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author | Wladimir J. van der Laan <laanwj@gmail.com> | 2018-05-16 17:49:29 +0200 |
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committer | Wladimir J. van der Laan <laanwj@gmail.com> | 2018-05-16 18:30:35 +0200 |
commit | 11e7bdfd903ef342c0ff2dcd062d6eab8dd25350 (patch) | |
tree | b90f03f22cacde7fa3874b3224f9743a31a4e25f /src | |
parent | 40c34a0a29f6314c01597a0b9d9e97e5869eaf23 (diff) | |
parent | dd435ad40267f5c50ff17533c696f9302829a6a6 (diff) | |
download | bitcoin-11e7bdfd903ef342c0ff2dcd062d6eab8dd25350.tar.xz |
Merge #13023: Fix some concurrency issues in ActivateBestChain()
dd435ad Add unit tests for signals generated by ProcessNewBlock() (Jesse Cohen)
a3ae8e6 Fix concurrency-related bugs in ActivateBestChain (Jesse Cohen)
ecc3c4a Do not unlock cs_main in ABC unless we've actually made progress. (Matt Corallo)
Pull request description:
Originally this PR was just to add tests around concurrency in block validation - those tests seem to have uncovered another bug in ActivateBestChain - this now fixes that bug and adds tests.
ActivateBestChain (invoked after a new block is validated) proceeds in steps - acquiring and releasing cs_main while incrementally disconnecting and connecting blocks to sync to the most work chain known (FindMostWorkChain()). Every time cs_main is released the result of FindMostWorkChain() can change - but currently that value is cached across acquisitions of cs_main and only refreshed when an invalid chain is explored. It needs to be refreshed every time cs_main is reacquired. The test added in https://github.com/bitcoin/bitcoin/pull/13023/commits/6094ce73045fe0b4654ff94327c2059512af88fb will occasionally fail without the commit fixing this issue https://github.com/bitcoin/bitcoin/pull/13023/commits/26bfdbaddbb9f13864deb7241c6d513f22c5ab62
Original description below
--
After a bug discovered where UpdatedBlockTip() notifications could be triggered out of order (#12978), these unit tests check certain invariants about these signals.
The scheduler test asserts that a SingleThreadedSchedulerClient processes callbacks fully and sequentially.
The block validation test generates a random chain and calls ProcessNewBlock from multiple threads at random and in parallel. ValidationInterface callbacks verify that the ordering of BlockConnected BlockDisconnected and UpdatedBlockTip events occur as expected.
Tree-SHA512: 4102423a03d2ea28580c7a70add8a6bdb22ef9e33b107c3aadef80d5af02644cdfaae516c44933924717599c81701e0b96fbf9cf38696e9e41372401a5ee1f3c
Diffstat (limited to 'src')
-rw-r--r-- | src/Makefile.test.include | 5 | ||||
-rw-r--r-- | src/test/test_bitcoin.cpp | 6 | ||||
-rw-r--r-- | src/test/test_bitcoin.h | 3 | ||||
-rw-r--r-- | src/test/validation_block_tests.cpp | 184 | ||||
-rw-r--r-- | src/validation.cpp | 78 | ||||
-rw-r--r-- | src/validationinterface.h | 6 |
6 files changed, 251 insertions, 31 deletions
diff --git a/src/Makefile.test.include b/src/Makefile.test.include index 91d3a3d47c..7174b3e8df 100644 --- a/src/Makefile.test.include +++ b/src/Makefile.test.include @@ -86,9 +86,10 @@ BITCOIN_TESTS =\ test/txindex_tests.cpp \ test/txvalidation_tests.cpp \ test/txvalidationcache_tests.cpp \ - test/versionbits_tests.cpp \ test/uint256_tests.cpp \ - test/util_tests.cpp + test/util_tests.cpp \ + test/validation_block_tests.cpp \ + test/versionbits_tests.cpp if ENABLE_WALLET BITCOIN_TESTS += \ diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp index 9857827f05..e9814edc23 100644 --- a/src/test/test_bitcoin.cpp +++ b/src/test/test_bitcoin.cpp @@ -39,6 +39,12 @@ FastRandomContext insecure_rand_ctx(insecure_rand_seed); extern bool fPrintToConsole; extern void noui_connect(); +std::ostream& operator<<(std::ostream& os, const uint256& num) +{ + os << num.ToString(); + return os; +} + BasicTestingSetup::BasicTestingSetup(const std::string& chainName) { SHA256AutoDetect(); diff --git a/src/test/test_bitcoin.h b/src/test/test_bitcoin.h