Count wiki page creation

This adds a counter to count page creation, which is reflected in the
usage-data we collect.

The number created is stored in Redis, avoiding DB access.

12 files changed, 270 insertions, 16 deletions

diff --git a/app/services/wiki_pages/base_service.rb b/app/services/wiki_pages/base_service.rb
index e259f5bd1bc..b9df690c2b7 100644
--- a/app/services/wiki_pages/base_service.rb
+++ b/app/services/wiki_pages/base_service.rb
@@ -8,6 +8,12 @@ module WikiPages
       page_data = Gitlab::DataBuilder::WikiPage.build(page, current_user, action)
       @project.execute_hooks(page_data, :wiki_page_hooks)
       @project.execute_services(page_data, :wiki_page_hooks)
+      increment_usage(action)
+    end
+
+    # This method throws an error if the action is an unanticipated value.
+    def increment_usage(action)
+      Gitlab::UsageDataCounters::WikiPageCounter.count(action)
     end
   end
 end
diff --git a/changelogs/unreleased/wiki-usage-pings.yml b/changelogs/unreleased/wiki-usage-pings.yml
new file mode 100644
index 00000000000..c3d084228c3
--- /dev/null
+++ b/changelogs/unreleased/wiki-usage-pings.yml
@@ -0,0 +1,5 @@
+---
+title: Count wiki creation, update and delete events
+merge_request: 30864
+author:
+type: added
diff --git a/lib/gitlab/usage_data.rb b/lib/gitlab/usage_data.rb
index 43072053e57..db1086c9cae 100644
--- a/lib/gitlab/usage_data.rb
+++ b/lib/gitlab/usage_data.rb
@@ -6,7 +6,9 @@ module Gitlab
 
     class << self
       def data(force_refresh: false)
-        Rails.cache.fetch('usage_data', force: force_refresh, expires_in: 2.weeks) { uncached_data }
+        Rails.cache.fetch('usage_data', force: force_refresh, expires_in: 2.weeks) do
+          uncached_data
+        end
       end
 
       def uncached_data
@@ -128,12 +130,15 @@ module Gitlab
         }
       end
 
+      # @return [Hash<Symbol, Integer>]
       def usage_counters
-        {
-          web_ide_commits: Gitlab::UsageDataCounters::WebIdeCounter.total_commits_count,
-          web_ide_merge_requests: Gitlab::UsageDataCounters::WebIdeCounter.total_merge_requests_count,
-          web_ide_views: Gitlab::UsageDataCounters::WebIdeCounter.total_views_count
-        }
+        usage_data_counters.map(&:totals).reduce({}) { |a, b| a.merge(b) }
+      end
+
+      # @return [Array<#totals>] An array of objects that respond to `#totals`
+      def usage_data_counters
+        [Gitlab::UsageDataCounters::WikiPageCounter,
+         Gitlab::UsageDataCounters::WebIdeCounter]
       end
 
       def components_usage_data
diff --git a/lib/gitlab/usage_data_counters/web_ide_counter.rb b/lib/gitlab/usage_data_counters/web_ide_counter.rb
index 899ad0db9c0..0718c1dd761 100644
--- a/lib/gitlab/usage_data_counters/web_ide_counter.rb
+++ b/lib/gitlab/usage_data_counters/web_ide_counter.rb
@@ -33,6 +33,14 @@ module Gitlab
         def total_views_count
           total_count(VIEWS_COUNT_KEY)
         end
+
+        def totals
+          {
+            web_ide_commits: total_commits_count,
+            web_ide_views: total_views_count,
+            web_ide_merge_requests: total_merge_requests_count
+          }
+        end
       end
     end
   end
diff --git a/lib/gitlab/usage_data_counters/wiki_page_counter.rb b/lib/gitlab/usage_data_counters/wiki_page_counter.rb
new file mode 100644
index 00000000000..c8b59a3160c
--- /dev/null
+++ b/lib/gitlab/usage_data_counters/wiki_page_counter.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module Gitlab::UsageDataCounters
+  class WikiPageCounter
+    extend RedisCounter
+
+    KNOWN_EVENTS = %w[create update delete].map(&:freeze).freeze
+
+    UnknownEvent = Class.new(StandardError)
+
+    class << self
+      # Each event gets a unique Redis key
+      def redis_key(event)
+        raise UnknownEvent, event unless KNOWN_EVENTS.include?(event.to_s)
+
+        "USAGE_WIKI_PAGES_#{event}".upcase
+      end
+
+      def count(event)
+        increment(redis_key event)
+      end
+
+      def read(event)
+        total_count(redis_key event)
+      end
+
+      def totals
+        KNOWN_EVENTS.map { |e| ["wiki_pages_#{e}".to_sym, read(e)] }.to_h
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/usage_data_counters/web_ide_counter_spec.rb b/spec/lib/gitlab/usage_data_counters/web_ide_counter_spec.rb
index b5e32d1875f..7a01f7d1de8 100644
--- a/spec/lib/gitlab/usage_data_counters/web_ide_counter_spec.rb
+++ b/spec/lib/gitlab/usage_data_counters/web_ide_counter_spec.rb
@@ -33,4 +33,24 @@ describe Gitlab::UsageDataCounters::WebIdeCounter, :clean_gitlab_redis_shared_st
 
