82 lines
3.0 KiB
Ruby
82 lines
3.0 KiB
Ruby
# frozen_string_literal: true
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require 'spec_helper'
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RSpec.describe 'Load balancer behavior with errors inside a transaction', :redis, :delete, feature_category: :database do
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include StubENV
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let(:model) { ActiveRecord::Base }
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let(:db_host) { model.connection_pool.db_config.host }
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let(:test_table_name) { '_test_foo' }
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before do
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# Patch in our load balancer config, simply pointing at the test database twice
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allow(Gitlab::Database::LoadBalancing::Configuration).to receive(:for_model).with(model) do |base_model|
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Gitlab::Database::LoadBalancing::Configuration.new(base_model, [db_host, db_host])
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end
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Gitlab::Database::LoadBalancing::Setup.new(model).setup
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model.connection.execute(<<~SQL)
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CREATE TABLE IF NOT EXISTS #{test_table_name} (id SERIAL PRIMARY KEY, value INTEGER)
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SQL
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# The load balancer sleeps between attempts to retry a query.
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# Mocking the sleep call significantly reduces the runtime of this spec file.
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allow(model.connection.load_balancer).to receive(:sleep)
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end
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after do
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model.connection.execute(<<~SQL)
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DROP TABLE IF EXISTS #{test_table_name}
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SQL
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# reset load balancing to original state
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allow(Gitlab::Database::LoadBalancing::Configuration).to receive(:for_model).and_call_original
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Gitlab::Database::LoadBalancing::Setup.new(model).setup
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end
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def execute(conn)
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conn.execute("INSERT INTO #{test_table_name} (value) VALUES (1)")
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backend_pid = conn.execute("SELECT pg_backend_pid() AS pid").to_a.first['pid']
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# This will result in a PG error, which is not raised.
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# Instead, we retry the statement on a fresh connection (where the pid is different and it does nothing)
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# and the load balancer continues with a fresh connection and no transaction if a transaction was open previously
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conn.execute(<<~SQL)
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SELECT CASE
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WHEN pg_backend_pid() = #{backend_pid} THEN
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pg_terminate_backend(#{backend_pid})
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END
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SQL
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# This statement will execute on a new connection, and violate transaction semantics
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# if we were in a transaction before
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conn.execute("INSERT INTO #{test_table_name} (value) VALUES (2)")
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end
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context 'in a transaction' do
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it 'raises an exception when a retry would occur' do
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expect(::Gitlab::Database::LoadBalancing::Logger)
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.not_to receive(:warn).with(hash_including(event: :transaction_leak))
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expect do
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model.transaction do
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execute(model.connection)
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end
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end.to raise_error(ActiveRecord::StatementInvalid) { |e| expect(e.cause).to be_a(PG::ConnectionBad) }
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end
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end
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context 'without a transaction' do
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it 'retries' do
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expect(::Gitlab::Database::LoadBalancing::Logger)
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.not_to receive(:warn).with(hash_including(event: :transaction_leak))
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expect(::Gitlab::Database::LoadBalancing::Logger)
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.to receive(:warn).with(hash_including(event: :read_write_retry))
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expect { execute(model.connection) }.not_to raise_error
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end
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end
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end
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