3aa06f185a
The ssync Receiver performs some checks on request parameters
in initialize_request() before starting the exchange of missing
hashes and updates e.g. the destination device must be available;
the policy must be valid. Currently if any of these checks fails
then the receiver just closes the connection, so the Sender gets
no useful response code and noise is generated in logs by httplib
and wsgi Exceptions.
This change moves the request parameter checks to the Receiver
constructor so that the HTTPExceptions raised are actually sent
as responses. (The 'connection close' exception handling still
applies once the 'missing_check' and 'updates' handshakes are in
progress.)
Moving initialize_request() revealed the following lurking bug:
* initialize_request() sets
req.environ['eventlet.minimum_write_chunk_size'] = 0
* this was previously ineffective because the Response environ
had already been copied from Request environ before this value
was set, so the Response never used the value :/
* Now that it is effective (a good thing) it causes the empty string
yielded by the receiver when there are no missing hashes in
missing_checks() to be sent to the sender immediately. This makes
the Sender.readline() think there has been an early disconnect
and raise an Exception (a bad thing), as revealed by
test/unit/obj/test_ssync_sender.py:TestSsync.test_nothing_to_sync
The fix for this is to simply make the receiver skip sending the empty
string if there are no missing object_hashes.
Change-Id: I036a6919fead6e970505dccbb0da7bfbdf8cecc3
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://docs.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.
If you would like to start contributing, check out these notes to help you get started.
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