Merge bitcoin/bitcoin#24304: [kernel 0/n] Introduce `bitcoin-chainstate`

2c03cec2ff8cdbfd5da92bfb507d218e5c6435b0 ci: Build bitcoin-chainstate (Carl Dong)
095aa6ca37bf0bd5c5e221bab779978a99b2a34c build: Add example bitcoin-chainstate executable (Carl Dong)

Pull request description:

  Part of: #24303

  This PR introduces an example/demo `bitcoin-chainstate` executable using said library which can print out information about a datadir and take in new blocks on stdin.

  Please read the commit messages for more details.

  -----

  #### You may ask: WTF?! Why is `index/*.cpp`, etc. being linked in?

  This PR is meant only to capture the state of dependencies in our consensus engine as of right now. There are many things to decouple from consensus, which will be done in subsequent PRs. Listing the files out right now in `bitcoin_chainstate_SOURCES` is purely to give us a clear picture of the task at hand, it is **not** to say that these dependencies _belongs_ there in any way.

  ### TODO

  1. Clean up `bitcoin-chainstate.cpp`
     It is quite ugly, with a lot of comments I've left for myself, I should clean it up to the best of my abilities (the ugliness of our init/shutdown might be the upper bound on cleanliness here...)

ACKs for top commit:
  ajtowns:
    ACK 2c03cec2ff8cdbfd5da92bfb507d218e5c6435b0
  ryanofsky:
    Code review ACK 2c03cec2ff8cdbfd5da92bfb507d218e5c6435b0. Just rebase, comments, formatting change since last review
  MarcoFalke:
    re-ACK 2c03cec2ff8cdbfd5da92bfb507d218e5c6435b0 🏔

Tree-SHA512: 86e7fb5718caa577df8abc8288c754f4a590650d974df9d2f6476c87ed25c70f923c4db651c6963f33498fc7a3a31f6692b9a75cbc996bf4888c5dac2f34a13b

6 files changed, 380 insertions, 4 deletions

diff --git a/.cirrus.yml b/.cirrus.yml
index 9b0e2dbd2e..80546fb85e 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -258,13 +258,13 @@ task:
     FILE_ENV: "./ci/test/00_setup_env_i686_multiprocess.sh"
 
 task:
-  name: '[no wallet] [bionic]'
+  name: '[no wallet, libbitcoinkernel] [bionic]'
   << : *GLOBAL_TASK_TEMPLATE
   container:
     image: ubuntu:bionic
   env:
     << : *CIRRUS_EPHEMERAL_WORKER_TEMPLATE_ENV
-    FILE_ENV: "./ci/test/00_setup_env_native_nowallet.sh"
+    FILE_ENV: "./ci/test/00_setup_env_native_nowallet_libbitcoinkernel.sh"
 
 task:
   name: 'macOS 10.15 [gui, no tests] [focal]'
diff --git a/.gitignore b/.gitignore
index f84a53178e..0f07a86401 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ src/bitcoin-gui
 src/bitcoin-node
 src/bitcoin-tx
 src/bitcoin-util
+src/bitcoin-chainstate
 src/bitcoin-wallet
 src/test/fuzz/fuzz
 src/test/test_bitcoin
diff --git a/ci/test/00_setup_env_native_nowallet.sh b/ci/test/00_setup_env_native_nowallet_libbitcoinkernel.sh
index d80a7f9633..89d6256298 100755
--- a/ci/test/00_setup_env_native_nowallet.sh
+++ b/ci/test/00_setup_env_native_nowallet_libbitcoinkernel.sh
@@ -6,9 +6,9 @@
 
