WorkQueueThread: rework Cancel/Shutdown workflow
- Cancel doesn't shut down anymore. Allowing it to be used multiple times thoughout the life of the WorkQueue - Remove Clear, so we only have Cancel semantics - Add IsCancelling so work items can abort early if cancelling - Replace m_cancelled and m_thread.joinable() guars with m_shutdown. - Rename Flush to WaitForCompletion (As it's ambiguous if a function called flush should be blocking or not) - Add documentation
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@ -3,13 +3,13 @@
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#pragma once
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#pragma once
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#include <atomic>
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#include <condition_variable>
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#include <functional>
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#include <functional>
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#include <queue>
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#include <queue>
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#include <string>
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#include <string>
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#include <thread>
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#include <thread>
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#include "Common/Event.h"
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#include "Common/Flag.h"
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#include "Common/Thread.h"
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#include "Common/Thread.h"
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// A thread that executes the given function for every item placed into its queue.
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// A thread that executes the given function for every item placed into its queue.
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@ -26,120 +26,104 @@ public:
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Reset(std::move(function));
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Reset(std::move(function));
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}
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}
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~WorkQueueThread() { Shutdown(); }
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~WorkQueueThread() { Shutdown(); }
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// Shuts the current work thread down (if any) and starts a new thread with the given function
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// Note: Some consumers of this API push items to the queue before starting the thread.
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void Reset(std::function<void(T)> function)
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void Reset(std::function<void(T)> function)
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{
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{
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Shutdown();
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Shutdown();
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std::lock_guard lg(m_lock);
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std::lock_guard lg(m_lock);
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m_cancelled = false;
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m_shutdown = false;
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m_function = std::move(function);
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m_function = std::move(function);
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m_thread = std::thread(&WorkQueueThread::ThreadLoop, this);
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m_thread = std::thread(&WorkQueueThread::ThreadLoop, this);
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}
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}
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// Adds an item to the work queue
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template <typename... Args>
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template <typename... Args>
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void EmplaceItem(Args&&... args)
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void EmplaceItem(Args&&... args)
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{
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{
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std::lock_guard lg(m_lock);
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std::lock_guard lg(m_lock);
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if (m_shutdown)
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if (m_shutdown)
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{
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return;
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return;
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}
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m_items.emplace(std::forward<Args>(args)...);
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m_items.emplace(std::forward<Args>(args)...);
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m_idle = false;
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m_idle = false;
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m_worker_cond_var.notify_one();
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m_worker_cond_var.notify_one();
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}
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}
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// Adds an item to the work queue
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void Push(T&& item)
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void Push(T&& item)
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{
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{
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std::lock_guard lg(m_lock);
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std::lock_guard lg(m_lock);
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if (m_cancelled)
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if (m_shutdown)
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{
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return;
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return;
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}
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m_items.push(item);
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m_items.push(item);
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m_idle = false;
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m_idle = false;
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m_worker_cond_var.notify_one();
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m_worker_cond_var.notify_one();
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}
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}
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// Adds an item to the work queue
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void Push(const T& item)
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void Push(const T& item)
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{
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{
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std::lock_guard lg(m_lock);
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std::lock_guard lg(m_lock);
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if (m_cancelled)
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if (m_shutdown)
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{
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return;
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return;
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}
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m_items.push(item);
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m_items.push(item);
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m_idle = false;
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m_idle = false;
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m_worker_cond_var.notify_one();
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m_worker_cond_var.notify_one();
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}
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}
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void Clear()
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// Empties the queue
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// If the worker polls IsCanceling(), it can abort it's work when Cancelling
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void Cancel()
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{
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{
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std::lock_guard lg(m_lock);
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std::unique_lock lg(m_lock);
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if (m_shutdown)
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return;
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m_cancelling = true;
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m_items = std::queue<T>();
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m_items = std::queue<T>();
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m_worker_cond_var.notify_one();
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m_worker_cond_var.notify_one();
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}
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}
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void Cancel()
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// Tells the worker to shut down when it's queue is empty
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// Blocks until the worker thread exits.
