1 files changed, 67 insertions, 0 deletions
diff --git a/media/libcubeb/src/cubeb_utils_win.h b/media/libcubeb/src/cubeb_utils_win.h
new file mode 100644
index 0000000000..48e7b1b6d0
--- /dev/null
+++ b/media/libcubeb/src/cubeb_utils_win.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright © 2016 Mozilla Foundation
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ */
+
+#if !defined(CUBEB_UTILS_WIN)
+#define CUBEB_UTILS_WIN
+
+#include "cubeb-internal.h"
+#include <windows.h>
+
+/* This wraps an SRWLock to track the owner in debug mode, adapted from
+   NSPR and http://blogs.msdn.com/b/oldnewthing/archive/2013/07/12/10433554.aspx
+ */
+class owned_critical_section {
+public:
+  owned_critical_section()
+      : srwlock(SRWLOCK_INIT)
+#ifndef NDEBUG
+        ,
+        owner(0)
+#endif
+  {
+  }
+
+  void lock()
+  {
+    AcquireSRWLockExclusive(&srwlock);
+#ifndef NDEBUG
+    XASSERT(owner != GetCurrentThreadId() && "recursive locking");
+    owner = GetCurrentThreadId();
+#endif
+  }
+
+  void unlock()
+  {
+#ifndef NDEBUG
+    /* GetCurrentThreadId cannot return 0: it is not a the valid thread id */
+    owner = 0;
+#endif
+    ReleaseSRWLockExclusive(&srwlock);
+  }
+
+  /* This is guaranteed to have the good behaviour if it succeeds. The behaviour
+     is undefined otherwise. */
+  void assert_current_thread_owns()
+  {
+#ifndef NDEBUG
+    /* This implies owner != 0, because GetCurrentThreadId cannot return 0. */
+    XASSERT(owner == GetCurrentThreadId());
+#endif
+  }
+
+private:
+  SRWLOCK srwlock;
+#ifndef NDEBUG
+  DWORD owner;
+#endif
+
+  // Disallow copy and assignment because SRWLock cannot be copied.
+  owned_critical_section(const owned_critical_section &);
+  owned_critical_section & operator=(const owned_critical_section &);
+};
+
+#endif /* CUBEB_UTILS_WIN */