From 29e92840c5eb6e56e047d1b0d2b80db66e9eaae5 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 8 Feb 2017 15:27:06 +0200
Subject: Make scheduler::async() indicate whether the task executed
 synchronously

---
 build2/scheduler     | 9 ++++++---
 build2/scheduler.txx | 6 ++++--
 2 files changed, 10 insertions(+), 5 deletions(-)

(limited to 'build2')

diff --git a/build2/scheduler b/build2/scheduler
index 16cc217..7447021 100644
--- a/build2/scheduler
+++ b/build2/scheduler
@@ -67,17 +67,20 @@ namespace build2
     // subtlety can become important when passing shared locks; you would
     // only want it to be copied if the task is queued).
     //
+    // Return true if the task was queued and false if it was executed
+    // synchronously.
+    //
     // If the scheduler is shutdown, throw system_error(ECANCELED).
     //
     template <typename F, typename... A>
-    void
+    bool
     async (size_t start_count, atomic_count& task_count, F&&, A&&...);
 
     template <typename F, typename... A>
-    void
+    bool
     async (atomic_count& task_count, F&& f, A&&... a)
     {
-      async (0, task_count, forward<F> (f), forward<A> (a)...);
+      return async (0, task_count, forward<F> (f), forward<A> (a)...);
     }
 
     // Wait until the task count reaches the start count. If the scheduler is
diff --git a/build2/scheduler.txx b/build2/scheduler.txx
index 01408ca..d5e9afa 100644
--- a/build2/scheduler.txx
+++ b/build2/scheduler.txx
@@ -7,7 +7,7 @@
 namespace build2
 {
   template <typename F, typename... A>
-  void scheduler::
+  bool scheduler::
   async (size_t start_count, atomic_count& task_count, F&& f, A&&... a)
   {
     using task = task_type<F, A...>;
@@ -56,7 +56,7 @@ namespace build2
     if (td == nullptr)
     {
       forward<F> (f) (forward<A> (a)...);
-      return;
+      return false;
     }
 
     // Increment the task count.
@@ -70,6 +70,8 @@ namespace build2
     //
     if (active_ < max_active_)
       activate_helper (l);
+
+    return true;
   }
 
   template <typename F, typename... A>
-- 
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