Transactional hash map

internals/CMakeLists.txt

@@ -1,2 +1,4 @@
-add_conventional_library(testing PUBLIC trade_v1)
+add_conventional_library(testing)
+target_link_libraries(testing INTERFACE dumpster_v1 trade_v1)
+
 add_conventional_executable_tests(PRIVATE testing trade_v1 testing_v1 std_thread)

internals/include/testing/config.hpp

@@ -1,9 +1,11 @@
 #pragma once
 
+#include "dumpster_v1/config.hpp"
 #include "trade_v1/config.hpp"
 
 namespace testing {
 
+namespace dumpster = dumpster_v1;
 namespace trade = trade_v1;
 
-}
+} // namespace testing

internals/include/testing/hash_map_tm.hpp

@@ -0,0 +1,231 @@
+#pragma once
+
+#include "testing/config.hpp"
+
+#include "trade_v1/trade.hpp"
+
+#include "dumpster_v1/primes.hpp"
+
+#include "polyfill_v1/memory.hpp"
+#include <functional>
+#include <optional>
+#include <utility>
+
+namespace testing {
+
+/// A transactional hash map for testing purposes.
+template <class Key,
+          class Mapped,
+          class Hash = std::hash<Key>,
+          class Equal = std::equal_to<Key>>
+class hash_map_tm;
+
+class hash_map_tm_private {
+  template <class, class, class, class> friend class hash_map_tm;
+
+  // This hack is a workaround for not having std::shared_ptr<T[]> support
+  // in AppleClang.
+  template <class T> struct array_hack {
+    void operator delete(void *self) { delete[] reinterpret_cast<T *>(self); }
+    T &at(size_t i) { return reinterpret_cast<T *>(this)[i]; }
+  };
+};
+
+template <class Key, class Mapped, class Hash, class Equal>
+class hash_map_tm : hash_map_tm_private {
+  template <class T> using ptr_t = std::shared_ptr<T>;
+
+  struct node_t;
+
+  using link = trade::atom<std::shared_ptr<node_t>>;
+
+  trade::atom<size_t> m_item_count;
+  trade::atom<size_t> m_buckets_count;
+  trade::atom<ptr_t<array_hack<link>>> m_buckets;
+
+public:
+  using size_type = size_t;
+
+  using key_type = Key;
+  using mapped_type = Mapped;
+
+  hash_map_tm();
+
+  hash_map_tm(const hash_map_tm &) = delete;
+  hash_map_tm &operator=(const hash_map_tm &) = delete;
+
+  size_t size() const;
+
+  bool empty() const;
+
+  void clear();
+
+  void swap(hash_map_tm &that);
+
+  template <class ForwardableMapped, class Config = trade::stack_t<1024>>
+  bool add_or_set(const Key &key,
+                  ForwardableMapped &&mapped,
+                  Config config = trade::stack<1024>);
+
+  std::optional<Mapped> try_get(const Key &key) const;
+
+  bool remove(const Key &key);
+
+#ifndef NDEBUG
+  static std::atomic<size_t> s_live_nodes; // Only for testing purposes
+#endif
+};
+
+// -----------------------------------------------------------------------------
+
+template <class Key, class Mapped, class Hash, class Equal>
+struct hash_map_tm<Key, Mapped, Hash, Equal>::node_t {
+#ifndef NDEBUG
+  ~node_t() { --s_live_nodes; }
+#endif
+  template <class ForwardableKey, class ForwardableMapped>
+  node_t(ForwardableKey &&key, ForwardableMapped &&value)
+      : m_next(nullptr), m_key(std::forward<ForwardableKey>(key)),
+        m_mapped(std::forward<ForwardableMapped>(value)) {
+#ifndef NDEBUG
+    ++s_live_nodes;
+#endif
+  }
+  link m_next;
+  const Key m_key;
+  trade::atom<Mapped> m_mapped;
+};
+
+//
+
+template <class Key, class Mapped, class Hash, class Equal>
+hash_map_tm<Key, Mapped, Hash, Equal>::hash_map_tm()
+    : m_item_count(0), m_buckets_count(0), m_buckets(nullptr) {}
+
+template <class Key, class Mapped, class Hash, class Equal>
+size_t hash_map_tm<Key, Mapped, Hash, Equal>::size() const {
+  return trade::atomically(trade::assume_readonly,
+                           [&]() { return m_item_count.load(); });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+bool hash_map_tm<Key, Mapped, Hash, Equal>::empty() const {
+  return trade::atomically(trade::assume_readonly,
