Merge pull request #4201 from kittywhiskers/txEpochs

merge bitcoin#17925, #16805: auxilliary backports

src/Makefile.am

@@ -199,6 +199,7 @@ BITCOIN_CORE_H = \
   llmq/quorums_signing_shares.h \
   llmq/quorums_utils.h \
   logging.h \
+  logging/timer.h \
   masternode/activemasternode.h \
   masternode/masternode-meta.h \
   masternode/masternode-payments.h \

src/Makefile.test.include

@@ -69,6 +69,7 @@ BITCOIN_TESTS =\
   test/key_tests.cpp \
   test/lcg.h \
   test/limitedmap_tests.cpp \
+  test/logging_tests.cpp \
   test/dbwrapper_tests.cpp \
   test/main_tests.cpp \
   test/mempool_tests.cpp \

src/logging/timer.h

@@ -0,0 +1,104 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_LOGGING_TIMER_H
+#define BITCOIN_LOGGING_TIMER_H
+
+#include <logging.h>
+#include <sync.h>
+#include <utiltime.h>
+
+#include <chrono>
+#include <string>
+
+
+namespace BCLog {
+
+//! RAII-style object that outputs timing information to logs.
+template <typename TimeType>
+class Timer
+{
+public:
+    //! If log_category is left as the default, end_msg will log unconditionally
+    //! (instead of being filtered by category).
+    Timer(
+        std::string prefix,
+        std::string end_msg,
+        BCLog::LogFlags log_category = BCLog::LogFlags::ALL) :
+            m_prefix(std::move(prefix)),
+            m_title(std::move(end_msg)),
+            m_log_category(log_category)
+    {
+        this->Log(strprintf("%s started", m_title));
+        m_start_t = GetTime<std::chrono::microseconds>();
+    }
+
+    ~Timer()
+    {
+        this->Log(strprintf("%s completed", m_title));
+    }
+
+    void Log(const std::string& msg)
+    {
+        const std::string full_msg = this->LogMsg(msg);
+
+        if (m_log_category == BCLog::LogFlags::ALL) {
+            LogPrintf("%s\n", full_msg);
+        } else {
+            LogPrint(m_log_category, "%s\n", full_msg);
+        }
+    }
+
+    std::string LogMsg(const std::string& msg)
+    {
+        const auto end_time = GetTime<std::chrono::microseconds>() - m_start_t;
+        if (m_start_t.count() <= 0) {
+            return strprintf("%s: %s", m_prefix, msg);
+        }
+
+        std::string units = "";
+        float divisor = 1;
+
+        if (std::is_same<TimeType, std::chrono::microseconds>::value) {
+            units = "μs";
+        } else if (std::is_same<TimeType, std::chrono::milliseconds>::value) {
+            units = "ms";
+            divisor = 1000.;
+        } else if (std::is_same<TimeType, std::chrono::seconds>::value) {
+            units = "s";
+            divisor = 1000. * 1000.;
+        }
+
+        const float time_ms = end_time.count() / divisor;
+        return strprintf("%s: %s (%.2f%s)", m_prefix, msg, time_ms, units);
+    }
+
+private:
+    std::chrono::microseconds m_start_t{};
+
+    //! Log prefix; usually the name of the function this was created in.
+    const std::string m_prefix{};
+
+    //! A descriptive message of what is being timed.
+    const std::string m_title{};
+
+    //! Forwarded on to LogPrint if specified - has the effect of only
+    //! outputing the timing log when a particular debug= category is specified.
+    const BCLog::LogFlags m_log_category{};
+
+};
+
+} // namespace BCLog
+
+
+#define LOG_TIME_MICROS(end_msg, ...) \
+    BCLog::Timer<std::chrono::microseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
+#define LOG_TIME_MILLIS(end_msg, ...) \
+    BCLog::Timer<std::chrono::milliseconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
+#define LOG_TIME_SECONDS(end_msg, ...) \
+    BCLog::Timer<std::chrono::seconds> PASTE2(logging_timer, __COUNTER__)(__func__, end_msg, ## __VA_ARGS__)
+
+
+#endif // BITCOIN_LOGGING_TIMER_H

