diff --git a/src/Makefile.am b/src/Makefile.am
index 8b12c38deb..d0fe3d0d88 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,638 +1,639 @@
 # Copyright (c) 2013-2016 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 DIST_SUBDIRS = secp256k1 univalue
 
 AM_LDFLAGS = $(PTHREAD_CFLAGS) $(LIBTOOL_LDFLAGS) $(HARDENED_LDFLAGS) $(SANITIZER_LDFLAGS)
 AM_CXXFLAGS = $(HARDENED_CXXFLAGS) $(ERROR_CXXFLAGS) $(SANITIZER_CXXFLAGS)
 AM_CPPFLAGS = $(HARDENED_CPPFLAGS)
 EXTRA_LIBRARIES =
 
 if EMBEDDED_UNIVALUE
 LIBUNIVALUE = univalue/libunivalue.la
 
 $(LIBUNIVALUE): $(wildcard univalue/lib/*) $(wildcard univalue/include/*)
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)
 else
 LIBUNIVALUE = $(UNIVALUE_LIBS)
 endif
 
 BITCOIN_INCLUDES=-I$(builddir) -I$(builddir)/obj $(BDB_CPPFLAGS) $(BOOST_CPPFLAGS) $(LEVELDB_CPPFLAGS) $(CRYPTO_CFLAGS) $(SSL_CFLAGS)
 
 BITCOIN_INCLUDES += -I$(srcdir)/secp256k1/include
 BITCOIN_INCLUDES += $(UNIVALUE_CFLAGS)
 
 BITCOIN_SEEDER_INCLUDES = -I$(srcdir)/seeder
 BITCOIN_SEEDER_INCLUDES += $(BITCOIN_INCLUDES)
 
 LIBBITCOIN_SERVER=libbitcoin_server.a
 LIBBITCOIN_COMMON=libbitcoin_common.a
 LIBBITCOIN_CONSENSUS=libbitcoin_consensus.a
 LIBBITCOIN_CLI=libbitcoin_cli.a
 LIBBITCOIN_UTIL=libbitcoin_util.a
 LIBBITCOIN_CRYPTO_BASE=crypto/libbitcoin_crypto_base.a
 LIBBITCOINQT=qt/libbitcoinqt.a
 LIBSECP256K1=secp256k1/libsecp256k1.la
 
 if ENABLE_ZMQ
 LIBBITCOIN_ZMQ=libbitcoin_zmq.a
 endif
 if BUILD_BITCOIN_LIBS
 LIBBITCOINCONSENSUS=libbitcoinconsensus.la
 endif
 if BUILD_BITCOIN_SEEDER
 LIBBITCOIN_SEEDER=libbitcoin_seeder.a
 endif
 if ENABLE_WALLET
 LIBBITCOIN_WALLET=libbitcoin_wallet.a
 endif
 
 LIBBITCOIN_CRYPTO= $(LIBBITCOIN_CRYPTO_BASE)
 if ENABLE_SSE41
 LIBBITCOIN_CRYPTO_SSE41 = crypto/libbitcoin_crypto_sse41.a
 LIBBITCOIN_CRYPTO += $(LIBBITCOIN_CRYPTO_SSE41)
 endif
 if ENABLE_AVX2
 LIBBITCOIN_CRYPTO_AVX2 = crypto/libbitcoin_crypto_avx2.a
 LIBBITCOIN_CRYPTO += $(LIBBITCOIN_CRYPTO_AVX2)
 endif
 if ENABLE_SHANI
 LIBBITCOIN_CRYPTO_SHANI = crypto/libbitcoin_crypto_shani.a
 LIBBITCOIN_CRYPTO += $(LIBBITCOIN_CRYPTO_SHANI)
 endif
 
 $(LIBSECP256K1): $(wildcard secp256k1/src/*) $(wildcard secp256k1/include/*)
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C $(@D) $(@F)
 
 # Make is not made aware of per-object dependencies to avoid limiting building parallelization
 # But to build the less dependent modules first, we manually select their order here:
 EXTRA_LIBRARIES += \
   $(LIBBITCOIN_CRYPTO) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_CLI) \
   $(LIBBITCOIN_SEEDER) \
   $(LIBBITCOIN_WALLET) \
   $(LIBBITCOIN_ZMQ)
 
 lib_LTLIBRARIES = $(LIBBITCOINCONSENSUS)
 
 bin_PROGRAMS =
 noinst_PROGRAMS =
 TESTS =
 BENCHMARKS =
 
 if BUILD_BITCOIND
   bin_PROGRAMS += bitcoind
 endif
 
 if BUILD_BITCOIN_SEEDER
   bin_PROGRAMS += bitcoin-seeder
 endif
 
 if BUILD_BITCOIN_UTILS
   bin_PROGRAMS += bitcoin-cli bitcoin-tx
 endif
 
 .PHONY: FORCE check-symbols check-security
 # bitcoin core #
 BITCOIN_CORE_H = \
   addrdb.h \
   addrman.h \
   base58.h \
   bloom.h \
   blockencodings.h \
   blockfileinfo.h \
   blockindexworkcomparator.h \
   blockstatus.h \
   blockvalidity.h \
   cashaddr.h \
   cashaddrenc.h \
   chain.h \
   chainparams.h \
   chainparamsbase.h \
   chainparamsseeds.h \
   checkpoints.h \
   checkqueue.h \
   clientversion.h \
   coins.h \
   compat.h \
   compat/byteswap.h \
   compat/endian.h \
   compat/sanity.h \
   compressor.h \
   config.h \
   consensus/activation.h \
   consensus/consensus.h \
   consensus/tx_verify.h \
   core_io.h \
   core_memusage.h \
   cuckoocache.h \
   diskblockpos.h \
   dstencode.h \
   fs.h \
   globals.h \
   httprpc.h \
   httpserver.h \
   indirectmap.h \
   init.h \
   key.h \
   keystore.h \
   dbwrapper.h \
   limitedmap.h \
   logging.h \
   memusage.h \
   merkleblock.h \
   miner.h \
   net.h \
   net_processing.h \
   netaddress.h \
   netbase.h \
   netmessagemaker.h \
   noui.h \
   policy/fees.h \
   policy/policy.h \
   pow.h \
   protocol.h \
   random.h \
   reverselock.h \
   rpc/blockchain.h \
   rpc/client.h \
   rpc/jsonrpcrequest.h \
   rpc/mining.h \
   rpc/misc.h \
   rpc/protocol.h \
   rpc/safemode.h \
   rpc/server.h \
   rpc/tojson.h \
   rpc/register.h \
+  rwcollection.h \
   scheduler.h \
   script/scriptcache.h \
   script/sigcache.h \
   script/sign.h \
   script/standard.h \
   script/ismine.h \
   streams.h \
   support/allocators/secure.h \
   support/allocators/zeroafterfree.h \
   support/cleanse.h \
   support/events.h \
   support/lockedpool.h \
   sync.h \
   threadsafety.h \
   threadinterrupt.h \
   timedata.h \
   torcontrol.h \
   txdb.h \
   txmempool.h \
   ui_interface.h \
   undo.h \
   util.h \
   utilmoneystr.h \
   utiltime.h \
   validation.h \
   validationinterface.h \
   versionbits.h \
   wallet/coincontrol.h \
   wallet/crypter.h \
   wallet/db.h \
   wallet/finaltx.h \
   wallet/rpcdump.h \
   wallet/fees.h \
   wallet/init.h \
   wallet/rpcwallet.h \
   wallet/wallet.h \
   wallet/walletdb.h \
   warnings.h \
   zmq/zmqabstractnotifier.h \
   zmq/zmqconfig.h\
   zmq/zmqnotificationinterface.h \
   zmq/zmqpublishnotifier.h
 
 
 obj/build.h: FORCE
 	@$(MKDIR_P) "$(builddir)/obj"
 	@$(top_srcdir)/share/genbuild.sh "$(abs_top_builddir)/src/obj/build.h" \
 	  "$(abs_top_srcdir)"
 libbitcoin_util_a-clientversion.$(OBJEXT): obj/build.h
 
