More robust PuSH subscription refreshes (#2799)

* Fix #2473 - Use sidekiq scheduler to refresh PuSH subscriptions instead of cron

Fix an issue where / in domain would raise exception in TagManager#normalize_domain

PuSH subscriptions refresh done in a round-robin way to avoid hammering a single
server's hub in sequence. Correct handling of failures/retries through Sidekiq (see
also #2613). Optimize Account#with_followers scope. Also, since subscriptions
are now delegated to Sidekiq jobs, an uncaught exception will not stop the entire
refreshing operation halfway through

Fix #2702 - Correct user agent header on outgoing http requests

* Add test for SubscribeService

* Extract #expiring_accounts into method

* Make mastodon:push:refresh no-op

* Queues are now defined in sidekiq.yml

* Queues are now in sidekiq.yml

10 files changed, 81 insertions, 17 deletions

diff --git a/app/helpers/http_helper.rb b/app/helpers/http_helper.rb
index 1697de746..e39a52da0 100644
--- a/app/helpers/http_helper.rb
+++ b/app/helpers/http_helper.rb
@@ -1,13 +1,17 @@
 # frozen_string_literal: true
 
 module HttpHelper
-  USER_AGENT = "#{HTTP::Request::USER_AGENT} (Mastodon/#{Mastodon::Version}; +http://#{Rails.configuration.x.local_domain}/)"
-
   def http_client(options = {})
     timeout = { write: 10, connect: 10, read: 10 }.merge(options)
 
-    HTTP.headers(user_agent: USER_AGENT)
+    HTTP.headers(user_agent: user_agent)
         .timeout(:per_operation, timeout)
         .follow
   end
+
+  private
+
+  def user_agent
+    @user_agent ||= "#{HTTP::Request::USER_AGENT} (Mastodon/#{Mastodon::Version}; +http://#{Rails.configuration.x.local_domain}/)"
+  end
 end
diff --git a/app/lib/tag_manager.rb b/app/lib/tag_manager.rb
index 3bddfba7c..6170a90de 100644
--- a/app/lib/tag_manager.rb
+++ b/app/lib/tag_manager.rb
@@ -65,8 +65,10 @@ class TagManager
   end
 
   def normalize_domain(domain)
+    return if domain.nil?
+
     uri = Addressable::URI.new
-    uri.host = domain
+    uri.host = domain.gsub(/[\/]/, '')
     uri.normalize.host
   end
 
diff --git a/app/models/account.rb b/app/models/account.rb
index d64591641..87b97a20d 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -103,9 +103,10 @@ class Account < ApplicationRecord
 
   scope :remote, -> { where.not(domain: nil) }
   scope :local, -> { where(domain: nil) }
-  scope :without_followers, -> { where('(select count(f.id) from follows as f where f.target_account_id = accounts.id) = 0') }
-  scope :with_followers, -> { where('(select count(f.id) from follows as f where f.target_account_id = accounts.id) > 0') }
+  scope :without_followers, -> { where(followers_count: 0) }
+  scope :with_followers, -> { where('followers_count > 0') }
   scope :expiring, ->(time) { where(subscription_expires_at: nil).or(where('subscription_expires_at < ?', time)).remote.with_followers }
+  scope :partitioned, -> { order('row_number() over (partition by domain)') }
   scope :silenced, -> { where(silenced: true) }
   scope :suspended, -> { where(suspended: true) }
   scope :recent, -> { reorder(id: :desc) }
diff --git a/app/services/follow_service.rb b/app/services/follow_service.rb
index 844f5282d..23e721fac 100644
--- a/app/services/follow_service.rb
+++ b/app/services/follow_service.rb
@@ -40,7 +40,7 @@ class FollowService < BaseService
     if target_account.local?
       NotifyService.new.call(target_account, follow)
     else
-      SubscribeService.new.call(target_account) unless target_account.subscribed?
+      Pubsubhubbub::SubscribeWorker.perform_async(target_account.id) unless target_account.subscribed?
       NotificationWorker.perform_async(build_follow_xml(follow), source_account.id, target_account.id)
       AfterRemoteFollowWorker.perform_async(follow.id)
     end
diff --git a/app/services/process_interaction_service.rb b/app/services/process_interaction_service.rb
index 1f15a265d..16eac2353 100644
--- a/app/services/process_interaction_service.rb
+++ b/app/services/process_interaction_service.rb
@@ -77,7 +77,7 @@ class ProcessInteractionService < BaseService
   def authorize_follow_request!(account, target_account)
     follow_request = FollowRequest.find_by(account: target_account, target_account: account)
     follow_request&.authorize!
-    SubscribeService.new.call(account) unless account.subscribed?
+    Pubsubhubbub::SubscribeWorker.perform_async(account.id) unless account.subscribed?
   end
 
   def reject_follow_request!(account, target_account)
diff --git a/app/services/subscribe_service.rb b/app/services/subscribe_service.rb
index 820b208e9..138718f14 100644
--- a/app/services/subscribe_service.rb
+++ b/app/services/subscribe_service.rb
@@ -5,15 +5,31 @@ class SubscribeService < BaseService
     account.secret = SecureRandom.hex
 
     subscription = account.subscription(api_subscription_url(account.id))
-    response = subscription.subscribe
+    response     = subscription.subscribe
 
