Add graphs showing commits ahead and behind default to branches page

CHANGELOG

@@ -16,6 +16,7 @@ v 8.2.0 (unreleased)
   - Fix: 500 error returned if destroy request without HTTP referer (Kazuki Shimizu)
   - Remove deprecated CI events from project settings page
   - Use issue editor as cross reference comment author when issue is edited with a new mention.
+  - Add graphs of commits ahead and behind default branch (Jeff Stubler)
 
 v 8.1.1
   - Fix cloning Wiki repositories via HTTP (Stan Hu)

app/assets/stylesheets/pages/commits.scss

@@ -113,3 +113,62 @@ li.commit {
     }
   }
 }
+
+.divergence-graph {
+  padding: 12px 12px 0 0;
+  float: right;
+  
+  .graph-side {
+    position: relative;
+    width: 80px;
+    height: 22px;
+    padding: 5px 0 13px;
+    float: left;
+    
+    .bar {
+      position: absolute;
+      height: 4px;
+      background-color: #ccc;
+    }
+
+    .bar-behind {
+      right: 0;
+      border-radius: 3px 0 0 3px;
+    }
+
+    .bar-ahead {
+      left: 0;
+      border-radius: 0 3px 3px 0;
+    }
+    
+    .count {
+      padding-top: 6px;
+      padding-bottom: 0px;
+      font-size: 12px;
+      color: #333;
+      display: block;
+    }
+
+    .count-behind {
+      padding-right: 4px;
+      text-align: right;
+    }
+
+    .count-ahead {
+      padding-left: 4px;
+      text-align: left;
+    }
+  }
+
+  .graph-separator {
+    position: relative;
+    width: 1px;
+    height: 18px;
+    margin: 5px 0 0;
+    float: left;
+    background-color: #ccc;
+  }
+}
+
+
+

app/controllers/projects/branches_controller.rb

@@ -9,6 +9,12 @@ class Projects::BranchesController < Projects::ApplicationController
     @sort = params[:sort] || 'name'
     @branches = @repository.branches_sorted_by(@sort)
     @branches = Kaminari.paginate_array(@branches).page(params[:page]).per(PER_PAGE)
+    
+    @max_commits = @branches.reduce(0) do
+      |memo, branch|
+      diverging_commit_counts = repository.diverging_commit_counts(branch)
+      [memo, diverging_commit_counts[:behind], diverging_commit_counts[:ahead]].max
+    end
   end
 
   def recent

app/models/project.rb

@@ -714,6 +714,8 @@ class Project < ActiveRecord::Base
   end
 
   def change_head(branch)
+    # Cached divergent commit counts are based on repository head
+    repository.expire_branch_cache
     gitlab_shell.update_repository_head(self.path_with_namespace, branch)
     reload_default_branch
   end

app/models/repository.rb

@@ -147,9 +147,26 @@ class Repository
     cache.fetch(:size) { raw_repository.size }
   end
   
+  def diverging_commit_counts(branch)
+    branch_cache_key = ('diverging_commit_counts_' + branch.name).to_sym
+    cache.fetch(branch_cache_key) do
+      number_commits_behind = commits_between(branch.name, root_ref).size
+      number_commits_ahead = commits_between(root_ref, branch.name).size
+      
+      { behind: number_commits_behind, ahead: number_commits_ahead }
+    end
+  end
+
   def cache_keys
-    %i(size branch_names tag_names commit_count
-       readme version contribution_guide changelog license)
+    %i(size branch_names tag_names commit_count readme
+       contribution_guide changelog license)
+  end
+  
+  def branch_cache_keys
+    branches.map do
+      |branch|
+      ('diverging_commit_counts_' + branch.name).to_sym
+    end
   end
 
   def build_cache
@@ -158,12 +175,28 @@ class Repository
         send(key)
       end
     end
+    
+    branches.each do |branch|
+      unless cache.exist?(('diverging_commit_counts_' + branch.name).to_sym)
+        send(:diverging_commit_counts, branch)
+      end
+    end
   end
 
   def expire_cache
     cache_keys.each do |key|
       cache.expire(key)
     end
+    
+    branches.each do |branch|
+      cache.expire(('diverging_commit_counts_' + branch.name).to_sym)
+    end
+  end
+  
+  def expire_branch_cache
+    branches.each do |branch|
+      cache.expire(('diverging_commit_counts_' + branch.name).to_sym)
+    end
   end
 
   def rebuild_cache
@@ -171,6 +204,11 @@ class Repository
       cache.expire(key)
       send(key)
     end
+    
+    branches.each do |branch|
+      cache.expire(('diverging_commit_counts_' + branch.name).to_sym)
+      send(:diverging_commit_counts, branch)
+    end
   end
 
   def lookup_cache

app/views/projects/branches/_branch.html.haml

 - commit = @repository.commit(branch.target)
+- bar_graph_width_factor = @max_commits > 0 ? 100.0/@max_commits : 0
+- number_commits_behind = @repository.diverging_commit_counts(branch)[:behind]
+- number_commits_ahead = @repository.diverging_commit_counts(branch)[:ahead]
 %li(class="js-branch-#{branch.name}")
   %div
     = link_to namespace_project_tree_path(@project.namespace, @project, branch.name) do
@@ -29,6 +32,17 @@
         = link_to namespace_project_branch_path(@project.namespace, @project, branch.name), class: 'btn btn-grouped btn-xs btn-remove remove-row', method: :delete, data: { confirm: 'Removed branch cannot be restored. Are you sure?'}, remote: true do
           = icon("trash-o")
 
+    - if branch.name != @repository.root_ref
+      .divergence-graph{ :title => "#{number_commits_ahead} commits ahead, #{number_commits_behind} commits behind #{@repository.root_ref}" }
+        .graph-side
+          .bar.bar-behind{ :style => "width: #{number_commits_behind * bar_graph_width_factor}%" }
+          %span.count.count-behind= number_commits_behind
+        .graph-separator
+        .graph-side
+          .bar.bar-ahead{ :style => "width: #{number_commits_ahead * bar_graph_width_factor}%" }
+          %span.count.count-ahead= number_commits_ahead
+
+
   - if commit
     = render 'projects/branches/commit', commit: commit, project: @project
   - else