libcamera: signal: Make slots list private

The slots list is touched from most of the Signal template functions. In
order to prepare for thread-safety, move handling of the list to a small
number of non-template functions in the SignalBase class.

This incidently fixes a bug in signal disconnection handling where the
signal wasn't removed from the object's signals list, as pointed out by
the signals unit test.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/libcamera/object.cpp b/src/libcamera/object.cpp
index 21aad565..f2a8be17 100644
--- a/src/libcamera/object.cpp
+++ b/src/libcamera/object.cpp
@@ -76,7 +76,12 @@ Object::Object(Object *parent)
  */
 Object::~Object()
 {
-	for (SignalBase *signal : signals_)
+	/*
+	 * Move signals to a private list to avoid concurrent iteration and
+	 * deletion of items from Signal::disconnect().
+	 */
+	std::list<SignalBase *> signals(std::move(signals_));
+	for (SignalBase *signal : signals)
 		signal->disconnect(this);
 
 	if (pendingMessages_)