[PATCH] xmlrpc: Don't load all Patches into memory

[Andy Doan]

On 07/13/2016 04:57 AM, Stephen Finucane wrote:
> The way that reverse indexing of patches was implemented is broken.
> At present, it will retrieve all patches in memory and return the
> length from that data, then the slicing operation will then happen
> without querying the DB and slice the results cached from the len()
> evaluation. This is memory intensive, particularly for larger
> instances.
>
> Take advantage of Django's lazy loading to avoid this.
>
> Signed-off-by: Stephen Finucane <stephen.finucane at intel.com>
> Suggested-by: Damien Lespiau <damien.lespiau at intel.com>
> ---
Reviewed-by: Andy Doan <andy.doan at linaro.org>

>   patchwork/views/xmlrpc.py |   14 ++++++++------
>   1 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/patchwork/views/xmlrpc.py b/patchwork/views/xmlrpc.py
> index 638b3b1..8f759aa 100644
> --- a/patchwork/views/xmlrpc.py
> +++ b/patchwork/views/xmlrpc.py
> @@ -406,8 +406,8 @@ def project_list(search_str=None, max_count=0):
>           if max_count > 0:
>               return list(map(project_to_dict, projects[:max_count]))
>           elif max_count < 0:
> -            return list(map(project_to_dict,
> -                            projects[len(projects) + max_count:]))
> +            query = projects.reverse()[:-max_count]
> +            return list(map(project_to_dict, reversed(query)))
>           else:
>               return list(map(project_to_dict, projects))
>       except Project.DoesNotExist:
> @@ -461,7 +461,8 @@ def person_list(search_str=None, max_count=0):
>           if max_count > 0:
>               return list(map(person_to_dict, people[:max_count]))
>           elif max_count < 0:
> -            return list(map(person_to_dict, people[len(people) + max_count:]))
> +            query = people.reverse()[:-max_count]
> +            return list(map(person_to_dict, reversed(query)))
>           else:
>               return list(map(person_to_dict, people))
>       except Person.DoesNotExist:
> @@ -606,8 +607,8 @@ def patch_list(filt=None):
>           if max_count > 0:
>               return list(map(patch_to_dict, patches[:max_count]))
>           elif max_count < 0:
> -            return list(map(patch_to_dict,
> -                            patches[len(patches) + max_count:]))
> +            query = patches.reverse()[:-max_count]
> +            return list(map(patch_to_dict, reversed(query)))
>           else:
>               return list(map(patch_to_dict, patches))
>       except Patch.DoesNotExist:
> @@ -802,7 +803,8 @@ def state_list(search_str=None, max_count=0):
>           if max_count > 0:
>               return list(map(state_to_dict, states[:max_count]))
>           elif max_count < 0:
> -            return list(map(state_to_dict, states[len(states) + max_count:]))
> +            query = states.reverse()[:-max_count]
> +            return list(map(state_to_dict, reversed(query)))
>           else:
>               return list(map(state_to_dict, states))
>       except State.DoesNotExist:
>