Merge bitcoin/bitcoin#28535: [24.x] Further backports

9077f214f5 depends: fix unusable memory_resource in macos qt build (fanquake)
dccacf0bf7 build, macos: Fix `qt` package build with new Xcode 15 linker (Hennadii Stepanov)
43596499b2 ci: Switch to `amd64` container in "ARM" task (Hennadii Stepanov)
805f98b79a ci: Nuke Android APK task, Use credits for tsan (MarcoFalke)
cb5512da23 test: ensure old fee_estimate.dat not read on restart and flushed (ismaelsadeeq)
01f8ee48ef tx fees, policy: read stale fee estimates with a regtest-only option (ismaelsadeeq)
1c98029b39 tx fees, policy: do not read estimates of old fee_estimates.dat (ismaelsadeeq)
77979e0172 tx fees, policy: periodically flush fee estimates to fee_estimates.dat (ismaelsadeeq)
67b6d99aea Do not use std::vector = {} to release memory (Pieter Wuille)
defdc15023 ci: Use podman stop over podman kill (MarcoFalke)
7f1357de51 ci: Use podman for persistent workers (MarcoFalke)
0db69a3d50 ci: Prune dangling images on RESTART_CI_DOCKER_BEFORE_RUN (MarcoFalke)

Pull request description:

  Backports to the 24.x branch. Currently:
  * https://github.com/bitcoin/bitcoin/pull/27622
  * https://github.com/bitcoin/bitcoin/pull/27777
  * https://github.com/bitcoin/bitcoin/pull/27834
  * https://github.com/bitcoin/bitcoin/pull/27844
  * https://github.com/bitcoin/bitcoin/pull/27886
  * https://github.com/bitcoin/bitcoin/pull/28452
  * https://github.com/bitcoin/bitcoin/pull/28543
  * https://github.com/bitcoin/bitcoin/pull/28571

ACKs for top commit:
  stickies-v:
    ACK 9077f214f5

Tree-SHA512: abaafc9a048b67b494993134fd332457ea52695ec007b963c283f962ec40c3b6b3a7e98407481be55d3271a595088a0281cc84b79dad4f24d260381ea0153076

.cirrus.yml

@@ -189,14 +189,12 @@ task:
 task:
   name: 'ARM [unit tests, no functional tests] [bullseye]'
   << : *GLOBAL_TASK_TEMPLATE
-  arm_container:
-    image: debian:bullseye
-    cpu: 2
-    memory: 8G
+  container:
+    docker_arguments:
+      CI_IMAGE_NAME_TAG: debian:bullseye
+      FILE_ENV: "./ci/test/00_setup_env_arm.sh"
   env:
     << : *CIRRUS_EPHEMERAL_WORKER_TEMPLATE_ENV
-    FILE_ENV: "./ci/test/00_setup_env_arm.sh"
-    QEMU_USER_CMD: ""  # Disable qemu and run the test natively
 
 task:
   name: 'Win64 [unit tests, no gui tests, no boost::process, no functional tests] [jammy]'
@@ -322,19 +320,3 @@ task:
     CI_USE_APT_INSTALL: "no"
     PACKAGE_MANAGER_INSTALL: "echo"  # Nothing to do
     FILE_ENV: "./ci/test/00_setup_env_mac_native_arm64.sh"
-
-task:
-  name: 'ARM64 Android APK [focal]'
-  << : *BASE_TEMPLATE
-  android_sdk_cache:
-    folder: "depends/SDKs/android"
-    fingerprint_key: "ANDROID_API_LEVEL=28 ANDROID_BUILD_TOOLS_VERSION=28.0.3 ANDROID_NDK_VERSION=23.2.8568313"
-  depends_sources_cache:
-    folder: "depends/sources"
-    fingerprint_script: git rev-list -1 HEAD ./depends
-  << : *MAIN_TEMPLATE
-  container:
-    image: ubuntu:focal
-  env:
-    << : *CIRRUS_EPHEMERAL_WORKER_TEMPLATE_ENV
-    FILE_ENV: "./ci/test/00_setup_env_android.sh"

ci/test/04_install.sh

@@ -31,7 +31,9 @@ if [ -z "$DANGER_RUN_CI_ON_HOST" ]; then
 
   if [ -n "${RESTART_CI_DOCKER_BEFORE_RUN}" ] ; then
     echo "Restart docker before run to stop and clear all containers started with --rm"
-    systemctl restart docker
+    podman container stop --all  # Similar to "systemctl restart docker"
+    echo "Prune all dangling images"
+    docker image prune --force
   fi
 
