Concurrent data structure design

Question

I am trying to come up with the best data structure for use in a high throughput C++ server. The data structure will be used to store anything from a few to several million obje

Answer 1

The only way I think this is achievable is through something similar to multiversion concurrency protocol used in databases such as oracle/postgresql etc. This guarantees that readers doesn't block readers, writers doesn't block readers, but writers block only those writers which update the same piece of data. This property of writers blocking the writer(s) which update the same piece of data is important in concurrent programming world, otherwise data/system inconsistencies are possible. For each and every write operation to the data structure you take a snapshot of the data structure or atleast the portion of the data-structure nodes affected by the write operation to a different location in the memory before doing the write. So when the write is in progress, a reader thread requests to read a portion of data from the writer portion, you always refer to the latest snapshot & iterate over that snapshot, there by providing consistent view of data to all the readers. Snapshot's are costly since they consume more memory, but yes for your given requirement, this technique is the right one to go for. And yes use locks (mutex/semaphore/spinlock) to protect the write operation from other writer threads/processes needing to update the same piece of data.