Simple Lock (Mutex) implementation and test

include/pando-lib-galois/sync/simple_lock.hpp

@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2023. University of Texas at Austin. All rights reserved.
+
+#ifndef PANDO_LIB_GALOIS_SYNC_SIMPLE_LOCK_HPP_
+#define PANDO_LIB_GALOIS_SYNC_SIMPLE_LOCK_HPP_
+
+#include <pando-rt/export.h>
+
+#include <pando-rt/memory/allocate_memory.hpp>
+#include <pando-rt/memory/global_ptr.hpp>
+#include <pando-rt/pando-rt.hpp>
+#include <pando-rt/sync/atomic.hpp>
+
+namespace galois {
+/**
+ * @brief This is a termination detection mechanism that is used for detecting nested parallelism
+ */
+class SimpleLock {
+  using LockState = std::uint64_t;
+  enum class State : LockState { IsUnlocked = 0, IsLocked = 1 };
+
+  /**
+   * @brief This is a pointer to the state used by everyone
+   */
+  pando::GlobalPtr<LockState> m_state = nullptr;
+
+public:
+  // construct
+  constexpr SimpleLock() noexcept = default;
+  // movable
+  constexpr SimpleLock(SimpleLock&&) noexcept = default;
+  // copyable
+  constexpr SimpleLock(const SimpleLock&) noexcept = default;
+  // destruct
+  ~SimpleLock() = default;
+
+  // copy-assignable
+  constexpr SimpleLock& operator=(const SimpleLock&) noexcept = default;
+  // move-assignable
+  constexpr SimpleLock& operator=(SimpleLock&&) noexcept = default;
+
+  /**
+   * @brief initializes the SimpleLock
+   *
+   * @param[in] place        the location the counter should be allocated at
+   * @param[in] memoryType   the type of memory the waitgroup should be allocated in
+   *
+   * @warning one of the initialize methods must be called before use
+   */
+  [[nodiscard]] pando::Status initialize(pando::Place place, pando::MemoryType memoryType) {
+    // auto desiredValue = static_cast<LockState>(State::IsUnlocked);
+    // pando::atomicStore(pando::GlobalPtr<LockState>(&m_state), pando::GlobalPtr<const
+    // LockState>(&desiredValue),
+    //             std::memory_order_release);
+
+    const auto desiredValue = pando::allocateMemory<LockState>(1, place, memoryType);
+    if (!desiredValue.hasValue()) {
+      return desiredValue.error();
+    }
+    m_state = desiredValue.value();
+    *m_state = static_cast<LockState>(State::IsUnlocked);
+    pando::atomicThreadFence(std::memory_order_release);
+    return pando::Status::Success;
+  }
+
+  /**
+   * @brief initializes the SimpleLock
+   *
+   * @warning one of the initialize methods must be called before use
+   */
+  [[nodiscard]] pando::Status initialize() {
+    return initialize(pando::getCurrentPlace(), pando::MemoryType::Main);
+  }
+
+  /**
+   * @brief deinitializes the SimpleLock and frees associated memory
+   *
+   * @warning not threadsafe but designed to be idempotent.
+   */
+  void deinitialize() {
+    if (m_state != nullptr) {
+      pando::deallocateMemory(m_state, 1);
+      m_state = nullptr;
+    }
+  }
+
+  /**
+   * @brief Acquire the lock or block until the lock is acquired.
+   */
+  void lock() {
+    while (!try_lock()) {}
+  }
+
+  /**
+   * @brief Attempt to acquire the lock and returns immediately on success or failure.
+   *
+   * @return true If the lock was successfully acquired.
+   * @return false If the lock acquire attempt failed.
+   */
+  bool try_lock() {
+    constexpr auto success = std::memory_order_acquire;
+    constexpr auto failure = std::memory_order_relaxed;
+    auto expected = static_cast<LockState>(State::IsUnlocked);
+    auto desired = static_cast<LockState>(State::IsLocked);
+    return pando::atomicCompareExchange(m_state, pando::GlobalPtr<LockState>(&expected),
+                                        pando::GlobalPtr<const LockState>(&desired), success,
+                                        failure);
+  }
+  /**
+   * @brief Release the lock.
+   */
+  void unlock() {
+    auto desiredValue = static_cast<LockState>(State::IsUnlocked);
+    pando::atomicStore(m_state, pando::GlobalPtr<const LockState>(&desiredValue),
+                       std::memory_order_release);
+  }
+};
+} // namespace galois
+#endif // PANDO_LIB_GALOIS_SYNC_SIMPLE_LOCK_HPP_

test/sync/CMakeLists.txt

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: MIT
 # Copyright (c) 2023. University of Texas at Austin. All rights reserved.
 
