[Feature] Added some concurrent utilities, GenericThreadPool, etc.

.gitignore

@@ -8,5 +8,7 @@ common/base/Base.h.gch
 CMakeCache.txt
 Makefile
 cmake_install.cmake
+CTestTestfile.cmake
 CMakeFiles/
+Testing/
 

CMakeLists.txt

@@ -6,6 +6,8 @@ set(CMAKE_SKIP_RPATH TRUE)
 
 set(CMAKE_VERBOSE_MAKEFILE TRUE)
 
+enable_testing()
+
 if (!CMAKE_CXX_COMPILER)
     message(FATAL_ERROR "No C++ compiler found")
 endif()

common/CMakeLists.txt

@@ -1,11 +1,12 @@
 add_custom_target(
     common ALL
-    DEPENDS base_obj time proc network fs
+    DEPENDS base_obj time proc network fs concurrent
 )
 
 add_subdirectory(base)
 add_subdirectory(time)
 add_subdirectory(proc)
 add_subdirectory(network)
 add_subdirectory(fs)
+add_subdirectory(concurrent)
 

common/concurrent/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_library(concurrent_obj OBJECT thread/NamedThread.cpp
+        thread/GenericWorker.cpp
+        thread/GenericThreadPool.cpp
+        sync/Barrier.cpp
+        sync/Latch.cpp
+)
+add_subdirectory(test)

common/concurrent/sync/Barrier.cpp

@@ -0,0 +1,37 @@
+/* Copyright (c) 2018 - present, VE Software Inc. All rights reserved
+ *
+ * This source code is licensed under Apache 2.0 License
+ *  (found in the LICENSE.Apache file in the root directory)
+ */
+#include "concurrent/sync/Barrier.h"
+
+
+namespace vesoft {
+namespace concurrent {
+
+Barrier::Barrier(size_t counter, std::function<void()> completion) {
+    if (counter == 0) {
+        throw std::invalid_argument("Zero barrier counter");
+    }
+    completion_ = std::move(completion);
+    counter_ = counter;
+    ages_ = counter_;
+}
+
+void Barrier::wait() {
+    std::unique_lock<std::mutex> unique(lock_);
+    if (--ages_ == 0) {
+        ages_ = counter_;
+        ++generation_;
+        if (completion_ != nullptr) {
+            completion_();
+        }
+        cond_.notify_all();
+    } else {
+        auto current = generation_;
+        cond_.wait(unique, [=] () { return current != generation_; });
+    }
+}
+
+}   // namespace concurrent
+}   // namespace vesoft

common/concurrent/sync/Barrier.h

@@ -0,0 +1,54 @@
+/* Copyright (c) 2018 - present, VE Software Inc. All rights reserved
+ *
+ * This source code is licensed under Apache 2.0 License
+ *  (found in the LICENSE.Apache file in the root directory)
+ */
+#ifndef COMMON_CONCURRENT_SYNC_BARRIER_H_
+#define COMMON_CONCURRENT_SYNC_BARRIER_H_
+#include <mutex>
+#include <condition_variable>
+#include <functional>
+
+/**
+ * Like `Latch', `Barrier' is a synchronization object, except that
+ * `Barrier' is reusable.
+ * Besides, `Barrier' features with an optional callable object,
+ * which would be invoked at the completion phase, i.e. synchronization point,
+ * by the last participating thread entering `wait'.
+ */
+
+namespace vesoft {
+namespace concurrent {
+
+class Barrier {
+public:
+    explicit Barrier(size_t counter, std::function<void()> completion = nullptr);
+    Barrier() = delete;
+    ~Barrier() = default;
+    Barrier(const Barrier&) = delete;
+    Barrier(Barrier&&) = delete;
+    Barrier& operator=(const Barrier&) = delete;
+    Barrier& operator=(Barrier&&) = delete;
+    /**
+     * Decrements the internal counter.
+     * If the counter reaches zero, the completion callback would be invoked if present,
+     * then all preceding blocked threads would be woken up, with the internal counter
+     * reset to the original value.
+     * Otherwise, the calling thread would be blocked to wait for
+     * other participants' arrival.
+     */
+    void wait();
+
+private:
+    std::function<void()>   completion_{nullptr};
+    size_t                  counter_{0};
+    size_t                  ages_{0};
+    size_t                  generation_{0};
+    std::mutex              lock_;
+    std::condition_variable cond_;
+};
+
+}   // namespace concurrent
+}   // namespace vesoft
+
+#endif  // COMMON_CONCURRENT_SYNC_BARRIER_H_

