122 lines
4.4 KiB
Python
122 lines
4.4 KiB
Python
# Copyright 2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License"). You
|
|
# may not use this file except in compliance with the License. A copy of
|
|
# the License is located at
|
|
#
|
|
# http://aws.amazon.com/apache2.0/
|
|
#
|
|
# or in the "license" file accompanying this file. This file 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.
|
|
import logging
|
|
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
def register_table_methods(base_classes, **kwargs):
|
|
base_classes.insert(0, TableResource)
|
|
|
|
|
|
# This class can be used to add any additional methods we want
|
|
# onto a table resource. Ideally to avoid creating a new
|
|
# base class for every method we can just update this
|
|
# class instead. Just be sure to move the bulk of the
|
|
# actual method implementation to another class.
|
|
class TableResource(object):
|
|
def __init__(self, *args, **kwargs):
|
|
super(TableResource, self).__init__(*args, **kwargs)
|
|
|
|
def batch_writer(self):
|
|
"""Create a batch writer object.
|
|
|
|
This method creates a context manager for writing
|
|
objects to Amazon DynamoDB in batch.
|
|
|
|
The batch writer will automatically handle buffering and sending items
|
|
in batches. In addition, the batch writer will also automatically
|
|
handle any unprocessed items and resend them as needed. All you need
|
|
to do is call ``put_item`` for any items you want to add, and
|
|
``delete_item`` for any items you want to delete.
|
|
|
|
Example usage::
|
|
|
|
with table.batch_writer() as batch:
|
|
for _ in xrange(1000000):
|
|
batch.put_item(Item={'HashKey': '...',
|
|
'Otherstuff': '...'})
|
|
# You can also delete_items in a batch.
|
|
batch.delete_item(Key={'HashKey': 'SomeHashKey'})
|
|
|
|
"""
|
|
return BatchWriter(self.name, self.meta.client)
|
|
|
|
|
|
class BatchWriter(object):
|
|
"""Automatically handle batch writes to DynamoDB for a single table."""
|
|
def __init__(self, table_name, client, flush_amount=25):
|
|
"""
|
|
|
|
:type table_name: str
|
|
:param table_name: The name of the table. The class handles
|
|
batch writes to a single table.
|
|
|
|
:type client: ``botocore.client.Client``
|
|
:param client: A botocore client. Note this client
|
|
**must** have the dynamodb customizations applied
|
|
to it for transforming AttributeValues into the
|
|
wire protocol. What this means in practice is that
|
|
you need to use a client that comes from a DynamoDB
|
|
resource if you're going to instantiate this class
|
|
directly, i.e
|
|
``boto3.resource('dynamodb').Table('foo').meta.client``.
|
|
|
|
:type flush_amount: int
|
|
:param flush_amount: The number of items to keep in
|
|
a local buffer before sending a batch_write_item
|
|
request to DynamoDB.
|
|
|
|
|
|
"""
|
|
self._table_name = table_name
|
|
self._client = client
|
|
self._items_buffer = []
|
|
self._flush_amount = flush_amount
|
|
|
|
def put_item(self, Item):
|
|
self._items_buffer.append({'PutRequest': {'Item': Item}})
|
|
self._flush_if_needed()
|
|
|
|
def delete_item(self, Key):
|
|
self._items_buffer.append({'DeleteRequest': {'Key': Key}})
|
|
self._flush_if_needed()
|
|
|
|
def _flush_if_needed(self):
|
|
if len(self._items_buffer) >= self._flush_amount:
|
|
self._flush()
|
|
|
|
def _flush(self):
|
|
response = self._client.batch_write_item(
|
|
RequestItems={self._table_name: self._items_buffer})
|
|
unprocessed_items = response['UnprocessedItems']
|
|
|
|
if unprocessed_items and unprocessed_items[self._table_name]:
|
|
# Any unprocessed_items are immediately added to the
|
|
# next batch we send.
|
|
self._items_buffer = unprocessed_items[self._table_name]
|
|
else:
|
|
self._items_buffer = []
|
|
logger.debug("Batch write sent %s, unprocessed: %s",
|
|
self._flush_amount, len(self._items_buffer))
|
|
|
|
def __enter__(self):
|
|
return self
|
|
|
|
def __exit__(self, exc_type, exc_value, tb):
|
|
# When we exit, we need to keep flushing whatever's left
|
|
# until there's nothing left in our items buffer.
|
|
while self._items_buffer:
|
|
self._flush()
|