Latch implementations

#1 Blocking OS Mutex

• Simple to use

• Non-scalable (about 25ns per lick/unlock invocation)

• Example std::mutex

#2 Test-and-Set Spin Latch (TAS)

• Very efficient (single instruction to latch/unlatch)

• Non-scalable, not cache friendly

• Example: std::atomic<T>

#3 Reader-Writer Latch

• Allows for concurrent readers

• Must manage read/write queues to avoid starvation

• Can be implemented on top of spinlocks