bitcoin · achow101 · Apr 20, 2023 · Jun 11, 2022 · Jun 11, 2022 · Jun 11, 2022
diff --git a/src/Makefile.am b/src/Makefile.am
@@ -261,6 +261,7 @@ BITCOIN_CORE_H = \
   shutdown.h \
   signet.h \
   streams.h \
+  support/allocators/pool.h \
   support/allocators/secure.h \
   support/allocators/zeroafterfree.h \
   support/cleanse.h \

diff --git a/src/Makefile.bench.include b/src/Makefile.bench.include
@@ -42,6 +42,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/nanobench.h \
   bench/peer_eviction.cpp \
   bench/poly1305.cpp \
+  bench/pool.cpp \
   bench/prevector.cpp \
   bench/rollingbloom.cpp \
   bench/rpc_blockchain.cpp \

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
@@ -116,6 +116,7 @@ BITCOIN_TESTS =\
   test/pmt_tests.cpp \
   test/policy_fee_tests.cpp \
   test/policyestimator_tests.cpp \
+  test/pool_tests.cpp \
   test/pow_tests.cpp \
   test/prevector_tests.cpp \
   test/raii_event_tests.cpp \
@@ -300,6 +301,7 @@ test_fuzz_fuzz_SOURCES = \
  test/fuzz/partially_downloaded_block.cpp \
  test/fuzz/policy_estimator.cpp \
  test/fuzz/policy_estimator_io.cpp \
+ test/fuzz/poolresource.cpp \
  test/fuzz/pow.cpp \
  test/fuzz/prevector.cpp \
  test/fuzz/primitives_transaction.cpp \

diff --git a/src/Makefile.test_util.include b/src/Makefile.test_util.include
@@ -15,6 +15,7 @@ TEST_UTIL_H = \
   test/util/logging.h \
   test/util/mining.h \
   test/util/net.h \
+  test/util/poolresourcetester.h \
   test/util/random.h \
   test/util/script.h \
   test/util/setup_common.h \

diff --git a/src/bench/pool.cpp b/src/bench/pool.cpp
@@ -0,0 +1,50 @@
+// 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.
+
+#include <bench/bench.h>
+#include <support/allocators/pool.h>
+
+#include <unordered_map>
+
+template <typename Map>
+void BenchFillClearMap(benchmark::Bench& bench, Map& map)
+{
+    size_t batch_size = 5000;
+
+    // make sure each iteration of the benchmark contains exactly 5000 inserts and one clear.
+    // do this at least 10 times so we get reasonable accurate results
+
+    bench.batch(batch_size).minEpochIterations(10).run([&] {
+        auto rng = ankerl::nanobench::Rng(1234);
+        for (size_t i = 0; i < batch_size; ++i) {
+            map[rng()];
+        }
+        map.clear();
+    });
+}
+
+static void PoolAllocator_StdUnorderedMap(benchmark::Bench& bench)
+{
+    auto map = std::unordered_map<uint64_t, uint64_t>();
+    BenchFillClearMap(bench, map);
+}
+
+static void PoolAllocator_StdUnorderedMapWithPoolResource(benchmark::Bench& bench)
+{
+    using Map = std::unordered_map<uint64_t,
+                                   uint64_t,
+                                   std::hash<uint64_t>,
+                                   std::equal_to<uint64_t>,
+                                   PoolAllocator<std::pair<const uint64_t, uint64_t>,
+                                                 sizeof(std::pair<const uint64_t, uint64_t>) + 4 * sizeof(void*),
+                                                 alignof(void*)>>;
+
+    // make sure the resource supports large enough pools to hold the node. We do this by adding the size of a few pointers to it.
+    auto pool_resource = Map::allocator_type::ResourceType();
+    auto map = Map{0, std::hash<uint64_t>{}, std::equal_to<uint64_t>{}, &pool_resource};
+    BenchFillClearMap(bench, map);
+}
+
+BENCHMARK(PoolAllocator_StdUnorderedMap, benchmark::PriorityLevel::HIGH);
+BENCHMARK(PoolAllocator_StdUnorderedMapWithPoolResource, benchmark::PriorityLevel::HIGH);
diff --git a/src/coins.cpp b/src/coins.cpp
@@ -34,7 +34,7 @@ size_t CCoinsViewBacked::EstimateSize() const { return base->EstimateSize(); }
 
 CCoinsViewCache::CCoinsViewCache(CCoinsView* baseIn, bool deterministic) :
     CCoinsViewBacked(baseIn), m_deterministic(deterministic),
-    cacheCoins(0, SaltedOutpointHasher(/*deterministic=*/deterministic))
+    cacheCoins(0, SaltedOutpointHasher(/*deterministic=*/deterministic), CCoinsMap::key_equal{}, &m_cache_coins_memory_resource)
 {}
 
 size_t CCoinsViewCache::DynamicMemoryUsage() const {
@@ -253,9 +253,12 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
 
