lazy_db_creation_and_replication.js

// Licensed under the Apache License, Version 2.0 (the 'License'); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an 'AS IS' BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

var nano    = require('nano')
  , couch   =
    { "master"  : "http://localhost:5984/landing_m"
    , "replica" : "http://localhost:5984/landing_r"
    }
  ;

function insert_with_retry(db, email, retries, callback) {
  if (typeof retries === 'function') {
   callback = retries;
   retries  = 0;
  }
  callback = callback || function(){};
  db.insert(email, function(err, resp, head) {
    if(err) {
      if(err.message === 'no_db_file'  && retries < 1) {
        var db_name = db.config.db
          , server  = nano(db.config.url)
          ;
        server.db.create(db_name, function (err2,resp2,head2) {
          if(err2) { return callback(err2,resp2,head2); }
          insert_with_retry(db,email,retries+1,callback);
        });
      } else { return callback(err,resp,head); }
    }
    callback(err, resp, head);
  });
}

function replicate_with_retry(master_uri, replica_uri, retries, callback) {
  if (typeof retries === 'function') {
    callback = retries;
    retries  = 0;
  }
  callback   = callback || function(){};
  retries    = retries  || 0;
  var master = nano(couch.master);
  master.replicate(couch.replica, function(err, resp, head) {
    if(err && err['error'] === 'db_not_found' && retries < 1) {
      var replica = nano(couch.replica)
        , db_name = replica.config.db
        , server  = nano(replica.config.url)
        ;
      server.db.create(db_name, function (err2, resp2, head2) {
        if(err2) { return callback(err2,resp2,head2); }
        replicate_with_retry(master_uri, replica_uri, retries+1, callback);
      });
    }
    callback(err, resp, head);
  });
}

module.exports = {insert: insert_with_retry, replicate: replicate_with_retry};