Merge pull request #321 from openstax/retry_prepared_statement_cache_expired

Retry ActiveRecord::PreparedStatementCacheExpired exceptions

Author: Dantemss

Gemfile

@@ -71,6 +71,9 @@ gem 'openstax_api'
 gem 'apipie-rails'
 gem 'maruku'
 
+# Retry failed database transactions
+gem 'transaction_retry', github: 'openstax/transaction_retry'
+
 # Lev framework
 gem 'lev'
 

Gemfile.lock

@@ -1,3 +1,11 @@
+GIT
+  remote: https://github.com/openstax/transaction_retry.git
+  revision: 5a148396c3b332a7e6a1ad5c7e6eb86b68f09829
+  specs:
+    transaction_retry (1.0.3)
+      activerecord (>= 3.0.11)
+      transaction_isolation (>= 1.0.2)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -480,9 +488,6 @@ GEM
     timecop (0.9.2)
     transaction_isolation (1.0.5)
       activerecord (>= 3.0.11)
-    transaction_retry (1.0.3)
-      activerecord (>= 3.0.11)
-      transaction_isolation (>= 1.0.2)
     turbolinks (5.2.1)
       turbolinks-source (~> 5.2)
     turbolinks-source (5.2.0)
@@ -575,6 +580,7 @@ DEPENDENCIES
   sortability
   thin
   timecop
+  transaction_retry!
   turbolinks
   uglifier (>= 1.3.0)
   web-console

config/initializers/transaction_retry.rb

@@ -0,0 +1,4 @@
+# TransactionRetry.max_retries = 3
+# TransactionRetry.wait_times = [0, 1, 2, 4, 8, 16, 32] # seconds to sleep after retry n
+TransactionRetry.retry_on = ActiveRecord::PreparedStatementCacheExpired # or an array of classes is valid too (ActiveRecord::TransactionIsolationConflict is by default always included)
+# TransactionRetry.before_retry = ->(retry_num, error) { ... }

spec/lib/transaction_retry_spec.rb

@@ -0,0 +1,20 @@
+require 'rails_helper'
+
+# Need truncation: true because transaction_retry only retries top-level transactions
+RSpec.describe TransactionRetry, type: :lib, truncation: true do
+  it 'retries ActiveRecord::PreparedStatementCacheExpired' do
+    result = nil
+
+    ActiveRecord::Base.transaction do
+      if result.nil?
+        result = 21
+
+        raise ActiveRecord::PreparedStatementCacheExpired.new('test')
+      else
+        result = 42
+      end
+    end
+
+    expect(result).to eq 42
+  end
+end

spec/rails_helper.rb

@@ -43,7 +43,7 @@
   # If you're not using ActiveRecord, or you'd prefer not to run each of your
   # examples within a transaction, remove the following line or assign false
   # instead of true.
-  config.use_transactional_fixtures = true
+  config.use_transactional_fixtures = false
 
   # RSpec Rails can automatically mix in different behaviours to your tests
   # based on their file location, for example enabling you to call `get` and
@@ -59,6 +59,31 @@
   # The different available types are documented in the features, such as in
   # https://relishapp.com/rspec/rspec-rails/docs
   config.infer_spec_type_from_file_location!
+
+  config.prepend_before(:suite) do
+    DatabaseCleaner.clean_with(:truncation)
+  end
+
+  config.prepend_before(:all) do
+    metadata = self.class.metadata
+    DatabaseCleaner.strategy = metadata[:js] || metadata[:truncation] ? :truncation : :transaction
+    DatabaseCleaner.start
+  end
+
+  config.prepend_before(:each) do
+    DatabaseCleaner.start
+  end
+
+  # https://github.com/DatabaseCleaner/database_cleaner#rspec-with-capybara-example says:
+  #   "It's also recommended to use append_after to ensure DatabaseCleaner.clean
+  #    runs after the after-test cleanup capybara/rspec installs."
+  config.append_after(:each) do
+    DatabaseCleaner.clean
+  end
+
+  config.append_after(:all) do
+    DatabaseCleaner.clean
+  end
 end
 
 # Adds a convenience method to get interpret the body as JSON and convert to a hash;