New logging system

src/common/logging/backend.h

@@ -0,0 +1,134 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <cstdarg>
+#include <memory>
+#include <vector>
+
+#include "common/concurrent_ring_buffer.h"
+
+#include "common/logging/log.h"
+
+namespace Log {
+
+/**
+ * A log entry. Log entries are store in a structured format to permit more varied output
+ * formatting on different frontends, as well as facilitating filtering and aggregation.
+ */
+struct Entry {
+    std::chrono::microseconds timestamp;
+    Class log_class;
+    Level log_level;
+    std::string location;
+    std::string message;
+
+    Entry() = default;
+
+    // TODO(yuriks) Use defaulted move constructors once MSVC supports them
+#define MOVE(member) member(std::move(o.member))
+    Entry(Entry&& o)
+        : MOVE(timestamp), MOVE(log_class), MOVE(log_level),
+        MOVE(location), MOVE(message)
+    {}
+#undef MOVE
+
+    Entry& operator=(const Entry&& o) {
+#define MOVE(member) member = std::move(o.member)
+        MOVE(timestamp);
+        MOVE(log_class);
+        MOVE(log_level);
+        MOVE(location);
+        MOVE(message);
+#undef MOVE
+        return *this;
+    }
+};
+
+struct ClassInfo {
+    Class log_class;
+
+    /**
+        * Total number of (direct or indirect) sub classes this class has. If any, they follow in
+        * sequence after this class in the class list.
+        */
+    unsigned int num_children = 0;
+
+    ClassInfo(Class log_class) : log_class(log_class) {}
+};
+
+/**
+ * Logging management class. This class has the dual purpose of acting as an exchange point between
+ * the logging clients and the log outputter, as well as containing reflection info about available
+ * log classes.
+ */
+class Logger {
+private:
+    using Buffer = Common::ConcurrentRingBuffer<Entry, 16 * 1024 / sizeof(Entry)>;
+
+public:
+    static const size_t QUEUE_CLOSED = Buffer::QUEUE_CLOSED;
+
+    Logger();
+
+    /**
+     * Returns a list of all vector classes and subclasses. The sequence returned is a pre-order of
+     * classes and subclasses, which together with the `num_children` field in ClassInfo, allows
+     * you to recover the hierarchy.
+     */
+    const std::vector<ClassInfo>& GetClasses() const { return all_classes; }
+
+    /**
+     * Returns the name of the passed log class as a C-string. Subclasses are separated by periods
+     * instead of underscores as in the enumeration.
+     */
+    static const char* GetLogClassName(Class log_class);
+
+    /**
+     * Returns the name of the passed log level as a C-string.
+     */
+    static const char* GetLevelName(Level log_level);
+
+    /**
+     * Appends a messages to the log buffer.
+     * @note This function is thread safe.
+     */
+    void LogMessage(Entry entry);
+
+    /**
+     * Retrieves a batch of messages from the log buffer, blocking until they are available.
+     * @note This function is thread safe.
+     *
+     * @param out_buffer Destination buffer that will receive the log entries.
+     * @param buffer_len The maximum size of `out_buffer`.
+     * @return The number of entries stored. In case the logger is shutting down, `QUEUE_CLOSED` is
+     *         returned, no entries are stored and the logger should shutdown.
+     */
+    size_t GetEntries(Entry* out_buffer, size_t buffer_len);
+
+    /**
+     * Initiates a shutdown of the logger. This will indicate to log output clients that they
+     * should shutdown.
+     */
+    void Close() { ring_buffer.Close(); }
+
+    /**
+     * Returns true if Close() has already been called on the Logger.
+     */
+    bool IsClosed() const { return ring_buffer.IsClosed(); }
+
+private:
+    Buffer ring_buffer;
+    std::vector<ClassInfo> all_classes;
+};
+
+/// Creates a log entry by formatting the given source location, and message.
+Entry CreateEntry(Class log_class, Level log_level,
+                        const char* filename, unsigned int line_nr, const char* function,
+                        const char* format, va_list args);
+/// Initializes the default Logger.
+std::shared_ptr<Logger> InitGlobalLogger();
+
+}