There are some potential feefilter cleanups mentioned and motivated in comment https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-805808485 . If you address the locking one, please be careful and make sure that `round()` is only called under a lock. See https://github.com/bitcoin/bitcoin/pull/21509#issuecomment-807992199

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* Bitcoin protocol messages
* Bitcoin Core P2P design
* Running our unit and functional tests

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#include <util/check.h>
#include <util/moneystr.h>
#include <util/string.h>
#include <util/system.h>
#include <util/thread.h>
#include <util/threadnames.h>
#include <util/translation.h>
#include <validation.h>
#include <validationinterface.h>
#include <walletinitinterface.h>
#include <functional>
#include <set>
#include <stdint.h>
#include <stdio.h>
#include <thread>
#include <vector>
#ifndef WIN32
#include <attributes.h>
#include <cerrno>
#include <signal.h>
#include <sys/stat.h>
#endif
#include <boost/algorithm/string/replace.hpp>
#include <boost/signals2/signal.hpp>
#if ENABLE_ZMQ
#include <zmq/zmqabstractnotifier.h>
#include <zmq/zmqnotificationinterface.h>
#include <zmq/zmqrpc.h>
#endif
static const bool DEFAULT_PROXYRANDOMIZE = true;