Change Details

The following pattern was duplicated in CConnman: ```cpp lock create a copy of vNodes, add a reference to each one unlock ... use the copy ... lock release each node from the copy unlock ``` Put that code in a RAII helper that reduces it to: ```cpp create snapshot "snap" ... use the copy ... // release happens when "snap" goes out of scope ``` This is a partial backport of core#21943

The following pattern was duplicated in CConnman: ```cpp lock create a copy of vNodes, add a reference to each one unlock ... use the copy ... lock release each node from the copy unlock ``` Put that code in a RAII helper that reduces it to: ```cpp create snapshot "snap" ... use the copy ... // release happens when "snap" goes out of scope ``` This is a partial backport of [[https://github.com/bitcoin/bitcoin/pull/21943 | core#21943]]

The following pattern was duplicated in CConnman: ```cpp lock create a copy of vNodes, add a reference to each one unlock ... use the copy ... lock release each node from the copy unlock ``` Put that code in a RAII helper that reduces it to: ```cpp create snapshot "snap" ... use the copy ... // release happens when "snap" goes out of scope ``` This is a partial backport of [[https://github.com/bitcoin/bitcoin/pull/21943 | core#21943]]