1 files changed, 85 insertions, 0 deletions
diff --git a/js/src/threading/windows/MutexImpl.cpp b/js/src/threading/windows/MutexImpl.cpp
new file mode 100644
index 000000000..385d1c8de
--- /dev/null
+++ b/js/src/threading/windows/MutexImpl.cpp
@@ -0,0 +1,85 @@
+/* -*- 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 "mozilla/DebugOnly.h"
+
+#include "jswin.h"
+
+#include "js/Utility.h"
+
+#include "threading/Mutex.h"
+#include "threading/windows/MutexPlatformData.h"
+
+namespace {
+
+// We build with a toolkit that supports WinXP, so we have to probe
+// for modern features at runtime. This is necessary because Vista and
+// later automatically allocate and subsequently leak a debug info
+// object for each critical section that we allocate unless we tell it
+// not to. In order to tell it not to, we need the extra flags field
+// provided by the Ex version of InitializeCriticalSection.
+struct MutexNativeImports
+{
+  using InitializeCriticalSectionExT = BOOL (WINAPI*)(CRITICAL_SECTION*, DWORD, DWORD);
+  InitializeCriticalSectionExT InitializeCriticalSectionEx;
+
+  MutexNativeImports() {
+    HMODULE kernel32_dll = GetModuleHandle("kernel32.dll");
+    MOZ_RELEASE_ASSERT(kernel32_dll != NULL);
+    InitializeCriticalSectionEx = reinterpret_cast<InitializeCriticalSectionExT>(
+      GetProcAddress(kernel32_dll, "InitializeCriticalSectionEx"));
+  }
+
+  bool hasInitializeCriticalSectionEx() const {
+    return InitializeCriticalSectionEx;
+  }
+};
+
+static MutexNativeImports NativeImports;
+
+} // (anonymous namespace)
+
+js::detail::MutexImpl::MutexImpl()
+{
+  AutoEnterOOMUnsafeRegion oom;
+  platformData_ = js_new<PlatformData>();
+  if (!platformData_)
+    oom.crash("js::Mutex::Mutex");
+
+  // This number was adopted from NSPR.
+  const static DWORD LockSpinCount = 1500;
+  BOOL r;
+  if (NativeImports.hasInitializeCriticalSectionEx()) {
+    r = NativeImports.InitializeCriticalSectionEx(&platformData()->criticalSection,
+                                                  LockSpinCount,
+                                                  CRITICAL_SECTION_NO_DEBUG_INFO);
+  } else {
+    r = InitializeCriticalSectionAndSpinCount(&platformData()->criticalSection,
+                                              LockSpinCount);
+  }
+  MOZ_RELEASE_ASSERT(r);
+}
+
+js::detail::MutexImpl::~MutexImpl()
+{
+  if (!platformData_)
+    return;
+
+  DeleteCriticalSection(&platformData()->criticalSection);
+  js_delete(platformData());
+}
+
+void
+js::detail::MutexImpl::lock()
+{
+  EnterCriticalSection(&platformData()->criticalSection);
+}
+
+void
+js::detail::MutexImpl::unlock()
+{
+  LeaveCriticalSection(&platformData()->criticalSection);
+}