config: expose locking via the main API

This lock/unlock pair allows for the cller to lock a configuration file
to avoid concurrent operations.

It also allows for a transactional approach to updating a configuration
file. If multiple updates must be made atomically, they can be done
while the config is locked.

1 files changed, 27 insertions, 0 deletions

diff --git a/include/git2/config.h b/include/git2/config.h
index 6d3fdb0c2..2550f8edb 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -689,6 +689,33 @@ GIT_EXTERN(int) git_config_backend_foreach_match(
 	void *payload);
 
 
+/**
+ * Lock the backend with the highest priority
+ *
+ * Locking disallows anybody else from writing to that backend. Any
+ * updates made after locking will not be visible to a reader until
+ * the file is unlocked.
+ *
+ * @param cfg the configuration in which to lock
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_config_lock(git_config *cfg);
+
+/**
+ * Unlock the backend with the highest priority
+ *
+ * Unlocking will allow other writers to updat the configuration
+ * file. Optionally, any changes performed since the lock will be
+ * applied to the configuration.
+ *
+ * @param cfg the configuration
+ * @param commit boolean which indicates whether to commit any changes
+ * done since locking
+ * @return 0 or an error code
+ */
+GIT_EXTERN(int) git_config_unlock(git_config *cfg, int commit);
+
+
 /** @} */
 GIT_END_DECL
 #endif