discourse/spec/components/discourse_redis_spec.rb

# frozen_string_literal: true

require 'rails_helper'

describe DiscourseRedis do
  let(:slave_host) { 'testhost' }
  let(:slave_port) { 1234 }

  let(:config) do
    DiscourseRedis.config.dup.merge(slave_host: 'testhost', slave_port: 1234, connector: DiscourseRedis::Connector)
  end

  let(:fallback_handler) { DiscourseRedis::FallbackHandler.instance }

  it "ignore_readonly returns nil from a pure exception" do
    result = DiscourseRedis.ignore_readonly { raise Redis::CommandError.new("READONLY") }
    expect(result).to eq(nil)
  end

  describe 'redis commands' do
    let(:raw_redis) { Redis.new(DiscourseRedis.config) }

    before do
      raw_redis.flushdb
    end

    after do
      raw_redis.flushdb
    end

    describe 'when namespace is enabled' do
      let(:redis) { DiscourseRedis.new }

      it 'should append namespace to the keys' do
        raw_redis.set('default:key', 1)
        raw_redis.set('test:key2', 1)

        expect(redis.keys).to include('key')
        expect(redis.keys).to_not include('key2')
        expect(redis.scan_each.to_a).to eq(['key'])

        redis.scan_each.each do |key|
          expect(key).to eq('key')
        end

        redis.del('key')

        expect(raw_redis.get('default:key')).to eq(nil)
        expect(redis.scan_each.to_a).to eq([])

        raw_redis.set('default:key1', '1')
        raw_redis.set('default:key2', '2')

        expect(redis.mget('key1', 'key2')).to eq(['1', '2'])
        expect(redis.scan_each.to_a).to contain_exactly('key1', 'key2')
      end
    end

    describe 'when namespace is disabled' do
      let(:redis) { DiscourseRedis.new(nil, namespace: false) }

      it 'should not append any namespace to the keys' do
        raw_redis.set('default:key', 1)
        raw_redis.set('test:key2', 1)

        expect(redis.keys).to include('default:key', 'test:key2')

        redis.del('key')

        expect(raw_redis.get('key')).to eq(nil)

        raw_redis.set('key1', '1')
        raw_redis.set('key2', '2')

        expect(redis.mget('key1', 'key2')).to eq(['1', '2'])
      end

      it 'should noop a readonly redis' do
        expect(Discourse.recently_readonly?).to eq(false)

        redis.without_namespace
          .expects(:set)
          .raises(Redis::CommandError.new("READONLY"))

        redis.set('key', 1)

        expect(Discourse.recently_readonly?).to eq(true)
      end
    end

    describe '.exists' do
      it 'should return false when key is not present' do
        expect(Discourse.redis.exists('test')).to eq(false)
      end

      it 'should return false when keys are not present' do
        expect(Discourse.redis.exists('test', 'test2')).to eq(false)
      end

      it 'should return true when key is present' do
        Discourse.redis.set('test', 1)

        expect(Discourse.redis.exists('test')).to eq(true)
      end

      it 'should return true when any key is present' do
        Discourse.redis.set('test', 1)
        Discourse.redis.set('test2', 1)

        expect(Discourse.redis.exists('test')).to eq(true)
        expect(Discourse.redis.exists('test', 'test2')).to eq(true)
        expect(Discourse.redis.exists('test2', 'test3')).to eq(true)
      end
    end
  end

  context '.slave_host' do
    it 'should return the right config' do
      slave_config = DiscourseRedis.slave_config(config)
      expect(slave_config[:host]).to eq(slave_host)
      expect(slave_config[:port]).to eq(slave_port)
    end
  end

  context 'when redis connection is to a slave redis server' do
    it 'should check the status of the master server' do
      begin
        fallback_handler.master = false
        Discourse.redis.without_namespace.expects(:set).raises(Redis::CommandError.new("READONLY"))
        fallback_handler.expects(:verify_master).once
        Discourse.redis.set('test', '1')
      ensure
        fallback_handler.master = true
        Discourse.redis.del('test')
      end
    end
  end

  describe DiscourseRedis::Connector do
    let(:connector) { DiscourseRedis::Connector.new(config) }

    after do
      fallback_handler.master = true
    end

    it 'should return the master config when master is up' do
      expect(connector.resolve).to eq(config)
    end

    class BrokenRedis
      def initialize(error)
        @error = error
      end

      def call(*args)
        raise @error
      end

      def disconnect
      end
    end

    it 'should return the slave config when master is down' do
      error = Redis::CannotConnectError

      expect do
        connector.resolve(BrokenRedis.new(error))
      end.to raise_error(Redis::CannotConnectError)

      config = connector.resolve

      expect(config[:host]).to eq(slave_host)
      expect(config[:port]).to eq(slave_port)
    end

    it "should return the slave config when master's hostname cannot be resolved" do
      error = RuntimeError.new('Name or service not known')

      expect do
        connector.resolve(BrokenRedis.new(error))
      end.to raise_error(error)

      expect(fallback_handler.master).to eq(false)

      config = connector.resolve

      expect(config[:host]).to eq(slave_host)
      expect(config[:port]).to eq(slave_port)
      expect(fallback_handler.master).to eq(false)
    end

    it "should return the slave config when master is still loading data" do
      Redis::Client.any_instance
        .expects(:call)
        .with([:info, :persistence])
        .returns("
          someconfig:haha\r
          #{DiscourseRedis::FallbackHandler::MASTER_LOADING_STATUS}
        ")

      config = connector.resolve

      expect(config[:host]).to eq(slave_host)
      expect(config[:port]).to eq(slave_port)
    end

    it "should raise the right error" do
      error = RuntimeError.new('test')

      2.times do
        expect { connector.resolve(BrokenRedis.new(error)) }
          .to raise_error(error)
      end
    end
  end

  describe DiscourseRedis::FallbackHandler do
    before do
      @original_keepalive_interval = MessageBus.keepalive_interval
    end

    after do
      fallback_handler.master = true
      MessageBus.keepalive_interval = @original_keepalive_interval
    end

    describe '#initiate_fallback_to_master' do
      it 'should return the right value if the master server is still down' do
        fallback_handler.master = false
        Redis::Client.any_instance.expects(:call).with([:info]).returns("Some other stuff")

        expect(fallback_handler.initiate_fallback_to_master).to eq(false)
        expect(MessageBus.keepalive_interval).to eq(0)
      end

      it 'should fallback to the master server once it is up' do
        fallback_handler.master = false
        master_conn = mock('master')
        slave_conn = mock('slave')

        Redis::Client.expects(:new)
          .with(DiscourseRedis.config)
          .returns(master_conn)

        Redis::Client.expects(:new)
          .with(DiscourseRedis.slave_config)
          .returns(slave_conn)

        master_conn.expects(:call)
          .with([:info])
          .returns("
            #{DiscourseRedis::FallbackHandler::MASTER_ROLE_STATUS}\r\n
            #{DiscourseRedis::FallbackHandler::MASTER_LOADED_STATUS}
          ")

        DiscourseRedis::FallbackHandler::CONNECTION_TYPES.each do |connection_type|
          slave_conn.expects(:call).with(
            [:client, [:kill, 'type', connection_type]]
          )
        end

        master_conn.expects(:disconnect)
        slave_conn.expects(:disconnect)

        expect(fallback_handler.initiate_fallback_to_master).to eq(true)
        expect(fallback_handler.master).to eq(true)
        expect(Discourse.recently_readonly?).to eq(false)
        expect(MessageBus.keepalive_interval).to eq(-1)
      end
    end
  end
end