utils/ConcurrentQueue.hpp
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|---|---|---|---|
| 1 | // <ConcurrentQueue.hpp> -*- C++ -*- | ||
| 2 | |||
| 3 | #pragma once | ||
| 4 | |||
| 5 | #include "simdb/Assert.hpp" | ||
| 6 | #include <deque> | ||
| 7 | #include <functional> | ||
| 8 | #include <mutex> | ||
| 9 | |||
| 10 | namespace simdb { | ||
| 11 | |||
| 12 | /*! | ||
| 13 | * \class ConcurrentQueue<T> | ||
| 14 | * | ||
| 15 | * \brief Thread-safe wrapper around std::queue | ||
| 16 | */ | ||
| 17 | template <typename T> class ConcurrentQueue | ||
| 18 | { | ||
| 19 | public: | ||
| 20 | /// \brief Construct. | ||
| 21 | 52 | ConcurrentQueue() | |
| 22 | 52 | { | |
| 23 | // Get size() code coverage | ||
| 24 | 52 | simdb_assert(size() == 0); | |
| 25 | 52 | } | |
| 26 | |||
| 27 | /// \brief Push an item to the back of the queue. | ||
| 28 | 22683 | void push(const T& item) | |
| 29 | { | ||
| 30 | 22683 | std::lock_guard<std::mutex> guard(mutex_); | |
| 31 | 22683 | queue_.push_back(item); | |
| 32 | 22683 | } | |
| 33 | |||
| 34 | /// \brief Push an item to the back of the queue (move version). | ||
| 35 | 44702 | void emplace(T&& item) | |
| 36 | { | ||
| 37 | 44702 | std::lock_guard<std::mutex> guard(mutex_); | |
| 38 | 44702 | queue_.emplace_back(std::move(item)); | |
| 39 | 44702 | } | |
| 40 | |||
| 41 | /// \brief Construct an item on the back of the queue. | ||
| 42 | /// | ||
| 43 | /// \param args Forwarding arguments for the <T> constructor. | ||
| 44 | template <typename... Args> void emplace(Args&&... args) | ||
| 45 | { | ||
| 46 | std::lock_guard<std::mutex> guard(mutex_); | ||
| 47 | queue_.emplace_back(std::forward<Args>(args)...); | ||
| 48 | } | ||
| 49 | |||
| 50 | /// \brief Get the item at the front of the queue. | ||
| 51 | /// | ||
| 52 | /// \param item Output argument for the popped item. | ||
| 53 | /// | ||
| 54 | /// \return Returns true if successful, or false if there | ||
| 55 | /// was no data in the queue. | ||
| 56 | 105657 | bool try_pop(T& item) | |
| 57 | { | ||
| 58 | 105657 | std::lock_guard<std::mutex> guard(mutex_); | |
| 59 | 105657 | if (queue_.empty()) | |
| 60 | { | ||
| 61 | 38272 | return false; | |
| 62 | } | ||
| 63 | 67385 | std::swap(item, queue_.front()); | |
| 64 | 67385 | queue_.pop_front(); | |
| 65 | 67385 | return true; | |
| 66 | 105657 | } | |
| 67 | |||
| 68 | /// \brief Get the number of items in this queue. | ||
| 69 | 53 | size_t size() const | |
| 70 | { | ||
| 71 | 53 | std::lock_guard<std::mutex> guard(mutex_); | |
| 72 | 106 | return queue_.size(); | |
| 73 | 53 | } | |
| 74 | |||
| 75 | /// \brief Check for empty | ||
| 76 | 42869 | bool empty() const | |
| 77 | { | ||
| 78 | 42869 | std::lock_guard<std::mutex> guard(mutex_); | |
| 79 | 85738 | return queue_.empty(); | |
| 80 | 42869 | } | |
| 81 | |||
| 82 | /// \brief Invoke a callback function to peek into this queue's | ||
| 83 | /// items. This will be invoked until the callback returns TRUE | ||
| 84 | /// or until we have iterated over all queue items. | ||
| 85 | 39292 | bool snoop(const std::function<bool(const T& queue_item)>& cb) const | |
| 86 | { | ||
| 87 | 39292 | std::lock_guard<std::mutex> guard(mutex_); | |
| 88 | 110122 | for (const auto& item : queue_) | |
| 89 | { | ||
| 90 | 72592 | if (cb(item)) | |
| 91 | { | ||
| 92 | 1762 | return true; | |
| 93 | } | ||
| 94 | } | ||
| 95 | 37530 | return false; | |
| 96 | 39292 | } | |
| 97 | |||
| 98 | private: | ||
| 99 | /// Mutex for thread safety. | ||
| 100 | mutable std::mutex mutex_; | ||
| 101 | |||
| 102 | /// FIFO queue to hold the data. A deque is used to support snooping. | ||
| 103 | std::deque<T> queue_; | ||
| 104 | }; | ||
| 105 | |||
| 106 | } // namespace simdb | ||
| 107 |