 # server: shared between bitcoind and bitcoin-qt
 libbitcoin_server_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(MINIUPNPC_CPPFLAGS) $(EVENT_CFLAGS) $(EVENT_PTHREADS_CFLAGS)
 libbitcoin_server_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_server_a_SOURCES = \
   addrman.cpp \
   addrdb.cpp \
   bloom.cpp \
   blockencodings.cpp \
   chain.cpp \
   checkpoints.cpp \
   config.cpp \
   consensus/activation.cpp \
   consensus/tx_verify.cpp \
   globals.cpp \
   httprpc.cpp \
   httpserver.cpp \
   init.cpp \
   dbwrapper.cpp \
   merkleblock.cpp \
   miner.cpp \
   net.cpp \
   net_processing.cpp \
   noui.cpp \
   policy/fees.cpp \
   policy/policy.cpp \
   pow.cpp \
   rest.cpp \
   rpc/abc.cpp \
   rpc/blockchain.cpp \
   rpc/jsonrpcrequest.cpp \
   rpc/mining.cpp \
   rpc/misc.cpp \
   rpc/net.cpp \
   rpc/rawtransaction.cpp \
   rpc/safemode.cpp \
   rpc/server.cpp \
   script/scriptcache.cpp \
   script/sigcache.cpp \
   script/ismine.cpp \
   timedata.cpp \
   torcontrol.cpp \
   txdb.cpp \
   txmempool.cpp \
   ui_interface.cpp \
   validation.cpp \
   validationinterface.cpp \
   versionbits.cpp \
   $(BITCOIN_CORE_H)
 
 if ENABLE_ZMQ
 libbitcoin_zmq_a_CPPFLAGS = $(BITCOIN_INCLUDES) $(ZMQ_CFLAGS)
 libbitcoin_zmq_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_zmq_a_SOURCES = \
   zmq/zmqabstractnotifier.cpp \
   zmq/zmqnotificationinterface.cpp \
   zmq/zmqpublishnotifier.cpp
 endif
 
 
 # wallet: shared between bitcoind and bitcoin-qt, but only linked
 # when wallet enabled
 libbitcoin_wallet_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_wallet_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_wallet_a_SOURCES = \
   wallet/crypter.cpp \
   wallet/db.cpp \
   wallet/finaltx.cpp \
   wallet/fees.cpp \
   wallet/init.cpp \
   wallet/rpcdump.cpp \
   wallet/rpcwallet.cpp \
   wallet/wallet.cpp \
   wallet/walletdb.cpp \
   $(BITCOIN_CORE_H)
 
 # crypto primitives library
 crypto_libbitcoin_crypto_base_a_CPPFLAGS = $(AM_CPPFLAGS)
 crypto_libbitcoin_crypto_base_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_base_a_SOURCES = \
   crypto/aes.cpp \
   crypto/aes.h \
   crypto/chacha20.h \
   crypto/chacha20.cpp \
   crypto/common.h \
   crypto/hmac_sha256.cpp \
   crypto/hmac_sha256.h \
   crypto/hmac_sha512.cpp \
   crypto/hmac_sha512.h \
   crypto/ripemd160.cpp \
   crypto/ripemd160.h \
   crypto/sha1.cpp \
   crypto/sha1.h \
   crypto/sha256.cpp \
   crypto/sha256.h \
   crypto/sha512.cpp \
   crypto/sha512.h
 
 if USE_ASM
 crypto_libbitcoin_crypto_base_a_SOURCES += crypto/sha256_sse4.cpp
 endif
 
 crypto_libbitcoin_crypto_sse41_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_sse41_a_CPPFLAGS = $(AM_CPPFLAGS)
 crypto_libbitcoin_crypto_sse41_a_CXXFLAGS += $(SSE41_CXXFLAGS)
 crypto_libbitcoin_crypto_sse41_a_CPPFLAGS += -DENABLE_SSE41
 crypto_libbitcoin_crypto_sse41_a_SOURCES = crypto/sha256_sse41.cpp
 
 crypto_libbitcoin_crypto_avx2_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_avx2_a_CPPFLAGS = $(AM_CPPFLAGS)
 crypto_libbitcoin_crypto_avx2_a_CXXFLAGS += $(AVX2_CXXFLAGS)
 crypto_libbitcoin_crypto_avx2_a_CPPFLAGS += -DENABLE_AVX2
 crypto_libbitcoin_crypto_avx2_a_SOURCES = crypto/sha256_avx2.cpp
 
 crypto_libbitcoin_crypto_shani_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_shani_a_CPPFLAGS = $(AM_CPPFLAGS)
 crypto_libbitcoin_crypto_shani_a_CXXFLAGS += $(SHANI_CXXFLAGS)
 crypto_libbitcoin_crypto_shani_a_CPPFLAGS += -DENABLE_SHANI
 crypto_libbitcoin_crypto_shani_a_SOURCES = crypto/sha256_shani.cpp
 
 # consensus: shared between all executables that validate any consensus rules.
 libbitcoin_consensus_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_consensus_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_consensus_a_SOURCES = \
   amount.h \
   arith_uint256.cpp \
   arith_uint256.h \
   consensus/merkle.cpp \
   consensus/merkle.h \
   consensus/params.h \
   consensus/validation.h \
   feerate.h \
   hash.cpp \
   hash.h \
   prevector.h \
   primitives/block.cpp \
   primitives/block.h \
   primitives/transaction.cpp \
   primitives/transaction.h \
   primitives/txid.h \
   pubkey.cpp \
   pubkey.h \
   script/bitcoinconsensus.cpp \
   script/sighashtype.h \
   script/interpreter.cpp \
   script/interpreter.h \
   script/script.cpp \
   script/script.h \
   script/script_error.cpp \
   script/script_error.h \
   script/script_flags.h \
   script/sigencoding.cpp \
   script/sigencoding.h \
   serialize.h \
   tinyformat.h \
   uint256.cpp \
   uint256.h \
   utilstrencodings.cpp \
   utilstrencodings.h \
   version.h
 
 # common: shared between bitcoind, and bitcoin-qt and non-server tools
 libbitcoin_common_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_common_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_common_a_SOURCES = \
   amount.cpp \
   base58.cpp \
   cashaddr.cpp \
   cashaddrenc.cpp \
   chainparams.cpp \
   config.cpp \
   coins.cpp \
   compressor.cpp \
   dstencode.cpp \
   feerate.cpp \
   globals.cpp \
   core_read.cpp \
   core_write.cpp \
   key.cpp \
   keystore.cpp \
   netaddress.cpp \
   netbase.cpp \
   protocol.cpp \
   scheduler.cpp \
   script/sign.cpp \
   script/standard.cpp \
   warnings.cpp \
   $(BITCOIN_CORE_H)
 
 # util: shared between all executables.
 # This library *must* be included to make sure that the glibc
 # backward-compatibility objects and their sanity checks are linked.
 libbitcoin_util_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_util_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_util_a_SOURCES = \
   support/lockedpool.cpp \
   chainparamsbase.cpp \
   clientversion.cpp \
   compat/glibc_sanity.cpp \
   compat/glibcxx_sanity.cpp \
   compat/strnlen.cpp \
   fs.cpp \
   logging.cpp \
   random.cpp \
   rpc/protocol.cpp \
   support/cleanse.cpp \
   sync.cpp \
   threadinterrupt.cpp \
   uint256.cpp \
   uint256.h \
   util.cpp \
   utilmoneystr.cpp \
   utilstrencodings.cpp \
   utiltime.cpp \
   $(BITCOIN_CORE_H)
 
 if GLIBC_BACK_COMPAT
 libbitcoin_util_a_SOURCES += compat/glibc_compat.cpp
 AM_LDFLAGS += $(COMPAT_LDFLAGS)
 endif
 
