[gnome-builder] configuration: add sequence number for configuration changes

[Christian Hergert <chergert src gnome org>]

commit 3584fd55578657854185d10a95274437f6fb0d59
Author: Christian Hergert <christian hergert me>
Date:   Mon Feb 29 16:55:08 2016 -0800

    configuration: add sequence number for configuration changes
    
    Build systems can use this to disable the dirty bit after they have
    bootstrapped the build.

 libide/ide-configuration.c |   24 ++++++++++++++++++++++++
 libide/ide-configuration.h |    1 +
 2 files changed, 25 insertions(+), 0 deletions(-)
---
diff --git a/libide/ide-configuration.c b/libide/ide-configuration.c
index f796218..815c164 100644
--- a/libide/ide-configuration.c
+++ b/libide/ide-configuration.c
@@ -42,6 +42,7 @@ struct _IdeConfiguration
   IdeEnvironment *environment;
 
   gint            parallelism;
+  guint           sequence;
 
   guint           dirty : 1;
   guint           debug : 1;
@@ -747,6 +748,7 @@ ide_configuration_set_dirty (IdeConfiguration *self,
    * Always emit the changed signal so that the configuration manager
    * can queue a writeback of the configuration.
    */
+  self->sequence++;
   g_signal_emit (self, signals [CHANGED], 0);
 }
 
@@ -823,3 +825,25 @@ ide_configuration_duplicate (IdeConfiguration *self)
 
   return copy;
 }
+
+/**
+ * ide_configuration_get_sequence:
+ * @self: An #IdeConfiguration
+ *
+ * This returns a sequence number for the configuration. This is useful
+ * for build systems that want to clear the "dirty" bit on the configuration
+ * so that they need not bootstrap a second time. This should be done by
+ * checking the sequence number before executing the bootstrap, and only
+ * cleared if the sequence number matches after performing the bootstrap.
+ * This indicates no changes have been made to the configuration in the
+ * mean time.
+ *
+ * Returns: A monotonic sequence number.
+ */
+guint
+ide_configuration_get_sequence (IdeConfiguration *self)
+{
+  g_return_val_if_fail (IDE_IS_CONFIGURATION (self), 0);
+
+  return self->sequence;
+}
diff --git a/libide/ide-configuration.h b/libide/ide-configuration.h
index e4d0596..81f19f2 100644
--- a/libide/ide-configuration.h
+++ b/libide/ide-configuration.h
@@ -73,6 +73,7 @@ void                 ide_configuration_set_parallelism  (IdeConfiguration  *self
                                                          gint               parallelism);
 IdeEnvironment      *ide_configuration_get_environment  (IdeConfiguration  *self);
 IdeConfiguration    *ide_configuration_duplicate        (IdeConfiguration  *self);
+guint                ide_configuration_get_sequence     (IdeConfiguration  *self);
 
 G_END_DECLS