From 5182e007931b2ebf034d1a9ed42737ed30b2ac13 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 21 Aug 2024 09:35:31 +0200
Subject: Don't work own queue in wait_guard dtor

There is suspicion this causes a deadlock for reasons so far unclear.
See also GH issue #319.
---
 libbuild2/context.hxx |  2 +-
 libbuild2/context.ixx | 14 +++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

(limited to 'libbuild2')

diff --git a/libbuild2/context.hxx b/libbuild2/context.hxx
index 33fc892..828c41e 100644
--- a/libbuild2/context.hxx
+++ b/libbuild2/context.hxx
@@ -904,7 +904,7 @@ namespace build2
                 bool unlock_phase = false);
 
     void
-    wait ();
+    wait (bool work_queue = true);
 
     // Note: move-assignable to empty only.
     //
diff --git a/libbuild2/context.ixx b/libbuild2/context.ixx
index 6c8c428..2c62a45 100644
--- a/libbuild2/context.ixx
+++ b/libbuild2/context.ixx
@@ -26,8 +26,11 @@ namespace build2
   inline wait_guard::
   ~wait_guard () noexcept (false)
   {
+    // Don't work our own queue since we are most likely in stack unwinding
+    // causes by an exception.
+    //
     if (task_count != nullptr)
-      wait ();
+      wait (false);
   }
 
   inline wait_guard::
@@ -54,10 +57,15 @@ namespace build2
   }
 
   inline void wait_guard::
-  wait ()
+  wait (bool wq)
   {
     phase_unlock u (phase ? ctx : nullptr, true /* delay */);
-    ctx->sched->wait (start_count, *task_count, u);
+    ctx->sched->wait (start_count,
+                      *task_count,
+                      u,
+                      (wq
+                       ? scheduler::work_queue::work_all
+                       : scheduler::work_queue::work_none));
     task_count = nullptr;
   }
 }
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