PHP API Client Retries with Exponential Backoff

Retry retryable network failures and HTTP 429/503 with capped exponential backoff. The examples separate the essential operation from the conditions a production implementation must enforce.

What It Does

Retry retryable network failures and HTTP 429/503 with capped exponential backoff.

Prerequisites

Use a dedicated development environment with test accounts and records. Separate authorization, validation and error handling from response formatting; never copy demonstration-only secrets into production.

Example 1: Core Behavior

The first example isolates the core operation so its result is easy to understand.

<?php
$attempt=2; $delay=min(8, (2**$attempt)+random_int(0,100)/100);
echo 'Delay: '.$delay.'s';

Example 2: Alternative or Failure Case

The second example demonstrates an alternative outcome, rule or failure condition.

<?php
$status=429; $retryAfter='3';
$delay=ctype_digit($retryAfter)?min(30,(int)$retryAfter):5;
echo $status===429?"Wait $delay seconds":'Do not retry';

Practical Example: Applying the Rule

This practical workflow performs the relevant operation, with strict error checks. Configure the required transport or database driver before running it.

<?php
$url = 'https://api.example.test/status';
for ($attempt = 0; $attempt < 3; $attempt++) {
    $ch = curl_init($url);
    curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER => true, CURLOPT_TIMEOUT => 4, CURLOPT_CONNECTTIMEOUT => 2, CURLOPT_FOLLOWLOCATION => false]);
    $body = curl_exec($ch);
    $status = $body === false ? 0 : curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
    if ($status >= 200 && $status < 300) { echo $body; break; }
    if ($attempt === 2 || !in_array($status, [0, 429, 503], true)) throw new RuntimeException('Request failed');
    usleep((int) ((2 ** $attempt) * 100000 + random_int(0, 100000)));
}

Important Behavior and Edge Cases

Respect Retry-After, avoid retrying unsafe writes without idempotency keys and set a total deadline.

Comparison with Related Functions or Patterns

Common Beginner Mistakes

Key Takeaways

• Retry retryable network failures and HTTP 429/503 with capped exponential backoff.
• Respect Retry-After, avoid retrying unsafe writes without idempotency keys and set a total deadline.
• Circuit breakers prevent hammering a persistently failing dependency.

Select this API or pattern based on its documented behavior and the trust boundaries in your own application, and test all external integrations against their actual deployments.