future.py 文件源码

def GenerateOnAllChildSuccess(parentkey, initialvalue, combineresultf, failonerror=True):
    def OnAllChildSuccess():
        logdebug("Enter GenerateOnAllChildSuccess: %s" % parentkey)
        parentfuture = parentkey.get() if parentkey else None
        if parentfuture and not parentfuture.has_result():
            if not parentfuture.initialised or not parentfuture.readyforresult:
                raise Exception("Parent not initialised, retry")

            @ndb.transactional()
            def get_children_trans():
                return get_children(parentfuture.key)
            children = get_children_trans()

            logdebug("children: %s" % [child.key for child in children])
            if children:
                result = initialvalue
                error = None
                finished = True
                for childfuture in children:
                    logdebug("childfuture: %s" % childfuture.key)
                    if childfuture.has_result():
                        try:
                            childresult = childfuture.get_result()
                            logdebug("childresult(%s): %s" % (childfuture.status, childresult))
                            result = combineresultf(result, childresult)
                            logdebug("hasresult:%s" % result)
                        except Exception, ex:
                            logdebug("haserror:%s" % repr(ex))
                            error = ex
                            break
                    else:
                        logdebug("noresult")
                        finished = False

                if error:
                    logwarning("Internal error, child has error in OnAllChildSuccess: %s" % error)
                    if failonerror:
                        parentfuture.set_failure(error)
                    else:
                        raise error
                elif finished:
                    logdebug("result: %s" % result)
                    parentfuture.set_success(result)#(result, initialamount, keyrange))
                else:
                    logdebug("child not finished in OnAllChildSuccess, skipping")
            else:
                logwarning("Internal error, parent has no children in OnAllChildSuccess")
                parentfuture.set_failure(Exception("no children found"))

    return OnAllChildSuccess