Jira (PUP-10113) Functions are slower if called with chained syntax than with prefix syntax

Henrik Lindberg (JIRA) Mon, 28 Oct 2019 07:52:30 -0700

Title: Message Title

The peformance issue is this bit in the evaluator:

  def eval_CallMethodExpression(o, scope)

    unless o.functor_expr.is_a? Model::NamedAccessExpression

      fail(Issues::ILLEGAL_EXPRESSION, o.functor_expr, {:feature=>'function accessor', :container => o})

end

    receiver = unfold([], [o.functor_expr.left_expr], scope)

    name = o.functor_expr.right_expr

    unless name.is_a? Model::QualifiedName

      fail(Issues::ILLEGAL_EXPRESSION, o.functor_expr, {:feature=>'function name', :container => o})

end

    name = name.value # the string function name

    obj = receiver[0]

    receiver_type = Types::TypeCalculator.infer(obj)

    if receiver_type.is_a?(Types::TypeWithMembers)

      member = receiver_type[name]

      unless member.nil?

        args = unfold([], o.arguments || [], scope)

        return o.lambda.nil? ? member.invoke(obj, scope, args) : member.invoke(obj, scope, args, &proc_from_lambda(o.lambda, scope))

end

end

    call_function_with_block(name, unfold(receiver, o.arguments || [], scope), o, scope)

end

Line 13 in this snippet does a full inference to determine if the object has member attributes. For a very large facts hash, that is a very expensive operation.
We need to quickly filter out values that we know cannot possibly have methods, and possibly also find a much faster way to determine if object has members that can be called.

A very simple hack is to add:

unless obj.is_a?(Hash) || obj.is_a?(Array)

but we probably want to speed this up for all Scalar. Ping Thomas Hallgren - any thoughts on what would be the fastest here?

This also brings up a possibility to cache type inference for larger data types...

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Jira (PUP-10113) Functions are slower if called with chained syntax than with prefix syntax

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