1 files changed, 74 insertions, 0 deletions
diff --git a/js/src/threading/Mutex.cpp b/js/src/threading/Mutex.cpp
new file mode 100644
index 000000000..154129dee
--- /dev/null
+++ b/js/src/threading/Mutex.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "threading/Mutex.h"
+
+#include "js/Utility.h"
+
+using namespace js;
+
+#ifdef DEBUG
+
+MOZ_THREAD_LOCAL(js::Mutex::MutexVector*) js::Mutex::HeldMutexStack;
+
+/* static */ bool
+js::Mutex::Init()
+{
+  return HeldMutexStack.init();
+}
+
+/* static */ void
+js::Mutex::ShutDown()
+{
+  js_delete(HeldMutexStack.get());
+  HeldMutexStack.set(nullptr);
+}
+
+/* static */ js::Mutex::MutexVector&
+js::Mutex::heldMutexStack()
+{
+  auto stack = HeldMutexStack.get();
+  if (!stack) {
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+    stack = js_new<MutexVector>();
+    if (!stack)
+      oomUnsafe.crash("js::Mutex::heldMutexStack");
+    HeldMutexStack.set(stack);
+  }
+  return *stack;
+}
+
+void
+js::Mutex::lock()
+{
+  auto& stack = heldMutexStack();
+  if (!stack.empty()) {
+    const Mutex& prev = *stack.back();
+    if (id_.order <= prev.id_.order) {
+      fprintf(stderr,
+              "Attempt to acquire mutex %s with order %d while holding %s with order %d\n",
+              id_.name, id_.order, prev.id_.name, prev.id_.order);
+      MOZ_CRASH("Mutex ordering violation");
+    }
+  }
+
+  MutexImpl::lock();
+
+  AutoEnterOOMUnsafeRegion oomUnsafe;
+  if (!stack.append(this))
+    oomUnsafe.crash("js::Mutex::lock");
+}
+
+void
+js::Mutex::unlock()
+{
+  auto& stack = heldMutexStack();
+  MOZ_ASSERT(stack.back() == this);
+  MutexImpl::unlock();
+  stack.popBack();
+}
+
+#endif