pthread.h>
+#else
+#include <emscripten/wasm_worker.h>
+#endif
+
+emscripten_condvar_t condvar = EMSCRIPTEN_CONDVAR_T_STATIC_INITIALIZER;
+emscripten_lock_t mutex = EMSCRIPTEN_LOCK_T_STATIC_INITIALIZER;
+
+int globalVar = 0;
+_Atomic bool waiterStarted = false;
+
+#ifndef __EMSCRIPTEN_PTHREADS__
+void do_exit() {
+  emscripten_out("do_exit");
+  emscripten_terminate_all_wasm_workers();
+  emscripten_force_exit(0);
+}
+#endif
+
+void waiter_main() {
+  emscripten_out("waiter_main");
+  emscripten_lock_waitinf_acquire(&mutex);
+  emscripten_out("waiter: got mutex");
+  assert(!globalVar);
+  waiterStarted = true;
+
+  while (!globalVar) {
+    emscripten_out("waiter: condvar wait");
+    emscripten_condvar_waitinf(&condvar, &mutex);
+  }
+
+  emscripten_out("waiter: done");
+  emscripten_lock_release(&mutex);
+
+#ifndef __EMSCRIPTEN_PTHREADS__
+  emscripten_wasm_worker_post_function_v(EMSCRIPTEN_WASM_WORKER_ID_PARENT,
+                                         do_exit);
+#endif
+}
+
+void signaler_main() {
+  emscripten_out("signaler_main");
+  while (!waiterStarted) {
+    // busy-wait for waiter
+  }
+  // At this point we know the waiter took the lock already.
+  // That means that once we acquire the lock here the waiter
+  // muste be `emscripten_condvar_waitinf`.
+
+  emscripten_out("signaler: aquiring lock");
+  emscripten_lock_waitinf_acquire(&mutex);
+
+  emscripten_out("signaler: incrementing globalVar");
+  globalVar += 1;
+
+  emscripten_out("signaler: signaling condition");
+  emscripten_condvar_signal(&condvar, 1);
+
+  emscripten_out("signaler: done");
+  emscripten_lock_release(&mutex);
+}
+
+#ifdef __EMSCRIPTEN_PTHREADS__
+void* waiter_pthread(void* arg) {
+  waiter_main();
+  return NULL;
+}
+void* signaler_pthread(void* arg) {
+  signaler_main();
+  return NULL;
+}
+#endif
+
+int main() {
+  emscripten_out("in main");
+
+#ifdef __EMSCRIPTEN_PTHREADS__
+  pthread_t waiter;
+  pthread_t signaler;
+  pthread_create(&waiter, NULL, waiter_pthread, NULL);
+  pthread_create(&signaler, NULL, signaler_pthread, NULL);
+  pthread_join(waiter, NULL);
+  pthread_join(signaler, NULL);
+  emscripten_out("done");
+#else
+  emscripten_wasm_worker_t waiter = emscripten_malloc_wasm_worker(1024);
+  emscripten_wasm_worker_post_function_v(waiter, waiter_main);
+
+  emscripten_wasm_worker_t signaler = emscripten_malloc_wasm_worker(1024);
+  emscripten_wasm_worker_post_function_v(signaler, signaler_main);
+#endif
+}