kafka-node-avro/lib/schemaPool.js

kafka avro serialization

const Schema = require('./schema');

const Pool = {
  busy : {}
};

/*
 * Add List
 * */
Pool.addList = function(list){
  return new Promise(function(resolve, reject){
    if(!list || !list.length){ return resolve(false); }
    let done = after(list.length, function(){ return resolve(true); });

    list.forEach( topic => {
      Pool.add(topic).then(done, reject);
    });
  });
};

/*
 * Add
 * */
Pool.add = function(topic){
  return new Promise(function(resolve, reject){
    let key = JSON.stringify(topic);

    // Load busy pool
    if(Pool.busy[key]){ return Pool.busy[key].push({resolve, reject}); }
    Pool.busy[key] = [{resolve, reject}];

    let schema = new Schema(topic);

    // Flush busy pool
    schema.fetch().then( fetchedSchema => {
      Pool.busy[key].forEach( waiting => { waiting.resolve(fetchedSchema); });
      delete Pool.busy[key];   // Delete busy pool
      Pool.set(fetchedSchema); // Set schema on pool
    }, error => {
      Pool.busy[key].forEach( waiting => { waiting.reject(error); });
      delete Pool.busy[key]; // Delete busy pool
    });
  });
};

/*
 * Setter
 * */
Pool.set = function(schema){
  Pool[schema.id] = schema;
  if(schema.name){ Pool[schema.name] = schema; }
  return schema;
};

/*
 * Get by Id
 * */
Pool.getById = function(id) {
  return new Promise(function(resolve, reject){
    let schema = Pool[id];
    if(schema){ return resolve(schema); }
    Pool.add({id}).then(resolve, reject);
  });
};

/*
 * Get by Name
 * */
Pool.getByName = function(name) {
  return new Promise(function(resolve, reject){
    let schema = Pool[name];
    if(schema){ return resolve(schema); }
    Pool.add({ name }).then(resolve, reject);
  });
};

function after(times, func) {
  return function() { if (--times < 1) { return func.apply(this, arguments); } };
};

module.exports = Pool;