Markus Armbruster wrote: > Jan Kiszka <jan.kis...@web.de> writes: > >> Markus Armbruster wrote: >>> Jan Kiszka <jan.kis...@web.de> writes: >>> >>>> Luiz, >>>> >>>> I missed this when the API was first proposed: >>>> >>>> cur_mon is scheduled for removal (one day...). It's just an intermediate >>>> step to convert all users to explicit 'mon' passing. Thus, new APIs >>>> should not rely it. >>>> >>>> I just realized that monitor_cur_is_qmp() does so. It should be >>>> refactored to monitor_is_qmp(Monitor *mon). And qerror should be enhance >>>> by a 'mon' argument as well. Callers that aren't passed a 'mon' >>>> themselves should either be fixed at this chance or could fall back to >>>> cur_mon for the time being. >>>> >>>> So far for the theory - do you see any pitfalls in the existing usage? >>> I put in the new uses of cur_mon, Luiz "only" ACKed them. >>> >>> At any point in the program execution, we have one current monitor, or >>> none. Passing around the current monitor within monitor code is >>> workable, if somewhat tedious. But we need it not just in monitor code, >>> we need it anywhere where we report errors. In other words, pretty much >>> everywhere. Including places that do not and should not know about the >>> monitor. Handing a monitor parameter down pretty much every call chain >>> is beyond tedious, it's impractical. >> It's a process, but I don't think it's impractical per se. >> >>> The code reporting an error generally does not and should not know >>> anything about *how* the error gets communicated to the user. >>> Insulating it from that detail is proper separation of concerns, and >>> global variable cur_mon is my tool to get it. Good software >>> engineering. Like many powerful tools, global variables should be used >>> sparingly and with care. I feel this use is well justified. >>> >>> Instead of eliminating cur_mon, I'd like it to be hidden within >>> monitor.c. There are a few uses left outside it. >> If we start to allow cur_mon for error reporting, there is no reason not >> to convert monitor_printf back to where it came from. Back then we >> agreed on the current path. If we now decide to roll back, then let's >> make it consistently. > > Makes sense. > >> But we already refactored quite a lot of code for >> explicit monitor passing... >> >> Jan >> >> PS: A patch for establishing monitor_is_qmp is in my queue. Holding it >> back for now until we agreed how to proceed. > > monitor_is_qmp() is used only in a few places. The real troublemakers > are error_report() & friends, and qerror_report(). These are all over > the place, with more to come.
Right, therefore we need a quick decision avoid introducing more [q]error_report users without mon if cur_mon shall not stay. Just noticed: As long as we rely on cur_mon, user_monitor_complete and qmp_monitor_complete need to establish this context just link the command callers. Without this error messages and the qmp test use a wrong monitor. Jan
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