strong-trace/should_instrument.js

StrongTrace Node.js Tracer

"use strict";

module.exports = shouldInstrument
module.exports.complexityStats = complexityStats

var est = require("estraverse")

// check vs:
//   "min_calls"
//   "min_nodes"
//   "max_scope_depth"
//   "min_length"

function shouldInstrument(node, config, stats) {
  if (node == null || node.body == null) {
    return false
  }
  if (node.path.length === 0 || stats.depth > config.max_scope_depth) {
    // Node is a Program body or past the nested scope limit
    return false
  }

  // Calls are calls to other functions. Zero calls is a "leaf"
  if (stats.calls >= config.min_calls) {
    return true
  }

  // Nodes approximates how much this function "does"
  if (stats.nodes >= config.min_nodes) {
    return true
  }

  if (stats.nodes >= config.min_length) {
    return true
  }

  return false
}

var complexityRe = /(?:Expression|Statement)$/
function complexityStats(node) {
  // nodes starts at -1 because it will count itself
  var stats = {
    calls: 0,
    nodes: -1,
    length: node.range[1] - node.range[0],
    depth: node.path.length
  }

  est.traverse(node, {
    enter: function (node, parent) {
      if (node.type == "FunctionDeclaration" || node.type == "FunctionExpression") {
        return est.VisitorOption.Skip
      }
      if (complexityRe.test(node.type)) {
        stats.nodes++
      }
      if (node.type == "CallExpression" || node.type == "NewExpression") {
        stats.calls++
      }
    }
  })
  return stats
}