 bool CCoinsViewCache::Flush() {
     bool fOk = base->BatchWrite(cacheCoins, hashBlock, /*erase=*/true);
-    if (fOk && !cacheCoins.empty()) {
-        /* BatchWrite must erase all cacheCoins elements when erase=true. */
-        throw std::logic_error("Not all cached coins were erased");
+    if (fOk) {
+        if (!cacheCoins.empty()) {
+            /* BatchWrite must erase all cacheCoins elements when erase=true. */
+            throw std::logic_error("Not all cached coins were erased");
+        }
+        ReallocateCache();
     }
     cachedCoinsUsage = 0;
     return fOk;
@@ -314,7 +317,9 @@ void CCoinsViewCache::ReallocateCache()
     // Cache should be empty when we're calling this.
     assert(cacheCoins.size() == 0);
     cacheCoins.~CCoinsMap();
-    ::new (&cacheCoins) CCoinsMap(0, SaltedOutpointHasher(/*deterministic=*/m_deterministic));
+    m_cache_coins_memory_resource.~CCoinsMapMemoryResource();
+    ::new (&m_cache_coins_memory_resource) CCoinsMapMemoryResource{};
+    ::new (&cacheCoins) CCoinsMap{0, SaltedOutpointHasher{/*deterministic=*/m_deterministic}, CCoinsMap::key_equal{}, &m_cache_coins_memory_resource};
 }
 
 void CCoinsViewCache::SanityCheck() const

diff --git a/src/coins.h b/src/coins.h
@@ -11,6 +11,7 @@
 #include <memusage.h>
 #include <primitives/transaction.h>
 #include <serialize.h>
+#include <support/allocators/pool.h>
 #include <uint256.h>
 #include <util/hasher.h>
 
@@ -131,7 +132,23 @@ struct CCoinsCacheEntry
     CCoinsCacheEntry(Coin&& coin_, unsigned char flag) : coin(std::move(coin_)), flags(flag) {}
 };
 
-typedef std::unordered_map<COutPoint, CCoinsCacheEntry, SaltedOutpointHasher> CCoinsMap;
+/**
+ * PoolAllocator's MAX_BLOCK_SIZE_BYTES parameter here uses sizeof the data, and adds the size
+ * of 4 pointers. We do not know the exact node size used in the std::unordered_node implementation
+ * because it is implementation defined. Most implementations have an overhead of 1 or 2 pointers,
+ * so nodes can be connected in a linked list, and in some cases the hash value is stored as well.
+ * Using an additional sizeof(void*)*4 for MAX_BLOCK_SIZE_BYTES should thus be sufficient so that
+ * all implementations can allocate the nodes from the PoolAllocator.
+ */
+using CCoinsMap = std::unordered_map<COutPoint,
+                                     CCoinsCacheEntry,
+                                     SaltedOutpointHasher,
+                                     std::equal_to<COutPoint>,
+                                     PoolAllocator<std::pair<const COutPoint, CCoinsCacheEntry>,
+                                                   sizeof(std::pair<const COutPoint, CCoinsCacheEntry>) + sizeof(void*) * 4,
+                                                   alignof(void*)>>;
+
+using CCoinsMapMemoryResource = CCoinsMap::allocator_type::ResourceType;
 
 /** Cursor for iterating over CoinsView state */
 class CCoinsViewCursor
@@ -220,6 +237,7 @@ class CCoinsViewCache : public CCoinsViewBacked
      * declared as "const".
      */
     mutable uint256 hashBlock;
+    mutable CCoinsMapMemoryResource m_cache_coins_memory_resource{};
     mutable CCoinsMap cacheCoins;
 
     /* Cached dynamic memory usage for the inner Coin objects. */

diff --git a/src/memusage.h b/src/memusage.h
@@ -7,6 +7,7 @@
 
 #include <indirectmap.h>
 #include <prevector.h>
+#include <support/allocators/pool.h>
 
 #include <cassert>
 #include <cstdlib>
@@ -166,6 +167,25 @@ static inline size_t DynamicUsage(const std::unordered_map<X, Y, Z>& m)
     return MallocUsage(sizeof(unordered_node<std::pair<const X, Y> >)) * m.size() + MallocUsage(sizeof(void*) * m.bucket_count());
 }
 
+template <class Key, class T, class Hash, class Pred, std::size_t MAX_BLOCK_SIZE_BYTES, std::size_t ALIGN_BYTES>
+static inline size_t DynamicUsage(const std::unordered_map<Key,
+                                                           T,
+                                                           Hash,
+                                                           Pred,
+                                                           PoolAllocator<std::pair<const Key, T>,
+                                                                         MAX_BLOCK_SIZE_BYTES,
+                                                                         ALIGN_BYTES>>& m)
+{
+    auto* pool_resource = m.get_allocator().resource();
+
+    // The allocated chunks are stored in a std::list. Size per node should
+    // therefore be 3 pointers: next, previous, and a pointer to the chunk.
+    size_t estimated_list_node_size = MallocUsage(sizeof(void*) * 3);
+    size_t usage_resource = estimated_list_node_size * pool_resource->NumAllocatedChunks();
+    size_t usage_chunks = MallocUsage(pool_resource->ChunkSizeBytes()) * pool_resource->NumAllocatedChunks();
+    return usage_resource + usage_chunks + MallocUsage(sizeof(void*) * m.bucket_count());
 }
 
+} // namespace memusage
+
 #endif // BITCOIN_MEMUSAGE_H