76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
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#pragma once
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#include <atomic>
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#include <vector>
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#include <memory>
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// message queue
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struct BroadcastMessage {
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std::vector<uint8_t> frameData;
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int excludeClientId;
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BroadcastMessage() = default;
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BroadcastMessage(std::vector<uint8_t> data, int excludeId)
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: frameData(std::move(data)), excludeClientId(excludeId) {}
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};
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class LockFreeBroadcastQueue {
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private:
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static const size_t QUEUE_SIZE = 65536; // Must be power of 2
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static const size_t QUEUE_MASK = QUEUE_SIZE - 1;
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struct alignas(64) QueueSlot {
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std::atomic<bool> ready{false};
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BroadcastMessage message;
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};
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alignas(64) std::atomic<size_t> head{0};
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alignas(64) std::atomic<size_t> tail{0};
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QueueSlot queue[QUEUE_SIZE];
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public:
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bool push(BroadcastMessage&& message) {
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const size_t currentTail = tail.load(std::memory_order_relaxed);
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const size_t nextTail = (currentTail + 1) & QUEUE_MASK;
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// queue full
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if (nextTail == head.load(std::memory_order_acquire)) {
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return false;
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}
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QueueSlot& slot = queue[currentTail];
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slot.message = std::move(message);
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slot.ready.store(true, std::memory_order_release);
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tail.store(nextTail, std::memory_order_release);
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return true;
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}
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bool pop(BroadcastMessage& message) {
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const size_t currentHead = head.load(std::memory_order_relaxed);
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// empty
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if (currentHead == tail.load(std::memory_order_acquire)) {
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return false;
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}
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QueueSlot& slot = queue[currentHead];
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if (!slot.ready.load(std::memory_order_acquire)) {
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return false;
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}
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message = std::move(slot.message);
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slot.ready.store(false, std::memory_order_release);
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head.store((currentHead + 1) & QUEUE_MASK, std::memory_order_release);
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return true;
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}
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size_t size() const {
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return (tail.load(std::memory_order_relaxed) - head.load(std::memory_order_relaxed)) & QUEUE_MASK;
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}
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bool empty() const {
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return head.load(std::memory_order_relaxed) == tail.load(std::memory_order_relaxed);
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}
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};
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