--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/src/thread-common.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,175 @@
+/* Copyright libuv project contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "uv-common.h"
+
+#include <stdlib.h>
+#ifndef _WIN32
+#include <pthread.h>
+#endif
+
+#if defined(PTHREAD_BARRIER_SERIAL_THREAD)
+STATIC_ASSERT(sizeof(uv_barrier_t) == sizeof(pthread_barrier_t));
+#endif
+
+/* Note: guard clauses should match uv_barrier_t's in include/uv/unix.h. */
+#if defined(_AIX) || \
+    defined(__OpenBSD__) || \
+    !defined(PTHREAD_BARRIER_SERIAL_THREAD)
+int uv_barrier_init(uv_barrier_t* barrier, unsigned int count) {
+  int rc;
+#ifdef _WIN32
+  uv_barrier_t* b;
+  b = barrier;
+
+  if (barrier == NULL || count == 0)
+    return UV_EINVAL;
+#else
+  struct _uv_barrier* b;
+
+  if (barrier == NULL || count == 0)
+    return UV_EINVAL;
+
+  b = uv__malloc(sizeof(*b));
+  if (b == NULL)
+    return UV_ENOMEM;
+#endif
+
+  b->in = 0;
+  b->out = 0;
+  b->threshold = count;
+
+  rc = uv_mutex_init(&b->mutex);
+  if (rc != 0)
+    goto error2;
+
+  /* TODO(vjnash): remove these uv_cond_t casts in v2. */
+  rc = uv_cond_init((uv_cond_t*) &b->cond);
+  if (rc != 0)
+    goto error;
+
+#ifndef _WIN32
+  barrier->b = b;
+#endif
+  return 0;
+
+error:
+  uv_mutex_destroy(&b->mutex);
+error2:
+#ifndef _WIN32
+  uv__free(b);
+#endif
+  return rc;
+}
+
+
+int uv_barrier_wait(uv_barrier_t* barrier) {
+  int last;
+#ifdef _WIN32
+  uv_barrier_t* b;
+  b = barrier;
+#else
+  struct _uv_barrier* b;
+
+  if (barrier == NULL || barrier->b == NULL)
+    return UV_EINVAL;
+
+  b = barrier->b;
+#endif
+
+  uv_mutex_lock(&b->mutex);
+
+  while (b->out != 0)
+    uv_cond_wait((uv_cond_t*) &b->cond, &b->mutex);
+
+  if (++b->in == b->threshold) {
+    b->in = 0;
+    b->out = b->threshold;
+    uv_cond_broadcast((uv_cond_t*) &b->cond);
+  } else {
+    do
+      uv_cond_wait((uv_cond_t*) &b->cond, &b->mutex);
+    while (b->in != 0);
+  }
+
+  last = (--b->out == 0);
+  if (last)
+    uv_cond_broadcast((uv_cond_t*) &b->cond);
+
+  uv_mutex_unlock(&b->mutex);
+  return last;
+}
+
+
+void uv_barrier_destroy(uv_barrier_t* barrier) {
+#ifdef _WIN32
+  uv_barrier_t* b;
+  b = barrier;
+#else
+  struct _uv_barrier* b;
+  b = barrier->b;
+#endif
+
+  uv_mutex_lock(&b->mutex);
+
+  assert(b->in == 0);
+  while (b->out != 0)
+    uv_cond_wait((uv_cond_t*) &b->cond, &b->mutex);
+
+  if (b->in != 0)
+    abort();
+
+  uv_mutex_unlock(&b->mutex);
+  uv_mutex_destroy(&b->mutex);
+  uv_cond_destroy((uv_cond_t*) &b->cond);
+
+#ifndef  _WIN32
+  uv__free(barrier->b);
+  barrier->b = NULL;
+#endif
+}
+
+#else
+
+int uv_barrier_init(uv_barrier_t* barrier, unsigned int count) {
+  return UV__ERR(pthread_barrier_init(barrier, NULL, count));
+}
+
+
+int uv_barrier_wait(uv_barrier_t* barrier) {
+  int rc;
+
+  rc = pthread_barrier_wait(barrier);
+  if (rc != 0)
+    if (rc != PTHREAD_BARRIER_SERIAL_THREAD)
+      abort();
+
+  return rc == PTHREAD_BARRIER_SERIAL_THREAD;
+}
+
+
+void uv_barrier_destroy(uv_barrier_t* barrier) {
+  if (pthread_barrier_destroy(barrier))
+    abort();
+}
+
+#endif