On Friday 23 February 2007 07:01 pm, Peter Dimov wrote:
Timmo Stange wrote: I was never particularly fond of providing dual components with thread-safe and "thread-unsafe" interfaces (for the various definitions of that.) The ideal scenario, in my mind, is to provide a single component that is still as overhead-free as possible in the single-threaded scenario. Unfortunately, the straightforward approach of copying a vector
doesn't achieve that goal, but I _think_ that it's possible to implement the same interface in a more efficient way, using copy on write and versioning tricks. Maybe Frank's implementation already does this.
Yes, it uses a shared_ptr to hold the slot list, and uses shared_ptr::unique() to decide if it really needs to make a new full copy of the slot list before adding/removing slots from the list. Signal invocations are assured no slots will be added or removed from their slot list while they are running. For a single-threaded usage pattern, the only situations it will make a new full copy in is if you call connect() or set_combiner() from a slot. -- Frank