db/update: cancel the update on shutdown

1 files changed, 23 insertions, 0 deletions

diff --git a/src/db/update/Walk.hxx b/src/db/update/Walk.hxx
index bf3eb8ae4..353f6f3ed 100644
--- a/src/db/update/Walk.hxx
+++ b/src/db/update/Walk.hxx
@@ -48,6 +48,13 @@ class UpdateWalk final {
 	bool walk_discard;
 	bool modified;
 
+	/**
+	 * Set to true by the main thread when the update thread shall
+	 * cancel as quickly as possible.  Access to this flag is
+	 * unprotected.
+	 */
+	volatile bool cancel;
+
 	Storage &storage;
 
 	DatabaseEditor editor;
@@ -57,6 +64,22 @@ public:
 		   Storage &_storage);
 
 	/**
+	 * Cancel the current update and quit the Walk() method as
+	 * soon as possible.
+	 */
+	void Cancel() {
+		cancel = true;
+	}
+
+	/**
+	 * Call from the main thread before starting the update
+	 * thread.
+	 */
+	void Prepare() {
+		cancel = false;
+	}
+
+	/**
 	 * Returns true if the database was modified.
 	 */
 	bool Walk(Directory &root, const char *path, bool discard);