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import os | |
import boto3 | |
import hashlib | |
from .helpers import safe_dumps | |
MESSAGE_TABLE_NAME = os.environ['DYNAMO_TABLE_NAME'] | |
# DynamoDB stuff | |
def get_dynamodb(): # pragma: no cover | |
"""Return a dynamodb resource""" | |
return boto3.resource('dynamodb') | |
def get_table(table_name=MESSAGE_TABLE_NAME): # pragma: no cover | |
"""Create a dynamodb resource""" | |
dynamodb = get_dynamodb() | |
return dynamodb.Table(table_name) | |
def set_connection_id(connection_id, channel='general'): | |
"""Save an individual connection to a given channel""" | |
table = get_table() | |
conn_key = _get_channel_connections_key(channel) | |
coll_name = _get_connection_column_name(connection_id) | |
update_expr = 'SET {} = :value'.format(coll_name) | |
table.update_item( | |
Key=conn_key, | |
UpdateExpression=update_expr, | |
ExpressionAttributeValues={ | |
':value': { | |
'connection_id': connection_id, | |
'channel': channel, | |
} | |
}, | |
ReturnValues='UPDATED_NEW', | |
) | |
# Also update the list of channels | |
table.update_item( | |
Key=_get_channels_list_key(), | |
UpdateExpression='ADD channels :value', | |
ExpressionAttributeValues={':value': set([channel])}, | |
) | |
def delete_connection_id(connection_id, channel='general'): | |
"""Delete an item from DynamoDB which represents a client being connected""" | |
table = get_table() | |
conn_key = _get_channel_connections_key(channel) | |
coll_name = _get_connection_column_name(connection_id) | |
update_expr = 'REMOVE {}'.format(coll_name) | |
table.update_item( | |
Key=conn_key, | |
UpdateExpression=update_expr, | |
) | |
def get_channels_list(): | |
table = get_table() | |
row = table.get_item(Key=_get_channels_list_key()) | |
return row.get('Item')['channels'] | |
def get_user(connection_id): | |
table = get_table() | |
key = _get_user_key(connection_id) | |
row = table.get_item(Key=key) | |
return row.get('Item', key) | |
def update_channel_name(connection_id, name): | |
item = get_user(connection_id) | |
old_channel = item.get('channel_name', 'general') | |
delete_connection_id(connection_id, old_channel) | |
item['channel_name'] = name | |
table = get_table() | |
table.put_item(Item=item) | |
set_connection_id(connection_id, name) | |
def save_username(connection_id, name): | |
update_expr = 'SET username = :value' | |
table = get_table() | |
table.update_item( | |
Key=_get_user_key(connection_id), | |
UpdateExpression=update_expr, | |
ExpressionAttributeValues={':value': name}, | |
) | |
def save_message(connection_id, epoch, message, channel='general'): | |
"""Save a message from a user""" | |
item = { | |
'pk': channel, | |
'epoch': epoch, | |
'connectionId': connection_id, | |
'channel': channel, | |
'message': message, | |
} | |
table = get_table() | |
table.put_item(Item=item) | |
def get_connected_connection_ids(channel='general'): | |
table = get_table() | |
key = _get_channel_connections_key(channel) | |
row = table.get_item(Key=key) | |
for key, payload in row.get('Item', {}).items(): | |
if key.startswith('CONN'): | |
yield payload['connection_id'] | |
def _get_channel_conn_pk(channel): | |
return '%s:::connections' % (channel, ) | |
def _get_channel_message_pk(channel, connection_id): | |
return '%s:::%s' % (channel, connection_id) | |
def _get_channel_connections_key(channel): | |
pk = _get_channel_conn_pk(channel) | |
return {'pk': pk, 'epoch': 0} | |
def _get_channels_list_key(): | |
return {'pk': 'channels', 'epoch': 0} | |
def _get_user_key(connection_id): | |
return {'pk': connection_id, 'epoch': 0} | |
def _get_connection_column_name(connection_id): | |
return 'CONN' + hashlib.md5(connection_id.encode()).hexdigest()[:16] | |
# Lambda stuff | |
def invoke_lambda_async(function_name, payload): | |
"""Invoke a Lambda function with an Event invocation type""" | |
_lambda = boto3.client('lambda') | |
return _lambda.invoke( | |
FunctionName=function_name, | |
Payload=safe_dumps(payload), | |
InvocationType='Event', | |
) |