src/allmydata/util/deferredutil.py

   1 from twisted.internet import defer
   2
   3 # utility wrapper for DeferredList
   4 def _check_deferred_list(results):
   5     # if any of the component Deferreds failed, return the first failure such
   6     # that an addErrback() would fire. If all were ok, return a list of the
   7     # results (without the success/failure booleans)
   8     for success,f in results:
   9         if not success:
  10             return f
  11     return [r[1] for r in results]
  12 def DeferredListShouldSucceed(dl):
  13     d = defer.DeferredList(dl)
  14     d.addCallback(_check_deferred_list)
  15     return d
  16
  17 def _parseDListResult(l):
  18     return [x[1] for x in l]
  19
  20 def _unwrapFirstError(f):
  21     f.trap(defer.FirstError)
  22     raise f.value.subFailure
  23
  24 def gatherResults(deferredList):
  25     """Returns list with result of given Deferreds.
  26
  27     This builds on C{DeferredList} but is useful since you don't
  28     need to parse the result for success/failure.
  29
  30     @type deferredList:  C{list} of L{Deferred}s
  31     """
  32     d = defer.DeferredList(deferredList, fireOnOneErrback=True, consumeErrors=True)
  33     d.addCallbacks(_parseDListResult, _unwrapFirstError)
  34     return d
  35