Class: Sqreen::Js::MiniRacerExecutableJs

Inherits:
ExecutableJs show all
Defined in:
lib/sqreen/js/mini_racer_executable_js.rb

Constant Summary collapse

@@ctx_defined =

rubocop:disable Style/ClassVars

false

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pool, code, vendored) ⇒ MiniRacerExecutableJs

Returns a new instance of MiniRacerExecutableJs.



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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 24

def initialize(pool, code, vendored)
  @pool = pool
  @code = code
  @code_id = self.class.code_id(code)

  @module = vendored ? Sqreen::MiniRacer : MiniRacer

  mod = vendored ? Sqreen::MiniRacer : MiniRacer

  return if ctx_defined?

  self.class.define_sqreen_context(mod)
  define_ctx!
end

Class Method Details

.code_id(code) ⇒ Object 



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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 64

def self.code_id(code)
  Digest::MD5.hexdigest(code)
end

.define_sqreen_context(modoole) ⇒ Object 



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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 69

def define_sqreen_context(modoole)
  # Context specialized for Sqreen usage
  Sqreen::Js.const_set 'SqreenContext', Class.new(modoole.const_get('Context'))
  SqreenContext.class_eval do
    attr_accessor :gc_threshold_in_bytes
    attr_accessor :gc_load
    attr_writer   :timeout

    def code?(code_id)
      return false unless @code_ids
      @code_ids.include?(code_id)
    end

    def code_failed?(code_id)
      return false unless @failed_code_ids
      @failed_code_ids.include?(code_id)
    end

    def add_code(code_id, code)
      # It's important that the definition is run in its own scope (by executing it inside an anonymous function)
      # Otherwise some auxiliary functions that the backend server sends will collide the name
      # Because they're defined with `var`, running the definitions inside a function is enough
      eval_unsafe "(function() { #{code} })()"
      transf_global_funcs code_id
      @code_ids ||= Set.new
      @code_ids << code_id
    rescue StandardError
      @failed_code_ids ||= Set.new
      @failed_code_ids << code_id
      raise
    end

    def eval_unsafe(str, filename = nil, timeoutv = nil)
      # Beware, timeout could be kept in the context
      # if perf cap is removed after having been activated
      # As it's unused by execjscb we are not cleaning it
      return super(str, filename) if timeoutv.nil?
      return if timeoutv <= 0.0
      timeoutv *= 1000 # Timeout are currently expressed in seconds
      @timeout = timeoutv
      @eval_thread = Thread.current
      timeout do
        super(str, filename)
      end
    end

    def possibly_gc
      @gc_threshold_in_bytes ||= DEFAULT_GC_THRESHOLD
      @gc_load ||= 0

      # garbage collections max 1 in every 4 calls (avg)
      if heap_stats[:total_heap_size] > @gc_threshold_in_bytes
        low_memory_notification if respond_to?(:low_memory_notification)
        @gc_load += 4
      else
        @gc_load = [0, @gc_load - 1].max
      end
    end

    private

    def transf_global_funcs(code_id)
      # Multiple callbacks may share the same name. In order to avoid collisions, we rename them here.
      eval_unsafe <<-JS
        Object.keys(this).forEach(name => {
          if (typeof this[name] === "function" && !name.startsWith("sqreen_")) {
            this['sqreen_#{code_id}_' + name] = this[name];
            this[name] = undefined;
          }
        });
      JS
    end
  end
end

Instance Method Details

#ctx_defined? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 16

def ctx_defined?
  @@ctx_defined
end

#define_ctx! ⇒ Object 



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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 20

def define_ctx!
  @@ctx_defined = true # rubocop:disable Style/ClassVars
end

#run_js_cb(cb_name, budget, arguments) ⇒ Object 



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# File 'lib/sqreen/js/mini_racer_executable_js.rb', line 39

def run_js_cb(cb_name, budget, arguments)
  Sqreen.log.debug { "js:#{self.class} callback:#{cb_name} pool:#{@pool.inspect}" }
  @pool.with_context do |ctx|
    Sqreen.log.debug { "js:#{self.class} callback:#{cb_name} context:#{ctx.inspect}" }
    if ctx.code_failed?(@code_id)
      Sqreen.log.debug do
        "Skipping execution of callback #{cb_name} (code md5 #{@code_id})" \
        " due to prev failure of definition evaluation"
      end
      return nil
    end

    ctx.add_code(@code_id, @code) unless ctx.code?(@code_id)

    # mini_racer expects timeout to be in ms
    ctx.timeout = budget ? budget * 1000.0 : nil
    begin
      ctx.call("sqreen_#{@code_id}_#{cb_name}", *arguments)
    rescue @module::ScriptTerminatedError
      Sqreen.log.debug "ScriptTerminatedError/#{cb_name}"
      nil
    end
  end
end