Redis を使用して PHP でマークル ツリーを実装する

class Node {
    public $left = null;
    public $right = null;
    public $data = null;
    public $hash = null;
}

function makeTree($data) {
    if(count($data) == 1) {
        $node           = new Node();
        $node->data     = $data[0];
        $node->hash     = hash('sha256', $node->data, false);
        return $node;
    }

    $leftData       = array_slice($data, 0, count($data) >> 1);
    $rightData      = array_slice($data, count($data) >> 1);
    $left           = makeTree($leftData);
    $right          = makeTree($rightData);

    $node           = new Node();
    $node->left     = $left;
    $node->right    = $right;

    if(!is_null($node->left)) {
        $node->hash = hash('sha256', $node->left->hash . $node->right->hash, false);
    }

    return $node;
}

function storeToRedis($node, $redis, $key) {
    if(is_null($node)) {
        return;
    }

    $redis->hset($key, 'hash', $node->hash);
    $redis->hset($key, 'data', $node->data);

    if(!is_null($node->left)) {
        $leftKey    = $key . ':left';
        $rightKey   = $key . ':right';

        storeToRedis($node->left, $redis, $leftKey);
        storeToRedis($node->right, $redis, $rightKey);

        $redis->hset($key, 'left', $leftKey);
        $redis->hset($key, 'right', $rightKey);
    }
}

function loadFromRedis($redis, $key) {
    if(!$redis->hexists($key, 'hash')) {
        return null;
    }

    $node           = new Node();
    $node->hash     = $redis->hget($key, 'hash');
    $node->data     = $redis->hget($key, 'data');

    $leftKey        = $redis->hget($key, 'left');
    $rightKey       = $redis->hget($key, 'right');

    if(!is_null($leftKey)) {
        $node->left     = loadFromRedis($redis, $leftKey);
        $node->right    = loadFromRedis($redis, $rightKey);
    }

    return $node;
}

function verifyData($data, $rootHash, $redis, $key) {
    $node   = loadFromRedis($redis, $key);

    if(is_null($node)) {
        return;
    }

    if(!is_null($node->left)) {
        verifyData($data, $rootHash, $redis, $redis->hget($key, 'left'));
        verifyData($data, $rootHash, $redis, $redis->hget($key, 'right'));
    }

    if(!is_null($node->data)) {
        $dataHash = hash('sha256', $node->data, false);
        $index    = array_search($node->data, $data, true);

        if($node->hash != $rootHash || ($index === false && $node->hash != $dataHash)) {
            throw new Exception('Invalid data or hash');
        }
    }
}