Baby steps

Author: grendello

Documentation/guides/native-tracing.md

@@ -0,0 +1 @@
+# Tracing Android for .NET applications with built-in capabilities

Documentation/workflow/SystemProperties.md

@@ -171,6 +171,17 @@ categories:
     method execution timing which is written to a file named
     `methods.txt`.  `timing=bare` should be used in preference to this
     category.
+  * `native-tracing`
+    Enable built-in tracing capabilities, using default settings.
+    Tracing settings can be tuned using the [debug.mono.native-tracing](#debugmononative-tracing)
+    property.
+
+### debug.mono.native-tracing
+
+[Full documentation](../guides/native-tracing.md)
+
+Available options:
+
 
 #### Timing events format
 

src/Xamarin.Android.Build.Tasks/ManifestOverlays/Tracing.xml

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools">
   <application>
-    <receiver android:name="mono.android.app.DumpTracingData" tools:node="replace" android:exported="true">
+    <receiver android:name="mono.android.app.StopTracingAndDumpData" tools:node="replace" android:exported="true">
         <intent-filter>
-          <action android:name="mono.android.app.DUMP_TRACING_DATA"/>
+          <action android:name="mono.android.app.STOP_TRACING_AND_DUMP_DATA"/>
         </intent-filter>
       </receiver>
   </application>

src/java-runtime/java/mono/android/Runtime.java

@@ -35,7 +35,7 @@ public static native void initInternal (
 	public static native void destroyContexts (int[] contextIDs);
 	public static native void propagateUncaughtException (Thread javaThread, Throwable javaException);
 	public static native void dumpTimingData ();
-	public static native void dumpTracingData ();
+	public static native void stopTracingAndDumpData ();
 }
 
 final class XamarinUncaughtExceptionHandler implements Thread.UncaughtExceptionHandler {

src/java-runtime/java/mono/android/app/DumpTracingData.java renamed to src/java-runtime/java/mono/android/app/StopTracingAndDumpData.java

@@ -1,8 +1,8 @@
 package mono.android.app;
 
-public class DumpTracingData extends android.content.BroadcastReceiver {
+public class StopTracingAndDumpData extends android.content.BroadcastReceiver {
 	@Override
 	public void onReceive (android.content.Context context, android.content.Intent intent) {
-		mono.android.Runtime.dumpTracingData ();
+		mono.android.Runtime.stopTracingAndDumpData ();
 	}
 }

src/native/monodroid/mono_android_Runtime.h

@@ -12,6 +12,7 @@
 #include "cpp-util.hh"
 #include "xxhash.hh"
 #include "monodroid-dl.hh"
+#include "tracing.hh"
 
 #include <mono/utils/mono-counters.h>
 #include <mono/metadata/profiler.h>
@@ -214,8 +215,9 @@ namespace xamarin::android::internal
 
 		void gather_bundled_assemblies (jstring_array_wrapper &runtimeApks, size_t *out_user_assemblies_count, bool have_split_apks);
 		static bool should_register_file (const char *filename);
-		void set_trace_options ();
+		void set_mono_jit_trace_options ();
 		void set_profile_options ();
+		void initialize_native_tracing ();
 
 		void log_jit_event (MonoMethod *method, const char *event_name);
 		static void jit_begin (MonoProfiler *prof, MonoMethod *method);
@@ -261,6 +263,10 @@ namespace xamarin::android::internal
 		timing_period       jit_time;
 		FILE               *jit_log;
 		MonoProfilerHandle  profiler_handle;
+		TracingAutoStartMode tracing_auto_start_mode = TracingAutoStartMode::None;
+		TracingAutoStopMode  tracing_auto_stop_mode = TracingAutoStopMode::None;
+		size_t               tracing_start_delay_ms = 0;
+		size_t               tracing_stop_delay_ms = 0;
 
 		/*
 		 * If set, monodroid will spin in a loop until the debugger breaks the wait by

src/native/monodroid/monodroid-glue-internal.hh

@@ -1,4 +1,5 @@
 #include <array>
+#include <charconv>
 #include <cctype>
 #include <cerrno>
 #include <cstdarg>
@@ -1057,7 +1058,7 @@ MonodroidRuntime::set_debug_env_vars (void)
 #endif /* DEBUG */
 
 inline void
-MonodroidRuntime::set_trace_options (void)
+MonodroidRuntime::set_mono_jit_trace_options (void)
 {
 	dynamic_local_string<PROPERTY_VALUE_BUFFER_LEN> value;
 	if (AndroidSystem::monodroid_get_system_property (SharedConstants::DEBUG_MONO_TRACE_PROPERTY, value) == 0)
@@ -1066,6 +1067,108 @@ MonodroidRuntime::set_trace_options (void)
 	mono_jit_set_trace_options (value.get ());
 }
 
