lib/advanced_structures/Lock.js
function(client, key, ttl) {
    client.ttl(key, function(err, currentTtl) {
        if (currentTtl === -1) {
            // There is no expiry set on this key, set it
            client.expire(key, ttl);
        }
    });
}
function(client, key, ttl) {
    client.ttl(key, function(err, currentTtl) {
        if (currentTtl === -1) {
            // There is no expiry set on this key, set it
            client.expire(key, ttl);
        }
    });
}
function ( client , key , ttl ) { client . ttl ( key , function ( err , currentTtl ) { if ( currentTtl === - 1 ) { // There is no expiry set on this key, set it client . expire ( key , ttl ) ; } } ) ; }
Ensure the lock with the given key has a `ttl`. If it does not, the given expiry will be applied
to it.

@param   {RedisClient}   client  The Redis to use to apply the ttl
@param   {string}        key     The key of the lock to check
@param   {number}        ttl     If the lock does not have an expiry set, set this duration (in
seconds)
@api private
Ensure the lock with the given key has a ttl . If it does not the given expiry will be applied to it .