src/test/logging_tests.cpp

@@ -0,0 +1,36 @@
+// Copyright (c) 2019 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 <logging.h>
+#include <logging/timer.h>
+#include <test/test_dash.h>
+
+#include <chrono>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(logging_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(logging_timer)
+{
+
+    SetMockTime(1);
+    auto sec_timer = BCLog::Timer<std::chrono::seconds>("tests", "end_msg");
+    SetMockTime(2);
+    BOOST_CHECK_EQUAL(sec_timer.LogMsg("test secs"), "tests: test secs (1.00s)");
+
+    SetMockTime(1);
+    auto ms_timer = BCLog::Timer<std::chrono::milliseconds>("tests", "end_msg");
+    SetMockTime(2);
+    BOOST_CHECK_EQUAL(ms_timer.LogMsg("test ms"), "tests: test ms (1000.00ms)");
+
+    SetMockTime(1);
+    auto micro_timer = BCLog::Timer<std::chrono::microseconds>("tests", "end_msg");
+    SetMockTime(2);
+    BOOST_CHECK_EQUAL(micro_timer.LogMsg("test micros"), "tests: test micros (1000000.00μs)");
+
+    SetMockTime(0);
+}
+
+BOOST_AUTO_TEST_SUITE_END()

src/txmempool.cpp

@@ -29,7 +29,7 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFe
                                  int64_t _nTime, unsigned int _entryHeight,
                                  bool _spendsCoinbase, unsigned int _sigOps, LockPoints lp):
     tx(_tx), nFee(_nFee), nTime(_nTime), entryHeight(_entryHeight),
-    spendsCoinbase(_spendsCoinbase), sigOpCount(_sigOps), lockPoints(lp)
+    spendsCoinbase(_spendsCoinbase), sigOpCount(_sigOps), lockPoints(lp), m_epoch(0)
 {
     nTxSize = ::GetSerializeSize(*_tx, SER_NETWORK, PROTOCOL_VERSION);
     nUsageSize = RecursiveDynamicUsage(tx);
@@ -126,8 +126,6 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashes
     // setMemPoolChildren will be updated, an assumption made in
     // UpdateForDescendants.
     for (const uint256 &hash : reverse_iterate(vHashesToUpdate)) {
-        // we cache the in-mempool children to avoid duplicate updates
-        setEntries setChildren;
         // calculate children from mapNextTx
         txiter it = mapTx.find(hash);
         if (it == mapTx.end()) {
@@ -136,17 +134,21 @@ void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashes
         auto iter = mapNextTx.lower_bound(COutPoint(hash, 0));
         // First calculate the children, and update setMemPoolChildren to
         // include them, and update their setMemPoolParents to include this tx.
-        for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
-            const uint256 &childHash = iter->second->GetHash();
-            txiter childIter = mapTx.find(childHash);
-            assert(childIter != mapTx.end());
-            // We can skip updating entries we've encountered before or that
-            // are in the block (which are already accounted for).
-            if (setChildren.insert(childIter).second && !setAlreadyIncluded.count(childHash)) {
-                UpdateChild(it, childIter, true);
-                UpdateParent(childIter, it, true);
+        // we cache the in-mempool children to avoid duplicate updates
+        {
+            const auto epoch = GetFreshEpoch();
+            for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
+                const uint256 &childHash = iter->second->GetHash();
+                txiter childIter = mapTx.find(childHash);
+                assert(childIter != mapTx.end());
+                // We can skip updating entries we've encountered before or that
+                // are in the block (which are already accounted for).
+                if (!visited(childIter) && !setAlreadyIncluded.count(childHash)) {
+                    UpdateChild(it, childIter, true);
+                    UpdateParent(childIter, it, true);
+                }
             }
-        }
+        } // release epoch guard for UpdateForDescendants
         UpdateForDescendants(it, mapMemPoolDescendantsToUpdate, setAlreadyIncluded);
     }
 }
@@ -329,7 +331,7 @@ void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, CAmount modifyFee,
 }
 
