From d03bc6a984bf4e375b4629e7345eb1416487de8e Mon Sep 17 00:00:00 2001
From: Oliver Kowalke <oliver.kowalke@gmx.de>
Date: Wed, 4 Dec 2013 18:58:36 +0100
Subject: [PATCH] update scheduling algorithm as Nad suggested

---
 include/boost/fiber/detail/scheduler.hpp |  3 ++-
 include/boost/fiber/operations.hpp       |  4 ++--
 src/detail/scheduler.cpp                 | 29 ++++++++++--------------
 3 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/include/boost/fiber/detail/scheduler.hpp b/include/boost/fiber/detail/scheduler.hpp
index 4324e823..d6c9075b 100644
--- a/include/boost/fiber/detail/scheduler.hpp
+++ b/include/boost/fiber/detail/scheduler.hpp
@@ -31,6 +31,7 @@ namespace detail {
 class scheduler : private noncopyable
 {
 private:
+    static thread_specific_ptr< algorithm > default_algo_;
     static thread_specific_ptr< algorithm > instance_;
 
 public:
@@ -44,7 +45,7 @@ public:
 
     static algorithm * instance();
 
-    static algorithm * replace( algorithm * other);
+    static void replace( algorithm * other);
 };
 
 }}}
diff --git a/include/boost/fiber/operations.hpp b/include/boost/fiber/operations.hpp
index ea161b1b..b59ce6fa 100644
--- a/include/boost/fiber/operations.hpp
+++ b/include/boost/fiber/operations.hpp
@@ -69,8 +69,8 @@ void thread_affinity( bool req) BOOST_NOEXCEPT
 namespace fibers {
 
 inline
-algorithm * set_scheduling_algorithm( algorithm * al)
-{ return detail::scheduler::replace( al); }
+void set_scheduling_algorithm( algorithm * al)
+{ detail::scheduler::replace( al); }
 
 }}
 
diff --git a/src/detail/scheduler.cpp b/src/detail/scheduler.cpp
index 6c030f97..b9bdecc7 100644
--- a/src/detail/scheduler.cpp
+++ b/src/detail/scheduler.cpp
@@ -17,9 +17,11 @@ namespace boost {
 namespace fibers {
 namespace detail {
 
-static void cleanup_function( algorithm *) {}
+static void deleter_fn( algorithm * algo) { delete algo; }
+static void null_deleter_fn( algorithm *) {}
 
-thread_specific_ptr< algorithm > scheduler::instance_( cleanup_function);
+thread_specific_ptr< algorithm > scheduler::default_algo_( deleter_fn);
+thread_specific_ptr< algorithm > scheduler::instance_( null_deleter_fn);
 
 notify::ptr_t
 scheduler::make_notification( main_notifier & n) BOOST_NOEXCEPT {
@@ -31,27 +33,20 @@ scheduler::make_notification( main_notifier & n) BOOST_NOEXCEPT {
 algorithm *
 scheduler::instance()
 {
-#if ! defined(BOOST_FIBERS_DONT_USE_DEFAULT_SCHEDULER)
-    if ( ! instance_.get() ) instance_.reset( new round_robin() );
-#else
-    BOOST_ASSERT( instance_.get() );
-#endif
+    if ( ! instance_.get() )
+    {
+        default_algo_.reset( new round_robin() );
+        instance_.reset( default_algo_.get() );
+    }
     return instance_.get();
 }
 
-algorithm *
+void
 scheduler::replace( algorithm * other)
 {
-    algorithm * old = instance_.release();
+    BOOST_ASSERT( other);
+
     instance_.reset( other);
-#if ! defined(BOOST_FIBERS_DONT_USE_DEFAULT_SCHEDULER)
-    if ( dynamic_cast< round_robin * >( old) )
-    {
-        delete old;
-        old = 0;
-    }
-#endif
-    return old;
 }
 
 }}}