Merge branch 'fix/speed-up-commit-repo-changes' into 'master'

Speed up methods that depend on diff stats only

## What does this MR do?
Speeds up and reduces memory usage of `Commit#repo_changes`loop, `Repository#expire_avatar_cache` and `IrkerWorker`.  It's a WIP because it need a new version of `gitlab_git` released with [these changes](https://gitlab.com/gitlab-org/gitlab_git/merge_requests/109).

## Are there points in the code the reviewer needs to double check?
N/A

## Why was this MR needed?
For large files committed, this method ends up loading them in memory which can consume lots of memory.

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/19441#note_13425892

## Screenshots (if relevant)
N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- ~~Tests~~
  - [ ] ~~Added for this feature/bug~~
  - [ ] ~~All builds are passing~~
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5568

CHANGELOG

@@ -57,6 +57,7 @@ v 8.11.0 (unreleased)
   - Sensible state specific default sort order for issues and merge requests !5453 (tomb0y)
   - Fix RequestProfiler::Middleware error when code is reloaded in development
   - Catch what warden might throw when profiling requests to re-throw it
+  - Speed up and reduce memory usage of Commit#repo_changes, Repository#expire_avatar_cache and IrkerWorker
 
 v 8.10.3
   - Fix Import/Export issue importing milestones and labels not associated properly. !5426

Gemfile

@@ -53,7 +53,7 @@ gem 'browser', '~> 2.2'
 
 # Extracting information from a git repository
 # Provide access to Gitlab::Git library
-gem 'gitlab_git', '~> 10.4.2'
+gem 'gitlab_git', '~> 10.4.3'
 
 # LDAP Auth
 # GitLab fork with several improvements to original library. For full list of changes

Gemfile.lock

@@ -278,7 +278,7 @@ GEM
       diff-lcs (~> 1.1)
       mime-types (>= 1.16, < 3)
       posix-spawn (~> 0.3)
-    gitlab_git (10.4.2)
+    gitlab_git (10.4.3)
       activesupport (~> 4.0)
       charlock_holmes (~> 0.7.3)
       github-linguist (~> 4.7.0)
@@ -870,7 +870,7 @@ DEPENDENCIES
   github-linguist (~> 4.7.0)
   github-markup (~> 1.4)
   gitlab-flowdock-git-hook (~> 1.0.1)
-  gitlab_git (~> 10.4.2)
+  gitlab_git (~> 10.4.3)
   gitlab_meta (= 7.0)
   gitlab_omniauth-ldap (~> 1.2.1)
   gollum-lib (~> 4.2)

app/models/commit.rb

@@ -334,7 +334,7 @@ class Commit
   def repo_changes
     changes = { added: [], modified: [], removed: [] }
 
-    raw_diffs.each do |diff|
+    raw_diffs(deltas_only: true).each do |diff|
       if diff.deleted_file
         changes[:removed] << diff.old_path
       elsif diff.renamed_file || diff.new_file

app/models/repository.rb

@@ -372,7 +372,7 @@ class Repository
     # We don't want to flush the cache if the commit didn't actually make any
     # changes to any of the possible avatar files.
     if revision && commit = self.commit(revision)
-      return unless commit.raw_diffs.
+      return unless commit.raw_diffs(deltas_only: true).
         any? { |diff| AVATAR_FILES.include?(diff.new_path) }
     end
 

app/workers/irker_worker.rb

@@ -141,7 +141,7 @@ class IrkerWorker
   end
 
   def files_count(commit)
-    diffs = commit.raw_diffs
+    diffs = commit.raw_diffs(deltas_only: true)
 
     files = "#{diffs.real_size} file"
     files += 's' if diffs.size > 1