1 files changed, 102 insertions, 0 deletions
diff --git a/js/src/vm/Monitor.h b/js/src/vm/Monitor.h
new file mode 100644
index 000000000..c5ce9b843
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+++ b/js/src/vm/Monitor.h
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+#ifndef vm_Monitor_h
+#define vm_Monitor_h
+
+#include "mozilla/DebugOnly.h"
+
+#include <stddef.h>
+
+#include "js/Utility.h"
+
+namespace js {
+
+// A base class used for types intended to be used in a parallel
+// fashion.  Combines a lock and a condition variable.  You can
+// acquire the lock or signal the condition variable using the
+// |AutoLockMonitor| type.
+
+class Monitor
+{
+  protected:
+    friend class AutoLockMonitor;
+    friend class AutoUnlockMonitor;
+
+    Mutex lock_;
+    ConditionVariable condVar_;
+
+  public:
+    explicit Monitor(const MutexId& id)
+      : lock_(id)
+    { }
+};
+
+class AutoLockMonitor : public LockGuard<Mutex>
+{
+  private:
+    using Base = LockGuard<Mutex>;
+    Monitor& monitor;
+
+  public:
+    explicit AutoLockMonitor(Monitor& monitor)
+      : Base(monitor.lock_)
+      , monitor(monitor)
+    { }
+
+    bool isFor(Monitor& other) const {
+        return monitor.lock_ == other.lock_;
+    }
+
+    void wait(ConditionVariable& condVar) {
+        condVar.wait(*this);
+    }
+
+    void wait() {
+        wait(monitor.condVar_);
+    }
+
+    void notify(ConditionVariable& condVar) {
+        condVar.notify_one();
+    }
+
+    void notify() {
+        notify(monitor.condVar_);
+    }
+
+    void notifyAll(ConditionVariable& condVar) {
+        condVar.notify_all();
+    }
+
+    void notifyAll() {
+        notifyAll(monitor.condVar_);
+    }
+};
+
+class AutoUnlockMonitor
+{
+  private:
+    Monitor& monitor;
+
+  public:
+    explicit AutoUnlockMonitor(Monitor& monitor)
+      : monitor(monitor)
+    {
+        monitor.lock_.unlock();
+    }
+
+    ~AutoUnlockMonitor() {
+        monitor.lock_.lock();
+    }
+
+    bool isFor(Monitor& other) const {
+        return monitor.lock_ == other.lock_;
+    }
+};
+
+} // namespace js
+
+#endif /* vm_Monitor_h */