+pando_add_driver_test(test_simple_lock test_simple_lock.cpp)
 pando_add_driver_test(test_global_barrier test_global_barrier.cpp)
 pando_add_driver_test(test_wait_group test_wait_group.cpp)
 pando_add_driver_test(test_atomic test_atomic.cpp)

test/sync/test_simple_lock.cpp

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2023. University of Texas at Austin. All rights reserved.
+
+#include <gtest/gtest.h>
+#include <pando-rt/export.h>
+
+#include <cstdint>
+
+#include <pando-lib-galois/loops/do_all.hpp>
+#include <pando-lib-galois/sync/global_barrier.hpp>
+#include <pando-lib-galois/sync/simple_lock.hpp>
+#include <pando-rt/containers/vector.hpp>
+#include <pando-rt/memory/global_ptr.hpp>
+#include <pando-rt/pando-rt.hpp>
+
+TEST(SimpleLock, TryLock) {
+  auto test = [] {
+    galois::SimpleLock mutex;
+    EXPECT_EQ(mutex.initialize(), pando::Status::Success);
+    const bool wasUnlocked = mutex.try_lock();
+    EXPECT_TRUE(wasUnlocked);
+
+    const bool isUnlocked = mutex.try_lock();
+    EXPECT_FALSE(isUnlocked);
+
+    mutex.unlock();
+    mutex.deinitialize();
+
+    return true;
+  };
+
+  const auto thisPlace = pando::getCurrentPlace();
+  const auto place = pando::Place{thisPlace.node, pando::anyPod, pando::anyCore};
+  auto result = pando::executeOnWait(place, +test);
+  EXPECT_TRUE(result.hasValue());
+}
+
+TEST(SimpleLock, SimpleLockUnlock) {
+  auto test = [] {
+    galois::SimpleLock mutex;
+    EXPECT_EQ(mutex.initialize(), pando::Status::Success);
+    mutex.lock();
+    mutex.unlock();
+    mutex.deinitialize();
+    return true;
+  };
+
+  const auto thisPlace = pando::getCurrentPlace();
+  const auto place = pando::Place{thisPlace.node, pando::anyPod, pando::anyCore};
+  auto result = pando::executeOnWait(place, +test);
+  EXPECT_TRUE(result.hasValue());
+}
+
+TEST(SimpleLock, ActualLockUnlock) {
+  auto dims = pando::getPlaceDims();
+  galois::GlobalBarrier gb;
+  EXPECT_EQ(gb.initialize(dims.node.id), pando::Status::Success);
+  galois::SimpleLock mutex;
+  EXPECT_EQ(mutex.initialize(), pando::Status::Success);
+  pando::Array<int> array;
+  EXPECT_EQ(array.initialize(10), pando::Status::Success);
+  array.fill(0);
+
+  auto func = +[](galois::GlobalBarrier gb, galois::SimpleLock mutex, pando::Array<int> array) {
+    mutex.lock();
+    for (int i = 0; i < 10; i++) {
+      if ((i + 1 + pando::getCurrentPlace().node.id) <= 10) {
+        array[i] = i + 1 + pando::getCurrentPlace().node.id;
+      } else {
+        array[i] = i - 9 + pando::getCurrentPlace().node.id;
+      }
+    }
+    mutex.unlock();
+    gb.done();
+  };
+  for (std::int16_t nodeId = 0; nodeId < dims.node.id; nodeId++) {
+    EXPECT_EQ(
+        pando::executeOn(pando::Place{pando::NodeIndex{nodeId}, pando::anyPod, pando::anyCore},
+                         func, gb, mutex, array),
+        pando::Status::Success);
+  }
+
+  EXPECT_EQ(gb.wait(), pando::Status::Success);
+  for (int i = 0; i < 10; i++) {
+    std::cout << array[i] << " ";
+  }
+  std::cout << std::endl;
+  int sum = 0;
+  for (int i = 0; i < 10; i++) {
+    sum += array[i];
+  }
+  EXPECT_EQ(sum, 55);
+
+  gb.deinitialize();
+  array.deinitialize();
+}