   # shellcheck disable=SC2086

depends/packages/qt.mk

@@ -22,6 +22,8 @@ $(package)_patches += rcc_hardcode_timestamp.patch
 $(package)_patches += duplicate_lcqpafonts.patch
 $(package)_patches += fast_fixed_dtoa_no_optimize.patch
 $(package)_patches += guix_cross_lib_path.patch
+$(package)_patches += fix-macos-linker.patch
+$(package)_patches += memory_resource.patch
 
 $(package)_qttranslations_file_name=qttranslations-$($(package)_suffix)
 $(package)_qttranslations_sha256_hash=c92af4171397a0ed272330b4fa0669790fcac8d050b07c8b8cc565ebeba6735e
@@ -231,6 +233,7 @@ endef
 define $(package)_preprocess_cmds
   cp $($(package)_patch_dir)/qt.pro qt.pro && \
   cp $($(package)_patch_dir)/qttools_src.pro qttools/src/src.pro && \
+  patch -p1 -i $($(package)_patch_dir)/fix-macos-linker.patch && \
   patch -p1 -i $($(package)_patch_dir)/dont_hardcode_pwd.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix_qt_pkgconfig.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix_android_jni_static.patch && \
@@ -239,6 +242,7 @@ define $(package)_preprocess_cmds
   patch -p1 -i $($(package)_patch_dir)/qtbase-moc-ignore-gcc-macro.patch && \
   patch -p1 -i $($(package)_patch_dir)/fix_montery_include.patch && \
   patch -p1 -i $($(package)_patch_dir)/use_android_ndk23.patch && \
+  patch -p1 -i $($(package)_patch_dir)/memory_resource.patch && \
   patch -p1 -i $($(package)_patch_dir)/rcc_hardcode_timestamp.patch && \
   patch -p1 -i $($(package)_patch_dir)/duplicate_lcqpafonts.patch && \
   patch -p1 -i $($(package)_patch_dir)/fast_fixed_dtoa_no_optimize.patch && \

depends/patches/qt/fix-macos-linker.patch

@@ -0,0 +1,55 @@
+qmake: Don't error out if QMAKE_DEFAULT_LIBDIRS is empty on macOS
+
+The new linker in Xcode 15 doesn't provide any default linker or
+framework paths when requested via -v, but still seems to use the
+default paths documented in the ld man page.
+
+We trust that linker will do the right thing, even if we don't
+know of its default linker paths.
+
+We also need to opt out of the default fallback logic to
+set the libdirs to /lib and /usr/lib.
+
+This may result in UnixMakefileGenerator::findLibraries finding
+different libraries than expected, if additional paths are
+passed with -L, which will then take precedence for qmake,
+even if the linker itself will use the library from the
+SDK's default paths. This should hopefully not be an issue
+in practice, as we don't turn -lFoo into absolute paths in
+qmake, so the only risk is that we're picking up the wrong
+prl files and adding additional dependencies that the lib
+in the SDK doesn't have.
+
+Upstream commits:
+ - Qt 5.15.16: Not yet publicly available.
+ - Qt dev: cdf64b0e47115cc473e1afd1472b4b09e130b2a5
+
+For other Qt branches see
+https://codereview.qt-project.org/q/I2347b26e2df0828471373b0e15b8c9089274c65d
+
+--- old/qtbase/mkspecs/features/toolchain.prf
++++ new/qtbase/mkspecs/features/toolchain.prf
+@@ -283,9 +283,12 @@ isEmpty($${target_prefix}.INCDIRS) {
+                 }
+             }
+         }
+-        isEmpty(QMAKE_DEFAULT_LIBDIRS)|isEmpty(QMAKE_DEFAULT_INCDIRS): \
++        isEmpty(QMAKE_DEFAULT_INCDIRS): \
+             !integrity: \
+-                error("failed to parse default search paths from compiler output")
++                error("failed to parse default include paths from compiler output")
++        isEmpty(QMAKE_DEFAULT_LIBDIRS): \
++            !integrity:!darwin: \
++                error("failed to parse default library paths from compiler output")
+         QMAKE_DEFAULT_LIBDIRS = $$unique(QMAKE_DEFAULT_LIBDIRS)
+     } else: ghs {
+         cmd = $$QMAKE_CXX $$QMAKE_CXXFLAGS -$${LITERAL_HASH} -o /tmp/fake_output /tmp/fake_input.cpp
+@@ -407,7 +410,7 @@ isEmpty($${target_prefix}.INCDIRS) {
+         QMAKE_DEFAULT_INCDIRS = $$split(INCLUDE, $$QMAKE_DIRLIST_SEP)
+     }
+ 
+-    unix:if(!cross_compile|host_build) {
++    unix:!darwin:if(!cross_compile|host_build) {
+         isEmpty(QMAKE_DEFAULT_INCDIRS): QMAKE_DEFAULT_INCDIRS = /usr/include /usr/local/include
+         isEmpty(QMAKE_DEFAULT_LIBDIRS): QMAKE_DEFAULT_LIBDIRS = /lib /usr/lib
+     }

