Your problem can be solved using a sampling buffer pattern. The sampling buffer is a mutex-protected buffer with a single data element. It allows sampling a stream of data.

The thread producing the data writes to the sampling buffer at whatever rate it needs. The reading thread reads at its own rate. This allows the reader to always read the most recent value in the buffer without needing to synchronize the writing and reading rates. Creating a reader to read every second would be done using the sleep_until() function.