 # cli: shared between bitcoin-cli and bitcoin-qt
 libbitcoin_cli_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 libbitcoin_cli_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_cli_a_SOURCES = \
   rpc/client.cpp \
   $(BITCOIN_CORE_H)
 
 # seeder library
 libbitcoin_seeder_a_CPPFLAGS = $(AM_CPPFLAGS) $(PIE_FLAGS) $(BITCOIN_SEEDER_INCLUDES)
 libbitcoin_seeder_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_seeder_a_SOURCES = \
   seeder/bitcoin.cpp \
   seeder/bitcoin.h \
   seeder/compat.h \
   seeder/db.cpp \
   seeder/db.h \
   seeder/dns.cpp \
   seeder/dns.h \
   seeder/strlcpy.h \
   seeder/util.h
 
 nodist_libbitcoin_util_a_SOURCES = $(srcdir)/obj/build.h
 #
 
 # bitcoind binary #
 bitcoind_SOURCES = bitcoind.cpp
 bitcoind_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 bitcoind_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bitcoind_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 if TARGET_WINDOWS
 bitcoind_SOURCES += bitcoind-res.rc
 endif
 
 bitcoind_LDADD = \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_WALLET) \
   $(LIBBITCOIN_ZMQ) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
   $(LIBLEVELDB) \
   $(LIBLEVELDB_SSE42) \
   $(LIBMEMENV) \
   $(LIBSECP256K1)
 
 bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
 
 # bitcoin-cli binary #
 bitcoin_cli_SOURCES = bitcoin-cli.cpp
 bitcoin_cli_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(EVENT_CFLAGS)
 bitcoin_cli_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bitcoin_cli_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 if TARGET_WINDOWS
 bitcoin_cli_SOURCES += bitcoin-cli-res.rc
 endif
 
 bitcoin_cli_LDADD = \
   $(LIBBITCOIN_CLI) \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CRYPTO)
 
 bitcoin_cli_LDADD += $(BOOST_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(EVENT_LIBS)
 #
 
 # bitcoin-seeder binary #
 bitcoin_seeder_SOURCES = seeder/main.cpp
 bitcoin_seeder_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_SEEDER_INCLUDES)
 bitcoin_seeder_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bitcoin_seeder_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 bitcoin_seeder_LDADD = \
   $(LIBBITCOIN_SEEDER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CRYPTO)
 
 bitcoin_seeder_LDADD += $(BOOST_LIBS) $(CRYPTO_LIBS)
 #
 
 # bitcoin-tx binary #
 bitcoin_tx_SOURCES = bitcoin-tx.cpp
 bitcoin_tx_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 bitcoin_tx_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bitcoin_tx_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 if TARGET_WINDOWS
 bitcoin_tx_SOURCES += bitcoin-tx-res.rc
 endif
 
 bitcoin_tx_LDADD = \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
   $(LIBSECP256K1)
 
 bitcoin_tx_LDADD += $(BOOST_LIBS) $(CRYPTO_LIBS)
 #
 
 # bitcoinconsensus library #
 if BUILD_BITCOIN_LIBS
 include_HEADERS = script/bitcoinconsensus.h
 libbitcoinconsensus_la_SOURCES = $(crypto_libbitcoin_crypto_base_a_SOURCES) $(libbitcoin_consensus_a_SOURCES)
 
 if GLIBC_BACK_COMPAT
   libbitcoinconsensus_la_SOURCES += compat/glibc_compat.cpp
 endif
 
 libbitcoinconsensus_la_LDFLAGS = $(AM_LDFLAGS) -no-undefined $(RELDFLAGS)
 libbitcoinconsensus_la_LIBADD = $(LIBSECP256K1)
 libbitcoinconsensus_la_CPPFLAGS = $(AM_CPPFLAGS) -I$(builddir)/obj -I$(srcdir)/secp256k1/include -DBUILD_BITCOIN_INTERNAL
 libbitcoinconsensus_la_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 
 endif
 #
 
 CTAES_DIST =  crypto/ctaes/bench.c
 CTAES_DIST += crypto/ctaes/ctaes.c
 CTAES_DIST += crypto/ctaes/ctaes.h
 CTAES_DIST += crypto/ctaes/README.md
 CTAES_DIST += crypto/ctaes/test.c
 
 CLEANFILES = $(EXTRA_LIBRARIES)
 
 CLEANFILES += *.gcda *.gcno
 CLEANFILES += compat/*.gcda compat/*.gcno
 CLEANFILES += consensus/*.gcda consensus/*.gcno
 CLEANFILES += crypto/*.gcda crypto/*.gcno
 CLEANFILES += policy/*.gcda policy/*.gcno
 CLEANFILES += primitives/*.gcda primitives/*.gcno
 CLEANFILES += script/*.gcda script/*.gcno
 CLEANFILES += support/*.gcda support/*.gcno
 CLEANFILES += univalue/*.gcda univalue/*.gcno
 CLEANFILES += wallet/*.gcda wallet/*.gcno
 CLEANFILES += wallet/test/*.gcda wallet/test/*.gcno
 CLEANFILES += zmq/*.gcda zmq/*.gcno
 
 DISTCLEANFILES = obj/build.h
 
 EXTRA_DIST = $(CTAES_DIST)
 
 clean-local:
 	-$(MAKE) -C secp256k1 clean
 	-$(MAKE) -C univalue clean
 	-rm -f leveldb/*/*.gcda leveldb/*/*.gcno leveldb/helpers/memenv/*.gcda leveldb/helpers/memenv/*.gcno
 	-rm -rf test/__pycache__
 
 .rc.o:
 	@test -f $(WINDRES)
 	## FIXME: How to get the appropriate modulename_CPPFLAGS in here?
 	$(AM_V_GEN) $(WINDRES) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(CPPFLAGS) -DWINDRES_PREPROC -i $< -o $@
 
 .mm.o:
 	$(AM_V_CXX) $(OBJCXX) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) \
 	  $(CPPFLAGS) $(AM_CXXFLAGS) $(QT_INCLUDES) $(AM_CXXFLAGS) $(PIE_FLAGS) $(CXXFLAGS) -c -o $@ $<
 
 check-symbols: $(bin_PROGRAMS)
 if GLIBC_BACK_COMPAT
 	@echo "Checking glibc back compat..."
 	$(AM_V_at) READELF=$(READELF) CPPFILT=$(CPPFILT) $(top_srcdir)/contrib/devtools/symbol-check.py < $(bin_PROGRAMS)
 endif
 
 check-security: $(bin_PROGRAMS)
 if HARDEN
 	@echo "Checking binary security..."
 	$(AM_V_at) READELF=$(READELF) OBJDUMP=$(OBJDUMP) $(top_srcdir)/contrib/devtools/security-check.py < $(bin_PROGRAMS)
 endif
 
 %.pb.cc %.pb.h: %.proto
 	@test -f $(PROTOC)
 	$(AM_V_GEN) $(PROTOC) --cpp_out=$(@D) --proto_path=$(<D) $<
 
 if EMBEDDED_LEVELDB
 include Makefile.leveldb.include
 endif
 
 if ENABLE_TESTS
 include Makefile.test.include
 endif
 
 if ENABLE_BENCH
 include Makefile.bench.include
 endif
 
 if ENABLE_QT
 include Makefile.qt.include
 endif
 
 if ENABLE_QT_TESTS
 include Makefile.qttest.include
 endif
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 035faed95b..74ea379f5c 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -1,196 +1,197 @@
 # Copyright (c) 2013-2016 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 TESTS += test/test_bitcoin
 LOG_DRIVER = $(srcdir)/test/test-bitcoin-driver
 EXTRA_DIST += test/test-bitcoin-driver
 bin_PROGRAMS += test/test_bitcoin
 noinst_PROGRAMS += test/test_bitcoin_fuzzy
 TEST_SRCDIR = test
 TEST_BINARY=test/test_bitcoin$(EXEEXT)
 
