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<?php $iterations = 100000; $strings = []; for ($i = 0; $i < $iterations; $i++) { $strings[] = openssl_random_pseudo_bytes(rand(16, 50)); } echo 'String size: ', round(strlen(serialize($strings))/ 1024, 2), 'kb', PHP_EOL; $hashes_md5 = array(); $hashes_crc32 = array(); $t_md5 = microtime(true); foreach ($strings as $s) { $hashes_md5['x'.(crc32($s) >> 8)] = 0; } $t_md5 = microtime(true) - $t_md5; //$max = bindec('111111111111111111111111111111'); //$max = 0xFFFFFFF; //F; +5% size boost, collision: 0.1689%, time boost: 0% $max = 0xFFFFFF; //FF; +14% size boost, collision: 2.908%, time boost: -9% //$max = 0xFFFFF; //FFF; +47% size boost, collision: 35.5696%, time boost: 0% // modify 10% of data for ($i = 0; $i < $iterations; $i++) { if (rand(1,100) > 90) { $strings[$i] = openssl_random_pseudo_bytes(rand(16, 50)); } } $t_crc32 = microtime(true); foreach ($strings as $s) { $hashes_crc32['x'.(crc32($s) >> 8)] = 0; } $t_crc32 = microtime(true) - $t_crc32; function compareShingles(array $first, array $second) { $t_crc32 = microtime(true); echo 'func intersect: ', count(array_intersect_key($first, $second)), PHP_EOL; echo ' func unique: ', count(array_merge($first, $second)), PHP_EOL; $t_crc32 = microtime(true) - $t_crc32; echo ' time: ', $t_crc32, PHP_EOL; $t_crc32 = microtime(true); $diff_count = count(array_diff_key($first, $second)); $intersect_count = count($first) - $diff_count;// count(array_intersect_key($first, $second)); $unique_count = count($second) + $diff_count; echo 'calculated intersect: ', $intersect_count, PHP_EOL; echo ' calculated unique: ', $unique_count, PHP_EOL; $t_crc32 = microtime(true) - $t_crc32; echo ' time: ', $t_crc32, PHP_EOL; //return round(($intersect_count / $unique_count) / 0.01, 2); } $hashes_md5_flip = $hashes_md5; //array_flip($hashes_md5); $hashes_crc32_flip = $hashes_crc32; //array_flip($hashes_crc32); //ksort($hashes_md5_flip); //ksort($hashes_crc32_flip); $t_merge = microtime(true); $hashes_diff = array_diff_key($hashes_md5_flip, $hashes_crc32_flip); $t_merge = microtime(true) - $t_merge; $t_diff = microtime(true); $hashes_merge = array_merge($hashes_md5_flip, $hashes_crc32_flip); $t_diff = microtime(true) - $t_diff; $t_intersect = microtime(true); $hashes_intersect = array_intersect_key($hashes_md5_flip, $hashes_crc32_flip); $t_intersect = microtime(true) - $t_intersect; echo PHP_EOL; echo ' merge time: ', $t_merge, PHP_EOL; echo ' merge count: ', count($hashes_merge), PHP_EOL; echo ' diff time: ', $t_merge, PHP_EOL; echo ' diff count: ', count($hashes_diff), PHP_EOL; echo ' intersect time: ', $t_intersect, PHP_EOL; echo 'intersect count: ', count($hashes_intersect), PHP_EOL; echo ' md5 count: ', count($hashes_md5_flip), ' with diff:', count($hashes_md5_flip)+count($hashes_diff), ' intersect: ', count($hashes_md5_flip)-count($hashes_diff), PHP_EOL; echo ' crc32 count: ', count($hashes_crc32_flip), ' with diff:', count($hashes_crc32_flip)+count($hashes_diff), ' intersect: ', count($hashes_crc32_flip)-count($hashes_diff), PHP_EOL; echo PHP_EOL; compareShingles($hashes_md5_flip, $hashes_crc32_flip); echo PHP_EOL;