index 1f91eb622c..d013613de2 100644 --- a/src/test/test_bitcoin.h +++ b/src/test/test_bitcoin.h @@ -120,4 +120,7 @@ struct TestMemPoolEntryHelper CBlock getBlock13b8a(); +// define an implicit conversion here so that uint256 may be used directly in BOOST_CHECK_* +std::ostream& operator<<(std::ostream& os, const uint256& num); + #endif diff --git a/src/test/validation_block_tests.cpp b/src/test/validation_block_tests.cpp new file mode 100644 index 0000000000..f835570168 --- /dev/null +++ b/src/test/validation_block_tests.cpp @@ -0,0 +1,184 @@ +// Copyright (c) 2018 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 <boost/test/unit_test.hpp> + +#include <chainparams.h> +#include <consensus/merkle.h> +#include <consensus/validation.h> +#include <miner.h> +#include <pow.h> +#include <random.h> +#include <test/test_bitcoin.h> +#include <validation.h> +#include <validationinterface.h> + +struct RegtestingSetup : public TestingSetup { + RegtestingSetup() : TestingSetup(CBaseChainParams::REGTEST) {} +}; + +BOOST_FIXTURE_TEST_SUITE(validation_block_tests, RegtestingSetup) + +struct TestSubscriber : public CValidationInterface { + uint256 m_expected_tip; + + TestSubscriber(uint256 tip) : m_expected_tip(tip) {} + + void UpdatedBlockTip(const CBlockIndex* pindexNew, const CBlockIndex* pindexFork, bool fInitialDownload) + { + BOOST_CHECK_EQUAL(m_expected_tip, pindexNew->GetBlockHash()); + } + + void BlockConnected(const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex, const std::vector<CTransactionRef>& txnConflicted) + { + BOOST_CHECK_EQUAL(m_expected_tip, block->hashPrevBlock); + BOOST_CHECK_EQUAL(m_expected_tip, pindex->pprev->GetBlockHash()); + + m_expected_tip = block->GetHash(); + } + + void BlockDisconnected(const std::shared_ptr<const CBlock>& block) + { + BOOST_CHECK_EQUAL(m_expected_tip, block->GetHash()); + + m_expected_tip = block->hashPrevBlock; + } +}; + +std::shared_ptr<CBlock> Block(const uint256& prev_hash) +{ + static int i = 0; + static uint64_t time = Params().GenesisBlock().nTime; + + CScript pubKey; + pubKey << i++ << OP_TRUE; + + auto ptemplate = BlockAssembler(Params()).CreateNewBlock(pubKey, false); + auto pblock = std::make_shared<CBlock>(ptemplate->block); + pblock->hashPrevBlock = prev_hash; + pblock->nTime = ++time; + + CMutableTransaction txCoinbase(*pblock->vtx[0]); + txCoinbase.vout.resize(1); + txCoinbase.vin[0].scriptWitness.SetNull(); + pblock->vtx[0] = MakeTransactionRef(std::move(txCoinbase)); + + return pblock; +} + +std::shared_ptr<CBlock> FinalizeBlock(std::shared_ptr<CBlock> pblock) +{ + pblock->hashMerkleRoot = BlockMerkleRoot(*pblock); + + while (!CheckProofOfWork(pblock->GetHash(), pblock->nBits, Params().GetConsensus())) { + ++(pblock->nNonce); + } + + return pblock; +} + +// construct a valid block +const std::shared_ptr<const CBlock> GoodBlock(const uint256& prev_hash) +{ + return FinalizeBlock(Block(prev_hash)); +} + +// construct an invalid block (but with a valid header) +const std::shared_ptr<const CBlock> BadBlock(const uint256& prev_hash) +{ + auto pblock = Block(prev_hash); + + CMutableTransaction coinbase_spend; + coinbase_spend.vin.push_back(CTxIn(COutPoint(pblock->vtx[0]->GetHash(), 0), CScript(), 0)); + coinbase_spend.vout.push_back(pblock->vtx[0]->vout[0]); + + CTransactionRef tx = MakeTransactionRef(coinbase_spend); + pblock->vtx.push_back(tx); + + auto ret = FinalizeBlock(pblock); + return ret; +} + +void BuildChain(const uint256& root, int height, const unsigned int invalid_rate, const unsigned int branch_rate, const unsigned int max_size, std::vector<std::shared_ptr<const CBlock>>& blocks) +{ + if (height <= 0 || blocks.size() >= max_size) return; + + bool gen_invalid = GetRand(100) < invalid_rate; + bool gen_fork = GetRand(100) < branch_rate; + + const std::shared_ptr<const CBlock> pblock = gen_invalid ? BadBlock(root) : GoodBlock(root); + blocks.push_back(pblock); + if (!gen_invalid) { + BuildChain(pblock->GetHash(), height - 1, invalid_rate, branch_rate, max_size, blocks); + } + + if (gen_fork) { + blocks.push_back(GoodBlock(root)); + BuildChain(blocks.back()->GetHash(), height - 1, invalid_rate, branch_rate, max_size, blocks); + } +} + +BOOST_AUTO_TEST_CASE(processnewblock_signals_ordering) +{ + // build a large-ish chain that's likely to have some forks + std::vector<std::shared_ptr<const CBlock>> blocks; + while (blocks.size() < 50) { + blocks.clear(); + BuildChain(Params().GenesisBlock().GetHash(), 100, 15, 10, 500, blocks); + } + + bool ignored; + CValidationState state; + std::vector<CBlockHeader> headers; + std::transform(blocks.begin(), blocks.end(), std::back_inserter(headers), [](std::shared_ptr<const CBlock> b) { return b->GetBlockHeader(); }); + + // Process all the headers so we understand the toplogy of the chain + BOOST_CHECK(ProcessNewBlockHeaders(headers, state, Params())); + + // Connect the genesis block and drain any outstanding events + ProcessNewBlock(Params(), std::make_shared<CBlock>(Params().GenesisBlock()), true, &ignored); + SyncWithValidationInterfaceQueue(); + + // subscribe to events (this subscriber will validate event ordering) + const CBlockIndex* initial_tip = nullptr; + { + LOCK(cs_main); + initial_tip = chainActive.Tip(); + } + TestSubscriber sub(initial_tip->GetBlockHash()); + RegisterValidationInterface(&sub); + + // create a bunch of threads that repeatedly process a block generated above at random + // this will create parallelism and randomness inside validation - the ValidationInterface + // will subscribe to events generated during block validation and assert on ordering invariance + boost::thread_group threads; + for (int i = 0; i < 10; i++) { + threads.create_thread([&blocks]() { + bool ignored; + for (int i = 0; i < 1000; i++) { + auto block = blocks[GetRand(blocks.size() - 1)]; + ProcessNewBlock(Params(), block, true, &ignored); + } + + // to make sure that eventually we process the full chain - do it here + for (auto block : blocks) { + if (block->vtx.size() == 1) { + bool processed = ProcessNewBlock(Params(), block, true, &ignored); + assert(processed); + } + } + }); + } + + threads.join_all(); + while (GetMainSignals().CallbacksPending() > 0) { + MilliSleep(100); + } + + UnregisterValidationInterface(&sub); + + BOOST_CHECK_EQUAL(sub.m_expected_tip, chainActive.Tip()->GetBlockHash()); +} + +BOOST_AUTO_TEST_SUITE_END() diff --git a/src/validation.cpp b/src/validation.cpp index f22ae7f9be..3971906424 100644 --- a/src/validation.cpp +++ b/src/validation.cpp @@ -145,6 +145,12 @@ private: */ std::set<CBlockIndex*> m_failed_blocks; + /** + * the ChainState CriticalSection + * A lock that must be held when modifying this ChainState - held in ActivateBestChain() + */ + CCriticalSection m_cs_chainstate; + public: CChain chainActive; BlockMap mapBlockIndex; @@ -2519,6 +2525,7 @@ void CChainState::PruneBlockIndexCandidates() { bool CChainState::ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const std::shared_ptr<const CBlock>& pblock, bool& fInvalidFound, ConnectTrace& connectTrace) { AssertLockHeld(cs_main); + const CBlockIndex *pindexOldTip = chainActive.Tip(); const CBlockIndex *pindexFork = chainActive.FindFork(pindexMostWork); @@ -2635,6 +2642,12 @@ bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams& // sanely for performance or correctness! AssertLockNotHeld(cs_main); + // ABC maintains a fair degree of expensive-to-calculate internal state + // because this function periodically releases cs_main so that it does not lock up other threads for too long + // during large connects - and to allow for e.g. the callback queue to drain + // we use m_cs_chainstate to enforce mutual exclusion so that only one caller may execute this function at a time + LOCK(m_cs_chainstate); + CBlockIndex *pindexMostWork = nullptr; CBlockIndex *pindexNewTip = nullptr; int nStopAtHeight = gArgs.GetArg("-stopatheight", DEFAULT_STOPATHEIGHT); @@ -2648,45 +2661,53 @@ bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams& SyncWithValidationInterfaceQueue(); } - const