Code coverage report for lib/spdy-transport/priority.js

# all files / lib/spdy-transport/ priority.js

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100% Branches 28/28
100% Functions 16/16
100% Lines 94/94

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     'use strict'

    var transport = require('../spdy-transport')
    var utils = transport.utils

    var assert = require('assert')
    var debug = require('debug')('spdy:priority')

    function PriorityNode (tree, options) {
      this.tree = tree

      this.id = options.id
      this.parent = options.parent
      this.weight = options.weight

      // To be calculated in `addChild`
      this.priorityFrom = 0
      this.priorityTo = 1
      this.priority = 1

      this.children = {
        list: [],
        weight: 0
      }

      if (this.parent !== null) {
        this.parent.addChild(this)
      }
    }

    function compareChildren (a, b) {
      return a.weight === b.weight ? a.id - b.id : a.weight - b.weight
    }

    PriorityNode.prototype.toJSON = function toJSON () {
      return {
        parent: this.parent,
        weight: this.weight,
        exclusive: this.exclusive
      }
    }

    PriorityNode.prototype.getPriority = function getPriority () {
      return this.priority
    }

    PriorityNode.prototype.getPriorityRange = function getPriorityRange () {
      return { from: this.priorityFrom, to: this.priorityTo }
    }

    PriorityNode.prototype.addChild = function addChild (child) {
      child.parent = this
      utils.binaryInsert(this.children.list, child, compareChildren)
      this.children.weight += child.weight

      this._updatePriority(this.priorityFrom, this.priorityTo)
    }

    PriorityNode.prototype.remove = function remove () {
      assert(this.parent, 'Can\'t remove root node')

      this.parent.removeChild(this)
      this.tree._removeNode(this)

      // Move all children to the parent
      for (var i = 0; i < this.children.list.length; i++) {
        this.parent.addChild(this.children.list[i])
      }
    }

    PriorityNode.prototype.removeChild = function removeChild (child) {
      this.children.weight -= child.weight
      var index = utils.binarySearch(this.children.list, child, compareChildren)
      assert(index !== -1)

      // Remove the child
      this.children.list.splice(index, 1)
    }

    PriorityNode.prototype.removeChildren = function removeChildren () {
      var children = this.children.list
      this.children.list = []
      this.children.weight = 0
      return children
    }

    PriorityNode.prototype._updatePriority = function _updatePriority (from, to) {
      this.priority = to - from
      this.priorityFrom = from
      this.priorityTo = to

      var weight = 0
      for (var i = 0; i < this.children.list.length; i++) {
        var node = this.children.list[i]
        var nextWeight = weight + node.weight

        node._updatePriority(
          from + this.priority * (weight / this.children.weight),
          from + this.priority * (nextWeight / this.children.weight)
        )
        weight = nextWeight
      }
    }

    function PriorityTree (options) {
      this.map = {}
      this.list = []
      this.defaultWeight = options.defaultWeight || 16

      this.count = 0
      this.maxCount = options.maxCount

      // Root
      this.root = this.add({
        id: 0,
        parent: null,
        weight: 1
      })
    }
    module.exports = PriorityTree

    PriorityTree.create = function create (options) {
      return new PriorityTree(options)
    }

    PriorityTree.prototype.add = function add (options) {
      if (options.id === options.parent) {
        return this.addDefault(options.id)
      }

      var parent = options.parent === null ? null : this.map[options.parent]
      if (parent === undefined) {
        return this.addDefault(options.id)
      }

      debug('add node=%d parent=%d weight=%d exclusive=%d',
            options.id,
            options.parent === null ? -1 : options.parent,
            options.weight || this.defaultWeight,
            options.exclusive ? 1 : 0)

      var children
      if (options.exclusive) {
        children = parent.removeChildren()
      }

      var node = new PriorityNode(this, {
        id: options.id,
        parent: parent,
        weight: options.weight || this.defaultWeight
      })
      this.map[options.id] = node

      if (options.exclusive) {
        for (var i = 0; i < children.length; i++) {
          node.addChild(children[i])
        }
      }

      this.count++
      if (this.count > this.maxCount) {
        debug('hit maximum remove id=%d', this.list[0].id)
        this.list.shift().remove()
      }

      // Root node is not subject to removal
      if (node.parent !== null) {
        this.list.push(node)
      }

      return node
    }

    // Only for testing, should use `node`'s methods
    PriorityTree.prototype.get = function get (id) {
      return this.map[id]
    }

    PriorityTree.prototype.addDefault = function addDefault (id) {
      debug('creating default node')
      return this.add({ id: id, parent: 0, weight: this.defaultWeight })
    }

    PriorityTree.prototype._removeNode = function _removeNode (node) {
      delete this.map[node.id]
      this.count--
    }