 export LC_ALL=C.UTF-8
 
-export CONTAINER_NAME=ci_native_nowallet
+export CONTAINER_NAME=ci_native_nowallet_libbitcoinkernel
 export DOCKER_NAME_TAG=ubuntu:18.04  # Use bionic to have one config run the tests in python3.6, see doc/dependencies.md
 export PACKAGES="python3-zmq clang-7 llvm-7 libc++abi-7-dev libc++-7-dev"  # Use clang-7 to test C++17 compatibility, see doc/dependencies.md
 export DEP_OPTS="NO_WALLET=1 CC=clang-7 CXX='clang++-7 -stdlib=libc++'"
 export GOAL="install"
-export BITCOIN_CONFIG="--enable-reduce-exports CC=clang-7 CXX='clang++-7 -stdlib=libc++'"
+export BITCOIN_CONFIG="--enable-reduce-exports CC=clang-7 CXX='clang++-7 -stdlib=libc++' --enable-experimental-util-chainstate"
diff --git a/configure.ac b/configure.ac
index ef9d894d9e..48684c7c98 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,6 +24,7 @@ BITCOIN_GUI_NAME=bitcoin-qt
 BITCOIN_CLI_NAME=bitcoin-cli
 BITCOIN_TX_NAME=bitcoin-tx
 BITCOIN_UTIL_NAME=bitcoin-util
+BITCOIN_CHAINSTATE_NAME=bitcoin-chainstate
 BITCOIN_WALLET_TOOL_NAME=bitcoin-wallet
 dnl Multi Process
 BITCOIN_MP_NODE_NAME=bitcoin-node
@@ -645,6 +646,12 @@ AC_ARG_ENABLE([util-util],
   [build_bitcoin_util=$enableval],
   [build_bitcoin_util=$build_bitcoin_utils])
 
+AC_ARG_ENABLE([experimental-util-chainstate],
+  [AS_HELP_STRING([--enable-experimental-util-chainstate],
+  [build experimental bitcoin-chainstate executable (default=no)])],
+  [build_bitcoin_chainstate=$enableval],
+  [build_bitcoin_chainstate=no])
+
 AC_ARG_WITH([libs],
   [AS_HELP_STRING([--with-libs],
   [build libraries (default=yes)])],
@@ -1268,6 +1275,7 @@ if test "$enable_fuzz" = "yes"; then
   build_bitcoin_cli=no
   build_bitcoin_tx=no
   build_bitcoin_util=no
+  build_bitcoin_chainstate=no
   build_bitcoin_wallet=no
   build_bitcoind=no
   build_bitcoin_libs=no
@@ -1624,6 +1632,10 @@ AC_MSG_CHECKING([whether to build bitcoin-util])
 AM_CONDITIONAL([BUILD_BITCOIN_UTIL], [test $build_bitcoin_util = "yes"])
 AC_MSG_RESULT($build_bitcoin_util)
 
+AC_MSG_CHECKING([whether to build experimental bitcoin-chainstate])
+AM_CONDITIONAL([BUILD_BITCOIN_CHAINSTATE], [test $build_bitcoin_chainstate = "yes"])
+AC_MSG_RESULT($build_bitcoin_chainstate)
+
 AC_MSG_CHECKING([whether to build libraries])
 AM_CONDITIONAL([BUILD_BITCOIN_LIBS], [test $build_bitcoin_libs = "yes"])
 if test "$build_bitcoin_libs" = "yes"; then
@@ -1843,6 +1855,7 @@ AC_SUBST(BITCOIN_GUI_NAME)
 AC_SUBST(BITCOIN_CLI_NAME)
 AC_SUBST(BITCOIN_TX_NAME)
 AC_SUBST(BITCOIN_UTIL_NAME)
+AC_SUBST(BITCOIN_CHAINSTATE_NAME)
 AC_SUBST(BITCOIN_WALLET_TOOL_NAME)
 AC_SUBST(BITCOIN_MP_NODE_NAME)
 AC_SUBST(BITCOIN_MP_GUI_NAME)
diff --git a/src/Makefile.am b/src/Makefile.am
index 417a611181..8f4cbee62f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -106,6 +106,10 @@ if BUILD_BITCOIN_UTIL
   bin_PROGRAMS += bitcoin-util
 endif
 
+if BUILD_BITCOIN_CHAINSTATE
+  bin_PROGRAMS += bitcoin-chainstate
+endif
+
 .PHONY: FORCE check-symbols check-security
 # bitcoin core #
 BITCOIN_CORE_H = \
@@ -769,6 +773,102 @@ bitcoin_util_LDADD = \
   $(LIBSECP256K1)
 #
 
