From cf1670f9a6541e42f22d58e2de5940e64cb6637e Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 15 May 2020 06:50:05 +0200
Subject: Implement ad hoc recipe sharing and locking

---
 libbuild2/context.hxx | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'libbuild2/context.hxx')

diff --git a/libbuild2/context.hxx b/libbuild2/context.hxx
index 573b8d1..8e68784 100644
--- a/libbuild2/context.hxx
+++ b/libbuild2/context.hxx
@@ -553,9 +553,17 @@ namespace build2
   // Assuming we have a lock on the current phase, temporarily switch to a
   // new phase and switch back on destruction.
   //
+  // The second constructor can be used for a switch with an intermittent
+  // unlock:
+  //
+  // phase_unlock pu;
+  // phase_lock pl;
+  // phase_switch ps (move (pu), move (pl));
+  //
   struct LIBBUILD2_SYMEXPORT phase_switch
   {
-    explicit phase_switch (context&, run_phase);
+    phase_switch (context&, run_phase);
+    phase_switch (phase_unlock&&, phase_lock&&);
     ~phase_switch () noexcept (false);
 
     run_phase old_phase, new_phase;
-- 
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