depends/patches/qt/memory_resource.patch

@@ -0,0 +1,49 @@
+Fix unusable memory_resource on macos
+
+See https://bugreports.qt.io/browse/QTBUG-117484
+and https://bugreports.qt.io/browse/QTBUG-114316
+
+--- a/qtbase/src/corelib/tools/qduplicatetracker_p.h
++++ b/qtbase/src/corelib/tools/qduplicatetracker_p.h
+@@ -52,7 +52,7 @@
+ 
+ #include <qglobal.h>
+ 
+-#if QT_HAS_INCLUDE(<memory_resource>) && __cplusplus > 201402L
++#ifdef __cpp_lib_memory_resource
+ #  include <unordered_set>
+ #  include <memory_resource>
+ #else
+
+--- a/qtbase/src/corelib/global/qcompilerdetection.h
++++ b/qtbase/src/corelib/global/qcompilerdetection.h
+@@ -1041,16 +1041,22 @@
+ #   endif // !_HAS_CONSTEXPR
+ #  endif // !__GLIBCXX__ && !_LIBCPP_VERSION
+ # endif // Q_OS_QNX
+-# if (defined(Q_CC_CLANG) || defined(Q_CC_INTEL)) && defined(Q_OS_MAC) && defined(__GNUC_LIBSTD__) \
+-    && ((__GNUC_LIBSTD__-0) * 100 + __GNUC_LIBSTD_MINOR__-0 <= 402)
++# if (defined(Q_CC_CLANG) || defined(Q_CC_INTEL)) && defined(Q_OS_MAC)
++#  if defined(__GNUC_LIBSTD__) && ((__GNUC_LIBSTD__-0) * 100 + __GNUC_LIBSTD_MINOR__-0 <= 402)
+ // Apple has not updated libstdc++ since 2007, which means it does not have
+ // <initializer_list> or std::move. Let's disable these features
+-#  undef Q_COMPILER_INITIALIZER_LISTS
+-#  undef Q_COMPILER_RVALUE_REFS
+-#  undef Q_COMPILER_REF_QUALIFIERS
++#   undef Q_COMPILER_INITIALIZER_LISTS
++#   undef Q_COMPILER_RVALUE_REFS
++#   undef Q_COMPILER_REF_QUALIFIERS
+ // Also disable <atomic>, since it's clearly not there
+-#  undef Q_COMPILER_ATOMICS
+-# endif
++#   undef Q_COMPILER_ATOMICS
++#  endif
++#  if defined(__cpp_lib_memory_resource) \
++    && ((defined(__MAC_OS_X_VERSION_MIN_REQUIRED)  && __MAC_OS_X_VERSION_MIN_REQUIRED  < 140000) \
++     || (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED < 170000))
++#   undef __cpp_lib_memory_resource // Only supported on macOS 14 and iOS 17
++#  endif
++# endif // (defined(Q_CC_CLANG) || defined(Q_CC_INTEL)) && defined(Q_OS_MAC)
+ # if defined(Q_CC_CLANG) && defined(Q_CC_INTEL) && Q_CC_INTEL >= 1500
+ // ICC 15.x and 16.0 have their own implementation of std::atomic, which is activated when in Clang mode
+ // (probably because libc++'s <atomic> on OS X failed to compile), but they're missing some

src/headerssync.cpp

@@ -7,6 +7,7 @@
 #include <pow.h>
 #include <timedata.h>
 #include <util/check.h>
+#include <util/vector.h>
 
