From 8ae68924ed11c26b0fd59a29e2f8a6713102d67d Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Mon, 12 Dec 2016 11:58:38 -0800
Subject: [PATCH] Made ThreadPoolInterface::Cancel() an optional functionality

---
 unsupported/Eigen/CXX11/src/ThreadPool/ThreadPoolInterface.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/unsupported/Eigen/CXX11/src/ThreadPool/ThreadPoolInterface.h b/unsupported/Eigen/CXX11/src/ThreadPool/ThreadPoolInterface.h
index 5f2e1a013..84e1e6cc0 100644
--- a/unsupported/Eigen/CXX11/src/ThreadPool/ThreadPoolInterface.h
+++ b/unsupported/Eigen/CXX11/src/ThreadPool/ThreadPoolInterface.h
@@ -19,9 +19,10 @@ class ThreadPoolInterface {
   // Submits a closure to be run by a thread in the pool.
   virtual void Schedule(std::function<void()> fn) = 0;
 
-  // Stop processing the closures that have been enqueued.
+  // If implemented, stop processing the closures that have been enqueued.
   // Currently running closures may still be processed.
-  virtual void Cancel() = 0;
+  // If not implemented, does nothing.
+  virtual void Cancel() {}
 
   // Returns the number of threads in the pool.
   virtual int NumThreads() const = 0;