add auto-cancel for pending pipelines on branch, if they are not HEAD

fix changelog MR reference

add non-HEAD builds finder and add `created` pipelines to scope

add spec for auto-cancel non-HEAD pipelines and refactor create_pipeline_service_spec

more refactoring for spec

adds option for auto-cancel into CI/CD settings

fix spec to new configuration

fix rubocop

fix schema.rb

fix schema.rb

replace Gitlab 9.0 with 9.1 in doc

change wording on pipeline settings

added auto_canceled_by field as identifier of autocancel subject

remove unnecessary index

replace service with retry_lock

replace auto_cancel_pending_pipelines boolean setting with integer (and enum in model)

fix schema.rb

fix schema.rb

remove projekt attribute and clean up spec

clean up spec withcouple of shared examples

added spec for "It does not cancel current pipeline" scenario

add some specs to auto-cancel

add spec for another branch pipelines

app/controllers/projects/pipelines_settings_controller.rb

@@ -23,7 +23,7 @@ class Projects::PipelinesSettingsController < Projects::ApplicationController
   def update_params
     params.require(:project).permit(
       :runners_token, :builds_enabled, :build_allow_git_fetch, :build_timeout_in_minutes, :build_coverage_regex,
-      :public_builds
+      :public_builds, :auto_cancel_pending_pipelines
     )
   end
 end

app/models/ci/pipeline.rb

@@ -127,6 +127,14 @@ module Ci
       where.not(duration: nil).sum(:duration)
     end
 
+    def auto_cancelable_pipelines
+      project.pipelines
+        .where(ref: ref)
+        .where.not(id: id)
+        .where.not(sha: project.repository.sha_from_ref(ref))
+        .created_or_pending
+    end
+
     def stage(name)
       stage = Ci::Stage.new(self, name: name)
       stage unless stage.statuses_count.zero?

app/models/concerns/has_status.rb

@@ -76,6 +76,7 @@ module HasStatus
     scope :canceled, -> { where(status: 'canceled')  }
     scope :skipped, -> { where(status: 'skipped')  }
     scope :manual, -> { where(status: 'manual')  }
+    scope :created_or_pending, -> { where(status: [:created, :pending]) }
     scope :running_or_pending, -> { where(status: [:running, :pending]) }
     scope :finished, -> { where(status: [:success, :failed, :canceled]) }
     scope :failed_or_canceled, -> { where(status: [:failed, :canceled]) }

app/models/project.rb

@@ -256,6 +256,8 @@ class Project < ActiveRecord::Base
   scope :with_builds_enabled, -> { with_feature_enabled(:builds) }
   scope :with_issues_enabled, -> { with_feature_enabled(:issues) }
 
+  enum auto_cancel_pending_pipelines: { enabled: 1, disabled: 0 }
+
   # project features may be "disabled", "internal" or "enabled". If "internal",
   # they are only available to team members. This scope returns projects where
   # the feature is either enabled, or internal with permission for the user.

app/services/ci/create_pipeline_service.rb

@@ -53,6 +53,8 @@ module Ci
           .execute(pipeline)
       end
 
+      cancel_pending_pipelines if project.auto_cancel_pending_pipelines?
+
       pipeline.tap(&:process!)
     end
 
@@ -63,6 +65,16 @@ module Ci
       pipeline.git_commit_message =~ /\[(ci[ _-]skip|skip[ _-]ci)\]/i
     end
 
+    def cancel_pending_pipelines
+      Gitlab::OptimisticLocking.retry_lock(
+        pipeline.auto_cancelable_pipelines) do |cancelables|
+        cancelables.find_each do |cancelable|
+          cancelable.cancel_running
+          cancelable.update_attributes(auto_canceled_by: pipeline.id)
+        end
+      end
+    end
+
     def commit
       @commit ||= project.commit(origin_sha || origin_ref)
     end

app/views/projects/pipelines_settings/_show.html.haml

@@ -21,7 +21,7 @@
             Git strategy for pipelines
           %p
             Choose between <code>clone</code> or <code>fetch</code> to get the recent application code
-            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'git-strategy')
+            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'git-strategy'), target: '_blank'
           .radio
             = f.label :build_allow_git_fetch_false do
               = f.radio_button :build_allow_git_fetch, 'false'
@@ -43,7 +43,7 @@
           = f.number_field :build_timeout_in_minutes, class: 'form-control', min: '0'
           %p.help-block
             Per job in minutes. If a job passes this threshold, it will be marked as failed.
-            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'timeout')
+            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'timeout'), target: '_blank'
 