     it_behaves_like 'counter examples'
   end
+
+  describe '.totals' do
+    commits = 5
+    merge_requests = 3
+    views = 2
+
+    before do
+      commits.times { described_class.increment_commits_count }
+      merge_requests.times { described_class.increment_merge_requests_count }
+      views.times { described_class.increment_views_count }
+    end
+
+    it 'can report all totals' do
+      expect(described_class.totals).to include(
+        web_ide_commits: commits,
+        web_ide_views: views,
+        web_ide_merge_requests: merge_requests
+      )
+    end
+  end
 end
diff --git a/spec/lib/gitlab/usage_data_counters/wiki_page_counter_spec.rb b/spec/lib/gitlab/usage_data_counters/wiki_page_counter_spec.rb
new file mode 100644
index 00000000000..41afbbb191c
--- /dev/null
+++ b/spec/lib/gitlab/usage_data_counters/wiki_page_counter_spec.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::UsageDataCounters::WikiPageCounter, :clean_gitlab_redis_shared_state do
+  shared_examples :wiki_page_event do |event|
+    describe ".count(#{event})" do
+      it "increments the wiki page #{event} counter by 1" do
+        expect do
+          described_class.count(event)
+        end.to change { described_class.read(event) }.by 1
+      end
+    end
+
+    describe ".read(#{event})" do
+      event_count = 5
+
+      it "returns the total number of #{event} events" do
+        event_count.times do
+          described_class.count(event)
+        end
+
+        expect(described_class.read(event)).to eq(event_count)
+      end
+    end
+  end
+
+  include_examples :wiki_page_event, :create
+  include_examples :wiki_page_event, :update
+  include_examples :wiki_page_event, :delete
+
+  describe 'totals' do
+    creations = 5
+    edits = 3
+    deletions = 2
+
+    before do
+      creations.times do
+        described_class.count(:create)
+      end
+      edits.times do
+        described_class.count(:update)
+      end
+      deletions.times do
+        described_class.count(:delete)
+      end
+    end
+
+    it 'can report all totals' do
+      expect(described_class.totals).to include(
+        wiki_pages_update: edits,
+        wiki_pages_create: creations,
+        wiki_pages_delete: deletions
+      )
+    end
+  end
+
+  describe 'unknown events' do
+    error = described_class::UnknownEvent
+
+    it 'cannot increment' do
+      expect { described_class.count(:wibble) }.to raise_error error
+    end
+
+    it 'cannot read' do
+      expect { described_class.read(:wibble) }.to raise_error error
+    end
+  end
+end
diff --git a/spec/lib/gitlab/usage_data_spec.rb b/spec/lib/gitlab/usage_data_spec.rb
index 270dd652c20..2289d906944 100644
--- a/spec/lib/gitlab/usage_data_spec.rb
+++ b/spec/lib/gitlab/usage_data_spec.rb
@@ -57,20 +57,18 @@ describe Gitlab::UsageData do
         gitaly
         database
         avg_cycle_analytics
-        web_ide_views
-        web_ide_commits
-        web_ide_merge_requests
         influxdb_metrics_enabled
         prometheus_metrics_enabled
       ))
-    end
-
-    it 'calls expected usage data methods' do
-      expect(Gitlab::UsageDataCounters::WebIdeCounter).to receive(:total_commits_count)
-      expect(Gitlab::UsageDataCounters::WebIdeCounter).to receive(:total_merge_requests_count)
-      expect(Gitlab::UsageDataCounters::WebIdeCounter).to receive(:total_views_count)
 
-      subject
+      expect(subject).to include(
+        wiki_pages_create: a_kind_of(Integer),
+        wiki_pages_update: a_kind_of(Integer),
+        wiki_pages_delete: a_kind_of(Integer),
+        web_ide_views: a_kind_of(Integer),
+        web_ide_commits: a_kind_of(Integer),
+        web_ide_merge_requests: a_kind_of(Integer)
+      )
     end
 
     it "gathers usage counts" do
@@ -192,6 +190,28 @@ describe Gitlab::UsageData do
     end
   end
 
