Class: Middleware::AnonymousCache::Helper

Inherits:
Object
  • Object
show all
Defined in:
lib/middleware/anonymous_cache.rb

Overview

This gives us an API to insert anonymous cache segments

Constant Summary collapse

RACK_SESSION = 
"rack.session"
USER_AGENT = 
"HTTP_USER_AGENT"
ACCEPT_ENCODING = 
"HTTP_ACCEPT_ENCODING"
DISCOURSE_RENDER = 
"HTTP_DISCOURSE_RENDER"
REDIS_STORE_SCRIPT = 
DiscourseRedis::EvalHelper.new <<~LUA
  local current = redis.call("incr", KEYS[1])
  redis.call("expire",KEYS[1],ARGV[1])
  return current
LUA
MIN_TIME_TO_CHECK = 
0.05
ADP = 
"action_dispatch.request.parameters"

Instance Method Summary collapse

Constructor Details

#initialize(env, request = nil) ⇒ Helper

Returns a new instance of Helper.



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# File 'lib/middleware/anonymous_cache.rb', line 74

def initialize(env, request = nil)
  @env = env
  @request = request || Rack::Request.new(@env)
end

Instance Method Details

#blocked_crawler? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 79

def blocked_crawler?
  @request.get? && !@request.xhr? && !@request.path.ends_with?("robots.txt") &&
    !@request.path.ends_with?("srv/status") &&
    @request[Auth::DefaultCurrentUserProvider::API_KEY].nil? &&
    @env[Auth::DefaultCurrentUserProvider::USER_API_KEY].nil? &&
    @env[Auth::DefaultCurrentUserProvider::HEADER_API_KEY].nil? &&
    CrawlerDetection.is_blocked_crawler?(@env[USER_AGENT])
end

#cache(result, env = {}) ⇒ Object

NOTE in an ideal world cache still serves out cached content except for one magic worker

that fills it up, this avoids a herd killing you, we can probably do this using a job or redis tricks
but coordinating this is tricky



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# File 'lib/middleware/anonymous_cache.rb', line 293

def cache(result, env = {})
  return result if GlobalSetting.anon_cache_store_threshold == 0

  status, headers, response = result

  if status == 200 && cache_duration
    if GlobalSetting.anon_cache_store_threshold > 1
      count = REDIS_STORE_SCRIPT.eval(Discourse.redis, [cache_key_count], [cache_duration])

      # technically lua will cast for us, but might as well be
      # prudent here, hence the to_i
      if count.to_i < GlobalSetting.anon_cache_store_threshold
        headers["X-Discourse-Cached"] = "skip"
        return status, headers, response
      end
    end

    headers_stripped =
      headers.dup.delete_if { |k, _| %w[Set-Cookie X-MiniProfiler-Ids].include? k }
    headers_stripped["X-Discourse-Cached"] = "true"
    parts = []
    response.each { |part| parts << part }

    if req_params = env[ADP]
      headers_stripped[ADP] = {
        "action" => req_params["action"],
        "controller" => req_params["controller"],
      }
    end

    Discourse.redis.setex(cache_key_body, cache_duration, compress(parts.join))
    Discourse.redis.setex(cache_key_other, cache_duration, [status, headers_stripped].to_json)

    headers["X-Discourse-Cached"] = "store"
  else
    parts = response
  end

  [status, headers, parts]
end

#cache_duration ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 286

def cache_duration
  @env["ANON_CACHE_DURATION"]
end

#cache_key ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 152

def cache_key
  return @cache_key if defined?(@cache_key)

  @cache_key =
    +"ANON_CACHE_#{@env["HTTP_ACCEPT"]}_#{@env[Rack::RACK_URL_SCHEME]}_#{@env["HTTP_HOST"]}#{@env["REQUEST_URI"]}"
  @cache_key << AnonymousCache.build_cache_key(self)
  @cache_key
end

#cache_key_body ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 183

def cache_key_body
  @cache_key_body ||= "#{cache_key}_body"
end

#cache_key_count ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 179

def cache_key_count
  @cache_key_count ||= "#{cache_key}_count"
end

#cache_key_other ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 187

def cache_key_other
  @cache_key_other || "#{cache_key}_other"
end

#cacheable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 249

def cacheable?
  !!(
    GlobalSetting.anon_cache_store_threshold > 0 && !has_auth_cookie? && get? &&
      no_cache_bypass
  )
end

#cached(env = {}) ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 274

def cached(env = {})
  if body = decompress(Discourse.redis.get(cache_key_body))
    if other = Discourse.redis.get(cache_key_other)
      other = JSON.parse(other)
      if req_params = other[1].delete(ADP)
        env[ADP] = req_params
      end
      [other[0], other[1], [body]]
    end
  end
end

#check_logged_in_rate_limit! ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 230

def check_logged_in_rate_limit!
  !logged_in_anon_limiter.performed!(raise_error: false)
end

#clear_cache ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 334

def clear_cache
  Discourse.redis.del(cache_key_body)
  Discourse.redis.del(cache_key_other)
end

