odb/source: make `close()` function pluggable

Introduce a new callback function in `struct odb_source` to make the
function pluggable.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/odb/source.h b/odb/source.h
index 09cca839fe..0e6c6abdb1 100644
--- a/odb/source.h
+++ b/odb/source.h
@@ -59,6 +59,14 @@ struct odb_source {
 	void (*free)(struct odb_source *source);
 
 	/*
+	 * This callback is expected to close any open resources, like for
+	 * example file descriptors or connections. The source is expected to
+	 * still be usable after it has been closed. Closed resources may need
+	 * to be reopened in that case.
+	 */
+	void (*close)(struct odb_source *source);
+
+	/*
 	 * This callback is expected to clear underlying caches of the object
 	 * database source. The function is called when the repository has for
 	 * example just been repacked so that new objects will become visible.
@@ -104,6 +112,16 @@ void odb_source_free(struct odb_source *source);
 void odb_source_release(struct odb_source *source);
 
 /*
+ * Close the object database source without releasing he underlying data. The
+ * source can still be used going forward, but it first needs to be reopened.
+ * This can be useful to reduce resource usage.
+ */
+static inline void odb_source_close(struct odb_source *source)
+{
+	source->close(source);
+}
+
+/*
  * Reprepare the object database source and clear any caches. Depending on the
  * backend used this may have the effect that concurrently-written objects
  * become visible.