--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/cron/job.py Sat Apr 18 14:04:11 2009 +0000
@@ -0,0 +1,143 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2009 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Cron jobs.
+"""
+
+__authors__ = [
+ '"Sverre Rabbelier" <sverre@rabbelier.nl>',
+ ]
+
+
+import logging
+
+from google.appengine.ext import db
+from google.appengine.runtime import DeadlineExceededError
+
+from soc.models.job import Job
+
+
+class Handler(object):
+ """A handler that dispatches a cron job.
+
+ The tasks that are mapped into tasks will be called when a worker
+ has claimed the job. However, there is no guarantee as to how long
+ the task will be allowed to run. If an Exception is raised the task
+ is automatically rescheduled for execution.
+ """
+
+ def __init__(self):
+ """Constructs a new Handler with all known jobs set.
+ """
+
+ self.tasks = {}
+ self.tasks['sendAcceptanceEmail'] = logging.info
+
+ def claimJob(self, job_key):
+ """A transaction to claim a job.
+ """
+
+ job = Job.get_by_id(job_key)
+
+ if job.status != 'waiting':
+ raise db.Rollback()
+
+ job.status = 'started'
+
+ if job.put():
+ return job
+ else:
+ return None
+
+ def freeJob(self, job_key):
+ """A transaction to free a job.
+ """
+
+ job = Job.get_by_id(job_key)
+
+ job.status = 'waiting'
+
+ return job.put()
+
+ def failJob(self, job_key):
+ """A transaction to fail a job.
+ """
+
+ job = Job.get_by_id(job_key)
+
+ job.errors += 1
+
+ if job.errors > 5:
+ job.status = 'aborted'
+ else:
+ job.status = 'waiting'
+
+ job_id = job.key().id()
+ logging.warning("job %d now failed %d time(s)" % (job_id, job.errors))
+
+ return job.put()
+
+ def finishJob(self, job_key):
+ """A transaction to finish a job.
+ """
+
+ job = Job.get_by_id(job_key)
+ job.status = 'finished'
+
+ return job.put()
+
+ def abortJob(self, job_key):
+ """A transaction to abort a job.
+ """
+
+ job = Job.get_by_id(job_key)
+ job.status = 'aborted'
+
+ return job.put()
+
+ def handle(self, job_key):
+ """Handle one job.
+ """
+
+ try:
+ job = db.run_in_transaction(self.claimJob, job_key)
+
+ if not job:
+ # someone already claimed the job
+ return True
+
+ if job.task_name not in self.tasks:
+ logging.error("Unknown job %s" % job.task_name)
+ db.run_in_transaction(self.abortJob, job_key)
+ return True
+
+ task = self.tasks[job.task_name]
+
+ # excecute the actual job
+ task(job)
+
+ db.run_in_transaction(self.finishJob, job_key)
+ return True
+ except DeadlineExceededError, exception:
+ db.run_in_transaction(self.freeJob, job_key)
+ return False
+ except Exception, exception:
+ logging.exception(exception)
+ db.run_in_transaction(self.failJob, job_key)
+ return True
+
+
+handler = Handler()