+# bitcoin-chainstate binary #
+bitcoin_chainstate_SOURCES = \
+  bitcoin-chainstate.cpp \
+  arith_uint256.cpp \
+  blockfilter.cpp \
+  chain.cpp \
+  chainparamsbase.cpp \
+  chainparams.cpp \
+  clientversion.cpp \
+  coins.cpp \
+  compat/glibcxx_sanity.cpp \
+  compressor.cpp \
+  consensus/merkle.cpp \
+  consensus/tx_check.cpp \
+  consensus/tx_verify.cpp \
+  core_read.cpp \
+  dbwrapper.cpp \
+  deploymentinfo.cpp \
+  deploymentstatus.cpp \
+  flatfile.cpp \
+  fs.cpp \
+  hash.cpp \
+  index/base.cpp \
+  index/blockfilterindex.cpp \
+  index/coinstatsindex.cpp \
+  init/common.cpp \
+  key.cpp \
+  logging.cpp \
+  netaddress.cpp \
+  node/blockstorage.cpp \
+  node/chainstate.cpp \
+  node/coinstats.cpp \
+  node/ui_interface.cpp \
+  policy/feerate.cpp \
+  policy/fees.cpp \
+  policy/packages.cpp \
+  policy/policy.cpp \
+  policy/rbf.cpp \
+  policy/settings.cpp \
+  pow.cpp \
+  primitives/block.cpp \
+  primitives/transaction.cpp \
+  pubkey.cpp \
+  random.cpp \
+  randomenv.cpp \
+  scheduler.cpp \
+  script/interpreter.cpp \
+  script/script.cpp \
+  script/script_error.cpp \
+  script/sigcache.cpp \
+  script/standard.cpp \
+  shutdown.cpp \
+  signet.cpp \
+  support/cleanse.cpp \
+  support/lockedpool.cpp \
+  sync.cpp \
+  threadinterrupt.cpp \
+  timedata.cpp \
+  txdb.cpp \
+  txmempool.cpp \
+  uint256.cpp \
+  util/asmap.cpp \
+  util/bytevectorhash.cpp \
+  util/getuniquepath.cpp \
+  util/hasher.cpp \
+  util/moneystr.cpp \
+  util/rbf.cpp \
+  util/serfloat.cpp \
+  util/settings.cpp \
+  util/strencodings.cpp \
+  util/syscall_sandbox.cpp \
+  util/system.cpp \
+  util/thread.cpp \
+  util/threadnames.cpp \
+  util/time.cpp \
+  util/tokenpipe.cpp \
+  validation.cpp \
+  validationinterface.cpp \
+  versionbits.cpp \
+  warnings.cpp
+bitcoin_chainstate_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+bitcoin_chainstate_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+bitcoin_chainstate_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS) $(PTHREAD_FLAGS)
+bitcoin_chainstate_LDADD = \
+  $(LIBBITCOIN_CRYPTO) \
+  $(LIBUNIVALUE) \
+  $(LIBSECP256K1) \
+  $(LIBLEVELDB) \
+  $(LIBLEVELDB_SSE42) \
+  $(LIBMEMENV)
+
+# Required for obj/build.h to be generated first.
+# More details: https://www.gnu.org/software/automake/manual/html_node/Built-Sources-Example.html
+bitcoin_chainstate-clientversion.$(OBJEXT): obj/build.h
+#
+
 # bitcoinconsensus library #
 if BUILD_BITCOIN_LIBS
 include_HEADERS = script/bitcoinconsensus.h
diff --git a/src/bitcoin-chainstate.cpp b/src/bitcoin-chainstate.cpp
new file mode 100644
index 0000000000..f93197350d
--- /dev/null
+++ b/src/bitcoin-chainstate.cpp
@@ -0,0 +1,262 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+//
+// The bitcoin-chainstate executable serves to surface the dependencies required
+// by a program wishing to use Bitcoin Core's consensus engine as it is right
+// now.
+//
+// DEVELOPER NOTE: Since this is a "demo-only", experimental, etc. executable,
+//                 it may diverge from Bitcoin Core's coding style.
+//
+// It is part of the libbitcoinkernel project.
+
+#include <chainparams.h>
+#include <consensus/validation.h>
+#include <core_io.h>
+#include <init/common.h>
+#include <node/blockstorage.h>
+#include <node/chainstate.h>
+#include <scheduler.h>
+#include <script/sigcache.h>
+#include <util/system.h>
+#include <util/thread.h>
+#include <validation.h>
+#include <validationinterface.h>
+
+#include <filesystem>
+#include <functional>
+#include <iosfwd>
+
+const std::function<std::string(const char*)> G_TRANSLATION_FUN = nullptr;
+
+int main(int argc, char* argv[])
+{
+    // SETUP: Argument parsing and handling
+    if (argc != 2) {
+        std::cerr
+            << "Usage: " << argv[0] << " DATADIR" << std::endl
+            << "Display DATADIR information, and process hex-encoded blocks on standard input." << std::endl
+            << std::endl
+            << "IMPORTANT: THIS EXECUTABLE IS EXPERIMENTAL, FOR TESTING ONLY, AND EXPECTED TO" << std::endl
+            << "           BREAK IN FUTURE VERSIONS. DO NOT USE ON YOUR ACTUAL DATADIR." << std::endl;
+        return 1;
+    }
+    std::filesystem::path abs_datadir = std::filesystem::absolute(argv[1]);
+    std::filesystem::create_directories(abs_datadir);
+    gArgs.ForceSetArg("-datadir", abs_datadir.string());
+
+
