AFuture represents the result of anasynchronous operation. When created, it probably doesn't have any result data. When the operation finishes, theFuture gets the result. An application can call aFuture object'sget_result() method; if the result has arrived, the method returns it; otherwise, it waits for the result to arrive andthen returns it.

Note: There is no 1:1 mapping between RPCs and Futures. Multiple futures might be tied to a result from a single RPC.

Instance Methods

check_success()

Check to see if the operation succeeded. Waits if necessary. Raises an exception if there was a problem; returnsNone if there was no problem.

done()

ReturnsTrue if the result (or exception) has arrived; otherwise, returnsFalse. This function does not wait.

get_exception()

Waits if necessary; then returns the exception (orNone if there was no exception).Returns the exception, doesn't raise it.

get_result()

Waits if necessary; then returns the result or raises the exception.

get_traceback()

Waits if necessary; then returns the exception's traceback object (orNone if there was no traceback object). Python'straceback module has functions to print and work withtraceback objects.

wait()

Waits until a result or exception arrives. Always returnsNone.

Class Methods

wait_all(futures)

Wait until allFutures in the passed iterable are done.

Arguments

futures

Iterable ofFuture objects.

ReturnsNone.

wait_any(futures)

Wait until at least one of a iterable ofFutures is done.

Arguments

futures

Iterable ofFuture objects.

Returns oneFuture that is done. (ReturnsNone if thefutures iterable is empty.)