1 files changed, 65 insertions, 0 deletions
diff --git a/include/lld/Core/TaskGroup.h b/include/lld/Core/TaskGroup.h
new file mode 100644
index 000000000000..82e9122f4ae2
--- /dev/null
+++ b/include/lld/Core/TaskGroup.h
@@ -0,0 +1,65 @@
+//===- lld/Core/TaskGroup.h - Task Group ----------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_CORE_TASKGROUP_H
+#define LLD_CORE_TASKGROUP_H
+
+#include "lld/Core/LLVM.h"
+
+#include <condition_variable>
+#include <functional>
+#include <mutex>
+
+namespace lld {
+/// \brief Allows one or more threads to wait on a potentially unknown number of
+///   events.
+///
+/// A latch starts at \p count. inc() increments this, and dec() decrements it.
+/// All calls to sync() will block while the count is not 0.
+///
+/// Calling dec() on a Latch with a count of 0 has undefined behaivor.
+class Latch {
+  uint32_t _count;
+  mutable std::mutex _condMut;
+  mutable std::condition_variable _cond;
+
+public:
+  explicit Latch(uint32_t count = 0) : _count(count) {}
+  ~Latch() { sync(); }
+
+  void inc() {
+    std::unique_lock<std::mutex> lock(_condMut);
+    ++_count;
+  }
+
+  void dec() {
+    std::unique_lock<std::mutex> lock(_condMut);
+    if (--_count == 0)
+      _cond.notify_all();
+  }
+
+  void sync() const {
+    std::unique_lock<std::mutex> lock(_condMut);
+    _cond.wait(lock, [&] { return _count == 0; });
+  }
+};
+
+/// \brief Allows launching a number of tasks and waiting for them to finish
+///   either explicitly via sync() or implicitly on destruction.
+class TaskGroup {
+  Latch _latch;
+
+public:
+  void spawn(std::function<void()> f);
+
+  void sync() const { _latch.sync(); }
+};
+}
+
+#endif