local function acquire_lock (key, lock_id, lock_lifetime_milliseconds)
    if is_locked_by_another_owner(key, lock_id) then
        return { "locked_by_other" }
    end
    if owns_lock(key, lock_id) then
        debugLog("lock is already owned for key '%s' and lock ID '%s'", key, lock_id)
        return { "ok" }
    end
    local existing_lock = redis.call("SET", lock_key(key), lock_id, "NX", "PX", lock_lifetime_milliseconds, "GET")
    if existing_lock then
        errorLog("key '%s' was not expected to be locked but was locked by lock ID '%s'", key, existing_lock)
    else
    	store_lock_for_owner(lock_key(key))
        debugLog("successfully acquired new lock for key '%s' and lock ID '%s'", key, lock_id)
    end
    return { "ok" }
end

local function acquire_locks (keys, lock_id, lock_lifetime_milliseconds)
    for _, key in ipairs(keys) do
        acquire_lock(key, lock_id, lock_lifetime_milliseconds)
    end
end

local function release_lock (key, lock_id)
    local existing_lock_id = get_existing_lock(key)
    if existing_lock_id == lock_id then
        redis.call("DEL", lock_key(key))
        release_lock_for_owner(lock_key(key))
        debugLog("successfully released lock for key '%s' and lock ID '%s'", key, lock_id)
        return { "ok" }
    end
    debugLog("could not release lock for key '%s' and lock ID '%s' because lock ID did not match", key, lock_id)
    return { "lock_not_owned", existing_lock_id }
end

local function release_locks (keys, lock_id)
    for _, key in ipairs(keys) do
        release_lock(key, lock_id)
    end
end