common/concurrent/sync/Latch.cpp

@@ -0,0 +1,50 @@
+/* Copyright (c) 2018 - present, VE Software Inc. All rights reserved
+ *
+ * This source code is licensed under Apache 2.0 License
+ *  (found in the LICENSE.Apache file in the root directory)
+ */
+#include "concurrent/sync/Latch.h"
+
+namespace vesoft {
+namespace concurrent {
+
+Latch::Latch(size_t counter) {
+    if (counter == 0) {
+        throw std::invalid_argument("Zero Latch counter");
+    }
+    counter_ = counter;
+}
+
+void Latch::down() {
+    std::unique_lock<std::mutex>  unique(lock_);
+    if (counter_ == 0) {
+        throw std::runtime_error("Count down on zero Latch");
+    }
+    if (--counter_ == 0) {
+        cond_.notify_all();
+    }
+}
+
+void Latch::downWait() {
+    std::unique_lock<std::mutex> unique(lock_);
+    if (counter_ == 0) {
+        throw std::runtime_error("Count down on zero Latch");
+    }
+    if (--counter_ == 0) {
+        cond_.notify_all();
+        return;
+    }
+    cond_.wait(unique, [this] () { return counter_ == 0; });
+}
+
+void Latch::wait() {
+    std::unique_lock<std::mutex> unique(lock_);
+    cond_.wait(unique, [this] () { return counter_ == 0; });
+}
+
+bool Latch::isReady() {
+    return counter_ == 0;
+}
+
+}   // namespace concurrent
+}   // namespace vesoft

common/concurrent/sync/Latch.h

@@ -0,0 +1,67 @@
+/* Copyright (c) 2018 - present, VE Software Inc. All rights reserved
+ *
+ * This source code is licensed under Apache 2.0 License
+ *  (found in the LICENSE.Apache file in the root directory)
+ */
+#ifndef COMMON_CONCURRENT_SYNC_LATCH_H_
+#define COMMON_CONCURRENT_SYNC_LATCH_H_
+#include <mutex>
+#include <condition_variable>
+/**
+ * Latch is an one-shot synchronization object.
+ * It provides synchronization point for multiple threads.
+ * See shared/concurrent/test/LatchTest.cpp for use scenarios.
+ */
+
+namespace vesoft {
+namespace concurrent {
+
+class Latch {
+public:
+    /**
+     * @counter:  initial counter,
+     *            typically number of participating threads.
+     * Throws `std::invalid_argument' if counter is zero.
+     */
+    explicit Latch(size_t counter);
+    Latch(const Latch&) = delete;
+    Latch(Latch&&) = delete;
+    ~Latch() = default;
+    Latch& operator=(const Latch&) = delete;
+    Latch& operator=(Latch&&) = delete;
+    /**
+     * Decrements the internal counter by one.
+     * If the counter reaches 0, all blocking(in `wait')
+     * threads will be given the green light.
+     * Throws `std::runtime_error' if counter already zeroed.
+     */
+    void down();
+    /**
+     * Decrements the internal counter by one.
+     * If the counter reaches 0, returns immediately,
+     * and all blocking threads will be woken up.
+     * Otherwise, the calling thread blocks until being woken up.
+     * Throws `std::runtime_error' if counter already zeroed.
+     */
+    void downWait();
+    /**
+     * Blocks if internal counter not zero.
+     * Otherwise, returns immediately.
+     */
+    void wait();
+    /**
+     * Returns true if internal counter already zeroed.
+     * Otherwise, returns false.
+     */
+    bool isReady();
+
+private:
+    volatile size_t         counter_{0};
+    std::mutex              lock_;
+    std::condition_variable cond_;
+};
+
+}   // namespace concurrent
+}   // namespace vesoft
+
+#endif  // COMMON_CONCURRENT_SYNC_LATCH_H_