CBlockIndex *pindexFork; - bool fInitialDownload; { LOCK(cs_main); - ConnectTrace connectTrace(mempool); // Destructed before cs_main is unlocked + CBlockIndex* starting_tip = chainActive.Tip(); + bool blocks_connected = false; + do { + // We absolutely may not unlock cs_main until we've made forward progress + // (with the exception of shutdown due to hardware issues, low disk space, etc). + ConnectTrace connectTrace(mempool); // Destructed before cs_main is unlocked + + if (pindexMostWork == nullptr) { + pindexMostWork = FindMostWorkChain(); + } - CBlockIndex *pindexOldTip = chainActive.Tip(); - if (pindexMostWork == nullptr) { - pindexMostWork = FindMostWorkChain(); - } + // Whether we have anything to do at all. + if (pindexMostWork == nullptr || pindexMostWork == chainActive.Tip()) { + break; + } - // Whether we have anything to do at all. - if (pindexMostWork == nullptr || pindexMostWork == chainActive.Tip()) - return true; + bool fInvalidFound = false; + std::shared_ptr<const CBlock> nullBlockPtr; + if (!ActivateBestChainStep(state, chainparams, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : nullBlockPtr, fInvalidFound, connectTrace)) + return false; + blocks_connected = true; - bool fInvalidFound = false; - std::shared_ptr<const CBlock> nullBlockPtr; - if (!ActivateBestChainStep(state, chainparams, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : nullBlockPtr, fInvalidFound, connectTrace)) - return false; + if (fInvalidFound) { + // Wipe cache, we may need another branch now. + pindexMostWork = nullptr; + } + pindexNewTip = chainActive.Tip(); - if (fInvalidFound) { - // Wipe cache, we may need another branch now. - pindexMostWork = nullptr; - } - pindexNewTip = chainActive.Tip(); - pindexFork = chainActive.FindFork(pindexOldTip); - fInitialDownload = IsInitialBlockDownload(); + for (const PerBlockConnectTrace& trace : connectTrace.GetBlocksConnected()) { + assert(trace.pblock && trace.pindex); + GetMainSignals().BlockConnected(trace.pblock, trace.pindex, trace.conflictedTxs); + } + } while (!chainActive.Tip() || (starting_tip && CBlockIndexWorkComparator()(chainActive.Tip(), starting_tip))); + if (!blocks_connected) return true; - for (const PerBlockConnectTrace& trace : connectTrace.GetBlocksConnected()) { - assert(trace.pblock && trace.pindex); - GetMainSignals().BlockConnected(trace.pblock, trace.pindex, trace.conflictedTxs); - } + const CBlockIndex* pindexFork = chainActive.FindFork(starting_tip); + bool fInitialDownload = IsInitialBlockDownload(); // Notify external listeners about the new tip. // Enqueue while holding cs_main to ensure that UpdatedBlockTip is called in the order in which blocks are connected - GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload); - - // Always notify the UI if a new block tip was connected if (pindexFork != pindexNewTip) { + // Notify ValidationInterface subscribers + GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload); + + // Always notify the UI if a new block tip was connected uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip); } } @@ -2710,6 +2731,7 @@ bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams& return true; } + bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, std::shared_ptr<const CBlock> pblock) { return g_chainstate.ActivateBestChain(state, chainparams, std::move(pblock)); } diff --git a/src/validationinterface.h b/src/validationinterface.h index 3a5fed0106..0ca82235da 100644 --- a/src/validationinterface.h +++ b/src/validationinterface.h @@ -61,7 +61,11 @@ protected: */ ~CValidationInterface() = default; /** - * Notifies listeners of updated block chain tip + * Notifies listeners when the block chain tip advances. + * + * When multiple blocks are connected at once, UpdatedBlockTip will be called on the final tip + * but may not be called on every intermediate tip. If the latter behavior is desired, + * subscribe to BlockConnected() instead. * * Called on a background thread. */ |