GitHub user supertom opened a pull request:
https://github.com/apache/libcloud/pull/813
[GCE] LIBCLOUD-826: Improve performance of list nodes by caching volume
information
## [GCE] Improve performance of list nodes by caching volume information
### Description
When listing nodes, the GCE driver currently calls the disk API for each
disk attached to the node. This PR changes that behavior by using the
aggregatedLIst call for disks (once per list_node request) and using that
information to provide disk details.
See sample performance info in
[LIBCLOUD-826](https://issues.apache.org/jira/browse/LIBCLOUD-826)
#### Implementation:
For disk information, aggregated calls are now always used and the disk
information is stored in a dictionary, called 'volume_dict'. If the user would
like the most current information, they may set the use_cache keyword to false
and the call (and subsequent population of volume_dict) will be made prior to
returning disk information.
Code was added/changed in two classes. In GCENodeDriver, added two methods
and an additional parameter to build, lookup and toggle the refresh of the
volume cache. In GCEConnection, added convenience and helper methods to the
class, which not only support this performance improvement but also support the
longer term vision of leveraging aggregatedList calls elsewhere.
##### GCEConnection
* _(new method)_ **def request_aggregated_items(self, api_name)** - make
all necessary calls, handling maxresults and saving the 'items' portion of the
response.
* _(new method)_ **def _merge_response_items(self, list_name,
response_list)** - helper method to merge responses into a single dictionary
##### GCENodeDriver
* _(new member)_ **volume_dict** - dictionary organized by name, zone.
Name is always available to us, but is not unique across zones. Zones, though,
are optionally supplied. By organizing by name, we remove the need to search
through the entire list of disks each time and can do a single hash lookup to
have access to all disks by that name. If we have the zone, another hash
lookup, if not, we take the first key alphabetically.
* _(new method)_ **_build_name_zone_dict(self, zone_dict)** - internal
method to populate volume dict
* _(new method)_ **_ex_lookup_volume(self, name, zone=None)** - implements
the actual lookup. If zone is not provided, take the disk with that name from
the (alphabetical) first zone (this is only an issue if there are more than two
disks with the same name).
* _(new parameter)_ **list_nodes(self, ex_zone=None, use_disk_cache=True)**
- use_disk_cache parameter for list_nodes to pass through, defaults to True.
If set to true, no more than one call per 500 disks would be made to populate
all disk info for nodes
* _(new parameter, revision)_ **ex_get_volume(self, name, zone=None,
use_cache=False)** - revised to check if volume_dict has been populated or
should be used, followed by returning the call to _ex_lookup_volume
### Status
- done, ready for review
### Checklist (tick everything that applies)
- [X] [Code
linting](http://libcloud.readthedocs.org/en/latest/development.html#code-style-guide)
(required, can be done after the PR checks)
- [ ] Documentation
- [X] [Tests](http://libcloud.readthedocs.org/en/latest/testing.html)
- [ ]
[ICLA](http://libcloud.readthedocs.org/en/latest/development.html#contributing-bigger-changes)
(required for bigger changes)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/supertom/libcloud LIBCLOUD-826
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/libcloud/pull/813.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #813
----
commit ae8ce86eb899e7d33d558dd55b556c308b8a1449
Author: Tom Melendez <t...@supertom.com>
Date: 2016-05-31T16:57:43Z
Merge pull request #1 from apache/trunk
Update from head
commit c436531a190da59e5b1e64ba94e50e2e0bb7ddbd
Author: Tom Melendez <super...@google.com>
Date: 2016-06-06T15:57:17Z
Merge remote-tracking branch 'upstream/trunk' into trunk
commit 3e7a5398f2621363b4ec5d5b0602fc0f4287534c
Author: Tom Melendez <super...@google.com>
Date: 2016-06-13T20:16:21Z
Merge remote-tracking branch 'upstream/trunk' into LIBCLOUD-826
commit 66bf0a67951a5fcef31348d123973de9859e6f41
Author: Tom Melendez <super...@google.com>
Date: 2016-06-15T01:47:06Z
Merge remote-tracking branch 'upstream/trunk' into LIBCLOUD-826
commit d4022c4d8eaf982d7924d315610705532361255f
Author: Tom Melendez <super...@google.com>
Date: 2016-06-15T02:08:33Z
GCE list nodes performance improvement. Resolves LIBCLOUD-826.
We leverage the aggregated disk call and store the result. For the list
node operation, we've added an extra parameter to use the cached data, which
results to true.
Tests and fixtures updated as well.
----
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