 JSON_TEST_FILES = \
   test/data/script_tests.json \
   test/data/base58_keys_valid.json \
   test/data/base58_encode_decode.json \
   test/data/base58_keys_invalid.json \
   test/data/tx_invalid.json \
   test/data/tx_valid.json \
   test/data/sighash.json
 
 RAW_TEST_FILES =
 
 GENERATED_TEST_FILES = $(JSON_TEST_FILES:.json=.json.h) $(RAW_TEST_FILES:.raw=.raw.h)
 
 # test_bitcoin binary #
 BITCOIN_TESTS =\
   test/arith_uint256_tests.cpp \
   test/scriptnum10.h \
   test/addrman_tests.cpp \
   test/amount_tests.cpp \
   test/allocator_tests.cpp \
   test/base32_tests.cpp \
   test/base58_tests.cpp \
   test/base64_tests.cpp \
   test/bip32_tests.cpp \
   test/blockcheck_tests.cpp \
   test/blockencodings_tests.cpp \
   test/blockindex_tests.cpp \
   test/blockstatus_tests.cpp \
   test/bloom_tests.cpp \
   test/bswap_tests.cpp \
   test/cashaddr_tests.cpp \
   test/cashaddrenc_tests.cpp \
   test/checkdatasig_tests.cpp \
   test/checkpoints_tests.cpp \
   test/checkqueue_tests.cpp \
   test/coins_tests.cpp \
   test/compress_tests.cpp \
   test/config_tests.cpp \
   test/core_io_tests.cpp \
   test/crypto_tests.cpp \
   test/cuckoocache_tests.cpp \
   test/dbwrapper_tests.cpp \
   test/DoS_tests.cpp \
   test/dstencode_tests.cpp \
   test/excessiveblock_tests.cpp \
   test/feerate_tests.cpp \
   test/getarg_tests.cpp \
   test/hash_tests.cpp \
   test/inv_tests.cpp \
   test/jsonutil.cpp \
   test/jsonutil.h \
   test/key_tests.cpp \
   test/limitedmap_tests.cpp \
   test/main_tests.cpp \
   test/mempool_tests.cpp \
   test/merkle_tests.cpp \
   test/miner_tests.cpp \
   test/monolith_opcodes.cpp \
   test/multisig_tests.cpp \
   test/net_tests.cpp \
   test/netbase_tests.cpp \
   test/pmt_tests.cpp \
   test/policyestimator_tests.cpp \
   test/pow_tests.cpp \
   test/prevector_tests.cpp \
   test/raii_event_tests.cpp \
   test/random_tests.cpp \
   test/reverselock_tests.cpp \
   test/rpc_tests.cpp \
+  test/rwcollection_tests.cpp \
   test/sanity_tests.cpp \
   test/scheduler_tests.cpp \
   test/script_commitment_tests.cpp \
   test/script_P2SH_tests.cpp \
   test/script_tests.cpp \
   test/scriptflags.cpp \
   test/scriptflags.h \
   test/scriptnum_tests.cpp \
   test/serialize_tests.cpp \
   test/sigencoding_tests.cpp \
   test/sighash_tests.cpp \
   test/sighashtype_tests.cpp \
   test/sigopcount_tests.cpp \
   test/sigutil.cpp \
   test/sigutil.h \
   test/skiplist_tests.cpp \
   test/streams_tests.cpp \
   test/sync_tests.cpp \
   test/test_bitcoin.cpp \
   test/test_bitcoin.h \
   test/test_bitcoin_main.cpp \
   test/testutil.cpp \
   test/testutil.h \
   test/timedata_tests.cpp \
   test/transaction_tests.cpp \
   test/txvalidationcache_tests.cpp \
   test/versionbits_tests.cpp \
   test/uint256_tests.cpp \
   test/undo_tests.cpp \
   test/univalue_tests.cpp \
   test/util_tests.cpp \
   test/validation_tests.cpp \
   test/work_comparator_tests.cpp \
   rpc/test/server_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \
   wallet/test/wallet_test_fixture.cpp \
   wallet/test/wallet_test_fixture.h \
   wallet/test/accounting_tests.cpp \
   wallet/test/wallet_tests.cpp \
   wallet/test/walletdb_tests.cpp \
   wallet/test/crypto_tests.cpp
 endif
 
 test_test_bitcoin_SOURCES = $(BITCOIN_TESTS) $(JSON_TEST_FILES) $(RAW_TEST_FILES)
 test_test_bitcoin_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) -I$(builddir)/test/ $(TESTDEFS) $(EVENT_CFLAGS)
 test_test_bitcoin_LDADD =
 if ENABLE_WALLET
 test_test_bitcoin_LDADD += $(LIBBITCOIN_WALLET)
 endif
 
 test_test_bitcoin_LDADD += $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) \
   $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1) $(EVENT_LIBS) $(EVENT_PTHREADS_LIBS)
 test_test_bitcoin_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 
 test_test_bitcoin_LDADD += $(LIBBITCOIN_CONSENSUS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS)
 test_test_bitcoin_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS) -static
 
 if ENABLE_ZMQ
 test_test_bitcoin_LDADD += $(ZMQ_LIBS)
 endif
 #
 
 # test_bitcoin_fuzzy binary #
 test_test_bitcoin_fuzzy_SOURCES = test/test_bitcoin_fuzzy.cpp
 test_test_bitcoin_fuzzy_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_test_bitcoin_fuzzy_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_test_bitcoin_fuzzy_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 test_test_bitcoin_fuzzy_LDADD = \
   $(LIBUNIVALUE) \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \
   $(LIBBITCOIN_UTIL) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
   $(LIBSECP256K1)
 
 test_test_bitcoin_fuzzy_LDADD += $(BOOST_LIBS) $(CRYPTO_LIBS)
 #
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)
 
 $(BITCOIN_TESTS): $(GENERATED_TEST_FILES)
 
 CLEAN_BITCOIN_TEST = test/*.gcda test/*.gcno $(GENERATED_TEST_FILES)
 
 CLEANFILES += $(CLEAN_BITCOIN_TEST)
 
 bitcoin_test: $(TEST_BINARY)
 
 bitcoin_test_check: $(TEST_BINARY) FORCE
 	$(MAKE) check-TESTS TESTS=$^
 
 bitcoin_test_clean : FORCE
 	rm -f $(CLEAN_BITCOIN_TEST) $(test_test_bitcoin_OBJECTS) $(TEST_BINARY)
 
 check-local:
 	@echo "Running test/util/bitcoin-util-test.py..."
 	$(top_builddir)/test/util/bitcoin-util-test.py
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C secp256k1 check
 if EMBEDDED_UNIVALUE
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C univalue check
 endif
 
