This set of changes reworks the DiskFile class to remove the "extension" parameter from the put() method, offering the new put_metadata() method with an optional tombstone keyword boolean, and changes the mkstemp method to only return the file descriptor. Reviewing the code it was found that the temporary file name created as a result of calling DiskFile.mkstemp() was never used by the caller, but the caller was responsible for passing it back to the DiskFile.put() method. That seems like too much information is exposed to the caller, when all the caller requires is the file descriptor to write data into it. Upon further review, the mkstemp() method was used in three places: PUT, POST and DELETE method handling. Of those three cases, only PUT requires the file descriptor, since it is responsible for writing the object contents. For POST and DELETE, DiskFile only needs to associate metadata with the correct file name. We abstract the pattern that those two use (once we also refactor the code to move the fetch of the delete-at metadata, and subsequent delete-at-update initiation, from under the mkstemp context) by adding the new put_metadata() method. As a result, the DiskFile class is then free to do whatever file system operations it must to meet the API, without the caller having to know more than just how to write data to a file descriptor. Note that DiskFile itself key'd off of the '.ts' and '.meta' extensions for its operations, and for that to work properly, the caller had to know to use those correctly. With this change, the caller has no knowledge of how the file system is being used to accomplish data and metadata storage. See also Question 213796 at: https://answers.launchpad.net/swift/+question/213796 Change-Id: I267f68e64391ba627b2a13682393bec62600159d Signed-off-by: Peter Portante <peter.portante@redhat.com>
Swift
A distributed object storage system designed to scale from a single machine to thousands of servers. Swift is optimized for multi-tenancy and high concurrency. Swift is ideal for backups, web and mobile content, and any other unstructured data that can grow without bound.
Swift provides a simple, REST-based API fully documented at http://doc.openstack.org/.
Swift was originally developed as the basis for Rackspace's Cloud Files and was open-sourced in 2010 as part of the OpenStack project. It has since grown to include contributions from many companies and has spawned a thriving ecosystem of 3rd party tools. Swift's contributors are listed in the AUTHORS file.
Docs
To build documentation install sphinx (pip install sphinx), run
python setup.py build_sphinx, and then browse to /doc/build/html/index.html.
These docs are auto-generated after every commit and available online at
http://docs.openstack.org/developer/swift/.
For Developers
The best place to get started is the "SAIO - Swift All In One". This document will walk you through setting up a development cluster of Swift in a VM. The SAIO environment is ideal for running small-scale tests against swift and trying out new features and bug fixes.
You can run unit tests with .unittests and functional tests with
.functests.
Code Organization
- bin/: Executable scripts that are the processes run by the deployer
- doc/: Documentation
- etc/: Sample config files
- swift/: Core code
- account/: account server
- common/: code shared by different modules
- middleware/: "standard", officially-supported middleware
- ring/: code implementing Swift's ring
- container/: container server
- obj/: object server
- proxy/: proxy server
- test/: Unit and functional tests
Data Flow
Swift is a WSGI application and uses eventlet's WSGI server. After the
processes are running, the entry point for new requests is the Application
class in swift/proxy/server.py. From there, a controller is chosen, and the
request is processed. The proxy may choose to forward the request to a back-
end server. For example, the entry point for requests to the object server is
the ObjectController class in swift/obj/server.py.
For Deployers
Deployer docs are also available at http://docs.openstack.org/developer/swift/. A good starting point is at http://docs.openstack.org/developer/swift/deployment_guide.html
You can run functional tests against a swift cluster with .functests. These
functional tests require /etc/swift/test.conf to run. A sample config file
can be found in this source tree in test/sample.conf.
For Client Apps
For client applications, official Python language bindings are provided at http://github.com/openstack/python-swiftclient.
Complete API documentation at http://docs.openstack.org/api/openstack-object-storage/1.0/content/
For more information come hang out in #openstack-swift on freenode.
Thanks,
The Swift Development Team