From 1aa90adac3cb1764fed2de15465e1215a9c956be Mon Sep 17 00:00:00 2001
From: Joel Falknau <joel.falknau@gmail.com>
Date: Sun, 29 Dec 2024 14:51:33 +1000
Subject: [PATCH] Cron Offset Module

---
 allianceauth/framework/cron.py                | 47 +++++++++++++++++++
 .../framework/migrations/0001_initial.py      | 28 +++++++++++
 allianceauth/framework/migrations/__init__.py |  0
 allianceauth/framework/models.py              | 19 ++++++++
 4 files changed, 94 insertions(+)
 create mode 100644 allianceauth/framework/cron.py
 create mode 100644 allianceauth/framework/migrations/0001_initial.py
 create mode 100644 allianceauth/framework/migrations/__init__.py
 create mode 100644 allianceauth/framework/models.py

diff --git a/allianceauth/framework/cron.py b/allianceauth/framework/cron.py
new file mode 100644
index 00000000..044247cf
--- /dev/null
+++ b/allianceauth/framework/cron.py
@@ -0,0 +1,47 @@
+from celery.schedules import crontab
+import logging
+from allianceauth.framework.models import CronOffset
+from django.db import ProgrammingError
+
+logger = logging.getLogger(__name__)
+
+
+# CELERYBEAT_SCHEDULE['marketmanager_fetch_public_market_orders'] = {
+#     'task': 'marketmanager.tasks.fetch_public_market_orders',
+#     'schedule': crontab(minute=0, hour='*/3'),
+# }
+
+
+def offset_cron(schedule: crontab) -> crontab:
+    """Take a crontab and apply a series of precalculated offsets to spread out tasks execution on remote resources
+
+    Args:
+        schedule (crontab): celery.schedules.crontab()
+
+    Returns:
+        crontab: A crontab with offsetted Minute and Hour fields
+    """
+
+    try:
+        cron_offset = CronOffset.get_solo()
+        new_minute = [(m + (round(60 * cron_offset.minute))) % 60 for m in schedule.minute]
+        new_hour = [(m + (round(24 * cron_offset.hour))) % 24 for m in schedule.hour]
+
+        # Type hints are fine here, crontab _expand_cronspec handles sets, the hinting is old
+        return crontab(
+            minute=",".join(str(m) for m in sorted(new_minute)),
+            hour=",".join(str(h) for h in sorted(new_hour)),
+            day_of_month=schedule._orig_day_of_month,
+            month_of_year=schedule._orig_month_of_year,
+            day_of_week=schedule._orig_day_of_week)
+
+    except ProgrammingError as e:
+        # If this is called before migrations are run hand back the default schedule
+        # These offsets are stored in a Singleton Model,
+        logger.error(e)
+        return schedule
+
+    except Exception as e:
+        # We absolutely cant fail to hand back a schedule
+        logger.error(e)
+        return schedule
diff --git a/allianceauth/framework/migrations/0001_initial.py b/allianceauth/framework/migrations/0001_initial.py
new file mode 100644
index 00000000..e3fb6d2d
--- /dev/null
+++ b/allianceauth/framework/migrations/0001_initial.py
@@ -0,0 +1,28 @@
+# Generated by Django 4.2.16 on 2024-12-29 04:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='CronOffset',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('minute', models.FloatField(default=0.1850723825351236, verbose_name='Minute Offset')),
+                ('hour', models.FloatField(default=0.3449986529941984, verbose_name='Hour Offset')),
+                ('day_of_month', models.FloatField(default=0.8941823028373547, verbose_name='Day of Month Offset')),
+                ('month_of_year', models.FloatField(default=0.6068269517452, verbose_name='Month Of Year Offset')),
+                ('day_of_week', models.FloatField(default=0.8863389239634608, verbose_name='Day of Week Offset')),
+            ],
+            options={
+                'verbose_name': 'Cron Offsets',
+            },
+        ),
+    ]
diff --git a/allianceauth/framework/migrations/__init__.py b/allianceauth/framework/migrations/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/allianceauth/framework/models.py b/allianceauth/framework/models.py
new file mode 100644
index 00000000..287a13de
--- /dev/null
+++ b/allianceauth/framework/models.py
@@ -0,0 +1,19 @@
+from random import random
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+from solo.models import SingletonModel
+
+
+class CronOffset(SingletonModel):
+
+    minute = models.FloatField(_("Minute Offset"), default=random())
+    hour = models.FloatField(_("Hour Offset"), default=random())
+    day_of_month = models.FloatField(_("Day of Month Offset"), default=random())
+    month_of_year = models.FloatField(_("Month Of Year Offset"), default=random())
+    day_of_week = models.FloatField(_("Day of Week Offset"), default=random())
+
+    def __str__(self) -> str:
+        return "Cron Offsets"
+
+    class Meta:
+        verbose_name = "Cron Offsets"