         %hr
         .form-group
@@ -53,7 +53,16 @@
               %strong Public pipelines
             .help-block
               Allow everyone to access pipelines for public and internal projects
-              = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'visibility-of-pipelines')
+              = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'visibility-of-pipelines'), target: '_blank'
+        %hr
+        .form-group
+          .checkbox
+            = f.label :auto_cancel_pending_pipelines do
+              = f.check_box :auto_cancel_pending_pipelines, {}, 'enabled', 'disabled'
+              %strong Auto-cancel redundant, pending pipelines
+            .help-block
+              New pipelines will cancel older, pending pipelines on the same branch
+              = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'auto-cancel-pending-pipelines'), target: '_blank'
 
         %hr
         .form-group
@@ -65,7 +74,7 @@
           %p.help-block
             A regular expression that will be used to find the test coverage
             output in the job trace. Leave blank to disable
-            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'test-coverage-parsing')
+            = link_to icon('question-circle'), help_page_path('user/project/pipelines/settings', anchor: 'test-coverage-parsing'), target: '_blank'
           .bs-callout.bs-callout-info
             %p Below are examples of regex for existing tools:
             %ul

changelogs/unreleased/8998_skip_pending_commits_if_not_head.yml

+---
+title: Cancel pending pipelines if commits not HEAD
+merge_request: 9362
+author: Rydkin Maxim

db/migrate/20170305180853_add_auto_cancel_pending_pipelines_to_project.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddAutoCancelPendingPipelinesToProject < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = 'Creating column with default value'
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  disable_ddl_transaction!
+
+  def up
+    add_column_with_default(:projects, :auto_cancel_pending_pipelines, :integer, default: 0)
+  end
+
+  def down
+    remove_column(:projects, :auto_cancel_pending_pipelines)
+  end
+end

db/migrate/20170312114329_add_auto_canceled_by_to_pipeline.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddAutoCanceledByToPipeline < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = ''
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+
+  def change
+    add_column :ci_commits, :auto_canceled_by, :integer
+  end
+end

db/schema.rb

@@ -251,6 +251,7 @@ ActiveRecord::Schema.define(version: 20170402231018) do
     t.integer "duration"
     t.integer "user_id"
     t.integer "lock_version"
+    t.integer "auto_canceled_by"
   end
 
   add_index "ci_pipelines", ["project_id", "ref", "status"], name: "index_ci_pipelines_on_project_id_and_ref_and_status", using: :btree
@@ -687,8 +688,8 @@ ActiveRecord::Schema.define(version: 20170402231018) do
     t.string "avatar"
     t.boolean "share_with_group_lock", default: false
     t.integer "visibility_level", default: 20, null: false
-    t.boolean "request_access_enabled", default: false, null: false
     t.datetime "deleted_at"
+    t.boolean "request_access_enabled", default: false, null: false
     t.text "description_html"
     t.boolean "lfs_enabled"
     t.integer "parent_id"
@@ -920,6 +921,7 @@ ActiveRecord::Schema.define(version: 20170402231018) do
     t.text "description_html"
     t.boolean "only_allow_merge_if_all_discussions_are_resolved"
     t.boolean "printing_merge_request_link_enabled", default: true, null: false
+    t.integer "auto_cancel_pending_pipelines", default: 0, null: false
   end
 
   add_index "projects", ["ci_id"], name: "index_projects_on_ci_id", using: :btree
@@ -1239,9 +1241,9 @@ ActiveRecord::Schema.define(version: 20170402231018) do
     t.boolean "hide_project_limit", default: false
     t.string "unlock_token"
     t.datetime "otp_grace_period_started_at"
+    t.string "incoming_email_token"
     t.boolean "ldap_email", default: false, null: false
     t.boolean "external", default: false
-    t.string "incoming_email_token"
     t.string "organization"
     t.boolean "authorized_projects_populated"
     t.boolean "ghost"

doc/user/project/pipelines/settings.md

@@ -60,6 +60,14 @@ anyone and those logged in respectively. If you wish to hide it so that only
 the members of the project or group have access to it, uncheck the **Public
 pipelines** checkbox and save the changes.
 
+## Auto-cancel pending pipelines
+
+> [Introduced][ce-9362] in GitLab 9.1.
+
+If you want to auto-cancel all pending non-HEAD pipelines on branch, when 
+new pipeline will be created (after your git push or manually from UI), 
+check **Auto-cancel pending pipelines** checkbox and save the changes.
+
 ## Badges
 
 In the pipelines settings page you can find pipeline status and test coverage
@@ -111,3 +119,4 @@ into your `README.md`:
 
 [var]: ../../../ci/yaml/README.md#git-strategy
 [coverage report]: #test-coverage-parsing
+[ce-9362]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9362