 %.json.h: %.json
 	@$(MKDIR_P) $(@D)
 	@{ \
 	 echo "namespace json_tests{" && \
 	 echo "static unsigned const char $(*F)[] = {" && \
 	 $(HEXDUMP) -v -e '8/1 "0x%02x, "' -e '"\n"' $< | $(SED) -e 's/0x  ,//g' && \
 	 echo "};};"; \
 	} > "$@.new" && mv -f "$@.new" "$@"
 	@echo "Generated $@"
diff --git a/src/rwcollection.h b/src/rwcollection.h
new file mode 100644
index 0000000000..093362ba19
--- /dev/null
+++ b/src/rwcollection.h
@@ -0,0 +1,75 @@
+// Copyright (c) 2018 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_RWCOLLECTION_H
+#define BITCOIN_RWCOLLECTION_H
+
+#include <boost/noncopyable.hpp>
+#include <boost/range/iterator.hpp>
+#include <boost/thread/shared_mutex.hpp>
+
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+template <typename T, typename L> class RWCollectionView : boost::noncopyable {
+private:
+    L lock;
+    T *collection;
+
+    template <typename I> struct BracketType {
+        typedef decltype(std::declval<T &>()[std::declval<I>()]) type;
+    };
+
+public:
+    RWCollectionView(L l, T &c) : lock(std::move(l)), collection(&c) {}
+    RWCollectionView(RWCollectionView &&other)
+        : lock(std::move(other.lock)), collection(other.collection) {}
+
+    T *operator->() { return collection; }
+    const T *operator->() const { return collection; }
+
+    /**
+     * Iterator mechanics.
+     */
+    typedef typename boost::range_iterator<T>::type iterator;
+    iterator begin() { return std::begin(*collection); }
+    iterator end() { return std::end(*collection); }
+
+    typedef typename boost::range_iterator<const T>::type const_iterator;
+    const_iterator begin() const { return std::begin(*collection); }
+    const_iterator end() const { return std::end(*collection); }
+
+    /**
+     * Forward bracket operator.
+     */
+    template <typename I> typename BracketType<I>::type operator[](I &&index) {
+        return (*collection)[std::forward<I>(index)];
+    }
+};
+
+template <typename T> class RWCollection {
+private:
+    mutable boost::shared_mutex rwlock;
+    T collection;
+
+public:
+    RWCollection() : collection() {}
+
+    typedef RWCollectionView<const T, boost::shared_lock<boost::shared_mutex>>
+        ReadView;
+    ReadView getReadView() const {
+        return ReadView(boost::shared_lock<boost::shared_mutex>(rwlock),
+                        collection);
+    }
+
+    typedef RWCollectionView<T, boost::unique_lock<boost::shared_mutex>>
+        WriteView;
+    WriteView getWriteView() {
+        return WriteView(boost::unique_lock<boost::shared_mutex>(rwlock),
+                         collection);
+    }
+};
+
+#endif // BITCOIN_RWCOLLECTION_H
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index cc62a8e6ec..dad56df444 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -1,100 +1,100 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "sigcache.h"
 
 #include "cuckoocache.h"
 #include "memusage.h"
 #include "pubkey.h"
 #include "random.h"
 #include "uint256.h"
 #include "util.h"
 
-#include <boost/thread.hpp>
+#include <boost/thread/shared_mutex.hpp>
 
 namespace {
 
 /**
  * Valid signature cache, to avoid doing expensive ECDSA signature checking
  * twice for every transaction (once when accepted into memory pool, and
  * again when accepted into the block chain)
  */
 class CSignatureCache {
 private:
     //! Entries are SHA256(nonce || signature hash || public key || signature):
     uint256 nonce;
     typedef CuckooCache::cache<uint256, SignatureCacheHasher> map_type;
     map_type setValid;
     boost::shared_mutex cs_sigcache;
 
 public:
     CSignatureCache() { GetRandBytes(nonce.begin(), 32); }
 
     void ComputeEntry(uint256 &entry, const uint256 &hash,
                       const std::vector<uint8_t> &vchSig,
                       const CPubKey &pubkey) {
         CSHA256()
             .Write(nonce.begin(), 32)
             .Write(hash.begin(), 32)
             .Write(&pubkey[0], pubkey.size())
             .Write(&vchSig[0], vchSig.size())
             .Finalize(entry.begin());
     }
 
     bool Get(const uint256 &entry, const bool erase) {
         boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
         return setValid.contains(entry, erase);
     }
 
     void Set(uint256 &entry) {
         boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
         setValid.insert(entry);
     }
     uint32_t setup_bytes(size_t n) { return setValid.setup_bytes(n); }
 };
 
 /**
  * In previous versions of this code, signatureCache was a local static variable
  * in CachingTransactionSignatureChecker::VerifySignature. We initialize
  * signatureCache outside of VerifySignature to avoid the atomic operation per
  * call overhead associated with local static variables even though
  * signatureCache could be made local to VerifySignature.
  */
 static CSignatureCache signatureCache;
 } // namespace
 
 // To be called once in AppInit2/TestingSetup to initialize the signatureCache
 void InitSignatureCache() {
     // nMaxCacheSize is unsigned. If -maxsigcachesize is set to zero,
     // setup_bytes creates the minimum possible cache (2 elements).
     size_t nMaxCacheSize =
         std::min(std::max(int64_t(0),
                           gArgs.GetArg("-maxsigcachesize",
                                        DEFAULT_MAX_SIG_CACHE_SIZE)),
                  MAX_MAX_SIG_CACHE_SIZE) *
         (size_t(1) << 20);
     size_t nElems = signatureCache.setup_bytes(nMaxCacheSize);
     LogPrintf("Using %zu MiB out of %zu requested for signature cache, able to "
               "store %zu elements\n",
               (nElems * sizeof(uint256)) >> 20, nMaxCacheSize >> 20, nElems);
 }
 
 bool CachingTransactionSignatureChecker::VerifySignature(
     const std::vector<uint8_t> &vchSig, const CPubKey &pubkey,
     const uint256 &sighash) const {
     uint256 entry;
     signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey);
     if (signatureCache.Get(entry, !store)) {
         return true;
     }
     if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey,
                                                       sighash)) {
         return false;
     }
     if (store) {
         signatureCache.Set(entry);
     }
     return true;
 }
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
index d0a74411c7..c00c17ceba 100644
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -1,167 +1,168 @@
 # Copyright (c) 2018 The Bitcoin developers
 
 project(bitcoin-test)
 
 # Process json files.
 file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/data")
 
 find_program(PYTHON python)
 function(gen_json_header NAME)
 	set(HEADERS "")
 	foreach(f ${ARGN})
 		set(h "${CMAKE_CURRENT_BINARY_DIR}/${f}.h")
 
 		# Get the proper name for the test variable.
 		get_filename_component(TEST_NAME ${f} NAME_WE)
 		add_custom_command(OUTPUT ${h}
 			COMMAND ${PYTHON}
 			ARGS
 				"${CMAKE_CURRENT_SOURCE_DIR}/data/generate_header.py"
 				"${TEST_NAME}"
 				"${CMAKE_CURRENT_SOURCE_DIR}/${f}" > ${h}
 			MAIN_DEPENDENCY ${f}
 			DEPENDS
 				"data/generate_header.py"
 			VERBATIM
 		)
 		list(APPEND HEADERS ${h})
 	endforeach(f)
 	set(${NAME} "${HEADERS}" PARENT_SCOPE)
 endfunction()
 
 gen_json_header(JSON_HEADERS
 	data/script_tests.json
 	data/base58_keys_valid.json
 	data/base58_encode_decode.json
 	data/base58_keys_invalid.json
 	data/tx_invalid.json
 	data/tx_valid.json
 	data/sighash.json
 )
 
 include(TestSuite)
 create_test_suite(bitcoin)
 add_dependencies(check check-bitcoin)
 
 add_test_to_suite(bitcoin test_bitcoin
 	arith_uint256_tests.cpp
 	addrman_tests.cpp
 	amount_tests.cpp
 	allocator_tests.cpp
 	base32_tests.cpp
 	base58_tests.cpp
 	base64_tests.cpp
 	bip32_tests.cpp
 	blockcheck_tests.cpp
 	blockencodings_tests.cpp
 	blockindex_tests.cpp
 	blockstatus_tests.cpp
 	bloom_tests.cpp
 	bswap_tests.cpp
 	cashaddr_tests.cpp
 	cashaddrenc_tests.cpp
 	checkdatasig_tests.cpp
 	checkpoints_tests.cpp
 	checkqueue_tests.cpp
 	coins_tests.cpp
 	compress_tests.cpp
 	config_tests.cpp
 	core_io_tests.cpp
 	crypto_tests.cpp
 	cuckoocache_tests.cpp
 	dbwrapper_tests.cpp
 	DoS_tests.cpp
 	dstencode_tests.cpp
 	excessiveblock_tests.cpp
 	feerate_tests.cpp
 	getarg_tests.cpp
 	hash_tests.cpp
 	inv_tests.cpp
 	jsonutil.cpp
 	key_tests.cpp
 	limitedmap_tests.cpp
 	main_tests.cpp
 	mempool_tests.cpp
 	merkle_tests.cpp
 	miner_tests.cpp
 	monolith_opcodes.cpp
 	multisig_tests.cpp
 	net_tests.cpp
 	netbase_tests.cpp
 	pmt_tests.cpp
 	policyestimator_tests.cpp
 	pow_tests.cpp
 	prevector_tests.cpp
 	raii_event_tests.cpp
 	random_tests.cpp
 	reverselock_tests.cpp
 	rpc_tests.cpp
+	rwcollection_tests.cpp
 	sanity_tests.cpp
 	scheduler_tests.cpp
 	script_commitment_tests.cpp
 	script_P2SH_tests.cpp
 	script_tests.cpp
 	scriptflags.cpp
 	scriptnum_tests.cpp
 	serialize_tests.cpp
 	sigencoding_tests.cpp
 	sighash_tests.cpp
 	sighashtype_tests.cpp
 	sigopcount_tests.cpp
 	sigutil.cpp
 	skiplist_tests.cpp
 	streams_tests.cpp
 	sync_tests.cpp
 	test_bitcoin.cpp
 	test_bitcoin_main.cpp
 	testutil.cpp
 	timedata_tests.cpp
 	transaction_tests.cpp
 	txvalidationcache_tests.cpp
 	versionbits_tests.cpp
 	uint256_tests.cpp
 	undo_tests.cpp
 	univalue_tests.cpp
 	util_tests.cpp
 	validation_tests.cpp
 	work_comparator_tests.cpp
 