 // The two constants below are computed using the simulation script on
 // https://gist.github.com/sipa/016ae445c132cdf65a2791534dfb7ae1
@@ -51,9 +52,9 @@ HeadersSyncState::HeadersSyncState(NodeId id, const Consensus::Params& consensus
 void HeadersSyncState::Finalize()
 {
     Assume(m_download_state != State::FINAL);
-    m_header_commitments = {};
+    ClearShrink(m_header_commitments);
     m_last_header_received.SetNull();
-    m_redownloaded_headers = {};
+    ClearShrink(m_redownloaded_headers);
     m_redownload_buffer_last_hash.SetNull();
     m_redownload_buffer_first_prev_hash.SetNull();
     m_process_all_remaining_headers = false;

src/init.cpp

@@ -76,6 +76,7 @@
 #include <util/system.h>
 #include <util/thread.h>
 #include <util/threadnames.h>
+#include <util/time.h>
 #include <util/translation.h>
 #include <validation.h>
 #include <validationinterface.h>
@@ -561,6 +562,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-acceptnonstdtxn", strprintf("Relay and mine \"non-standard\" transactions (%sdefault: %u)", "testnet/regtest only; ", !testnetChainParams->RequireStandard()), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-incrementalrelayfee=<amt>", strprintf("Fee rate (in %s/kvB) used to define cost of relay, used for mempool limiting and replacement policy. (default: %s)", CURRENCY_UNIT, FormatMoney(DEFAULT_INCREMENTAL_RELAY_FEE)), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-dustrelayfee=<amt>", strprintf("Fee rate (in %s/kvB) used to define dust, the value of an output such that it will cost more than its value in fees at this fee rate to spend it. (default: %s)", CURRENCY_UNIT, FormatMoney(DUST_RELAY_TX_FEE)), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::NODE_RELAY);
+    argsman.AddArg("-acceptstalefeeestimates", strprintf("Read fee estimates even if they are stale (%sdefault: %u) fee estimates are considered stale if they are %s hours old", "regtest only; ", DEFAULT_ACCEPT_STALE_FEE_ESTIMATES, Ticks<std::chrono::hours>(MAX_FILE_AGE)), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-bytespersigop", strprintf("Equivalent bytes per sigop in transactions for relay and mining (default: %u)", DEFAULT_BYTES_PER_SIGOP), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-datacarrier", strprintf("Relay and mine data carrier transactions (default: %u)", DEFAULT_ACCEPT_DATACARRIER), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-datacarriersize", strprintf("Maximum size of data in data carrier transactions we relay and mine (default: %u)", MAX_OP_RETURN_RELAY), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
@@ -1253,7 +1255,17 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     assert(!node.fee_estimator);
     // Don't initialize fee estimation with old data if we don't relay transactions,
     // as they would never get updated.
-    if (!ignores_incoming_txs) node.fee_estimator = std::make_unique<CBlockPolicyEstimator>(FeeestPath(args));
+    if (!ignores_incoming_txs) {
+        bool read_stale_estimates = args.GetBoolArg("-acceptstalefeeestimates", DEFAULT_ACCEPT_STALE_FEE_ESTIMATES);
+        if (read_stale_estimates && (chainparams.NetworkIDString() != CBaseChainParams::REGTEST)) {
+            return InitError(strprintf(_("acceptstalefeeestimates is not supported on %s chain."), chainparams.NetworkIDString()));
+        }
+        node.fee_estimator = std::make_unique<CBlockPolicyEstimator>(FeeestPath(args), read_stale_estimates);
+
+        // Flush estimates to disk periodically
+        CBlockPolicyEstimator* fee_estimator = node.fee_estimator.get();
+        node.scheduler->scheduleEvery([fee_estimator] { fee_estimator->FlushFeeEstimates(); }, FEE_FLUSH_INTERVAL);
+    }
 
