>>>> Hi guys, >>>> >>>> As you may know the engine currently has the ability to fire >>>> an >>>> SPM >>>> task, and be asynchronously be "woken-up" when it ends. >>>> This is great, but we found the for the Live Storage >>>> Migration >>>> feature we need something a bit complex - the ability to >>>> have a >>>> series of async tasks in a single control flow. >>>> >>>> Here's my initial design for this, your comments and >>>> criticism >>>> would >>>> be welcome: >>>> http://wiki.ovirt.org/wiki/Features/Serial_Execution_of_Asynchronous_Tasks_D... >> -successful execution - >> * "CommandBase iterates over its SPMAsyncTaskHandlers" - when? > This is the new suggested format of executeCommand(). I'll > clarify > this too. > >> * If the second task is an HSM command (vs. SPM command), I >> think you >> should explain in the design how to handle such flows as well. > HSM commands do not create AsyncTasks, as they do today - I > will > clarify this. > >> * Why do we need before task? can you give a concrete example >> of what >> would you do in such a method. > Basically, /today/, command look like this: > executeCommand() { > doStuffInTheDB(); > runVdsCommand(someCommand); > } > > endSuccessfully() { > doMoreStuffInTheDB(); > } > > endWithFailure() { > doMoreStuffForFailureInTheDB(); > } > > In the new design, the entire doStuffInTheDB() should be moved > to a > breforeTask of the (only) SPMAsyncTaskHandler. > >> >> - I see you added SPMAsyncTaskHandler, any reason not to use >> SPMAsyncTasK to manage it own life-cycle? > Conserving today's design - The SPMAsyncTaskHandler is the > place to > add additional, non-SPM, logic around the SPM task execution, > like > CommandBase allows today. > >> >> - In the life-cycle managed by the SPMAsyncTaskHandler there >> is a >> step >> 'createTask - how to create the async task' can you please >> elaborate >> what are the options. > new [any type of async task]
(I cleaned thread a little.) The following design and it is implementation http://gerrit.ovirt.org/#/c/7956/ is bad. I don't see any reason for creating a new SPMAsyncTaskHandler and especially in the way as it's done in patch. The reason are following: 1. Performance , increased memory footprint, created CYCLIC REFERENCE. 2. Readability and robust of code: the code which is written as cyclic references is unreadable and difficult for debug. 3. Why I need a generic implementation and changes all over whole project because of series of async commands, for me it is a private case?