135 lines
4.5 KiB
Python
135 lines
4.5 KiB
Python
"""
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Add receivers for django signals, and feed data into the monitoring system.
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If a model has a class attribute 'METRIC_TAGS' that is a list of strings,
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those fields will be retrieved from the model instance, and added as tags to
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the recorded metrics.
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"""
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from django.db.models.signals import post_save, post_delete, m2m_changed, post_init
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from django.dispatch import receiver
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from dogapi import dog_stats_api
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def _database_tags(action, sender, kwargs):
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"""
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Return a tags for the sender and database used in django.db.models signals.
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Arguments:
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action (str): What action is being performed on the db model.
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sender (Model): What model class is the action being performed on.
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kwargs (dict): The kwargs passed by the model signal.
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"""
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tags = _model_tags(kwargs, 'instance')
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tags.append(u'action:{}'.format(action))
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if 'using' in kwargs:
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tags.append(u'database:{}'.format(kwargs['using']))
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return tags
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def _model_tags(kwargs, key):
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"""
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Return a list of all tags for all attributes in kwargs[key].MODEL_TAGS,
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plus a tag for the model class.
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"""
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if key not in kwargs:
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return []
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instance = kwargs[key]
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tags = [
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u'{}.{}:{}'.format(key, attr, getattr(instance, attr))
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for attr in getattr(instance, 'MODEL_TAGS', [])
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]
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tags.append(u'model_class:{}'.format(instance.__class__.__name__))
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return tags
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@receiver(post_init, dispatch_uid='edxapp.monitoring.post_init_metrics')
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def post_init_metrics(sender, **kwargs):
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"""
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Record the number of times that django models are instantiated.
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Args:
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sender (Model): The model class sending the signals.
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using (str): The name of the database being used for this initialization (optional).
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instance (Model instance): The instance being initialized (optional).
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"""
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tags = _database_tags('initialized', sender, kwargs)
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dog_stats_api.increment('edxapp.db.model', tags=tags)
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@receiver(post_save, dispatch_uid='edxapp.monitoring.post_save_metrics')
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def post_save_metrics(sender, **kwargs):
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"""
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Record the number of times that django models are saved (created or updated).
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Args:
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sender (Model): The model class sending the signals.
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using (str): The name of the database being used for this update (optional).
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instance (Model instance): The instance being updated (optional).
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"""
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action = 'created' if kwargs.pop('created', False) else 'updated'
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tags = _database_tags(action, sender, kwargs)
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dog_stats_api.increment('edxapp.db.model', tags=tags)
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@receiver(post_delete, dispatch_uid='edxapp.monitoring.post_delete_metrics')
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def post_delete_metrics(sender, **kwargs):
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"""
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Record the number of times that django models are deleted.
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Args:
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sender (Model): The model class sending the signals.
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using (str): The name of the database being used for this deletion (optional).
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instance (Model instance): The instance being deleted (optional).
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"""
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tags = _database_tags('deleted', sender, kwargs)
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dog_stats_api.increment('edxapp.db.model', tags=tags)
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@receiver(m2m_changed, dispatch_uid='edxapp.monitoring.m2m_changed_metrics')
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def m2m_changed_metrics(sender, **kwargs):
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"""
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Record the number of times that Many2Many fields are updated. This is separated
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from post_save and post_delete, because it's signaled by the database model in
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the middle of the Many2Many relationship, rather than either of the models
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that are the relationship participants.
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Args:
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sender (Model): The model class in the middle of the Many2Many relationship.
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action (str): The action being taken on this Many2Many relationship.
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using (str): The name of the database being used for this deletion (optional).
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instance (Model instance): The instance whose many-to-many relation is being modified.
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model (Model class): The model of the class being added/removed/cleared from the relation.
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"""
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if 'action' not in kwargs:
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return
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action = {
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'post_add': 'm2m.added',
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'post_remove': 'm2m.removed',
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'post_clear': 'm2m.cleared',
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}.get(kwargs['action'])
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if not action:
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return
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tags = _database_tags(action, sender, kwargs)
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if 'model' in kwargs:
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tags.append('target_class:{}'.format(kwargs['model'].__name__))
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pk_set = kwargs.get('pk_set', []) or []
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dog_stats_api.increment(
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'edxapp.db.model',
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value=len(pk_set),
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tags=tags
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)
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