+    // SETUP: Misc Globals
+    SelectParams(CBaseChainParams::MAIN);
+    const CChainParams& chainparams = Params();
+
+    init::SetGlobals(); // ECC_Start, etc.
+
+    // Necessary for CheckInputScripts (eventually called by ProcessNewBlock),
+    // which will try the script cache first and fall back to actually
+    // performing the check with the signature cache.
+    InitSignatureCache();
+    InitScriptExecutionCache();
+
+
+    // SETUP: Scheduling and Background Signals
+    CScheduler scheduler{};
+    // Start the lightweight task scheduler thread
+    scheduler.m_service_thread = std::thread(util::TraceThread, "scheduler", [&] { scheduler.serviceQueue(); });
+
+    // Gather some entropy once per minute.
+    scheduler.scheduleEvery(RandAddPeriodic, std::chrono::minutes{1});
+
+    GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
+
+
+    // SETUP: Chainstate
+    ChainstateManager chainman;
+
+    auto rv = node::LoadChainstate(false,
+                                   std::ref(chainman),
+                                   nullptr,
+                                   false,
+                                   chainparams.GetConsensus(),
+                                   false,
+                                   2 << 20,
+                                   2 << 22,
+                                   (450 << 20) - (2 << 20) - (2 << 22),
+                                   false,
+                                   false,
+                                   []() { return false; });
+    if (rv.has_value()) {
+        std::cerr << "Failed to load Chain state from your datadir." << std::endl;
+        goto epilogue;
+    } else {
+        auto maybe_verify_error = node::VerifyLoadedChainstate(std::ref(chainman),
+                                                               false,
+                                                               false,
+                                                               chainparams.GetConsensus(),
+                                                               DEFAULT_CHECKBLOCKS,
+                                                               DEFAULT_CHECKLEVEL,
+                                                               /*get_unix_time_seconds=*/static_cast<int64_t (*)()>(GetTime));
+        if (maybe_verify_error.has_value()) {
+            std::cerr << "Failed to verify loaded Chain state from your datadir." << std::endl;
+            goto epilogue;
+        }
+    }
+
+    for (CChainState* chainstate : WITH_LOCK(::cs_main, return chainman.GetAll())) {
+        BlockValidationState state;
+        if (!chainstate->ActivateBestChain(state, nullptr)) {
+            std::cerr << "Failed to connect best block (" << state.ToString() << ")" << std::endl;
+            goto epilogue;
+        }
+    }
+
+    // Main program logic starts here
+    std::cout
+        << "Hello! I'm going to print out some information about your datadir." << std::endl
+        << "\t" << "Path: " << gArgs.GetDataDirNet() << std::endl
+        << "\t" << "Reindexing: " << std::boolalpha << node::fReindex.load() << std::noboolalpha << std::endl
+        << "\t" << "Snapshot Active: " << std::boolalpha << chainman.IsSnapshotActive() << std::noboolalpha << std::endl
+        << "\t" << "Active Height: " << chainman.ActiveHeight() << std::endl
+        << "\t" << "Active IBD: " << std::boolalpha << chainman.ActiveChainstate().IsInitialBlockDownload() << std::noboolalpha << std::endl;
+    {
+        CBlockIndex* tip = chainman.ActiveTip();
+        if (tip) {
+            std::cout << "\t" << tip->ToString() << std::endl;
+        }
+    }
+
+    for (std::string line; std::getline(std::cin, line);) {
+        if (line.empty()) {
+            std::cerr << "Empty line found" << std::endl;
+            break;
+        }
+
+        std::shared_ptr<CBlock> blockptr = std::make_shared<CBlock>();
+        CBlock& block = *blockptr;
+
+        if (!DecodeHexBlk(block, line)) {
+            std::cerr << "Block decode failed" << std::endl;
+            break;
+        }
+
+        if (block.vtx.empty() || !block.vtx[0]->IsCoinBase()) {
+            std::cerr << "Block does not start with a coinbase" << std::endl;
+            break;
+        }
+
+        uint256 hash = block.GetHash();
+        {
+            LOCK(cs_main);
