Fix race conditions for AuthorizedProjectsWorkerrefresh-authorizations-fork-join

There were two cases that could be problematic:

1. Because sometimes AuthorizedProjectsWorker would be scheduled in a
   transaction it was possible for a job to run/complete before a
   COMMIT; resulting in it either producing an error, or producing no
   new data.

2. When scheduling jobs the code would not wait until completion. This
   could lead to a user creating a project and then immediately trying
   to push to it. Usually this will work fine, but given enough load it
   might take a few seconds before a user has access.

The first one is problematic, the second one is mostly just annoying
(but annoying enough to warrant a solution).

This commit changes two things to deal with this:

1. Sidekiq scheduling now takes places after a COMMIT, this is ensured
   by scheduling using Rails' after_commit hook instead of doing so in
   an arbitrary method.

2. When scheduling jobs the calling thread now waits for all jobs to
   complete.

Solution 2 requires tracking of job completions. Sidekiq provides a way
to find a job by its ID, but this involves scanning over the entire
queue; something that is very in-efficient for large queues. As such a
more efficient solution is necessary. There are two main Gems that can
do this in a more efficient manner:

* sidekiq-status
* sidekiq_status

No, this is not a joke. Both Gems do a similar thing (but slightly
different), and the only difference in their name is a dash vs an
underscore. Both Gems however provide far more than just checking if a
job has been completed, and both have their problems. sidekiq-status
does not appear to be actively maintained, with the last release being
in 2015. It also has some issues during testing as API calls are not
stubbed in any way. sidekiq_status on the other hand does not appear to
be very popular, and introduces a similar amount of code.

Because of this I opted to write a simple home grown solution. After
all, all we need is storing a job ID somewhere so we can efficiently
look it up; we don't need extra web UIs (as provided by sidekiq-status)
or complex APIs to update progress, etc.

This is where Gitlab::SidekiqStatus comes in handy. This namespace
contains some code used for tracking, removing, and looking up job IDs;
all without having to scan over an entire queue. Data is removed
explicitly, but also expires automatically just in case.

Using this API we can now schedule jobs in a fork-join like manner: we
schedule the jobs in Sidekiq, process them in parallel, then wait for
completion. By using Sidekiq we can leverage all the benefits such as
being able to scale across multiple cores and hosts, retrying failed
jobs, etc.

The one downside is that we need to make sure we can deal with
unexpected increases in job processing timings. To deal with this the
class Gitlab::JobWaiter (used for waiting for jobs to complete) will
only wait a number of seconds (30 by default). Once this timeout is
reached it will simply return.

For GitLab.com almost all AuthorizedProjectWorker jobs complete in
seconds, only very rarely do we spike to job timings of around a minute.
These in turn seem to be the result of external factors (e.g. deploys),
in which case a user is most likely not able to use the system anyway.

In short, this new solution should ensure that jobs are processed
properly and that in almost all cases a user has access to their
resources whenever they need to have access.

14 files changed, 37 insertions, 11 deletions

diff --git a/db/fixtures/development/01_admin.rb b/db/fixtures/development/01_admin.rb
index bba2fc4b186..6f241f6fa4a 100644
--- a/db/fixtures/development/01_admin.rb
+++ b/db/fixtures/development/01_admin.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   User.seed do |s|
     s.id = 1
diff --git a/db/fixtures/development/04_project.rb b/db/fixtures/development/04_project.rb
index a984eda5ab5..c2b8f7ba819 100644
--- a/db/fixtures/development/04_project.rb
+++ b/db/fixtures/development/04_project.rb
@@ -1,4 +1,4 @@
-require 'sidekiq/testing'
+require './spec/support/sidekiq'
 
 Sidekiq::Testing.inline! do
   Gitlab::Seeder.quiet do
diff --git a/db/fixtures/development/05_users.rb b/db/fixtures/development/05_users.rb
index 03da29c4c68..101ff3a1209 100644
--- a/db/fixtures/development/05_users.rb
+++ b/db/fixtures/development/05_users.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   20.times do |i|
     begin
diff --git a/db/fixtures/development/06_teams.rb b/db/fixtures/development/06_teams.rb
index 5c2a03fec3f..86e0a38aae1 100644
--- a/db/fixtures/development/06_teams.rb
+++ b/db/fixtures/development/06_teams.rb
@@ -1,4 +1,4 @@
-require 'sidekiq/testing'
+require './spec/support/sidekiq'
 
