Support Periodic Tasks with a start date and one-off tasks (#78)

* support periodic tasks with a start date and also one-off tasks. Change the list display in PeriodicTaskAdmin to show interval, start_date, one_off additionally - easier/quicker identifcation of task properties in admin list

* add migration

* rename start_date to start_time and add tests

* fix unit test

* update migrations and fix tests

django_celery_beat/admin.py

@@ -116,15 +116,16 @@ class PeriodicTaskAdmin(admin.ModelAdmin):
     form = PeriodicTaskForm
     model = PeriodicTask
     celery_app = current_app
-    list_display = ('__str__', 'enabled')
+    list_display = ('__str__', 'enabled', 'interval', 'start_time', 'one_off')
     actions = ('enable_tasks', 'disable_tasks', 'run_tasks')
     fieldsets = (
         (None, {
             'fields': ('name', 'regtask', 'task', 'enabled', 'description',),
             'classes': ('extrapretty', 'wide'),
         }),
         ('Schedule', {
-            'fields': ('interval', 'crontab', 'solar'),
+            'fields': ('interval', 'crontab', 'solar',
+                       'start_time', 'one_off'),
             'classes': ('extrapretty', 'wide', ),
         }),
         ('Arguments', {

django_celery_beat/migrations/0007_auto_20180521_0826.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.7 on 2018-05-21 08:26
+from __future__ import absolute_import, unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_celery_beat', '0006_auto_20180322_0932'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='periodictask',
+            name='one_off',
+            field=models.BooleanField(default=False,
+                                      verbose_name='one-off task'),
+        ),
+        migrations.AddField(
+            model_name='periodictask',
+            name='start_time',
+            field=models.DateTimeField(blank=True,
+                                       null=True,
+                                       verbose_name='start_time'),
+        ),
+    ]

django_celery_beat/models.py

@@ -276,6 +276,12 @@ class PeriodicTask(models.Model):
     expires = models.DateTimeField(
         _('expires'), blank=True, null=True,
     )
+    one_off = models.BooleanField(
+        _('one-off task'), default=False,
+    )
+    start_time = models.DateTimeField(
+        _('start_time'), blank=True, null=True,
+    )
     enabled = models.BooleanField(
         _('enabled'), default=True,
     )

django_celery_beat/schedulers.py

@@ -11,6 +11,7 @@
 from celery.five import values, items
 from celery.utils.encoding import safe_str, safe_repr
 from celery.utils.log import get_logger
+from celery.utils.time import maybe_make_aware
 from kombu.utils.json import dumps, loads
 
 from django.db import transaction, close_old_connections
@@ -96,6 +97,22 @@ def _disable(self, model):
     def is_due(self):
         if not self.model.enabled:
             return False, 5.0   # 5 second delay for re-enable.
+
+        # START DATE: only run after the `start_time`, if one exists.
+        if self.model.start_time is not None:
+            if maybe_make_aware(self._default_now()) < self.model.start_time:
+                # The datetime is before the start date - don't run.
+                _, delay = self.schedule.is_due(self.last_run_at)
+                return False, delay  # use original delay for re-check
+
+        # ONE OFF TASK: Disable one off tasks after they've ran once
+        if self.model.one_off and self.model.enabled \
+                and self.model.total_run_count > 0:
+            self.model.enabled = False
+            self.model.total_run_count = 0  # Reset
+            self.model.save()
+            return False, None  # Don't recheck
+
         return self.schedule.is_due(self.last_run_at)
 
     def _default_now(self):

t/unit/test_schedulers.py

@@ -131,6 +131,49 @@ def test_entry(self):
         assert e3.last_run_at > e2.last_run_at
         assert e3.total_run_count == 1
 
+    def test_task_with_start_time(self):
+        interval = 10
+        right_now = self.app.now()
+        one_interval_ago = right_now - timedelta(seconds=interval)
+        m = self.create_model_interval(schedule(timedelta(seconds=interval)),
+                                       start_time=right_now,
+                                       last_run_at=one_interval_ago)
+        e = self.Entry(m, app=self.app)
+        isdue, delay = e.is_due()
+        assert isdue
+        assert delay == interval
+
+        tomorrow = right_now + timedelta(days=1)
+        m2 = self.create_model_interval(schedule(timedelta(seconds=interval)),
+                                        start_time=tomorrow,
+                                        last_run_at=one_interval_ago)
+        e2 = self.Entry(m2, app=self.app)
+        isdue, delay = e2.is_due()
+        assert not isdue
+        assert delay == interval
+
+    def test_one_off_task(self):
+        interval = 10
+        right_now = self.app.now()
+        one_interval_ago = right_now - timedelta(seconds=interval)
+        m = self.create_model_interval(schedule(timedelta(seconds=interval)),
+                                       one_off=True,
+                                       last_run_at=one_interval_ago,
+                                       total_run_count=0)
+        e = self.Entry(m, app=self.app)
+        isdue, delay = e.is_due()
+        assert isdue
+        assert delay == interval
+
+        m2 = self.create_model_interval(schedule(timedelta(seconds=interval)),
+                                        one_off=True,
+                                        last_run_at=one_interval_ago,
+                                        total_run_count=1)
+        e2 = self.Entry(m2, app=self.app)
+        isdue, delay = e2.is_due()
+        assert not isdue
+        assert delay is None
+
 
 @pytest.mark.django_db()
 class test_DatabaseSchedulerFromAppConf(SchedulerCase):