Increment load_generation between operations in batch

4 files changed, 26 insertions, 4 deletions

diff --git a/libbuild2/cc/init.cxx b/libbuild2/cc/init.cxx
index d691bc5..64c70f8 100644
--- a/libbuild2/cc/init.cxx
+++ b/libbuild2/cc/init.cxx
@@ -764,7 +764,7 @@ namespace build2
               perform_update_id,
               context::operation_callback {&compiledb_pre, &compiledb_post});
 
-          if (ctx.load_generation > 1)
+          if (!ctx.phase_mutex.unlocked ()) // Interrupting load.
           {
             action a (ctx.current_action ());
 
diff --git a/libbuild2/context.cxx b/libbuild2/context.cxx
index 6e4fd6f..31d218b 100644
--- a/libbuild2/context.cxx
+++ b/libbuild2/context.cxx
@@ -1061,6 +1061,13 @@ namespace build2
     return r ? optional<bool> (s) : nullopt;
   }
 
+  bool run_phase_mutex::
+  unlocked () const
+  {
+    mlock l (m_);
+    return lc_ == 0 && mc_ == 0 && ec_ == 0;
+  }
+
   // C++17 deprecated uncaught_exception() so use uncaught_exceptions() if
   // available.
   //
diff --git a/libbuild2/context.hxx b/libbuild2/context.hxx
index 46dbfaa..12b11d5 100644
--- a/libbuild2/context.hxx
+++ b/libbuild2/context.hxx
@@ -49,6 +49,12 @@ namespace build2
     optional<bool>
     relock (run_phase unlock, run_phase lock);
 
+    // Return true if the mutex is unlocked, meaning we are in the initial
+    // load phase.
+    //
+    bool
+    unlocked () const;
+
     // Statistics.
     //
   public:
@@ -78,7 +84,7 @@ namespace build2
     //
     context& ctx_;
 
-    mutex m_;
+    mutable mutex m_;
 
     bool fail_;
 
@@ -209,8 +215,12 @@ namespace build2
     // hierarchy would "see" a new value from the newly inserted scope.
     //
     // The special load_generation value 0 indicates initialization before
-    // anything has been loaded. Currently, it is changed to 1 at the end
-    // of the context constructor.
+    // anything has been loaded. Currently, it is changed to 1 at the end of
+    // the context constructor. Note also that subsequent operations in a
+    // batch may trigger loading of additional buildfiles, in fact, entire new
+    // projects. As a result, load_generation is also incremented after each
+    // operation in a batch. If you need to detect the initial load in each
+    // operation, check that phase_mutex is unlocked.
     //
     // Note must come (and thus initialized) before the data_ member.
     //
@@ -817,6 +827,9 @@ namespace build2
 
     // Set current meta-operation and operation.
     //
+    // Remember to also increment load_generation for subsequent operations in
+    // a batch if additional buildfiles are loaded between them.
+    //
     // Note that the context instance is not to be re-used between different
     // meta-operations.
     //
diff --git a/libbuild2/module.cxx b/libbuild2/module.cxx
index df0da48..9a12d01 100644
--- a/libbuild2/module.cxx
+++ b/libbuild2/module.cxx
@@ -204,6 +204,8 @@ namespace build2
                         0,       /* diag (none) */
                         false    /* progress */);
 
+    ctx.module_context->load_generation++;
+
     assert (tgs.size () == 1);
     return tgs[0].as<target> ();
   }