Performance Considerations for Generating a Large Number of Keys with SunLicense

Generating a large number of keys with SunLicense creates O(n²) complexity due to linear duplicate checks and unbounded memory growth, requiring hash-set optimizations and streaming for batches exceeding 10,000 keys.

The msbatal/php-license-key-generator repository provides a lightweight solution for creating license keys, but the SunLicense class exhibits specific performance constraints when scaling to high-volume generation. Understanding these architectural limitations is essential before deploying the library for bulk key provisioning. When generating a large number of keys with SunLicense, developers must account for quadratic time complexity and linear memory consumption that degrade performance beyond modest batch sizes.

How SunLicense Generates Keys

Template-Based Character Generation

In SunLicense.php (lines 79-97), the license() method constructs each key by iterating over the template string character-by-character using a for loop with strlen($this->template). For every alphabetic or numeric placeholder, the code invokes the legacy rand() function to select random characters. This approach results in O(template-length) computational work per key, meaning longer templates directly increase CPU time linearly.

The Uniqueness Verification Process

The generate() method (lines 106-112) stores every created key in the $this->keys array and relies on the check() method to prevent duplicates. According to the source code in SunLicense.php (lines 56-71), the check() method uses in_array($key, $this->keys) to scan the entire existing key set for each new generation attempt. This linear search creates a bottleneck that scales quadratically as the batch size grows.

Performance Bottlenecks in Bulk Generation

Quadratic Time Complexity

The in_array operation performs a linear scan of all previously generated keys. When generating n keys, the total number of comparisons equals the sum of integers from 1 to n, resulting in O(n²) time complexity. As implemented in msbatal/php-license-key-generator, this quadratic cost becomes noticeable around 10,000 keys and dominates runtime for larger batches.

Unbounded Memory Consumption

The class maintains an indexed array $this->keys that retains every generated string in memory throughout the execution. For a template producing 20-character keys, generating 100,000 keys consumes approximately 2 MB of raw string data plus PHP array overhead, often exceeding default memory_limit settings on shared hosting environments.

Random Number Generator Overhead

The implementation uses PHP's legacy rand() function (lines 86, 90, 92 in SunLicense.php) for each character position. While sufficient for small batches, rand() is slower than modern alternatives like mt_rand() or random_int(), becoming a measurable bottleneck when called millions of times during large-scale generation.

Practical Performance Thresholds

For batches of 10,000 keys or fewer, the default SunLicense implementation operates efficiently on modern hardware, with template processing dominating execution time. However, beyond this threshold, the quadratic uniqueness check begins to dominate, causing generation time to increase disproportionately with batch size. Memory pressure compounds this issue, as PHP must maintain the entire key history in RAM.

Optimization Strategies for High-Volume Generation

Replace Linear Search with Hash Sets

Convert the $this->keys storage from an indexed array to an associative array using keys as indexes. Modify the check() method to use isset($this->keys[$key]) instead of in_array(). This reduces duplicate detection from O(n) to O(1), eliminating the quadratic bottleneck entirely.

Stream Keys Using Generators

Instead of buffering all keys in memory, override the generate() method to use PHP generators (yield). This approach keeps memory usage constant regardless of batch size by emitting each key immediately upon creation, allowing downstream processes to write directly to databases or files without accumulating arrays.

Upgrade the Random Generator

Replace rand() with mt_rand() for speed improvements, or random_int() for cryptographically secure randomness. In SunLicense.php, update the character selection logic (lines 86, 90, 92) to use the preferred function based on your security requirements.

Implement Batch Processing

Split massive generation requests into smaller chunks (e.g., 5,000 keys per batch). Process each chunk sequentially while clearing the keys array between iterations. This strategy limits peak memory usage and keeps the quadratic check manageable if you cannot modify the source code.

Implementation Examples

The following examples demonstrate basic usage and optimized approaches for the msbatal/php-license-key-generator library.

Basic generation with default settings:

<?php
require_once __DIR__ . '/../SunLicense.php';

$sl = new SunLicense(null, null, 'upper', 5);
$keys = $sl->generate();
print_r($keys);

Streaming large batches with constant memory:

<?php
require_once __DIR__ . '/../SunLicense.php';

class SunLicenseStream extends SunLicense {
    public function generate() {
        $generated = 0;
        while ($generated < $this->keyCount) {
            $key = $this->license();
            if (!isset($this->keys[$key])) {
                $this->keys[$key] = true;
                $generated++;
                yield $key;
            }
        }
    }
}

$stream = new SunLicenseStream(null, null, 'upper', 20000);
foreach ($stream->generate() as $key) {
    echo $key . PHP_EOL;
}

High-performance generation with faster RNG:

<?php
require_once __DIR__ . '/../SunLicense.php';

class SunLicenseFast extends SunLicense {
    private function license() {
        $key = !empty($this->prefix) ? $this->prefix . '-' : '';
        $len = strlen($this->template);
        for ($i = 0; $i < $len; $i++) {
            $char = $this->template[$i];
            if (ctype_alpha($char)) {
                $key .= $this->case === 'lower'
                      ? chr(mt_rand(97, 122))
                      : chr(mt_rand(65, 90));
            } elseif (ctype_digit($char)) {
                $key .= mt_rand(0, 9);
            } else {
                $key .= '-';
            }
        }
        return $key;
    }
}

$fast = new SunLicenseFast(null, null, 'upper', 10000);
$keys = $fast->generate();
echo 'Generated ' . count($keys) . ' keys using mt_rand().' . PHP_EOL;

Summary

• Quadratic complexity: The default in_array duplicate check in SunLicense.php creates O(n²) time complexity when generating a large number of keys with SunLicense.
• Memory growth: The class stores every key in the $this->keys array, causing linear memory consumption that can exhaust PHP limits.
• Template overhead: Character-by-character template processing with rand() calls adds linear CPU cost per key based on template length.
• Hash sets: Replacing in_array with isset() on associative arrays reduces duplicate detection to O(1).
• Streaming: Using generators eliminates memory buffering, enabling unlimited batch sizes.
• RNG selection: mt_rand() offers speed improvements over rand() for high-volume generation.

Frequently Asked Questions

What is the maximum number of keys SunLicense can generate?

The theoretical limit depends on template entropy and available memory. Practically, the default implementation encounters severe performance degradation beyond 10,000 keys due to O(n²) duplicate checking. With hash-set optimizations and streaming, you can generate millions of keys limited only by your storage I/O capacity.

Why does key generation slow down exponentially as the batch grows?

The check() method in SunLicense.php uses in_array() to verify uniqueness, which performs a linear scan of all previously generated keys. As the array grows, each new key requires comparing against an increasingly large set, creating exponential time complexity. Switching to isset() with associative arrays restores linear time complexity.

How can I reduce memory usage when generating hundreds of thousands of keys?

Override the generate() method to use PHP's yield keyword instead of returning an array. This streams each key individually, keeping memory usage constant regardless of batch size. Additionally, write keys directly to persistent storage (database or file) within the generation loop rather than accumulating them in RAM.

Is the default rand() function secure enough for commercial license keys?

While rand() provides sufficient randomness for basic obfuscation, it is not cryptographically secure and exhibits statistical weaknesses. For security-critical applications, replace rand() with random_int() in the license() method (lines 86, 90, 92 of SunLicense.php). Note that random_int() is slower than mt_rand(), so choose based on your security versus performance requirements.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}