+  describe '#usage_data_counters' do
+    subject { described_class.usage_data_counters }
+
+    it { is_expected.to all(respond_to :totals) }
+
+    describe 'the results of calling #totals on all objects in the array' do
+      subject { described_class.usage_data_counters.map(&:totals) }
+
+      it do
+        is_expected
+          .to all(be_a Hash)
+          .and all(have_attributes(keys: all(be_a Symbol), values: all(be_a Integer)))
+      end
+    end
+
+    it 'does not have any conflicts' do
+      all_keys = subject.flat_map { |counter| counter.totals.keys }
+
+      expect(all_keys.size).to eq all_keys.to_set.size
+    end
+  end
+
   describe '#features_usage_data_ce' do
     subject { described_class.features_usage_data_ce }
 
diff --git a/spec/services/wiki_pages/base_service_spec.rb b/spec/services/wiki_pages/base_service_spec.rb
new file mode 100644
index 00000000000..2e70246c6f2
--- /dev/null
+++ b/spec/services/wiki_pages/base_service_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe WikiPages::BaseService do
+  let(:project) { double('project') }
+  let(:user) { double('user') }
+
+  subject(:service) { described_class.new(project, user, {}) }
+
+  describe '#increment_usage' do
+    counter = Gitlab::UsageDataCounters::WikiPageCounter
+    error = counter::UnknownEvent
+
+    it 'raises an error on unknown events' do
+      expect { subject.send(:increment_usage, :bad_event) }.to raise_error error
+    end
+
+    context 'the event is valid' do
+      counter::KNOWN_EVENTS.each do |e|
+        it "updates the #{e} counter" do
+          expect { subject.send(:increment_usage, e) }.to change { counter.read(e) }
+        end
+      end
+    end
+  end
+end
diff --git a/spec/services/wiki_pages/create_service_spec.rb b/spec/services/wiki_pages/create_service_spec.rb
index 84510dcf700..ef03a2e9788 100644
--- a/spec/services/wiki_pages/create_service_spec.rb
+++ b/spec/services/wiki_pages/create_service_spec.rb
@@ -14,6 +14,10 @@ describe WikiPages::CreateService do
     }
   end
 
+  let(:bad_opts) do
+    { title: '' }
+  end
+
   subject(:service) { described_class.new(project, user, opts) }
 
   before do
@@ -36,5 +40,26 @@ describe WikiPages::CreateService do
 
       service.execute
     end
+
+    it 'counts wiki page creation' do
+      counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+      expect { service.execute }.to change { counter.read(:create) }.by 1
+    end
+
+    context 'when the options are bad' do
+      subject(:service) { described_class.new(project, user, bad_opts) }
+
+      it 'does not count a creation event' do
+        counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+        expect { service.execute }.not_to change { counter.read(:create) }
+      end
+
+      it 'reports the error' do
+        expect(service.execute).to be_invalid
+          .and have_attributes(errors: be_present)
+      end
+    end
   end
 end
diff --git a/spec/services/wiki_pages/destroy_service_spec.rb b/spec/services/wiki_pages/destroy_service_spec.rb
index c74eac4dad6..350a7eb123b 100644
--- a/spec/services/wiki_pages/destroy_service_spec.rb
+++ b/spec/services/wiki_pages/destroy_service_spec.rb
@@ -20,5 +20,17 @@ describe WikiPages::DestroyService do
 
       service.execute(page)
     end
+
+    it 'increments the delete count' do
+      counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+      expect { service.execute(page) }.to change { counter.read(:delete) }.by 1
+    end
+
+    it 'does not increment the delete count if the deletion failed' do
+      counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+      expect { service.execute(nil) }.not_to change { counter.read(:delete) }
+    end
   end
 end
diff --git a/spec/services/wiki_pages/update_service_spec.rb b/spec/services/wiki_pages/update_service_spec.rb
index 19866bd3bfc..d5f46e7b2db 100644
--- a/spec/services/wiki_pages/update_service_spec.rb
+++ b/spec/services/wiki_pages/update_service_spec.rb
@@ -16,6 +16,10 @@ describe WikiPages::UpdateService do
     }
   end
 
+  let(:bad_opts) do
+    { title: '' }
+  end
+
   subject(:service) { described_class.new(project, user, opts) }
 
   before do
@@ -39,5 +43,26 @@ describe WikiPages::UpdateService do
 
       service.execute(page)
     end
+
+    it 'counts edit events' do
+      counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+      expect { service.execute page }.to change { counter.read(:update) }.by 1
+    end
+
+    context 'when the options are bad' do
+      subject(:service) { described_class.new(project, user, bad_opts) }
+
+      it 'does not count an edit event' do
+        counter = Gitlab::UsageDataCounters::WikiPageCounter
+
+        expect { service.execute page }.not_to change { counter.read(:update) }
+      end
+
+      it 'reports the error' do
+        expect(service.execute page).to be_invalid
+          .and have_attributes(errors: be_present)
+      end
+    end
   end
 end