redis_cache_spec.rb

#   Copyright (c) 2010-2011, Diaspora Inc.  This file is
#   licensed under the Affero General Public License version 3 or later.  See
#   the COPYRIGHT file.

require 'spec_helper'

describe RedisCache do
  before do
    @redis = MockRedis.new
    @cache = RedisCache.new(bob, :created_at)
    @cache.stub(:redis).and_return(@redis)
  end

  it 'gets initialized with user and an created_at order' do
    cache = RedisCache.new(bob, :created_at)
    [:@user, :@order_field].each do |var|
      cache.instance_variable_get(var).should_not be_blank
    end
  end

  describe "#cache_exists?" do
    it 'returns true if the sorted set exists' do
      timestamp = Time.now.to_i
      @redis.zadd("cache_stream_#{bob.id}_created_at", timestamp, "post_1")

      @cache.cache_exists?.should be_true
    end

    it 'returns false if there is nothing in the set' do
      @cache.cache_exists?.should be_false
    end
  end

  describe "#post_ids" do
    before do
      @timestamps = []
      @timestamp = Time.now.to_i
      30.times do |n|
        created_time = @timestamp - n*1000
        @redis.zadd("cache_stream_#{bob.id}_created_at", created_time, n.to_s)
        @timestamps << created_time
      end
    end

    it 'returns the most recent post ids (default created at, limit 15)' do
      @cache.post_ids.should =~ 15.times.map { |n| n.to_s }
    end

    it 'returns posts ids after the specified time' do
      @cache.post_ids(@timestamps[15]).should =~ (15...30).map { |n| n.to_s }
    end

    it 'returns post ids with a non-default limit' do
      @cache.post_ids(@timestamp, 20).should =~ 20.times.map { |n| n.to_s }
    end
  end

  describe "#ensure_populated!" do
    it 'does nothing if the cache is populated' do
      @cache.stub(:cache_exists?).and_return(true)
      @cache.should_not_receive(:repopulate!)

      @cache.ensure_populated!
    end

    it 'calls #repopulate' do
      opts = {:here_is => "something"}
      @cache.stub(:cache_exists?).and_return(false)
      @cache.should_receive(:repopulate!).with(opts)

      @cache.ensure_populated!(opts)
    end
  end

  describe "#repopulate!" do
    it 'calls #purge!' do
      @cache.should_receive(:purge!)
      @cache.repopulate!
    end

    it 'populates' do
      opts = {:here_is => "something"}
      @cache.stub(:trim!).and_return(true)
      @cache.should_receive(:populate!).with(opts).and_return(true)
      @cache.repopulate!(opts)
    end

    it 'trims' do
      @cache.stub(:populate!).and_return(true)
      @cache.should_receive(:trim!)
      @cache.repopulate!
    end
  end

  describe '#purge!' do
    it 'clears the set in redis' do
      @cache.stub(:redis).and_return(@redis)
      @redis.should_receive(:del).with(@cache.send(:set_key))
      @cache.purge!
    end
  end

  describe "#populate!" do
    it 'queries the db with the visible post sql string' do
      sql = "long_sql"
      order = "created_at DESC"
      @cache.should_receive(:order).and_return(order)
      bob.should_receive(:visible_shareable_sql).with(
        Post,
        hash_including(
          :type => RedisCache.acceptable_types,
          :limit => RedisCache::CACHE_LIMIT,
          :order => order)).
        and_return(sql)

      Post.connection.should_receive(:select_all).with(sql).and_return([])

      @cache.populate!
    end
  end

  describe "#trim!" do
    it 'does nothing if the set is smaller than the cache limit' do
      @timestamps = []
      @timestamp = Time.now.to_i
      30.times do |n|
        created_time = @timestamp - n*1000
        @redis.zadd("cache_stream_#{bob.id}_created_at", created_time, n.to_s)
        @timestamps << created_time
      end

      post_ids = @cache.post_ids(Time.now.to_i, @cache.size)
      @cache.trim!
      @cache.post_ids(Time.now.to_i, @cache.size).should == post_ids
    end

    it 'trims the set to the cache limit' do
      @timestamps = []
      @timestamp = Time.now.to_i
      120.times do |n|
        created_time = @timestamp - n*1000
        @redis.zadd("cache_stream_#{bob.id}_created_at", created_time, n.to_s)
        @timestamps << created_time
      end

      post_ids = 100.times.map { |n| n.to_s }
      @cache.trim!
      @cache.post_ids(Time.now.to_i, @cache.size).should == post_ids[0...100]
    end
  end

  describe "#add" do
    before do
      @cache.stub(:cache_exists?).and_return(true)
      @id = 1
      @score = 123
    end

    it "adds an id with a given score" do
      @redis.should_receive(:zadd).with(@cache.send(:set_key), @score, @id)
      @cache.add(@score, @id)
    end

    it 'trims' do
      @cache.should_receive(:trim!)
      @cache.add(@score, @id)
    end

    it "doesn't add if the cache does not exist" do
      @cache.stub(:cache_exists?).and_return(false)

      @redis.should_not_receive(:zadd)
      @cache.add(@score, @id)
    end
  end

  describe "#remove" do
    before do
      @id = 1
    end

    it "doesn't add if the cache does not exist" do
      @cache.stub(:cache_exists?).and_return(false)

      @redis.should_not_receive(:zrem)
      @cache.remove(@id).should be_false
    end

    it "removes a given id" do
      @cache.stub(:cache_exists?).and_return(true)

      @redis.should_receive(:zrem).with(@cache.send(:set_key), @id)
      @cache.remove(@id)
    end
  end

  describe "#set_key" do
    it 'uses the correct prefix and order' do
      user = @cache.instance_variable_get(:@user)
      order_field = @cache.instance_variable_get(:@order_field)
      @cache.send(:set_key).should == "#{RedisCache.cache_prefix}_#{user.id}_#{order_field}"
    end
  end

  describe '.cache_setup?' do
    it 'returns true if configuration is properly set' do
      AppConfig[:redis_cache] = true
      RedisCache.should be_configured
    end

    it 'returns false if configuration is not present' do
      AppConfig[:redis_cache] = false
      RedisCache.should_not be_configured
    end
  end

  describe '.acceptable_types' do
    #exposing the need to tie cache to a stream
    it 'returns the types from the aspect stream' do
      RedisCache.acceptable_types.should =~ Stream::Base::TYPES_OF_POST_IN_STREAM
    end
  end
end