This class is a high level injector over the concord-bft code to perform various performance related operations. It's instance can be injected to various modules via constructors, which is default pattern in Concord-bft for dependencies injection.
As the name suggests, this class is responsible for implementing slowdown methods. Sometimes in order to figure out performance bottleneck it makes sense to slow down some components and to evaluate overall system impact.
This class implements Delay<T> method, which can be called from various modules.
The slowdown_config_reference.yaml file can be used as a reference configuration file. Currently 5 modules are supported, each of them has it's own phases.
This is not a generic mechanism to handle slowdown configuration, but an example of how application can do it.
This file should be managed and parse by the application that uses concord-bft. Class' ctor expects configuration object to be passed from the calling application.
Policy defines how the slowdown is reached. We support Sleep, BusyWait and AddKeys policies, each of them can be used in appropriate place in the code. Sleep and BusyWait are trivial and the AddKeys can be used for storage related tasks and to create additional work by adding dummy keys to the write set.
The class depends on USE_SLOWDOWN preprocessor definition, which in turn is set by setting BUILD_SLOWDOWN option in the main CMakeLists.txt file.
The expectation is that the up level application will set this build flag.