     // sanitize comments per BIP-0014, format user agent and check total size
     std::vector<std::string> uacomments;

src/policy/fees.cpp

@@ -24,6 +24,7 @@
 
 #include <algorithm>
 #include <cassert>
+#include <chrono>
 #include <cmath>
 #include <cstddef>
 #include <cstdint>
@@ -527,7 +528,7 @@ bool CBlockPolicyEstimator::_removeTx(const uint256& hash, bool inBlock)
     }
 }
 
-CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath)
+CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath, const bool read_stale_estimates)
     : m_estimation_filepath{estimation_filepath}, nBestSeenHeight{0}, firstRecordedHeight{0}, historicalFirst{0}, historicalBest{0}, trackedTxs{0}, untrackedTxs{0}
 {
     static_assert(MIN_BUCKET_FEERATE > 0, "Min feerate must be nonzero");
@@ -545,9 +546,22 @@ CBlockPolicyEstimator::CBlockPolicyEstimator(const fs::path& estimation_filepath
     shortStats = std::unique_ptr<TxConfirmStats>(new TxConfirmStats(buckets, bucketMap, SHORT_BLOCK_PERIODS, SHORT_DECAY, SHORT_SCALE));
     longStats = std::unique_ptr<TxConfirmStats>(new TxConfirmStats(buckets, bucketMap, LONG_BLOCK_PERIODS, LONG_DECAY, LONG_SCALE));
 
-    // If the fee estimation file is present, read recorded estimations
     AutoFile est_file{fsbridge::fopen(m_estimation_filepath, "rb")};
-    if (est_file.IsNull() || !Read(est_file)) {
+
+    // Whenever the fee estimation file is not present return early
+    if (est_file.IsNull()) {
+        LogPrintf("%s is not found. Continue anyway.\n", fs::PathToString(m_estimation_filepath));
+        return;
+    }
+
+    std::chrono::hours file_age = GetFeeEstimatorFileAge();
+    // fee estimate file must not be too old to avoid wrong fee estimates.
+    if (file_age > MAX_FILE_AGE && !read_stale_estimates) {
+        LogPrintf("Fee estimation file %s too old (age=%lld > %lld hours) and will not be used to avoid serving stale estimates.\n", fs::PathToString(m_estimation_filepath), Ticks<std::chrono::hours>(file_age), Ticks<std::chrono::hours>(MAX_FILE_AGE));
+        return;
+    }
+
+    if (!Read(est_file)) {
         LogPrintf("Failed to read fee estimates from %s. Continue anyway.\n", fs::PathToString(m_estimation_filepath));
     }
 }
@@ -903,10 +917,16 @@ CFeeRate CBlockPolicyEstimator::estimateSmartFee(int confTarget, FeeCalculation
 
 void CBlockPolicyEstimator::Flush() {
     FlushUnconfirmed();
+    FlushFeeEstimates();
+}
 
+void CBlockPolicyEstimator::FlushFeeEstimates()
+{
     AutoFile est_file{fsbridge::fopen(m_estimation_filepath, "wb")};
     if (est_file.IsNull() || !Write(est_file)) {
         LogPrintf("Failed to write fee estimates to %s. Continue anyway.\n", fs::PathToString(m_estimation_filepath));
+    } else {
+        LogPrintf("Flushed fee estimates to %s.\n", fs::PathToString(m_estimation_filepath.filename()));
     }
 }
 
@@ -1010,6 +1030,13 @@ void CBlockPolicyEstimator::FlushUnconfirmed() {
     LogPrint(BCLog::ESTIMATEFEE, "Recorded %u unconfirmed txs from mempool in %gs\n", num_entries, (endclear - startclear)*0.000001);
 }
 
+std::chrono::hours CBlockPolicyEstimator::GetFeeEstimatorFileAge()
+{
+    auto file_time = std::filesystem::last_write_time(m_estimation_filepath);
+    auto now = std::filesystem::file_time_type::clock::now();
+    return std::chrono::duration_cast<std::chrono::hours>(now - file_time);
+}
+
 FeeFilterRounder::FeeFilterRounder(const CFeeRate& minIncrementalFee)
 {
     CAmount minFeeLimit = std::max(CAmount(1), minIncrementalFee.GetFeePerK() / 2);

