How do I use an arbitrary string as a lock in C++?

Question

Let\'s say I have a multithreaded C++ program that handles requests in the form of a function call to handleRequest(string key). Each call to handleRequest

Answer 1

You could do something similar to what you have in your question, but instead of a single global_key_map have several (probably in an array or vector) - which one is used is determined by some simple hash function on the string.

That way instead of a single global lock, you spread that out over several independent ones.

This is a pattern that is often used in memory allocators (I don't know if the pattern has a name - it should). When a request comes in, something determines which pool the allocation will come from (usually the size of the request, but other parameters can factor in as well), then only that pool needs to be locked. If an allocation request comes in from another thread that will use a different pool, there's no lock contention.