#compress(val) ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 256

def compress(val)
  if val && GlobalSetting.compress_anon_cache
    require "lz4-ruby" if !defined?(LZ4)
    LZ4.compress(val)
  else
    val
  end
end

#decompress(val) ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 265

def decompress(val)
  if val && GlobalSetting.compress_anon_cache
    require "lz4-ruby" if !defined?(LZ4)
    LZ4.uncompress(val)
  else
    val
  end
end

#force_anonymous! ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 207

def force_anonymous!
  @env[Auth::DefaultCurrentUserProvider::USER_API_KEY] = nil
  @env[Auth::DefaultCurrentUserProvider::HEADER_API_KEY] = nil
  @env["HTTP_COOKIE"] = nil
  @env["HTTP_DISCOURSE_LOGGED_IN"] = nil
  @env["rack.request.cookie.hash"] = {}
  @env["rack.request.cookie.string"] = ""
  @env["_bypass_cache"] = nil
  request = Rack::Request.new(@env)
  request.delete_param("api_username")
  request.delete_param("api_key")
end

#get? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 191

def get?
  @env["REQUEST_METHOD"] == "GET"
end

#has_auth_cookie? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 195

def has_auth_cookie?
  CurrentUser.has_auth_cookie?(@env)
end

#is_crawler? ⇒ Boolean Also known as: key_is_crawler?

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 123

def is_crawler?
  @is_crawler ||=
    begin
      user_agent = @env[USER_AGENT]

      if @env[DISCOURSE_RENDER] == "crawler" ||
           CrawlerDetection.crawler?(user_agent, @env["HTTP_VIA"])
        :true
      else
        if user_agent.downcase.include?("discourse") &&
             !user_agent.downcase.include?("mobile")
          :true
        else
          :false
        end
      end
    end
  @is_crawler == :true
end

#is_mobile=(val) ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 88

def is_mobile=(val)
  @is_mobile = val ? :true : :false
end

#is_mobile? ⇒ Boolean Also known as: key_is_mobile?

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 92

def is_mobile?
  @is_mobile ||=
    begin
      session = @env[RACK_SESSION]
      # don't initialize params until later
      # otherwise you get a broken params on the request
      params = {}

      MobileDetection.resolve_mobile_view!(@env[USER_AGENT], params, session) ? :true : :false
    end

  @is_mobile == :true
end

#key_cache_theme_ids ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 161

def key_cache_theme_ids
  theme_ids.join(",")
end

#key_compress_anon ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 165

def key_compress_anon
  GlobalSetting.compress_anon_cache
end

#key_has_brotli? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 107

def key_has_brotli?
  @has_brotli ||=
    begin
      @env[ACCEPT_ENCODING].to_s =~ /br/ ? :true : :false
    end
  @has_brotli == :true
end

#key_is_modern_mobile_device? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 144

def key_is_modern_mobile_device?
  MobileDetection.modern_mobile_device?(@env[USER_AGENT]) if @env[USER_AGENT]
end

#key_is_old_browser? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 148

def key_is_old_browser?
  CrawlerDetection.show_browser_update?(@env[USER_AGENT]) if @env[USER_AGENT]
end

#key_locale ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 115

def key_locale
  if locale = Discourse.anonymous_locale(@request)
    locale
  else
    "" # No need to key, it is the same for all anon users
  end
end

#logged_in_anon_limiter ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 220

def logged_in_anon_limiter
  @logged_in_anon_limiter ||=
    RateLimiter.new(
      nil,
      "logged_in_anon_cache_#{@env["HTTP_HOST"]}/#{@env["REQUEST_URI"]}",
      GlobalSetting.force_anonymous_min_per_10_seconds,
      10,
    )
end

#no_cache_bypass ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 199

def no_cache_bypass
  request = Rack::Request.new(@env)
  request.cookies["_bypass_cache"].nil? && (request.path != "/srv/status") &&
    request[Auth::DefaultCurrentUserProvider::API_KEY].nil? &&
    @env[Auth::DefaultCurrentUserProvider::HEADER_API_KEY].nil? &&
    @env[Auth::DefaultCurrentUserProvider::USER_API_KEY].nil?
end

#should_force_anonymous? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/middleware/anonymous_cache.rb', line 237

def should_force_anonymous?
  if (queue_time = @env["REQUEST_QUEUE_SECONDS"]) && get?
    if queue_time > GlobalSetting.force_anonymous_min_queue_seconds
      return check_logged_in_rate_limit!
    elsif queue_time >= MIN_TIME_TO_CHECK
      return check_logged_in_rate_limit! if !logged_in_anon_limiter.can_perform?
    end
  end

  false
end

#theme_ids ⇒ Object 



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# File 'lib/middleware/anonymous_cache.rb', line 169

def theme_ids
  ids, _ = @request.cookies["theme_ids"]&.split("|")
  id = ids&.split(",")&.map(&:to_i)&.first
  if id && Guardian.new.allow_themes?([id])
    Theme.transform_ids(id)
  else
    []
  end
end