src/policy/fees.h

@@ -14,12 +14,25 @@
 #include <uint256.h>
 
 #include <array>
+#include <chrono>
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
+
+// How often to flush fee estimates to fee_estimates.dat.
+static constexpr std::chrono::hours FEE_FLUSH_INTERVAL{1};
+
+/** fee_estimates.dat that are more than 60 hours (2.5 days) will not be read,
+ * as the estimates in the file are stale.
+ */
+static constexpr std::chrono::hours MAX_FILE_AGE{60};
+
+// Whether we allow importing a fee_estimates file older than MAX_FILE_AGE.
+static constexpr bool DEFAULT_ACCEPT_STALE_FEE_ESTIMATES{false};
+
 class AutoFile;
 class CTxMemPoolEntry;
 class TxConfirmStats;
@@ -183,7 +196,7 @@ private:
     const fs::path m_estimation_filepath;
 public:
     /** Create new BlockPolicyEstimator and initialize stats tracking classes with default values */
-    CBlockPolicyEstimator(const fs::path& estimation_filepath);
+    CBlockPolicyEstimator(const fs::path& estimation_filepath, const bool read_stale_estimates);
     ~CBlockPolicyEstimator();
 
     /** Process all the transactions that have been included in a block */
@@ -239,6 +252,13 @@ public:
     void Flush()
         EXCLUSIVE_LOCKS_REQUIRED(!m_cs_fee_estimator);
 
+    /** Record current fee estimations. */
+    void FlushFeeEstimates()
+        EXCLUSIVE_LOCKS_REQUIRED(!m_cs_fee_estimator);
+
+    /** Calculates the age of the file, since last modified */
+    std::chrono::hours GetFeeEstimatorFileAge();
+
 private:
     mutable Mutex m_cs_fee_estimator;
 

src/test/fuzz/policy_estimator.cpp

@@ -29,7 +29,7 @@ void initialize_policy_estimator()
 FUZZ_TARGET_INIT(policy_estimator, initialize_policy_estimator)
 {
     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
-    CBlockPolicyEstimator block_policy_estimator{FeeestPath(*g_setup->m_node.args)};
+    CBlockPolicyEstimator block_policy_estimator{FeeestPath(*g_setup->m_node.args), DEFAULT_ACCEPT_STALE_FEE_ESTIMATES};
     LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000) {
         CallOneOf(
             fuzzed_data_provider,

src/test/fuzz/policy_estimator_io.cpp

@@ -28,7 +28,7 @@ FUZZ_TARGET_INIT(policy_estimator_io, initialize_policy_estimator_io)
     FuzzedAutoFileProvider fuzzed_auto_file_provider = ConsumeAutoFile(fuzzed_data_provider);
     AutoFile fuzzed_auto_file{fuzzed_auto_file_provider.open()};
     // Re-using block_policy_estimator across runs to avoid costly creation of CBlockPolicyEstimator object.
-    static CBlockPolicyEstimator block_policy_estimator{FeeestPath(*g_setup->m_node.args)};
+    static CBlockPolicyEstimator block_policy_estimator{FeeestPath(*g_setup->m_node.args), DEFAULT_ACCEPT_STALE_FEE_ESTIMATES};
     if (block_policy_estimator.Read(fuzzed_auto_file)) {
         block_policy_estimator.Write(fuzzed_auto_file);
     }

src/test/util/setup_common.cpp

@@ -186,7 +186,7 @@ ChainTestingSetup::ChainTestingSetup(const std::string& chainName, const std::ve
     m_node.scheduler->m_service_thread = std::thread(util::TraceThread, "scheduler", [&] { m_node.scheduler->serviceQueue(); });
     GetMainSignals().RegisterBackgroundSignalScheduler(*m_node.scheduler);
 
-    m_node.fee_estimator = std::make_unique<CBlockPolicyEstimator>(FeeestPath(*m_node.args));
+    m_node.fee_estimator = std::make_unique<CBlockPolicyEstimator>(FeeestPath(*m_node.args), DEFAULT_ACCEPT_STALE_FEE_ESTIMATES);
     m_node.mempool = std::make_unique<CTxMemPool>(MemPoolOptionsForTest(m_node));
 
     m_cache_sizes = CalculateCacheSizes(m_args);

