portage.util.futures.extendedfutures module

class portage.util.futures.extendedfutures.ExtendedFuture(default_result=<object object>)

Bases: concurrent.futures._base.Future

Extended Future class adding convienince get and set operations with default result capabilities for unset result(). It also adds pass capability for duplicate set_result() calls.

_invoke_callbacks()

add_done_callback(fn)

Attaches a callable that will be called when the future finishes.

Args:

fn: A callable that will be called with this future as its only

argument when the future completes or is cancelled. The callable will always be called by a thread in the same process in which it was added. If the future has already completed or been cancelled then the callable will be called immediately. These callables are called in the order that they were added.

cancel()

Cancel the future if possible.

Returns True if the future was cancelled, False otherwise. A future cannot be cancelled if it is running or has already completed.

cancelled()

Return True if the future was cancelled.

done()

Return True if the future was cancelled or finished executing.

exception()

Return the exception raised by the call that the future represents.

Args:

timeout: The number of seconds to wait for the exception if the

future isn’t done. If None, then there is no limit on the wait time.

Returns:

The exception raised by the call that the future represents or None if the call completed without raising.

Raises:

CancelledError: If the future was cancelled. TimeoutError: If the future didn’t finish executing before the given

timeout.

get(default=<object object>)

Convienience function to wrap result() but adds an optional default value to return rather than raise an InvalidStateError

Parameters

default – Optional override for the classwide default_result

Returns

the result data or the default value, raisies an exception if result is unset and no default is defined.

result()

Return the result of the call that the future represents.

Args:

timeout: The number of seconds to wait for the result if the future

isn’t done. If None, then there is no limit on the wait time.

Returns:

The result of the call that the future represents.

Raises:

CancelledError: If the future was cancelled. TimeoutError: If the future didn’t finish executing before the given

timeout.

Exception: If the call raised then that exception will be raised.

running()

Return True if the future is currently executing.

set_exception(exception)

Sets the result of the future as being the given exception.

Should only be used by Executor implementations and unit tests.

set_result(data, ignore_InvalidState=False)

Set the Future’s result to the data, optionally don’t raise an error for ‘InvalidStateError’ errors

Parameters

ignore_exception – Boolean

set_running_or_notify_cancel()

Mark the future as running or process any cancel notifications.

Should only be used by Executor implementations and unit tests.

If the future has been cancelled (cancel() was called and returned True) then any threads waiting on the future completing (though calls to as_completed() or wait()) are notified and False is returned.

If the future was not cancelled then it is put in the running state (future calls to running() will return True) and True is returned.

This method should be called by Executor implementations before executing the work associated with this future. If this method returns False then the work should not be executed.

Returns:

False if the Future was cancelled, True otherwise.

Raises:

RuntimeError: if this method was already called or if set_result()

or set_exception() was called.