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Edit File: PoolNamespace.js

var Connection   = require('./Connection');
var PoolSelector = require('./PoolSelector');

module.exports = PoolNamespace;

/**
 * PoolNamespace
 * @constructor
 * @param {PoolCluster} cluster The parent cluster for the namespace
 * @param {string} pattern The selection pattern to use
 * @param {string} selector The selector name to use
 * @public
 */
function PoolNamespace(cluster, pattern, selector) {
  this._cluster = cluster;
  this._pattern = pattern;
  this._selector = new PoolSelector[selector]();
}

PoolNamespace.prototype.getConnection = function(cb) {
  var clusterNode = this._getClusterNode();
  var cluster     = this._cluster;
  var namespace   = this;

if (clusterNode === null) {
    var err = null;

if (this._cluster._findNodeIds(this._pattern, true).length !== 0) {
      err = new Error('Pool does not have online node.');
      err.code = 'POOL_NONEONLINE';
    } else {
      err = new Error('Pool does not exist.');
      err.code = 'POOL_NOEXIST';
    }

cb(err);
    return;
  }

cluster._getConnection(clusterNode, function(err, connection) {
    var retry = err && cluster._canRetry
      && cluster._findNodeIds(namespace._pattern).length !== 0;

if (retry) {
      namespace.getConnection(cb);
      return;
    }

if (err) {
      cb(err);
      return;
    }

cb(null, connection);
  });
};

PoolNamespace.prototype.query = function (sql, values, cb) {
  var cluster     = this._cluster;
  var clusterNode = this._getClusterNode();
  var query       = Connection.createQuery(sql, values, cb);
  var namespace   = this;

if (clusterNode === null) {
    var err = null;

process.nextTick(function () {
      query.on('error', function () {});
      query.end(err);
    });
    return query;
  }

if (!(typeof sql === 'object' && 'typeCast' in sql)) {
    query.typeCast = clusterNode.pool.config.connectionConfig.typeCast;
  }

if (clusterNode.pool.config.connectionConfig.trace) {
    // Long stack trace support
    query._callSite = new Error();
  }

cluster._getConnection(clusterNode, function (err, conn) {
    var retry = err && cluster._canRetry
      && cluster._findNodeIds(namespace._pattern).length !== 0;

if (retry) {
      namespace.query(query);
      return;
    }

if (err) {
      query.on('error', function () {});
      query.end(err);
      return;
    }

// Release connection based off event
    query.once('end', function() {
      conn.release();
    });

conn.query(query);
  });

return query;
};

PoolNamespace.prototype._getClusterNode = function _getClusterNode() {
  var foundNodeIds = this._cluster._findNodeIds(this._pattern);
  var nodeId;

switch (foundNodeIds.length) {
    case 0:
      nodeId = null;
      break;
    case 1:
      nodeId = foundNodeIds[0];
      break;
    default:
      nodeId = this._selector(foundNodeIds);
      break;
  }

return nodeId !== null
    ? this._cluster._getNode(nodeId)
    : null;
};

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