/**
* Executes a database command.
*
* @param cmd {@code DBObject} representation the command to be executed
* @param options query options to use
* @param readPrefs {@link ReadPreference} for this command (nodes selection is the biggest part
* of this)
* @param encoder {@link DBEncoder} to be used for command encoding
* @return result of the command execution
* @throws MongoException
* @dochub commands
*/
public CommandResult command(
DBObject cmd, int options, ReadPreference readPrefs, DBEncoder encoder) {
readPrefs = getCommandReadPreference(cmd, readPrefs);
cmd = wrapCommand(cmd, readPrefs);
Iterator<DBObject> i =
getCollection("$cmd")
.__find(
cmd,
new BasicDBObject(),
0,
-1,
0,
options,
readPrefs,
DefaultDBDecoder.FACTORY.create(),
encoder);
if (i == null || !i.hasNext()) return null;
DBObject res = i.next();
ServerAddress sa = (i instanceof Result) ? ((Result) i).getServerAddress() : null;
CommandResult cr = new CommandResult(sa);
cr.putAll(res);
return cr;
}
private CommandResult convertToCommandResult(DBObject cmd, Response res) {
if (res.size() == 0) return null;
if (res.size() > 1) throw new MongoInternalException("something is wrong. size:" + res.size());
DBObject data = res.get(0);
if (data == null) throw new MongoInternalException("something is wrong, no command result");
CommandResult cr = new CommandResult(cmd, res.serverUsed());
cr.putAll(data);
return cr;
}