src/test/util_tests.cpp

@@ -2782,4 +2782,29 @@ BOOST_AUTO_TEST_CASE(util_WriteBinaryFile)
     BOOST_CHECK(valid);
     BOOST_CHECK_EQUAL(actual_text, expected_text);
 }
+
+BOOST_AUTO_TEST_CASE(clearshrink_test)
+{
+    {
+        std::vector<uint8_t> v = {1, 2, 3};
+        ClearShrink(v);
+        BOOST_CHECK_EQUAL(v.size(), 0);
+        BOOST_CHECK_EQUAL(v.capacity(), 0);
+    }
+
+    {
+        std::vector<bool> v = {false, true, false, false, true, true};
+        ClearShrink(v);
+        BOOST_CHECK_EQUAL(v.size(), 0);
+        BOOST_CHECK_EQUAL(v.capacity(), 0);
+    }
+
+    {
+        std::deque<int> v = {1, 3, 3, 7};
+        ClearShrink(v);
+        BOOST_CHECK_EQUAL(v.size(), 0);
+        // std::deque has no capacity() we can observe.
+    }
+}
+
 BOOST_AUTO_TEST_SUITE_END()

src/util/vector.h

@@ -49,4 +49,22 @@ inline V Cat(V v1, const V& v2)
     return v1;
 }
 
+/** Clear a vector (or std::deque) and release its allocated memory. */
+template<typename V>
+inline void ClearShrink(V& v) noexcept
+{
+    // There are various ways to clear a vector and release its memory:
+    //
+    // 1. V{}.swap(v)
+    // 2. v = V{}
+    // 3. v = {}; v.shrink_to_fit();
+    // 4. v.clear(); v.shrink_to_fit();
+    //
+    // (2) does not appear to release memory in glibc debug mode, even if v.shrink_to_fit()
+    // follows. (3) and (4) rely on std::vector::shrink_to_fit, which is only a non-binding
+    // request. Therefore, we use method (1).
+
+    V{}.swap(v);
+}
+
 #endif // BITCOIN_UTIL_VECTOR_H

test/functional/feature_fee_estimation.py

@@ -7,6 +7,7 @@ from copy import deepcopy
 from decimal import Decimal
 import os
 import random
+import time
 
 from test_framework.messages import (
     COIN,
@@ -21,6 +22,8 @@ from test_framework.util import (
 )
 from test_framework.wallet import MiniWallet
 
+MAX_FILE_AGE = 60
+SECONDS_PER_HOUR = 60 * 60
 
 def small_txpuzzle_randfee(
     wallet, from_node, conflist, unconflist, amount, min_fee, fee_increment
@@ -273,6 +276,95 @@ class EstimateFeeTest(BitcoinTestFramework):
         est_feerate = node.estimatesmartfee(2)["feerate"]
         assert_equal(est_feerate, high_feerate_kvb)
 
