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node_modules/hpack.js/lib/hpack/table.js 2.16 KB
aaac7fed   liuqimichale   add
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  var hpack = require('../hpack');
  var utils = hpack.utils;
  var assert = utils.assert;
  
  function Table(options) {
    this['static'] = hpack['static-table'];
    this.dynamic = [];
    this.size = 0;
    this.maxSize = 0;
    this.length = this['static'].table.length;
    this.protocolMaxSize = options.maxSize;
    this.maxSize = this.protocolMaxSize;
    this.lookupDepth = options.lookupDepth || 32;
  }
  module.exports = Table;
  
  Table.create = function create(options) {
    return new Table(options);
  };
  
  Table.prototype.lookup = function lookup(index) {
    assert(index !== 0, 'Zero indexed field');
    assert(index <= this.length, 'Indexed field OOB')
  
    if (index <= this['static'].table.length)
      return this['static'].table[index - 1];
    else
      return this.dynamic[this.length - index];
  };
  
  Table.prototype.reverseLookup = function reverseLookup(name, value) {
    var staticEntry = this['static'].map[name];
    if (staticEntry && staticEntry.values[value])
      return staticEntry.values[value];
  
    // Reverse search dynamic table (new items are at the end of it)
    var limit = Math.max(0, this.dynamic.length - this.lookupDepth);
    for (var i = this.dynamic.length - 1; i >= limit; i--) {
      var entry = this.dynamic[i];
      if (entry.name === name && entry.value === value)
        return this.length - i;
  
      if (entry.name === name) {
        // Prefer smaller index
        if (staticEntry)
          break;
        return -(this.length - i);
      }
    }
  
    if (staticEntry)
      return -staticEntry.index;
  
    return 0;
  };
  
  Table.prototype.add = function add(name, value, nameSize, valueSize) {
    var totalSize = nameSize + valueSize + 32;
  
    this.dynamic.push({
      name: name,
      value: value,
      nameSize: nameSize,
      totalSize: totalSize
    });
    this.size += totalSize;
    this.length++;
  
    this.evict();
  };
  
  Table.prototype.evict = function evict() {
    while (this.size > this.maxSize) {
      var entry = this.dynamic.shift();
      this.size -= entry.totalSize;
      this.length--;
    }
    assert(this.size >= 0, 'Table size sanity check failed');
  };
  
  Table.prototype.updateSize = function updateSize(size) {
    assert(size <= this.protocolMaxSize, 'Table size bigger than maximum');
    this.maxSize = size;
    this.evict();
  };