 CTxMemPool::CTxMemPool(CBlockPolicyEstimator* estimator) :
-    nTransactionsUpdated(0), minerPolicyEstimator(estimator)
+    nTransactionsUpdated(0), minerPolicyEstimator(estimator), m_epoch(0), m_has_epoch_guard(false)
 {
     _clear(); //lock free clear
 
@@ -1591,4 +1593,22 @@ void CTxMemPool::GetTransactionAncestry(const uint256& txid, size_t& ancestors,
     }
 }
 
+CTxMemPool::EpochGuard CTxMemPool::GetFreshEpoch() const
+{
+    return EpochGuard(*this);
+}
+CTxMemPool::EpochGuard::EpochGuard(const CTxMemPool& in) : pool(in)
+{
+    assert(!pool.m_has_epoch_guard);
+    ++pool.m_epoch;
+    pool.m_has_epoch_guard = true;
+}
+
+CTxMemPool::EpochGuard::~EpochGuard()
+{
+    // prevents stale results being used
+    ++pool.m_epoch;
+    pool.m_has_epoch_guard = false;
+}
+
 SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}

src/txmempool.h

@@ -136,6 +136,7 @@ public:
     // If this is a proTx, this will be the hash of the key for which this ProTx was valid
     mutable uint256 validForProTxKey;
     mutable bool isKeyChangeProTx{false};
+    mutable uint64_t m_epoch; //!< epoch when last touched, useful for graph algorithms
 };
 
 // Helpers for modifying CTxMemPool::mapTx, which is a boost multi_index.
@@ -456,6 +457,8 @@ private:
     mutable int64_t lastRollingFeeUpdate;
     mutable bool blockSinceLastRollingFeeBump;
     mutable double rollingMinimumFeeRate; //!< minimum fee to get into the pool, decreases exponentially
+    mutable uint64_t m_epoch;
+    mutable bool m_has_epoch_guard;
 
     void trackPackageRemoved(const CFeeRate& rate) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
@@ -731,6 +734,55 @@ private:
      *  removal.
      */
     void removeUnchecked(txiter entry, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN) EXCLUSIVE_LOCKS_REQUIRED(cs);
+public:
+    /** EpochGuard: RAII-style guard for using epoch-based graph traversal algorithms.
+     *     When walking ancestors or descendants, we generally want to avoid
+     * visiting the same transactions twice. Some traversal algorithms use
+     * std::set (or setEntries) to deduplicate the transaction we visit.
+     * However, use of std::set is algorithmically undesirable because it both
+     * adds an asymptotic factor of O(log n) to traverals cost and triggers O(n)
+     * more dynamic memory allocations.
+     *     In many algorithms we can replace std::set with an internal mempool
+     * counter to track the time (or, "epoch") that we began a traversal, and
+     * check + update a per-transaction epoch for each transaction we look at to
+     * determine if that transaction has not yet been visited during the current
+     * traversal's epoch.
+     *     Algorithms using std::set can be replaced on a one by one basis.
+     * Both techniques are not fundamentally incomaptible across the codebase.
+     * Generally speaking, however, the remaining use of std::set for mempool
+     * traversal should be viewed as a TODO for replacement with an epoch based
+     * traversal, rather than a preference for std::set over epochs in that
+     * algorithm.
+     */
+    class EpochGuard {
+        const CTxMemPool& pool;
+        public:
+        EpochGuard(const CTxMemPool& in);
+        ~EpochGuard();
+    };
+    // N.B. GetFreshEpoch modifies mutable state via the EpochGuard construction
+    // (and later destruction)
+    EpochGuard GetFreshEpoch() const EXCLUSIVE_LOCKS_REQUIRED(cs);
+
+    /** visited marks a CTxMemPoolEntry as having been traversed
+     * during the lifetime of the most recently created EpochGuard
+     * and returns false if we are the first visitor, true otherwise.
+     *
+     * An EpochGuard must be held when visited is called or an assert will be
+     * triggered.
+     *
+     */
+    bool visited(txiter it) const EXCLUSIVE_LOCKS_REQUIRED(cs) {
+        assert(m_has_epoch_guard);
+        bool ret = it->m_epoch >= m_epoch;
+        it->m_epoch = std::max(it->m_epoch, m_epoch);
+        return ret;
+    }
+
+    bool visited(boost::optional<txiter> it) const EXCLUSIVE_LOCKS_REQUIRED(cs) {
+        assert(m_has_epoch_guard);
+        return !it || visited(*it);
+    }
 };
 