+                           [&]() { return m_item_count == 0; });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+void hash_map_tm<Key, Mapped, Hash, Equal>::clear() {
+  trade::atomically([&]() {
+    m_item_count = 0;
+    m_buckets_count = 0;
+    m_buckets = nullptr;
+  });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+void hash_map_tm<Key, Mapped, Hash, Equal>::swap(hash_map_tm &that) {
+  trade::atomically([&]() {
+    std::swap(m_item_count.ref(), that.m_item_count.ref());
+    std::swap(m_buckets_count.ref(), that.m_buckets_count.ref());
+    std::swap(m_buckets.ref(), that.m_buckets.ref());
+  });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+template <class ForwardableMapped, class Config>
+bool hash_map_tm<Key, Mapped, Hash, Equal>::add_or_set(
+    const Key &key, ForwardableMapped &&mapped, Config config) {
+  auto key_hash = Hash()(key);
+
+  return trade::atomically(config, [&]() {
+    auto item_count = m_item_count.load();
+    auto buckets_count = m_buckets_count.load();
+    auto buckets = m_buckets.load();
+
+    if (buckets_count <= item_count) {
+      auto old_buckets = std::move(buckets);
+      auto old_buckets_count = buckets_count;
+
+      m_buckets_count = buckets_count =
+          dumpster::prime_less_than_next_pow_2_or_1(old_buckets_count * 2 + 1);
+      m_buckets = buckets = ptr_t<array_hack<link>>(
+          reinterpret_cast<array_hack<link> *>(new link[buckets_count]));
+
+      for (size_t i = 0; i < old_buckets_count; ++i) {
+        auto work = old_buckets->at(i).load();
+        while (work) {
+          auto &ref_next = work->m_next.ref();
+          auto &ref_bucket =
+              buckets->at(Hash()(work->m_key) % buckets_count).ref();
+          auto next = std::move(ref_next);
+          ref_next = std::move(ref_bucket);
+          ref_bucket = std::move(work);
+          work = std::move(next);
+        }
+      }
+    }
+
+    auto prev = &buckets->at(key_hash % buckets_count);
+    while (true) {
+      if (auto node = prev->load()) {
+        if (Equal()(node->m_key, key)) {
+          node->m_mapped = std::forward<ForwardableMapped>(mapped);
+          return false;
+        } else {
+          prev = &node->m_next;
+        }
+      } else {
+        prev->ref().reset(
+            new node_t(key, std::forward<ForwardableMapped>(mapped)));
+        m_item_count = item_count + 1;
+        return true;
+      }
+    }
+  });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+std::optional<Mapped>
+hash_map_tm<Key, Mapped, Hash, Equal>::try_get(const Key &key) const {
+  auto key_hash = Hash()(key);
+  return trade::atomically(
+      trade::assume_readonly, [&]() -> std::optional<Mapped> {
+        if (auto buckets_count = m_buckets_count.load())
+          for (auto node =
+                   m_buckets.load()->at(key_hash % buckets_count).load();
+               node;
+               node = node->m_next)
+            if (Equal()(node->m_key, key))
+              return node->m_mapped.load();
+        return std::nullopt;
+      });
+}
+
+template <class Key, class Mapped, class Hash, class Equal>
+bool hash_map_tm<Key, Mapped, Hash, Equal>::remove(const Key &key) {
+  auto key_hash = Hash()(key);
+  return trade::atomically([&]() {
+    if (auto buckets_count = m_buckets_count.load()) {
+      auto prev = &m_buckets.load()->at(key_hash % buckets_count);
+      while (true) {
+        auto node = prev->load();
+        if (!node)
+          break;
+        if (Equal()(node->m_key, key)) {
+          *prev = node->m_next;
+          return true;
+        }
+        prev = &node->m_next;
+      }
+    }
+    return false;
+  });
+}
+
+#ifndef NDEBUG
+template <class Key, class Mapped, class Hash, class Equal>
+std::atomic<size_t> hash_map_tm<Key, Mapped, Hash, Equal>::s_live_nodes = 0;
+#endif
+
+} // namespace testing

