LibCore: Introduce REPORT_TIME() for per call timing information

This macro outputs the time taken to reach the end of the current scope
to the debug console. It also shows the average time, total cumulative
time and the total number of calls.

It is also possible to limit the amount of debug output using
`REPORT_TIME_EVERY(name, n)` to only print every `n` calls.

Libraries/LibCore/CMakeLists.txt

@@ -47,6 +47,7 @@ set(SOURCES
     MappedFile.cpp
     MimeData.cpp
     Notifier.cpp
+    ReportTime.cpp
     Resource.cpp
     ResourceImplementation.cpp
     ResourceImplementationFile.cpp

Libraries/LibCore/ReportTime.cpp

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025, Tim Ledbetter <tim.ledbetter@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "ReportTime.h"
+
+#include <AK/Format.h>
+#include <AK/HashMap.h>
+#include <AK/NumberFormat.h>
+
+namespace Core {
+
+static HashMap<ByteString, TimingInfo> g_timing_info_table;
+
+void log_timing_info(ByteString const& name, AK::Duration const& elapsed_time, u64 print_every_n_calls)
+{
+    auto& timing_info = g_timing_info_table.ensure(name);
+    timing_info.call_count++;
+    timing_info.cumulative_time_nanoseconds += elapsed_time.to_nanoseconds();
+
+    u64 average_nanoseconds = timing_info.cumulative_time_nanoseconds / timing_info.call_count;
+    if (timing_info.call_count % print_every_n_calls != 0)
+        return;
+    dbgln("[Timing info for: {}] current: {:10} | average: {:10} | total: {:10} | calls: {}",
+        name,
+        human_readable_short_time(elapsed_time),
+        human_readable_short_time(AK::Duration::from_nanoseconds(average_nanoseconds)),
+        human_readable_short_time(AK::Duration::from_nanoseconds(timing_info.cumulative_time_nanoseconds)),
+        timing_info.call_count);
+}
+
+}

Libraries/LibCore/ReportTime.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2025, Tim Ledbetter <tim.ledbetter@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/ScopeGuard.h>
+#include <AK/Time.h>
+#include <LibCore/ElapsedTimer.h>
+
+namespace Core {
+
+struct TimingInfo {
+    u64 cumulative_time_nanoseconds { 0 };
+    u64 call_count { 0 };
+};
+
+void log_timing_info(ByteString const& name, AK::Duration const& elapsed_time, u64 print_every_n_calls);
+
+#define CONCAT(a, b) a##b
+#define UNIQUE_NAME(base) CONCAT(base, __LINE__)
+
+#define REPORT_TIME_EVERY(name, print_every_n_calls)                                                \
+    auto UNIQUE_NAME(report_time_timer_) = Core::ElapsedTimer::start_new(Core::TimerType::Precise); \
+    ScopeGuard UNIQUE_NAME(report_time_guard_) = [&] {                                              \
+        auto elapsed_time = UNIQUE_NAME(report_time_timer_).elapsed_time();                         \
+        Core::log_timing_info(#name, elapsed_time, print_every_n_calls);                            \
+    };
+
+#define REPORT_TIME(name) \
+    REPORT_TIME_EVERY(name, 1)
+
+}