 	# RPC Tests
 	../rpc/test/server_tests.cpp
 
 	# Tests generated from JSON
 	${JSON_HEADERS}
 )
 
 target_include_directories(test_bitcoin
 	PUBLIC
 		# To access the generated json headers.
 		${CMAKE_CURRENT_BINARY_DIR}
 )
 
 find_package(Boost 1.58 REQUIRED unit_test_framework)
 
 target_link_libraries(test_bitcoin Boost::unit_test_framework rpcclient server)
 
 # We need to detect if the BOOST_TEST_DYN_LINK flag is required.
 set(CMAKE_REQUIRED_LIBRARIES Boost::unit_test_framework)
 check_cxx_source_compiles("
 	#define BOOST_TEST_DYN_LINK
 	#define BOOST_TEST_MAIN
 	#include <boost/test/unit_test.hpp>
 " BOOST_TEST_DYN_LINK)
 
 if(BOOST_TEST_DYN_LINK)
 	target_compile_definitions(test_bitcoin PRIVATE BOOST_TEST_DYN_LINK)
 endif(BOOST_TEST_DYN_LINK)
 
 if(BUILD_BITCOIN_WALLET)
 	target_sources(test_bitcoin
 		PRIVATE
 			../wallet/test/wallet_test_fixture.cpp
 			../wallet/test/accounting_tests.cpp
 			../wallet/test/wallet_tests.cpp
 			../wallet/test/walletdb_tests.cpp
 			../wallet/test/crypto_tests.cpp
 	)
 endif()
diff --git a/src/test/cuckoocache_tests.cpp b/src/test/cuckoocache_tests.cpp
index 84ddacb08e..8ef075ee8d 100644
--- a/src/test/cuckoocache_tests.cpp
+++ b/src/test/cuckoocache_tests.cpp
@@ -1,397 +1,397 @@
 // Copyright (c) 2012-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "cuckoocache.h"
 #include "random.h"
 #include "script/sigcache.h"
 #include "test/test_bitcoin.h"
 
-#include <thread>
+#include <boost/thread/shared_mutex.hpp>
 
 #include <boost/test/unit_test.hpp>
 
 /** Test Suite for CuckooCache
  *
  *  1) All tests should have a deterministic result (using insecure rand
  *  with deterministic seeds)
  *  2) Some test methods are templated to allow for easier testing
  *  against new versions / comparing
  *  3) Results should be treated as a regression test, i.e., did the behavior
  *  change significantly from what was expected. This can be OK, depending on
  *  the nature of the change, but requires updating the tests to reflect the new
  *  expected behavior. For example improving the hit rate may cause some tests
  *  using BOOST_CHECK_CLOSE to fail.
  */
 FastRandomContext local_rand_ctx(true);
 
 BOOST_AUTO_TEST_SUITE(cuckoocache_tests);
 
 /**
  * insecure_GetRandHash fills in a uint256 from local_rand_ctx
  */
 void insecure_GetRandHash(uint256 &t) {
     uint32_t *ptr = (uint32_t *)t.begin();
     for (uint8_t j = 0; j < 8; ++j) {
         *(ptr++) = local_rand_ctx.rand32();
     }
 }
 
 /**
  * Test that no values not inserted into the cache are read out of it.
  *
  * There are no repeats in the first 200000 insecure_GetRandHash calls
  */
 BOOST_AUTO_TEST_CASE(test_cuckoocache_no_fakes) {
     local_rand_ctx = FastRandomContext(true);
     CuckooCache::cache<uint256, SignatureCacheHasher> cc{};
     cc.setup_bytes(32 << 20);
     uint256 v;
     for (int x = 0; x < 100000; ++x) {
         insecure_GetRandHash(v);
         cc.insert(v);
     }
     for (int x = 0; x < 100000; ++x) {
         insecure_GetRandHash(v);
         BOOST_CHECK(!cc.contains(v, false));
     }
 };
 
 /**
  * This helper returns the hit rate when megabytes*load worth of entries are
  * inserted into a megabytes sized cache
  */
 template <typename Cache> double test_cache(size_t megabytes, double load) {
     local_rand_ctx = FastRandomContext(true);
     std::vector<uint256> hashes;
     Cache set{};
     size_t bytes = megabytes * (1 << 20);
     set.setup_bytes(bytes);
     uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256)));
     hashes.resize(n_insert);
     for (uint32_t i = 0; i < n_insert; ++i) {
         uint32_t *ptr = (uint32_t *)hashes[i].begin();
         for (uint8_t j = 0; j < 8; ++j) {
             *(ptr++) = local_rand_ctx.rand32();
         }
     }
     /**
      * We make a copy of the hashes because future optimizations of the
      * cuckoocache may overwrite the inserted element, so the test is "future
      * proofed".
      */
     std::vector<uint256> hashes_insert_copy = hashes;
     /** Do the insert */
     for (uint256 &h : hashes_insert_copy) {
         set.insert(h);
     }
     /** Count the hits */
     uint32_t count = 0;
     for (uint256 &h : hashes) {
         count += set.contains(h, false);
     }
     double hit_rate = double(count) / double(n_insert);
     return hit_rate;
 }
 
 /** The normalized hit rate for a given load.
  *
  * The semantics are a little confusing, so please see the below
  * explanation.
  *
  * Examples:
  *
  * 1) at load 0.5, we expect a perfect hit rate, so we multiply by
  * 1.0
  * 2) at load 2.0, we expect to see half the entries, so a perfect hit rate
  * would be 0.5. Therefore, if we see a hit rate of 0.4, 0.4*2.0 = 0.8 is the
  * normalized hit rate.
  *
  * This is basically the right semantics, but has a bit of a glitch depending on
  * how you measure around load 1.0 as after load 1.0 your normalized hit rate
  * becomes effectively perfect, ignoring freshness.
  */
 double normalize_hit_rate(double hits, double load) {
     return hits * std::max(load, 1.0);
 }
 
 /** Check the hit rate on loads ranging from 0.1 to 2.0 */
 BOOST_AUTO_TEST_CASE(cuckoocache_hit_rate_ok) {
     /**
      * Arbitrarily selected Hit Rate threshold that happens to work for this
      * test as a lower bound on performance.
      */
     double HitRateThresh = 0.98;
     size_t megabytes = 32;
     for (double load = 0.1; load < 2; load *= 2) {
         double hits =
             test_cache<CuckooCache::cache<uint256, SignatureCacheHasher>>(
                 megabytes, load);
         BOOST_CHECK(normalize_hit_rate(hits, load) > HitRateThresh);
     }
 }
 