+            const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(hash);
+            if (pindex) {
+                if (pindex->IsValid(BLOCK_VALID_SCRIPTS)) {
+                    std::cerr << "duplicate" << std::endl;
+                    break;
+                }
+                if (pindex->nStatus & BLOCK_FAILED_MASK) {
+                    std::cerr << "duplicate-invalid" << std::endl;
+                    break;
+                }
+            }
+        }
+
+        {
+            LOCK(cs_main);
+            const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(block.hashPrevBlock);
+            if (pindex) {
+                UpdateUncommittedBlockStructures(block, pindex, chainparams.GetConsensus());
+            }
+        }
+
+        // Adapted from rpc/mining.cpp
+        class submitblock_StateCatcher final : public CValidationInterface
+        {
+        public:
+            uint256 hash;
+            bool found;
+            BlockValidationState state;
+
+            explicit submitblock_StateCatcher(const uint256& hashIn) : hash(hashIn), found(false), state() {}
+
+        protected:
+            void BlockChecked(const CBlock& block, const BlockValidationState& stateIn) override
+            {
+                if (block.GetHash() != hash)
+                    return;
+                found = true;
+                state = stateIn;
+            }
+        };
+
+        bool new_block;
+        auto sc = std::make_shared<submitblock_StateCatcher>(block.GetHash());
+        RegisterSharedValidationInterface(sc);
+        bool accepted = chainman.ProcessNewBlock(chainparams, blockptr, /* force_processing */ true, /* new_block */ &new_block);
+        UnregisterSharedValidationInterface(sc);
+        if (!new_block && accepted) {
+            std::cerr << "duplicate" << std::endl;
+            break;
+        }
+        if (!sc->found) {
+            std::cerr << "inconclusive" << std::endl;
+            break;
+        }
+        std::cout << sc->state.ToString() << std::endl;
+        switch (sc->state.GetResult()) {
+        case BlockValidationResult::BLOCK_RESULT_UNSET:
+            std::cerr << "initial value. Block has not yet been rejected" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_CONSENSUS:
+            std::cerr << "invalid by consensus rules (excluding any below reasons)" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_RECENT_CONSENSUS_CHANGE:
+            std::cerr << "Invalid by a change to consensus rules more recent than SegWit." << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_CACHED_INVALID:
+            std::cerr << "this block was cached as being invalid and we didn't store the reason why" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_INVALID_HEADER:
+            std::cerr << "invalid proof of work or time too old" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_MUTATED:
+            std::cerr << "the block's data didn't match the data committed to by the PoW" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_MISSING_PREV:
+            std::cerr << "We don't have the previous block the checked one is built on" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_INVALID_PREV:
+            std::cerr << "A block this one builds on is invalid" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_TIME_FUTURE:
+            std::cerr << "block timestamp was > 2 hours in the future (or our clock is bad)" << std::endl;
+            break;
+        case BlockValidationResult::BLOCK_CHECKPOINT:
+            std::cerr << "the block failed to meet one of our checkpoints" << std::endl;
+            break;
+        }
+    }
+
+epilogue:
+    // Without this precise shutdown sequence, there will be a lot of nullptr
+    // dereferencing and UB.
+    scheduler.stop();
+    if (chainman.m_load_block.joinable()) chainman.m_load_block.join();
+    StopScriptCheckWorkerThreads();
+
+    GetMainSignals().FlushBackgroundCallbacks();
+    {
+        LOCK(cs_main);
+        for (CChainState* chainstate : chainman.GetAll()) {
+            if (chainstate->CanFlushToDisk()) {
+                chainstate->ForceFlushStateToDisk();
+                chainstate->ResetCoinsViews();
+            }
+        }
+    }
+    GetMainSignals().UnregisterBackgroundSignalScheduler();
+
+    UnloadBlockIndex(nullptr, chainman);
+
+    init::UnsetGlobals();
+}