Download the PHP package crowdstar/exponential-backoff without Composer

• Summary
• Installation
• Sample Usage
  • 1. Retry When Return Value Is Empty
  • 2. Retry When Certain Exceptions Thrown Out
    • Don't Throw Out an Exception When Finally Failed
  • 3. Retry When Customized Condition Met
  • 4. More Options When Doing Exponential Backoff
  • 5. To Disable Exponential Backoff Temporarily
• Sample Scripts

Summary

Exponential back-offs prevent overloading an unavailable service by doubling the timeout each iteration. This class uses an exponential back-off algorithm to calculate the timeout for the next request.

This library allows doing exponential backoff in non-blocking mode in Swoole.

Installation

Sample Usage

In following code pieces, we assume that you want to store return value of method MyClass::fetchData() in variable $result, and you want to do exponential backoff on that because something unexpected could happen when running method MyClass::fetchData().

1. Retry When Return Value Is Empty

Following code is to try to fetch some non-empty data back with method MyClass::fetchData(). This piece of code will try a few more times (by default 4) until either we get some non-empty data back, or we have reached maximum numbers of retries.

2. Retry When Certain Exceptions Thrown Out

Following code is to try to fetch some data back with method MyClass::fetchData(), which may throw out exceptions. This piece of code will try a few more times (by default 4) until either we get some data back, or we have reached maximum numbers of retries.

NOTE: Internal PHP errors (class Error) won't trigger exponential backoff. They should be fixed manually.

Don't Throw Out an Exception When Finally Failed

When method call MyClass::fetchData() finally fails with an exception caught, we can silence the exception without throwing it out by overriding method AbstractRetryCondition::throwable():

If needed, you can have more complex logic defined when overriding method AbstractRetryCondition::throwable().

3. Retry When Customized Condition Met

Following code is to try to fetch some non-empty data back with method MyClass::fetchData(). This piece of code works the same as the first example, except that here it's implemented with a customized condition class instead of class \CrowdStar\Backoff\EmptyValueCondition.

4. More Options When Doing Exponential Backoff

Following code is to try to fetch some data back with method MyClass::fetchData(). This piece of code works the same as the second example, except that here it's implemented with a customized condition class instead of class \CrowdStar\Backoff\ExceptionBasedCondition.

In this piece of code, we also show what options are available when doing exponential backoff with the package.

5. To Disable Exponential Backoff Temporarily

There are two ways to disable exponential backoff temporarily for code piece like following:

First, you may disable exponential backoff temporarily by calling method \CrowdStar\Backoff\ExponentialBackoff::disable(). For example:

You may also disable exponential backoff temporarily by using class \CrowdStar\Backoff\NullCondition:

All these 3 code piece work the same, having return value of method call MyClass::fetchData() assigned to variable $result.

Sample Scripts

Sample scripts can be found under folder examples/. Before running them under CLI, please do a composer update first: