Threads and events are two common abstractions for writing concurrent programs. Because threads are often more convenient, but events more efficient, it is natural to want to translate the former into the latter. However, whereas there are many different event-driven styles, existing translators often apply ad-hoc rules which do not reflect this diversity. We analyse various control-flow and data-flow encodings in real-world event-driven code, and we observe that it is possible to generate any of these styles automatically from threaded code, by applying certain carefully chosen classical program transformations. In particular, we implement two of these transformations, lambda lifting and environments, in CPC, an extension of the C language for writing concurrent systems. Finally, we find out that, although rarely used in real-world programs because it is tedious to perform manually, lambda lifting yields better performance than environments in most of our benchmarks.
Tame is a new event-based system for managing concurrency in network applications. Code written with Tame abstractions does not suffer from the "stack-ripping" problem associated with other event libraries. Like threaded code, tamed code uses standard control flow, automatically-managed local variables, and modular interfaces between callers and callees. Tame's implementation consists of C++ libraries and a source-to-source translator; no platform-specific support or compiler modifications are required, and Tame induces little runtime overhead. Experience with Tame in real-world systems, including a popular commercial Web site, suggests it is easy to adopt and deploy.