internals/include/testing/memory.hpp

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "trade_v1/trade.hpp"
+
+namespace testing {
+
+template <class Object> class unique {};
+
+template <class Object> class shared {};
+
+} // namespace testing
+
+namespace trade_v1 {
+
+using namespace testing;
+
+template <class Object> class atom<unique<Object>> {
+
+  shared<Object> load() const;
+};
+
+} // namespace trade_v1

internals/testing/contention_test.cpp

@@ -13,11 +13,11 @@ using namespace trade_v1;
 
 auto contention_test = test([]() {
   const size_t n_threads = std::thread::hardware_concurrency();
-  const size_t n_ops = 100000;
+  const size_t n_ops = 1000000;
 
   atom<size_t> n_threads_started = 0, n_threads_stopped = 0;
 
-  constexpr size_t n_atoms = 7;
+  constexpr size_t n_atoms = 7000;
 
   std::unique_ptr<atom<int>[]> atoms(new atom<int>[n_atoms]);
   for (size_t i = 0; i < n_atoms; ++i)

internals/testing/hash_map_tm_test.cpp

@@ -0,0 +1,67 @@
+#include "testing/hash_map_tm.hpp"
+
+#include "testing_v1/test.hpp"
+
+#include "dumpster_v1/ranqd1.hpp"
+
+#include "polyfill_v1/memory.hpp"
+#include <thread>
+
+using namespace testing_v1;
+
+using namespace testing;
+using namespace trade;
+
+auto hash_map_test = test([]() {
+  const size_t n_threads = std::thread::hardware_concurrency();
+  const size_t n_ops = 100000;
+  const uint32_t max_keys = 31;
+
+  using hash_map_tm_type = hash_map_tm<uint32_t, size_t>;
+
+  hash_map_tm_type map;
+
+  atom<size_t> done(0);
+
+  auto start = std::chrono::high_resolution_clock::now();
+
+  for (size_t t = 0; t < n_threads; ++t)
+    std::thread([&, t]() {
+      auto s = static_cast<uint32_t>(t);
+
+      for (size_t i = 0; i < n_ops; ++i) {
+        uint32_t key = (s = dumpster::ranqd1(s)) % max_keys;
+        map.add_or_set(key, t, trade::stack<8192>);
+      }
+
+      atomically([&]() { done.ref() += 1; });
+    }).detach();
+
+  atomically(assume_readonly, [&]() {
+    if (done != n_threads)
+      retry();
+  });
+
+  std::chrono::duration<double> elapsed =
+      std::chrono::high_resolution_clock::now() - start;
+  auto n_total = n_ops * n_threads;
+  fprintf(stderr,
+          "%f Mops in %f s = %f Mops/s\n",
+          n_total / 1000000.0,
+          elapsed.count(),
+          n_total / elapsed.count() / 1000000.0);
+
+  verify(map.size() == max_keys);
+
+  {
+    hash_map_tm_type other;
+    map.swap(other);
+    verify(other.size() == max_keys);
+    verify(map.size() == 0);
+    other.clear();
+  }
+
+#ifndef NDEBUG
+  verify(!hash_map_tm_type::s_live_nodes);
+#endif
+});