mongo ping函数实例

参考地址    http://php.net/manual/zh/mongocollection.findone.php

mongo 没有 ping函数 所以需要参照PDO的写法,   findOne   Throws MongoConnectionException if it cannot reach the database.

// mongo instancefunction getMongoCollection($col){    static $mongoClient, $collection = [];    try {        // init mongoClient        if (!$mongoClient) {            $mongoClient = mongoClientInit();        }        // check mongoClient        if (!is_object($mongoClient) || !method_exists($mongoClient, 'selectCollection')) {            throw new \MongoConnectionException('reconnect mongo failed');        }        // init mongoCollection        if (!isset($collection[$col])) {            $collection[$col] = mongoCollectionInit($mongoClient, $col);        }        // ping mongo        $collection[$col] = mongoPing($collection[$col], $col);        // check mongoPing again        if (!is_object($collection[$col])) {            throw new \MongoConnectionException('reconnect mongo failed');        }    } catch (\MongoConnectionException $e) {        error_log($e->getMessage(), 3, ERROR_LOG);    }    return $collection[$col] ?: null;}function mongoPing($collection, $col){    try {        // check collection        if (!$collection || !method_exists($collection, 'findOne')) {            throw new \MongoConnectionException('mongo connect failed');        }        // Throws MongoConnectionException if it cannot reach the database.        $collection->findOne([], ['_id' => 1]);    } catch (\MongoConnectionException $e) {        // log        error_log('mongo connect failed and try to reconnect', 3, ERROR_LOG);        // init MongoClient        $mongoClient = mongoClientInit();        // init MongoCollection        if (is_object($mongoClient) && method_exists($mongoClient, 'selectCollection')) {            $collection = mongoCollectionInit($mongoClient, $col);        } else {            $collection = null;        }    }    return $collection;}function mongoClientInit(){    $config = get_config('mongo');    // reconnect mongo 3 times    $mongoClient = null;    $i = 0;    while ($i < 3 && !$mongoClient) {        try {            $mongoClient = new MongoClient($config['dsn']);        } catch (\MongoConnectionException $e) {            $i++;        }    }    return $mongoClient;}function mongoCollectionInit($mongoClient, $col){    $config = get_config('mongo');    // get MongoCollection object    $i = 0;    $collection = null;    while ($i < 3 && !$collection) {        try {            $collection = $mongoClient->selectCollection($config['db'], $col);        } catch (\Exception $e) {            $i++;        }    }    return $collection;}