 /**

src/validation.cpp

@@ -19,6 +19,8 @@
 #include <hash.h>
 #include <index/txindex.h>
 #include <init.h>
+#include <logging.h>
+#include <logging/timer.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <pow.h>
@@ -2464,6 +2466,10 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
     static int64_t nLastFlush = 0;
     std::set<int> setFilesToPrune;
     bool full_flush_completed = false;
+
+    const size_t coins_count = pcoinsTip->GetCacheSize();
+    const size_t coins_mem_usage = pcoinsTip->DynamicMemoryUsage();
+
     try {
     {
         bool fFlushForPrune = false;
@@ -2471,8 +2477,12 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
         LOCK(cs_LastBlockFile);
         if (fPruneMode && (fCheckForPruning || nManualPruneHeight > 0) && !fReindex) {
             if (nManualPruneHeight > 0) {
+                LOG_TIME_MILLIS("find files to prune (manual)", BCLog::BENCHMARK);
+
                 FindFilesToPruneManual(setFilesToPrune, nManualPruneHeight);
             } else {
+                LOG_TIME_MILLIS("find files to prune", BCLog::BENCHMARK);
+
                 FindFilesToPrune(setFilesToPrune, chainparams.PruneAfterHeight());
                 fCheckForPruning = false;
             }
@@ -2512,9 +2522,17 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
             if (!CheckDiskSpace(0, true))
                 return state.Error("out of disk space");
             // First make sure all block and undo data is flushed to disk.
-            FlushBlockFile();
+            {
+                LOG_TIME_MILLIS("write block and undo data to disk", BCLog::BENCHMARK);
+
+                // First make sure all block and undo data is flushed to disk.
+                FlushBlockFile();
+            }
+
             // Then update all block file information (which may refer to block and undo files).
             {
+                LOG_TIME_MILLIS("write block index to disk", BCLog::BENCHMARK);
+
                 std::vector<std::pair<int, const CBlockFileInfo*> > vFiles;
                 vFiles.reserve(setDirtyFileInfo.size());
                 for (std::set<int>::iterator it = setDirtyFileInfo.begin(); it != setDirtyFileInfo.end(); ) {
@@ -2532,12 +2550,18 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
                 }
             }
             // Finally remove any pruned files
-            if (fFlushForPrune)
+            if (fFlushForPrune) {
+                LOG_TIME_MILLIS("unlink pruned files", BCLog::BENCHMARK);
+
                 UnlinkPrunedFiles(setFilesToPrune);
+            }
             nLastWrite = nNow;
         }
         // Flush best chain related state. This can only be done if the blocks / block index write was also done.
         if (fDoFullFlush && !pcoinsTip->GetBestBlock().IsNull()) {
+            LOG_TIME_SECONDS(strprintf("write coins cache to disk (%d coins, %.2fkB)",
+                coins_count, coins_mem_usage / 1000));
+
             // Typical Coin structures on disk are around 48 bytes in size.
             // Pushing a new one to the database can cause it to be written
             // twice (once in the log, and once in the tables). This is already