 /** This helper checks that erased elements are preferentially inserted onto and
  * that the hit rate of "fresher" keys is reasonable*/
 template <typename Cache> void test_cache_erase(size_t megabytes) {
     double load = 1;
     local_rand_ctx = FastRandomContext(true);
     std::vector<uint256> hashes;
     Cache set{};
     size_t bytes = megabytes * (1 << 20);
     set.setup_bytes(bytes);
     uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256)));
     hashes.resize(n_insert);
     for (uint32_t i = 0; i < n_insert; ++i) {
         uint32_t *ptr = (uint32_t *)hashes[i].begin();
         for (uint8_t j = 0; j < 8; ++j) {
             *(ptr++) = local_rand_ctx.rand32();
         }
     }
     /** We make a copy of the hashes because future optimizations of the
      * cuckoocache may overwrite the inserted element, so the test is
      * "future proofed".
      */
     std::vector<uint256> hashes_insert_copy = hashes;
 
     /** Insert the first half */
     for (uint32_t i = 0; i < (n_insert / 2); ++i) {
         set.insert(hashes_insert_copy[i]);
     }
     /** Erase the first quarter */
     for (uint32_t i = 0; i < (n_insert / 4); ++i) {
         set.contains(hashes[i], true);
     }
     /** Insert the second half */
     for (uint32_t i = (n_insert / 2); i < n_insert; ++i) {
         set.insert(hashes_insert_copy[i]);
     }
 
     /** elements that we marked erased but that are still there */
     size_t count_erased_but_contained = 0;
     /** elements that we did not erase but are older */
     size_t count_stale = 0;
     /** elements that were most recently inserted */
     size_t count_fresh = 0;
 
     for (uint32_t i = 0; i < (n_insert / 4); ++i) {
         count_erased_but_contained += set.contains(hashes[i], false);
     }
     for (uint32_t i = (n_insert / 4); i < (n_insert / 2); ++i) {
         count_stale += set.contains(hashes[i], false);
     }
     for (uint32_t i = (n_insert / 2); i < n_insert; ++i) {
         count_fresh += set.contains(hashes[i], false);
     }
 
     double hit_rate_erased_but_contained =
         double(count_erased_but_contained) / (double(n_insert) / 4.0);
     double hit_rate_stale = double(count_stale) / (double(n_insert) / 4.0);
     double hit_rate_fresh = double(count_fresh) / (double(n_insert) / 2.0);
 
     // Check that our hit_rate_fresh is perfect
     BOOST_CHECK_EQUAL(hit_rate_fresh, 1.0);
     // Check that we have a more than 2x better hit rate on stale elements than
     // erased elements.
     BOOST_CHECK(hit_rate_stale > 2 * hit_rate_erased_but_contained);
 }
 
 BOOST_AUTO_TEST_CASE(cuckoocache_erase_ok) {
     size_t megabytes = 32;
     test_cache_erase<CuckooCache::cache<uint256, SignatureCacheHasher>>(
         megabytes);
 }
 
 template <typename Cache> void test_cache_erase_parallel(size_t megabytes) {
     double load = 1;
     local_rand_ctx = FastRandomContext(true);
     std::vector<uint256> hashes;
     Cache set{};
     size_t bytes = megabytes * (1 << 20);
     set.setup_bytes(bytes);
     uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256)));
     hashes.resize(n_insert);
     for (uint32_t i = 0; i < n_insert; ++i) {
         uint32_t *ptr = (uint32_t *)hashes[i].begin();
         for (uint8_t j = 0; j < 8; ++j) {
             *(ptr++) = local_rand_ctx.rand32();
         }
     }
     /** We make a copy of the hashes because future optimizations of the
      * cuckoocache may overwrite the inserted element, so the test is
      * "future proofed".
      */
     std::vector<uint256> hashes_insert_copy = hashes;
     boost::shared_mutex mtx;
 
     {
         /** Grab lock to make sure we release inserts */
         boost::unique_lock<boost::shared_mutex> l(mtx);
         /** Insert the first half */
         for (uint32_t i = 0; i < (n_insert / 2); ++i) {
             set.insert(hashes_insert_copy[i]);
         }
     }
 
     /** Spin up 3 threads to run contains with erase.
      */
     std::vector<std::thread> threads;
     /** Erase the first quarter */
     for (uint32_t x = 0; x < 3; ++x)
         /** Each thread is emplaced with x copy-by-value */
         threads.emplace_back([&, x] {
             boost::shared_lock<boost::shared_mutex> l(mtx);
             size_t ntodo = (n_insert / 4) / 3;
             size_t start = ntodo * x;
             size_t end = ntodo * (x + 1);
             for (uint32_t i = start; i < end; ++i) {
                 set.contains(hashes[i], true);
             }
         });
 
     /** Wait for all threads to finish */
     for (std::thread &t : threads) {
         t.join();
     }
     /** Grab lock to make sure we observe erases */
     boost::unique_lock<boost::shared_mutex> l(mtx);
     /** Insert the second half */
     for (uint32_t i = (n_insert / 2); i < n_insert; ++i) {
         set.insert(hashes_insert_copy[i]);
     }
 
     /** elements that we marked erased but that are still there */
     size_t count_erased_but_contained = 0;
     /** elements that we did not erase but are older */
     size_t count_stale = 0;
     /** elements that were most recently inserted */
     size_t count_fresh = 0;
 
     for (uint32_t i = 0; i < (n_insert / 4); ++i) {
         count_erased_but_contained += set.contains(hashes[i], false);
     }
     for (uint32_t i = (n_insert / 4); i < (n_insert / 2); ++i) {
         count_stale += set.contains(hashes[i], false);
     }
     for (uint32_t i = (n_insert / 2); i < n_insert; ++i) {
         count_fresh += set.contains(hashes[i], false);
     }
 
     double hit_rate_erased_but_contained =
         double(count_erased_but_contained) / (double(n_insert) / 4.0);
     double hit_rate_stale = double(count_stale) / (double(n_insert) / 4.0);
     double hit_rate_fresh = double(count_fresh) / (double(n_insert) / 2.0);
 
     // Check that our hit_rate_fresh is perfect
     BOOST_CHECK_EQUAL(hit_rate_fresh, 1.0);
     // Check that we have a more than 2x better hit rate on stale elements than
     // erased elements.
     BOOST_CHECK(hit_rate_stale > 2 * hit_rate_erased_but_contained);
 }
 
 BOOST_AUTO_TEST_CASE(cuckoocache_erase_parallel_ok) {
     size_t megabytes = 32;
     test_cache_erase_parallel<
         CuckooCache::cache<uint256, SignatureCacheHasher>>(megabytes);
 }
 
 template <typename Cache> void test_cache_generations() {
     // This test checks that for a simulation of network activity, the fresh hit
     // rate is never below 99%, and the number of times that it is worse than
     // 99.9% are less than 1% of the time.
     double min_hit_rate = 0.99;
     double tight_hit_rate = 0.999;
     double max_rate_less_than_tight_hit_rate = 0.01;
     // A cache that meets this specification is therefore shown to have a hit
     // rate of at least tight_hit_rate * (1 - max_rate_less_than_tight_hit_rate)
     // +
     // min_hit_rate*max_rate_less_than_tight_hit_rate = 0.999*99%+0.99*1% ==
     // 99.89%
     // hit rate with low variance.
 
