logging: Make use of bounded queue

src/common/CMakeLists.txt

@@ -57,6 +57,7 @@ add_library(citra_common STATIC
     detached_tasks.h
     bit_field.h
     bit_set.h
+    bounded_threadsafe_queue.h
     cityhash.cpp
     cityhash.h
     color.h

src/common/bounded_threadsafe_queue.h

@@ -0,0 +1,250 @@
+// Copyright 2023 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+#include <condition_variable>
+#include <cstddef>
+#include <mutex>
+#include <new>
+
+#include "common/polyfill_thread.h"
+
+namespace Common {
+
+namespace detail {
+constexpr size_t DefaultCapacity = 0x1000;
+} // namespace detail
+
+template <typename T, size_t Capacity = detail::DefaultCapacity>
+class SPSCQueue {
+    static_assert((Capacity & (Capacity - 1)) == 0, "Capacity must be a power of two.");
+
+public:
+    template <typename... Args>
+    bool TryEmplace(Args&&... args) {
+        return Emplace<PushMode::Try>(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    void EmplaceWait(Args&&... args) {
+        Emplace<PushMode::Wait>(std::forward<Args>(args)...);
+    }
+
+    bool TryPop(T& t) {
+        return Pop<PopMode::Try>(t);
+    }
+
+    void PopWait(T& t) {
+        Pop<PopMode::Wait>(t);
+    }
+
+    void PopWait(T& t, std::stop_token stop_token) {
+        Pop<PopMode::WaitWithStopToken>(t, stop_token);
+    }
+
+    T PopWait() {
+        T t;
+        Pop<PopMode::Wait>(t);
+        return t;
+    }
+
+    T PopWait(std::stop_token stop_token) {
+        T t;
+        Pop<PopMode::WaitWithStopToken>(t, stop_token);
+        return t;
+    }
+
+private:
+    enum class PushMode {
+        Try,
+        Wait,
+        Count,
+    };
+
+    enum class PopMode {
+        Try,
+        Wait,
+        WaitWithStopToken,
+        Count,
+    };
+
+    template <PushMode Mode, typename... Args>
+    bool Emplace(Args&&... args) {
+        const size_t write_index = m_write_index.load(std::memory_order::relaxed);
+
+        if constexpr (Mode == PushMode::Try) {
+            // Check if we have free slots to write to.
+            if ((write_index - m_read_index.load(std::memory_order::acquire)) == Capacity) {
+                return false;
+            }
+        } else if constexpr (Mode == PushMode::Wait) {
+            // Wait until we have free slots to write to.
+            std::unique_lock lock{producer_cv_mutex};
+            producer_cv.wait(lock, [this, write_index] {
+                return (write_index - m_read_index.load(std::memory_order::acquire)) < Capacity;
+            });
+        } else {
+            static_assert(Mode < PushMode::Count, "Invalid PushMode.");
+        }
+
+        // Determine the position to write to.
+        const size_t pos = write_index % Capacity;
+
+        // Emplace into the queue.
+        std::construct_at(std::addressof(m_data[pos]), std::forward<Args>(args)...);
+
+        // Increment the write index.
+        ++m_write_index;
+
+        // Notify the consumer that we have pushed into the queue.
+        std::scoped_lock lock{consumer_cv_mutex};
+        consumer_cv.notify_one();
+
+        return true;
+    }
+
+    template <PopMode Mode>
+    bool Pop(T& t, [[maybe_unused]] std::stop_token stop_token = {}) {
+        const size_t read_index = m_read_index.load(std::memory_order::relaxed);
+
+        if constexpr (Mode == PopMode::Try) {
+            // Check if the queue is empty.
+            if (read_index == m_write_index.load(std::memory_order::acquire)) {
+                return false;
+            }
+        } else if constexpr (Mode == PopMode::Wait) {
+            // Wait until the queue is not empty.
+            std::unique_lock lock{consumer_cv_mutex};
+            consumer_cv.wait(lock, [this, read_index] {
+                return read_index != m_write_index.load(std::memory_order::acquire);
+            });
+        } else if constexpr (Mode == PopMode::WaitWithStopToken) {
+            // Wait until the queue is not empty.
+            std::unique_lock lock{consumer_cv_mutex};
+            Common::CondvarWait(consumer_cv, lock, stop_token, [this, read_index] {
+                return read_index != m_write_index.load(std::memory_order::acquire);
+            });
+            if (stop_token.stop_requested()) {
+                return false;
+            }
+        } else {
+            static_assert(Mode < PopMode::Count, "Invalid PopMode.");
+        }
+
+        // Determine the position to read from.
+        const size_t pos = read_index % Capacity;
+
+        // Pop the data off the queue, moving it.
+        t = std::move(m_data[pos]);
+
+        // Increment the read index.
+        ++m_read_index;
+
+        // Notify the producer that we have popped off the queue.
+        std::scoped_lock lock{producer_cv_mutex};
+        producer_cv.notify_one();
+
+        return true;
+    }
+
+    alignas(128) std::atomic_size_t m_read_index{0};
+    alignas(128) std::atomic_size_t m_write_index{0};
+
+    std::array<T, Capacity> m_data;
+
+    std::condition_variable_any producer_cv;
+    std::mutex producer_cv_mutex;
+    std::condition_variable_any consumer_cv;
+    std::mutex consumer_cv_mutex;
+};
+
+template <typename T, size_t Capacity = detail::DefaultCapacity>
+class MPSCQueue {
+public:
+    template <typename... Args>
+    bool TryEmplace(Args&&... args) {
+        std::scoped_lock lock{write_mutex};
+        return spsc_queue.TryEmplace(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    void EmplaceWait(Args&&... args) {
+        std::scoped_lock lock{write_mutex};
+        spsc_queue.EmplaceWait(std::forward<Args>(args)...);
+    }
+
+    bool TryPop(T& t) {
+        return spsc_queue.TryPop(t);
+    }
+
+    void PopWait(T& t) {
+        spsc_queue.PopWait(t);
+    }
+
+    void PopWait(T& t, std::stop_token stop_token) {
+        spsc_queue.PopWait(t, stop_token);
+    }
+
+    T PopWait() {
+        return spsc_queue.PopWait();
+    }
+
+    T PopWait(std::stop_token stop_token) {
+        return spsc_queue.PopWait(stop_token);
+    }
+
+private:
+    SPSCQueue<T, Capacity> spsc_queue;
+    std::mutex write_mutex;
+};
+
+template <typename T, size_t Capacity = detail::DefaultCapacity>
+class MPMCQueue {
+public:
+    template <typename... Args>
+    bool TryEmplace(Args&&... args) {
+        std::scoped_lock lock{write_mutex};
+        return spsc_queue.TryEmplace(std::forward<Args>(args)...);
+    }
+
+    template <typename... Args>
+    void EmplaceWait(Args&&... args) {
+        std::scoped_lock lock{write_mutex};
+        spsc_queue.EmplaceWait(std::forward<Args>(args)...);
+    }
+
+    bool TryPop(T& t) {
+        std::scoped_lock lock{read_mutex};
+        return spsc_queue.TryPop(t);
+    }
+
+    void PopWait(T& t) {
+        std::scoped_lock lock{read_mutex};
+        spsc_queue.PopWait(t);
+    }
+
+    void PopWait(T& t, std::stop_token stop_token) {
+        std::scoped_lock lock{read_mutex};
+        spsc_queue.PopWait(t, stop_token);
+    }
+
+    T PopWait() {
+        std::scoped_lock lock{read_mutex};
+        return spsc_queue.PopWait();
+    }
+
+    T PopWait(std::stop_token stop_token) {
+        std::scoped_lock lock{read_mutex};
+        return spsc_queue.PopWait(stop_token);
+    }
+
+private:
+    SPSCQueue<T, Capacity> spsc_queue;
+    std::mutex write_mutex;
+    std::mutex read_mutex;
+};
+
+} // namespace Common

