Background thread support with ZODB support
Project description
A library for creating background threads that can talk to the ZODB and use local site components.
We’re probably reinventing Celery.
Example
Let’s assume we have a DMS with a simple publication workflow. We have two states “DRAFT” and “PUBLISH”. The Problem in this example is: that the transition form “DRAFT” to “PUBLISH” takes some minutes, and we don’t want the user to be waiting.
First we have create a WorkflowTransition-BackgroundThread:
class MyWorkflowTransition(BackgroundWorkerThread):
execute = True
description = "background worker thread (%(class_name)s) for %(site_name)s User %(user_name)s"
def __init__(self, site_db, site_oid, site_name, user_name, daemon=True, object_oid=None):
self.object_oid = object_oid
super(MyWorker, self).__init__(site_db, site_oid, site_name, user_name, daemon=True)
def scheduleNextWork(self):
return self.execute
def getObjectFromOID(self):
conn = getSite()._p_jar
return conn.get(self.object_oid)
def doWork(self):
sleep(15) # This is our long TASK
self.execute = False
document = self.getObjectFromOID()
document.wf_status = "PUBLISHED"
We have a simple Document with an initial Workflow-State draft.
class Document(Persistent):
wf_state = "DRAFT"
Now we have to call our WorkflowTransition.
def setWorkflow(site, document_oid, user_name):
worker = MyWorkflowTransition(
site_db = site._p_jar.db(),
site_oid = site._p_oid,
site_name = site.__name__,
user_name = user_name,
object_oid = document_oid,
)
worker.start()
When calling worker.start() the thread goes into “Background” and the user don’t have to wait until the Transition is finished.
CHANGES
1.0.2 (2012-07-31)
Refactor BackgroundWorkerThread to have the site returned from getSite()
1.0.1 (2012-04-05)
1.0.0 (2012-02-10)
Initial release as a separate package.
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