     // We use deterministic values, but this test has also passed on many
     // iterations with non-deterministic values, so it isn't "overfit" to the
     // specific entropy in FastRandomContext(true) and implementation of the
     // cache.
     local_rand_ctx = FastRandomContext(true);
 
     // block_activity models a chunk of network activity. n_insert elements are
     // adde to the cache. The first and last n/4 are stored for removal later
     // and the middle n/2 are not stored. This models a network which uses half
     // the signatures of recently (since the last block) added transactions
     // immediately and never uses the other half.
     struct block_activity {
         std::vector<uint256> reads;
         block_activity(uint32_t n_insert, Cache &c) : reads() {
             std::vector<uint256> inserts;
             inserts.resize(n_insert);
             reads.reserve(n_insert / 2);
             for (uint32_t i = 0; i < n_insert; ++i) {
                 uint32_t *ptr = (uint32_t *)inserts[i].begin();
                 for (uint8_t j = 0; j < 8; ++j) {
                     *(ptr++) = local_rand_ctx.rand32();
                 }
             }
             for (uint32_t i = 0; i < n_insert / 4; ++i) {
                 reads.push_back(inserts[i]);
             }
             for (uint32_t i = n_insert - (n_insert / 4); i < n_insert; ++i) {
                 reads.push_back(inserts[i]);
             }
             for (auto h : inserts) {
                 c.insert(h);
             }
         }
     };
 
     const uint32_t BLOCK_SIZE = 10000;
     // We expect window size 60 to perform reasonably given that each epoch
     // stores 45% of the cache size (~472k).
     const uint32_t WINDOW_SIZE = 60;
     const uint32_t POP_AMOUNT = (BLOCK_SIZE / WINDOW_SIZE) / 2;
     const double load = 10;
     const size_t megabytes = 32;
     const size_t bytes = megabytes * (1 << 20);
     const uint32_t n_insert =
         static_cast<uint32_t>(load * (bytes / sizeof(uint256)));
 
     std::vector<block_activity> hashes;
     Cache set{};
     set.setup_bytes(bytes);
     hashes.reserve(n_insert / BLOCK_SIZE);
     std::deque<block_activity> last_few;
     uint32_t out_of_tight_tolerance = 0;
     uint32_t total = n_insert / BLOCK_SIZE;
     // we use the deque last_few to model a sliding window of blocks. at each
     // step, each of the last WINDOW_SIZE block_activities checks the cache for
     // POP_AMOUNT of the hashes that they inserted, and marks these erased.
     for (uint32_t i = 0; i < total; ++i) {
         if (last_few.size() == WINDOW_SIZE) last_few.pop_front();
         last_few.emplace_back(BLOCK_SIZE, set);
         uint32_t count = 0;
         for (auto &act : last_few) {
             for (uint32_t k = 0; k < POP_AMOUNT; ++k) {
                 count += set.contains(act.reads.back(), true);
                 act.reads.pop_back();
             }
         }
         // We use last_few.size() rather than WINDOW_SIZE for the correct
         // behavior on the first WINDOW_SIZE iterations where the deque is not
         // full yet.
         double hit = double(count) / (last_few.size() * POP_AMOUNT);
         // Loose Check that hit rate is above min_hit_rate
         BOOST_CHECK(hit > min_hit_rate);
         // Tighter check, count number of times we are less than tight_hit_rate
         // (and implicityly, greater than min_hit_rate)
         out_of_tight_tolerance += hit < tight_hit_rate;
     }
     // Check that being out of tolerance happens less than
     // max_rate_less_than_tight_hit_rate of the time
     BOOST_CHECK(double(out_of_tight_tolerance) / double(total) <
                 max_rate_less_than_tight_hit_rate);
 }
 BOOST_AUTO_TEST_CASE(cuckoocache_generations) {
     test_cache_generations<CuckooCache::cache<uint256, SignatureCacheHasher>>();
 }
 
 BOOST_AUTO_TEST_SUITE_END();
diff --git a/src/test/rwcollection_tests.cpp b/src/test/rwcollection_tests.cpp
new file mode 100644
index 0000000000..36e9a2e6e6
--- /dev/null
+++ b/src/test/rwcollection_tests.cpp
@@ -0,0 +1,135 @@
+// Copyright (c) 2018 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "rwcollection.h"
+
+#include "test/test_bitcoin.h"
+
+#include <boost/range/adaptor/reversed.hpp>
+#include <boost/test/unit_test.hpp>
+
+#include <set>
+#include <vector>
+
+BOOST_AUTO_TEST_SUITE(rwcollection_tests);
+
+BOOST_AUTO_TEST_CASE(vector) {
+    RWCollection<std::vector<int>> rwvector;
+
+    {
+        auto w = rwvector.getWriteView();
+        for (int i = 0; i < 100; i++) {
+            w->push_back(i + 10);
+            BOOST_CHECK_EQUAL(w[i], i + 10);
+            BOOST_CHECK_EQUAL(w->back(), i + 10);
+            BOOST_CHECK_EQUAL(w->size(), i + 1);
+
+            w[i] = i;
+            BOOST_CHECK_EQUAL(w[i], i);
+        }
+
+        int e = 0;
+        for (int &i : w) {
+            BOOST_CHECK_EQUAL(i, e++);
+            i *= 2;
+        }
+
+        e = 0;
+        for (int &i : boost::adaptors::reverse(w)) {
+            BOOST_CHECK_EQUAL(i, 198 - 2 * e);
+            i = e++;
+        }
+    }
+
+    {
+        auto r = rwvector.getReadView();
+        for (int i = 0; i < 100; i++) {
+            BOOST_CHECK_EQUAL(r[i], 99 - i);
+        }
+
+        int e = 0;
+        for (const int &i : r) {
+            BOOST_CHECK_EQUAL(i, 99 - (e++));
+        }
+
+        e = 0;
+        for (const int &i : boost::adaptors::reverse(r)) {
+            BOOST_CHECK_EQUAL(i, e++);
+        }
+    }
+}
+
+BOOST_AUTO_TEST_CASE(set) {
+    RWCollection<std::set<int>> rwset;
+
+    {
+        auto w = rwset.getWriteView();
+        for (int i = 0; i < 100; i++) {
+            w->insert(i);
+            BOOST_CHECK_EQUAL(w->count(i), 1);
+            BOOST_CHECK_EQUAL(*(w->find(i)), i);
+            BOOST_CHECK_EQUAL(w->size(), i + 1);
+        }
+
+        for (int i = 0; i < 100; i += 2) {
+            BOOST_CHECK_EQUAL(w->erase(i), 1);
+            BOOST_CHECK_EQUAL(w->count(i), 0);
+            BOOST_CHECK(w->find(i) == std::end(w));
+        }
+
+        int e = 0;
+        for (const int &i : w) {
+            BOOST_CHECK_EQUAL(i / 2, e++);
+        }
+    }
+
+    {
+        auto r = rwset.getReadView();
+        for (int i = 0; i < 100; i += 2) {
+            BOOST_CHECK_EQUAL(r->count(i), 0);
+            BOOST_CHECK(r->find(i) == std::end(r));
+        }
+
+        for (int i = 1; i < 100; i += 2) {
+            BOOST_CHECK_EQUAL(r->count(i), 1);
+            BOOST_CHECK_EQUAL(*(r->find(i)), i);
+        }
+
+        int e = 0;
+        for (const int &i : r) {
+            BOOST_CHECK_EQUAL(i / 2, e++);
+        }
+    }
+}
+
+BOOST_AUTO_TEST_CASE(map) {
+    RWCollection<std::map<std::string, std::string>> rwmap;
+
+    {
+        auto w = rwmap.getWriteView();
+        w["1"] = "one";
+        w["2"] = "two";
+        w["3"] = "three";
+        BOOST_CHECK_EQUAL(w["1"], "one");
+        BOOST_CHECK_EQUAL(w["2"], "two");
+        BOOST_CHECK_EQUAL(w["3"], "three");
+
+        for (const std::pair<std::string, std::string> &p : w) {
+            BOOST_CHECK_EQUAL(w[p.first], p.second);
+        }
+    }
+
+    {
+        auto r = rwmap.getReadView();
+        BOOST_CHECK_EQUAL(r->count("1"), 1);
+        BOOST_CHECK_EQUAL(r->find("1")->first, "1");
+        BOOST_CHECK_EQUAL(r->find("1")->second, "one");
+
+        for (const std::pair<std::string, std::string> &p : r) {
+            BOOST_CHECK_EQUAL(r->at(p.first), p.second);
+        }
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END();