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// If cancel is true, will Cancel before before telling the worker to exit
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void Shutdown(bool cancel = false)
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{
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{
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if (!m_thread.joinable())
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{
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return;
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}
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{
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{
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std::unique_lock lg(m_lock);
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std::unique_lock lg(m_lock);
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m_items = std::queue<T>();
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if (m_shutdown || !m_thread.joinable())
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m_cancelled = true;
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return;
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if (cancel)
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{
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m_cancelling = true;
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m_items = std::queue<T>();
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}
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m_shutdown = true;
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m_shutdown = true;
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m_worker_cond_var.notify_one();
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m_worker_cond_var.notify_one();
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}
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}
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m_thread.join();
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m_thread.join();
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}
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}
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void Shutdown()
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// Blocks until all items in the queue have been processed (or cancelled)
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void WaitForCompletion()
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{
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{
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if (!m_thread.joinable())
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{
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return;
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}
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{
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std::unique_lock lg(m_lock);
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m_shutdown = true;
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m_worker_cond_var.notify_one();
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}
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m_thread.join();
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}
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// Doesn't return until the most recent function invocation has finished.
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void ClearAndFlush()
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{
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if (!m_thread.joinable())
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{
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return;
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}
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std::unique_lock lg(m_lock);
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std::unique_lock lg(m_lock);
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m_items = std::queue<T>();
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if (m_idle) // Only check m_idle, we want this to work even another thread called Shutdown
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m_wait_cond_var.wait(lg, [&] {
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return m_idle;
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});
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}
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// Doesn't return until the most recent function invocation has finished.
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void Flush()
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{
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if (!m_thread.joinable())
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{
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return;
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return;
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}
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std::unique_lock lg(m_lock);
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m_wait_cond_var.wait(lg, [&] { return m_idle; });
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m_wait_cond_var.wait(lg, [&] {
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return m_idle;
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});
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}
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}
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// For the worker to check if it should abort it's work early.
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bool IsCancelling() const { return m_cancelling.load(); }
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private:
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private:
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void ThreadLoop()
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void ThreadLoop()
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{
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{
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@ -151,14 +135,13 @@ private:
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if (m_items.empty())
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if (m_items.empty())
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{
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{
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m_idle = true;
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m_idle = true;
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m_cancelling = false;
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m_wait_cond_var.notify_all();
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m_wait_cond_var.notify_all();
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m_worker_cond_var.wait(lg, [&] {
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m_worker_cond_var.wait(
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return m_shutdown || !m_items.empty();
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lg, [&] { return m_shutdown || m_cancelling.load() || !m_items.empty(); });
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});
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if (m_shutdown)
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if (m_shutdown)
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{
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break;
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break;
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}
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continue;
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continue;
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}
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}
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T item{std::move(m_items.front())};
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T item{std::move(m_items.front())};
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@ -176,9 +159,9 @@ private:
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std::queue<T> m_items;
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std::queue<T> m_items;
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std::condition_variable m_wait_cond_var;
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std::condition_variable m_wait_cond_var;
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std::condition_variable m_worker_cond_var;
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std::condition_variable m_worker_cond_var;
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std::atomic<bool> m_cancelling = false;
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bool m_idle = true;
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bool m_idle = true;
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bool m_shutdown = false;
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bool m_shutdown = false;
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bool m_cancelled = false;
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};
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};
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} // namespace Common
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} // namespace Common
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@ -37,7 +37,7 @@ GameTracker::GameTracker(QObject* parent) : QFileSystemWatcher(parent)
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connect(qApp, &QApplication::aboutToQuit, this, [this] {
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connect(qApp, &QApplication::aboutToQuit, this, [this] {
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m_processing_halted = true;
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m_processing_halted = true;
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m_load_thread.Cancel();
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m_load_thread.Shutdown(true);
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});
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});
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connect(this, &QFileSystemWatcher::directoryChanged, this, &GameTracker::UpdateDirectory);
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connect(this, &QFileSystemWatcher::directoryChanged, this, &GameTracker::UpdateDirectory);
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connect(this, &QFileSystemWatcher::fileChanged, this, &GameTracker::UpdateFile);
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connect(this, &QFileSystemWatcher::fileChanged, this, &GameTracker::UpdateFile);
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@ -203,7 +203,7 @@ void GameTracker::RemoveDirectory(const QString& dir)
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void GameTracker::RefreshAll()
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void GameTracker::RefreshAll()
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{
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{
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m_processing_halted = true;
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m_processing_halted = true;
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m_load_thread.Clear();
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m_load_thread.Cancel();
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m_load_thread.EmplaceItem(Command{CommandType::ResumeProcessing, {}});
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m_load_thread.EmplaceItem(Command{CommandType::ResumeProcessing, {}});
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if (m_needs_purge)
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if (m_needs_purge)
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