FoundationDB's Flow – Bringing Actor-Based Concurrency to C++11

FoundationDB developed Flow, a new programming language that brings actor-based concurrency to C++11 to meet the engineering challenges of achieving high performance, scalability, and reliability. Flow is implemented as a compiler that rewrites asynchronous functions (actors) into standard C++11 code while introducing keywords like `wait()`, `Promise`, and `Future` to enable efficient message-passing between concurrent processes. The system supports deterministic simulation of the entire distributed system, allowing FoundationDB to test for reliability and fault tolerance.