Beautiful Architecture

ThreadWeaver

ThreadWeaver is now one of the KDE 4 core libraries. It is discussed here because its genesis contrasts in many ways with that of the Akonadi project, and thus serves as an interesting comparison. ThreadWeaver schedules parallel operations. It was conceived at a time when it was technically pretty much impossible to implement it with the libraries used by KDE, namely Qt. The need for it was seen by a number of developers, but it took until the release of Qt 4 for it to mature and become mainstream. Today, it is used in major applications such as KOffice and KDevelop. It is typically applied in larger-scale, more complex software systems, where the need for concurrency and out-of-band processing becomes more pressing.

ThreadWeaver is a job scheduler for concurrency. Its purpose is to manage and arbitrate resource usage in multi-threaded software systems. Its second goal is to provide application developers with a tool to implement parallelism that is similar in its approach to the way they develop their GUI applications. These goals are high-level, and there are secondary ones at a smaller scale: to avoid brute-force synchronization and offer means for cooperative serialization of access to data; to make use of the features of modern C++ libraries, such as thread-safe, implicit sharing, and signal-slot-connections across threads; to integrate with the application’s graphical user interface by separating the processing elements from the delegates that represent them in ...