-    unless response.successful?
+    if response_failed_permanently?(response)
+      # An error in the 4xx range (except for 429, which is rate limiting)
+      # means we're not allowed to subscribe. Fail and move on
       account.secret = ''
-      Rails.logger.debug "PuSH subscription request for #{account.acct} failed: #{response.message}"
+      account.save!
+    elsif response_successful?(response)
+      # Anything in the 2xx range means the subscription will be confirmed
+      # asynchronously, we've done what we needed to do
+      account.save!
+    else
+      # What's left is the 5xx range and 429, which means we need to retry
+      # at a later time. Fail loudly!
+      raise "Subscription attempt failed for #{account.acct} (#{account.hub_url}): HTTP #{response.code}"
     end
+  end
+
+  private
+
+  def response_failed_permanently?(response)
+    response.code > 299 && response.code < 500 && response.code != 429
+  end
 
-    account.save!
-  rescue HTTP::Error, OpenSSL::SSL::SSLError
-    Rails.logger.debug "PuSH subscription request for #{account.acct} could not be made due to HTTP or SSL error"
+  def response_successful?(response)
+    response.code > 199 && response.code < 300
   end
 end
diff --git a/app/services/update_remote_profile_service.rb b/app/services/update_remote_profile_service.rb
index 31f4af2c1..f0c39ecc0 100644
--- a/app/services/update_remote_profile_service.rb
+++ b/app/services/update_remote_profile_service.rb
@@ -28,7 +28,7 @@ class UpdateRemoteProfileService < BaseService
 
     account.save_with_optional_avatar!
 
-    SubscribeService.new.call(account) if resubscribe && (account.hub_url != old_hub_url)
+    Pubsubhubbub::SubscribeWorker.perform_async(account.id) if resubscribe && (account.hub_url != old_hub_url)
   end
 
   private
diff --git a/app/workers/pubsubhubbub/delivery_worker.rb b/app/workers/pubsubhubbub/delivery_worker.rb
index f645b1e24..511ae14b3 100644
--- a/app/workers/pubsubhubbub/delivery_worker.rb
+++ b/app/workers/pubsubhubbub/delivery_worker.rb
@@ -25,8 +25,8 @@ class Pubsubhubbub::DeliveryWorker
                    .headers(headers)
                    .post(subscription.callback_url, body: payload)
 
-    return subscription.destroy! if response.code > 299 && response.code < 500 && response.code != 429 # HTTP 4xx means error is not temporary, except for 429 (throttling)
-    raise "Delivery failed for #{subscription.callback_url}: HTTP #{response.code}" unless response.code > 199 && response.code < 300
+    return subscription.destroy! if response_failed_permanently?(response) # HTTP 4xx means error is not temporary, except for 429 (throttling)
+    raise "Delivery failed for #{subscription.callback_url}: HTTP #{response.code}" unless response_successful?(response)
 
     subscription.touch(:last_successful_delivery_at)
   end
@@ -37,4 +37,12 @@ class Pubsubhubbub::DeliveryWorker
     hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha1'), secret, payload)
     "sha1=#{hmac}"
   end
+
+  def response_failed_permanently?(response)
+    response.code > 299 && response.code < 500 && response.code != 429
+  end
+
+  def response_successful?(response)
+    response.code > 199 && response.code < 300
+  end
 end
diff --git a/app/workers/pubsubhubbub/subscribe_worker.rb b/app/workers/pubsubhubbub/subscribe_worker.rb
new file mode 100644
index 000000000..0c4111a8c
--- /dev/null
+++ b/app/workers/pubsubhubbub/subscribe_worker.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class Pubsubhubbub::SubscribeWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: 'push'
+
+  def perform(account_id)
+    account = Account.find(account_id)
+    Rails.logger.debug "PuSH re-subscribing to #{account.acct}"
+    ::SubscribeService.new.call(account)
+  end
+end
diff --git a/app/workers/scheduler/subscriptions_scheduler.rb b/app/workers/scheduler/subscriptions_scheduler.rb
new file mode 100644
index 000000000..03622e95b
--- /dev/null
+++ b/app/workers/scheduler/subscriptions_scheduler.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+require 'sidekiq-scheduler'
+
+class Scheduler::SubscriptionsScheduler
+  include Sidekiq::Worker
+
+  def perform
+    Rails.logger.debug 'Queueing PuSH re-subscriptions'
+
+    expiring_accounts.pluck(:id) do |id|
+      Pubsubhubbub::SubscribeWorker.perform_async(id)
+    end
+  end
+
+  private
+
+  def expiring_accounts
+    Account.expiring(1.day.from_now).partitioned
+  end
+end