From e7095d0df98b6c91c6f722a44cf46fcd84e2c39c Mon Sep 17 00:00:00 2001
From: Paul McCarthy <pauld.mccarthy@gmail.com>
Date: Tue, 26 Jul 2016 16:45:41 +0100
Subject: [PATCH] TaskThread tasks can 'veto' the onFinish handler.
---
fsl/utils/async.py | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/fsl/utils/async.py b/fsl/utils/async.py
index c7289b7b9..28c255041 100644
--- a/fsl/utils/async.py
+++ b/fsl/utils/async.py
@@ -390,6 +390,15 @@ class Task(object):
self.enabled = True
+class TaskThreadVeto(Exception):
+ """Task functions which are added to a :class:`TaskThread` may raise
+ a ``TaskThreadVeto`` error to skip processing of the task's ``onFinish``
+ handler (if one has been specified). See the :meth:`TaskThread.enqueue`
+ method for more details.
+ """
+ pass
+
+
class TaskThread(threading.Thread):
"""The ``TaskThread`` is a simple thread which runs tasks. Tasks may be
enqueued and dequeued.
@@ -423,7 +432,9 @@ class TaskThread(threading.Thread):
:arg onFinish: An optional function to be called (via :func:`idle`)
when the task funtion has finished. Must be provided as
- a keyword argument.
+ a keyword argument. If the ``func`` raises a
+ :class`TaskThreadVeto` error, this function will not
+ be called.
All other arguments are passed through to the task function when it is
executed.
@@ -514,6 +525,13 @@ class TaskThread(threading.Thread):
log.debug('Task completed: {} [{}]'.format(
task.name,
getattr(task.func, '__name__', '<unknown>')))
+
+ # If the task raises a TaskThreadVeto error,
+ # we just have to skip the onFinish handler
+ except TaskThreadVeto:
+ log.debug('Task completed (vetoed onFinish): {} [{}]'.format(
+ task.name,
+ getattr(task.func, '__name__', '<unknown>')))
except Exception as e:
log.debug('Task crashed: {} [{}]: {}: {}'.format(
--
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