Simple C++ class to handle messages on different MPI tags. Requires C++11 and boost, which handles the MPI.
In a project, many tags may be user by different modules. If the order in which they are processed isn't important, the MPI could be probed by each module looking for each tag defined. However, if the order is relevant, probing in the wrong order of retrieval could lead to wrong results.
If any tag is probed, then the module should relinquish its control of the processor to allow another module to run if a unknown tag arrives. This requires some repeated logic.
Finally, it's easier to just define a callback function to be called when the required tag is received. This is the problem this class solves.
There are two kinds of handlers:
- handlers for specific tags, which receive an integer describing the source of the message and returns true if the message was consumed.
- generic handlers, which can handle messages all other handlers ignored and receives the source and tag, returning true if the message was consumed.
The handlers are called from specific to generic and in the order in which they were inserted.
Messages are only processed when the method run() is called, which returns if
there are no more MPI messages available or the current message wasn't
handled by any handler, and there's no inherit support for threads, which can
be implemented in the handler functions.
Example:
MPIHandler handler(world);
handler.insert(2, [](int tag) { /*do stuff*/ return true; }
handler.insert_generic([](int source, int tag)
{ if (source == 2) { /*do stuff*/ return true; } return false; });
handler.run();