Incremental backoff flow-control for any : fn(function(err, data) { ... });
npm install oibackoffIncremental backoff flow-control for any fn(function(err, data) { ... });.
Please note that this repo is stable. This means there may not be many commits, issues or releases. This is
normal. Please submit any issues for any queries you may have.
* three different backoff algorithms: 'exponential', 'fibonacci' and 'incremental'
* max number of tries
* max time to wait for any retry
* scaling of the delay between tries
Your code can stay the same plus you also get extra information about intermediate errors.
Original code:
``js
var dns = require('dns');
// original code
dns.resolve('chilts.org', function(err, addresses) {
if (err) {
// do something to recover from this error
return;
}
// do something with addresses
console.log(addresses);
});
`
Using exponential backoff, with a maxium of 5 tries, with delays of 0.2, 0.4, 0.8, 1.6 and 3.2 seconds is fairly
similar and you can reuse the 'backoff' function many times:
`js
var backoff = require('oibackoff').backoff({
algorithm : 'exponential',
delayRatio : 0.2,
maxTries : 5,
});
backoff(dns.resolve, 'chilts.org', function(err, addresses, priorErrors) {
if (err) {
// do something to recover from this error
return;
}
// do something with addresses
console.log(addresses);
});
`
You can also provide an intermediate function which is called after each error. This method can be useful for logging
or other operations between errors. By returning false you can cancel any additional tries.
`js
var intermediate = function(err, tries, delay) {
console.log(err); // last error
console.log(tries); // total number of tries performed thus far
console.log(delay); // the delay for the next attempt
return false; // this will cancel additional tries
};
backoff(dns.resolve, 'chilts.org', intermediate, callback);
`
Notes:
* 'err' contains the last error encountered (if maxTries was reached without success)
* 'addresses' contrains the same as the original upon success, or null if all attempts failed
* 'priorErrors' is informational and you may ignore it or use it to help you diagnose problems
Default: 3
Will retry a maximum number of times. If you don't want a maxiumum, set this to 0.
Default : 1
This is the ratio for each delay between each try (in seconds).
If you choose the exponential algorithm, then 1s delayRatio will result in delays of 1, 2, 4, 8 etc
Default : exponential
Valid Values : exponential, fibonacci, incremental ;)
No Default.
If your chosen backoff strategy reaches a point which is above this number, then each succesive retry will top-out at
'maxDelay' e.g. if you choose 'exponential', with a delayRatio of 1 and maxTries at 10, the retry delays will be 1, 2,
4, 8, 10, 10, ... (instead of 1, 2, 4, 8, 16, 32, ...).
`js
var oibackoff = require('oibackoff');
// 0.4, 0.8, 1.6, 3.2, 6.4, ...
var backoff = oibackoff.backoff({
algorithm : 'exponential',
delayRatio : 0.4,
});
// 1, 2, 3, 4, 5, ...
var backoff = oibackoff.backoff({
algorithm : 'incremental',
delayRatio : 1,
});
// 0.5, 0.5, 1.0, 1.5, 2.5, 4, ...
var backoff = oibackoff.backoff({
algorithm : 'fibonacci',
delayRatio : 0.5,
});
``
Written by: Andrew Chilton - Twitter.
Contributors:
Daniel Stevens - Senico
The MIT License : http://opensource.org/licenses/MIT
Copyright (c) 2011-2012 AppsAttic Ltd. http://appsattic.com/
Copyright (c) 2013-2016 Andrew Chilton. http://chilts.org/
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit
persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the
Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
(Ends)