common/concurrent/test/BarrierTest.cpp

@@ -0,0 +1,96 @@
+/* Copyright (c) 2018 - present, VE Software Inc. All rights reserved
+ *
+ * This source code is licensed under Apache 2.0 License
+ *  (found in the LICENSE.Apache file in the root directory)
+ */
+#include <gtest/gtest.h>
+#include <cstdlib>
+#include <thread>
+#include <mutex>
+#include <atomic>
+#include "concurrent/sync/Barrier.h"
+#include "concurrent/thread/GenericThreadPool.h"
+
+namespace vesoft {
+namespace concurrent {
+
+TEST(BarrierTest, BasicTest) {
+    // test for invalid initial counter
+    {
+        ASSERT_THROW({Barrier barrier(0UL);}, std::invalid_argument);
+    }
+    // test for single-thread normal case
+    {
+        Barrier barrier(1UL);
+        barrier.wait();
+        ASSERT_TRUE(true);
+    }
+    // test for multiple-thread normal case
+    {
+        Barrier barrier(2UL);
+        std::atomic<size_t> counter{0};
+        auto cb = [&] () {
+            barrier.wait();
+            ++counter;
+        };
+        std::thread thread(cb);
+        usleep(1000);
+        ASSERT_EQ(0UL, counter.load());
+        barrier.wait();
+        thread.join();
+        ASSERT_EQ(1UL, counter.load());
+    }
+    // test for multiple-thread completion
+    {
+        std::atomic<size_t> counter{0};
+        auto completion = [&] () {
+            ++counter;
+            ++counter;
+        };
+        Barrier barrier(2UL, completion);
+
+        auto cb = [&] () {
+            barrier.wait();
+            ++counter;
+        };
+
+        std::thread thread(cb);
+        usleep(1000);
+        ASSERT_EQ(0UL, counter.load());
+        barrier.wait();
+        ASSERT_GE(counter.load(), 2UL);
+        thread.join();
+        ASSERT_EQ(3UL, counter.load());
+    }
+}
+
+TEST(BarrierTest, ConsecutiveTest) {
+    std::atomic<size_t> counter{0};
+    constexpr auto N = 64UL;
+    constexpr auto iters = 100UL;
+    auto completion = [&] () {
+        // At the completion phase, `counter' should be multiple to `N'.
+        ASSERT_EQ(0UL, counter.load() % N);
+    };
+
+    Barrier barrier(N, completion);
+    auto cb = [&] () {
+        auto i = iters;
+        while (i-- != 0) {
+            ++counter;
+            barrier.wait();
+        }
+    };
+
+    std::vector<std::thread> threads;
+    for (auto i = 0UL; i < N; i++) {
+        threads.emplace_back(cb);
+    }
+    for (auto &thread : threads) {
+        thread.join();
+    }
+    ASSERT_EQ(0UL, counter.load() % N);
+}
+
+}   // namespace concurrent
+}   // namespace vesoft

common/concurrent/test/CMakeLists.txt

@@ -0,0 +1,9 @@
+add_executable(concurrent_test ThreadTest.cpp
+        GenericWorkerTest.cpp
+        GenericThreadPoolTest.cpp
+        ThreadLocalPtrTest.cpp
+        $<TARGET_OBJECTS:concurrent_obj>
+        $<TARGET_OBJECTS:time_obj>
+)
+target_link_libraries(concurrent_test ev gtest gtest_main pthread)
+add_test(NAME concurrent_test COMMAND concurrent_test)