src/common/logging/backend.cpp

@@ -21,6 +21,7 @@
 #define CITRA_LINUX_GCC_BACKTRACE
 #endif
 
+#include "common/bounded_threadsafe_queue.h"
 #include "common/common_paths.h"
 #include "common/file_util.h"
 #include "common/literals.h"
@@ -32,7 +33,6 @@
 #include "common/settings.h"
 #include "common/string_util.h"
 #include "common/thread.h"
-#include "common/threadsafe_queue.h"
 
 namespace Common::Log {
 
@@ -237,11 +237,11 @@ public:
 
     void PushEntry(Class log_class, Level log_level, const char* filename, unsigned int line_num,
                    const char* function, std::string message) {
-        if (!filter.CheckMessage(log_class, log_level))
+        if (!filter.CheckMessage(log_class, log_level)) {
             return;
-        const Entry& entry =
-            CreateEntry(log_class, log_level, filename, line_num, function, std::move(message));
-        message_queue.Push(entry);
+        }
+        message_queue.EmplaceWait(
+            CreateEntry(log_class, log_level, filename, line_num, function, std::move(message)));
     }
 
 private:
@@ -317,7 +317,7 @@ private:
                 ForEachBackend([&entry](Backend& backend) { backend.Write(entry); });
             };
             while (!stop_token.stop_requested()) {
-                entry = message_queue.PopWait(stop_token);
+                message_queue.PopWait(entry, stop_token);
                 if (entry.filename != nullptr) {
                     write_logs();
                 }
@@ -325,7 +325,7 @@ private:
             // Drain the logging queue. Only writes out up to MAX_LOGS_TO_WRITE to prevent a
             // case where a system is repeatedly spamming logs even on close.
             int max_logs_to_write = filter.IsDebug() ? INT_MAX : 100;
-            while (max_logs_to_write-- && message_queue.Pop(entry)) {
+            while (max_logs_to_write-- && message_queue.TryPop(entry)) {
                 write_logs();
             }
         });
@@ -395,7 +395,7 @@ private:
     ColorConsoleBackend color_console_backend{};
     FileBackend file_backend;
 
-    MPSCQueue<Entry, true> message_queue{};
+    MPSCQueue<Entry> message_queue{};
     std::chrono::steady_clock::time_point time_origin{std::chrono::steady_clock::now()};
     std::jthread backend_thread;