 Sidekiq::Testing.inline! do
   Gitlab::Seeder.quiet do
diff --git a/db/fixtures/development/07_milestones.rb b/db/fixtures/development/07_milestones.rb
index 540e4e68259..271bfbc97e0 100644
--- a/db/fixtures/development/07_milestones.rb
+++ b/db/fixtures/development/07_milestones.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   Project.all.each do |project|
     5.times do |i|
diff --git a/db/fixtures/development/09_issues.rb b/db/fixtures/development/09_issues.rb
index 4fa572fca9b..d93d133d157 100644
--- a/db/fixtures/development/09_issues.rb
+++ b/db/fixtures/development/09_issues.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   Project.all.each do |project|
     10.times do
diff --git a/db/fixtures/development/10_merge_requests.rb b/db/fixtures/development/10_merge_requests.rb
index 87fb8e3300d..c04afe97277 100644
--- a/db/fixtures/development/10_merge_requests.rb
+++ b/db/fixtures/development/10_merge_requests.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   # Limit the number of merge requests per project to avoid long seeds
   MAX_NUM_MERGE_REQUESTS = 10
diff --git a/db/fixtures/development/11_keys.rb b/db/fixtures/development/11_keys.rb
index 8b4bee384e1..51e22137d6f 100644
--- a/db/fixtures/development/11_keys.rb
+++ b/db/fixtures/development/11_keys.rb
@@ -1,12 +1,18 @@
-Gitlab::Seeder.quiet do
-  User.first(10).each do |user|
-    key = "ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt#{user.id + 100}6k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0="
+require './spec/support/sidekiq'
 
-    user.keys.create(
-      title: "Sample key #{user.id}",
-      key: key
-    )
+# Creating keys runs a gitlab-shell worker. Since we may not have the right
+# gitlab-shell path set (yet) we need to disable this for these fixtures.
+Sidekiq::Testing.disable! do
+  Gitlab::Seeder.quiet do
+    User.first(10).each do |user|
+      key = "ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt#{user.id + 100}6k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0="
 
-    print '.'
+      user.keys.create(
+        title: "Sample key #{user.id}",
+        key: key
+      )
+
+      print '.'
+    end
   end
 end
diff --git a/db/fixtures/development/12_snippets.rb b/db/fixtures/development/12_snippets.rb
index 74898544a69..4f3bdba043d 100644
--- a/db/fixtures/development/12_snippets.rb
+++ b/db/fixtures/development/12_snippets.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   content =<<eos
 class Member < ActiveRecord::Base
diff --git a/db/fixtures/development/13_comments.rb b/db/fixtures/development/13_comments.rb
index 566c0705638..29b8081055d 100644
--- a/db/fixtures/development/13_comments.rb
+++ b/db/fixtures/development/13_comments.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   Issue.all.each do |issue|
     project = issue.project
diff --git a/db/fixtures/development/14_pipelines.rb b/db/fixtures/development/14_pipelines.rb
index be95d788850..534847a7107 100644
--- a/db/fixtures/development/14_pipelines.rb
+++ b/db/fixtures/development/14_pipelines.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 class Gitlab::Seeder::Pipelines
   STAGES = %w[build test deploy notify]
   BUILDS = [
diff --git a/db/fixtures/development/15_award_emoji.rb b/db/fixtures/development/15_award_emoji.rb
index baac32f2d10..ea343c26b69 100644
--- a/db/fixtures/development/15_award_emoji.rb
+++ b/db/fixtures/development/15_award_emoji.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   emoji = Gitlab::AwardEmoji.emojis.keys
 
diff --git a/db/fixtures/development/16_protected_branches.rb b/db/fixtures/development/16_protected_branches.rb
index 103c7f9445c..39d466fb43f 100644
--- a/db/fixtures/development/16_protected_branches.rb
+++ b/db/fixtures/development/16_protected_branches.rb
@@ -1,3 +1,5 @@
+require './spec/support/sidekiq'
+
 Gitlab::Seeder.quiet do
   admin_user = User.find(1)
 
diff --git a/db/fixtures/development/17_cycle_analytics.rb b/db/fixtures/development/17_cycle_analytics.rb
index 916ee8dbac8..747901dd634 100644
--- a/db/fixtures/development/17_cycle_analytics.rb
+++ b/db/fixtures/development/17_cycle_analytics.rb
@@ -1,4 +1,4 @@
-require 'sidekiq/testing'
+require './spec/support/sidekiq'
 require './spec/support/test_env'
 
 class Gitlab::Seeder::CycleAnalytics