+    def test_old_fee_estimate_file(self):
+        # Get the initial fee rate while node is running
+        fee_rate = self.nodes[0].estimatesmartfee(1)["feerate"]
+
+        # Restart node to ensure fee_estimate.dat file is read
+        self.restart_node(0)
+        assert_equal(self.nodes[0].estimatesmartfee(1)["feerate"], fee_rate)
+
+        fee_dat = self.nodes[0].chain_path / "fee_estimates.dat"
+
+        # Stop the node and backdate the fee_estimates.dat file more than MAX_FILE_AGE
+        self.stop_node(0)
+        last_modified_time = time.time() - (MAX_FILE_AGE + 1) * SECONDS_PER_HOUR
+        os.utime(fee_dat, (last_modified_time, last_modified_time))
+
+        # Start node and ensure the fee_estimates.dat file was not read
+        self.start_node(0)
+        assert_equal(self.nodes[0].estimatesmartfee(1)["errors"], ["Insufficient data or no feerate found"])
+
+
+    def test_estimate_dat_is_flushed_periodically(self):
+        fee_dat = self.nodes[0].chain_path / "fee_estimates.dat"
+        os.remove(fee_dat) if os.path.exists(fee_dat) else None
+
+        # Verify that fee_estimates.dat does not exist
+        assert_equal(os.path.isfile(fee_dat), False)
+
+        # Verify if the string "Flushed fee estimates to fee_estimates.dat." is present in the debug log file.
+        # If present, it indicates that fee estimates have been successfully flushed to disk.
+        with self.nodes[0].assert_debug_log(expected_msgs=["Flushed fee estimates to fee_estimates.dat."], timeout=1):
+            # Mock the scheduler for an hour to flush fee estimates to fee_estimates.dat
+            self.nodes[0].mockscheduler(SECONDS_PER_HOUR)
+
+        # Verify that fee estimates were flushed and fee_estimates.dat file is created
+        assert_equal(os.path.isfile(fee_dat), True)
+
+        # Verify that the estimates remain the same if there are no blocks in the flush interval
+        block_hash_before = self.nodes[0].getbestblockhash()
+        fee_dat_initial_content = open(fee_dat, "rb").read()
+        with self.nodes[0].assert_debug_log(expected_msgs=["Flushed fee estimates to fee_estimates.dat."], timeout=1):
+            # Mock the scheduler for an hour to flush fee estimates to fee_estimates.dat
+            self.nodes[0].mockscheduler(SECONDS_PER_HOUR)
+
+        # Verify that there were no blocks in between the flush interval
+        assert_equal(block_hash_before, self.nodes[0].getbestblockhash())
+
+        fee_dat_current_content = open(fee_dat, "rb").read()
+        assert_equal(fee_dat_current_content, fee_dat_initial_content)
+
+        # Verify that the estimates remain the same after shutdown with no blocks before shutdown
+        self.restart_node(0)
+        fee_dat_current_content = open(fee_dat, "rb").read()
+        assert_equal(fee_dat_current_content, fee_dat_initial_content)
+
+        # Verify that the estimates are not the same if new blocks were produced in the flush interval
+        with self.nodes[0].assert_debug_log(expected_msgs=["Flushed fee estimates to fee_estimates.dat."], timeout=1):
+            # Mock the scheduler for an hour to flush fee estimates to fee_estimates.dat
+            self.generate(self.nodes[0], 5, sync_fun=self.no_op)
+            self.nodes[0].mockscheduler(SECONDS_PER_HOUR)
+
+        fee_dat_current_content = open(fee_dat, "rb").read()
+        assert fee_dat_current_content != fee_dat_initial_content
+
+        fee_dat_initial_content = fee_dat_current_content
+
+        # Generate blocks before shutdown and verify that the fee estimates are not the same
+        self.generate(self.nodes[0], 5, sync_fun=self.no_op)
+        self.restart_node(0)
+        fee_dat_current_content = open(fee_dat, "rb").read()
+        assert fee_dat_current_content != fee_dat_initial_content
+
+
+    def test_acceptstalefeeestimates_option(self):
+        # Get the initial fee rate while node is running
+        fee_rate = self.nodes[0].estimatesmartfee(1)["feerate"]
+
+        self.stop_node(0)
+
+        fee_dat = self.nodes[0].chain_path / "fee_estimates.dat"
+
+        # Stop the node and backdate the fee_estimates.dat file more than MAX_FILE_AGE
+        last_modified_time = time.time() - (MAX_FILE_AGE + 1) * SECONDS_PER_HOUR
+        os.utime(fee_dat, (last_modified_time, last_modified_time))
+
+        # Restart node with -acceptstalefeeestimates option to ensure fee_estimate.dat file is read
+        self.start_node(0,extra_args=["-acceptstalefeeestimates"])
+        assert_equal(self.nodes[0].estimatesmartfee(1)["feerate"], fee_rate)
+
+
     def run_test(self):
         self.log.info("This test is time consuming, please be patient")
         self.log.info("Splitting inputs so we can generate tx's")
@@ -296,12 +388,21 @@ class EstimateFeeTest(BitcoinTestFramework):
         self.log.info("Testing estimates with single transactions.")
         self.sanity_check_estimates_range()
 
+        self.log.info("Test fee_estimates.dat is flushed periodically")
+        self.test_estimate_dat_is_flushed_periodically()
+
         # check that the effective feerate is greater than or equal to the mempoolminfee even for high mempoolminfee
         self.log.info(
             "Test fee rate estimation after restarting node with high MempoolMinFee"
         )
         self.test_feerate_mempoolminfee()
 
+        self.log.info("Test acceptstalefeeestimates option")
+        self.test_acceptstalefeeestimates_option()
+
+        self.log.info("Test reading old fee_estimates.dat")
+        self.test_old_fee_estimate_file()
+
         self.log.info("Restarting node with fresh estimation")
         self.stop_node(0)
         fee_dat = os.path.join(self.nodes[0].datadir, self.chain, "fee_estimates.dat")