+inline void
+MonodroidRuntime::initialize_native_tracing ()
+{
+	if (!Logger::native_tracing_enabled ()) [[likely]] {
+		return;
+	}
+
+	dynamic_local_string<PROPERTY_VALUE_BUFFER_LEN> value;
+	if (AndroidSystem::monodroid_get_system_property (SharedConstants::DEBUG_MONO_NATIVE_TRACING, value) == 0 || value.empty ()) {
+		tracing_auto_start_mode = TracingAutoStartMode::Startup;
+		tracing_auto_stop_mode = TracingAutoStopMode::DelayFromStart;
+		tracing_stop_delay_ms = TracingConstants::DEFAULT_STOP_DELAY_MS;
+		return;
+	}
+
+	constexpr std::string_view param_start_mode_startup  { "start-mode=startup" };
+	constexpr std::string_view param_start_mode_delay    { "start-mode=delay" };
+	constexpr std::string_view param_start_mode_justinit { "start-mode=just-init" };
+
+	constexpr std::string_view param_stop_mode_delay     { "stop-mode=delay" };
+	constexpr std::string_view param_stop_mode_absolute_delay  { "stop-mode=absolute-delay" };
+
+	constexpr std::string_view param_start_delay         { "start-delay=" };
+	constexpr std::string_view param_stop_delay          { "stop-delay=" };
+
+	string_segment param;
+	while (value.next_token (',', param)) {
+		if (param.equal (param_start_mode_startup)) {
+			tracing_auto_start_mode = TracingAutoStartMode::Startup;
+			continue;
+		}
+
+		if (param.equal (param_start_mode_delay)) {
+			tracing_auto_start_mode = TracingAutoStartMode::Delay;
+			tracing_start_delay_ms = TracingConstants::DEFAULT_START_DELAY_MS;
+			continue;
+		}
+
+		if (param.equal (param_start_mode_justinit)) {
+			tracing_auto_start_mode = TracingAutoStartMode::JustInit;
+			continue;
+		}
+
+		if (param.equal (param_stop_mode_delay)) {
+			tracing_auto_stop_mode = TracingAutoStopMode::DelayFromStart;
+			tracing_stop_delay_ms = TracingConstants::DEFAULT_STOP_DELAY_MS;
+			continue;
+		}
+
+		if (param.equal (param_stop_mode_absolute_delay)) {
+			tracing_auto_stop_mode = TracingAutoStopMode::AbsoluteDelay;
+			tracing_stop_delay_ms = TracingConstants::DEFAULT_STOP_DELAY_MS;
+			continue;
+		}
+
+		auto convert_delay = [](string_segment const& s, size_t start, size_t default_value) {
+			if (s.length () <= start) {
+				log_warn (
+					LOG_DEFAULT,
+					"Expected value in tracing setting '%s', using the default value of %zums",
+					s.start (),
+					default_value
+				);
+				return default_value;
+			}
+
+			size_t ret{};
+			auto [ptr, errorc] = std::from_chars (s.start () + start, s.start () + s.length (), ret);
+			if (errorc == std::errc ()) {
+				return ret;
+			}
+
+			if (errorc == std::errc::invalid_argument) {
+				log_warn (
+					LOG_DEFAULT,
+					"Tracing setting value is not a decimal integer: %s.  Using the default value of %zums",
+					s.start (),
+					default_value
+				);
+			} else if (errorc == std::errc::result_out_of_range) {
+				log_warn (
+					LOG_DEFAULT,
+					"Tracing setting value exceeds the maximum allowed one (%zu): %s.  Using the default value of %zums",
+					std::numeric_limits<size_t>::max (),
+					s.start (),
+					default_value
+				);
+			}
+
+			return default_value;
+		};
+
+		if (param.starts_with (param_start_delay)) {
+			tracing_start_delay_ms = convert_delay (param, param_start_delay.length () + 1, TracingConstants::DEFAULT_START_DELAY_MS);
+		}
+
+		if (param.starts_with (param_stop_delay)) {
+			tracing_stop_delay_ms = convert_delay (param, param_stop_delay.length () + 1, TracingConstants::DEFAULT_STOP_DELAY_MS);
+		}
+	}
+}
+
 inline void
 MonodroidRuntime::set_profile_options ()
 {
@@ -1446,6 +1549,7 @@ MonodroidRuntime::Java_mono_android_Runtime_initInternal (JNIEnv *env, jclass kl
 		mono_trace_set_level_string (mono_log_level.get ());
 	}
 
+	initialize_native_tracing ();
 	setup_mono_tracing (mono_log_mask, have_log_assembly, have_log_gc);
 	install_logging_handlers ();
 
@@ -1460,7 +1564,7 @@ MonodroidRuntime::Java_mono_android_Runtime_initInternal (JNIEnv *env, jclass kl
 
 	set_profile_options ();
 
-	set_trace_options ();
+	set_mono_jit_trace_options ();
 
 #if defined (DEBUG)
 	debug.start_debugging_and_profiling ();
@@ -1635,7 +1739,7 @@ JNICALL Java_mono_android_Runtime_dumpTimingData ([[maybe_unused]] JNIEnv *env,
 }
 
 JNIEXPORT void
-JNICALL Java_mono_android_Runtime_dumpTracingData ([[maybe_unused]] JNIEnv *env, [[maybe_unused]] jclass klass)
+JNICALL Java_mono_android_Runtime_stopTracingAndDumpData ([[maybe_unused]] JNIEnv *env, [[maybe_unused]] jclass klass)
 {
 	// TODO: implement
 }

src/native/monodroid/monodroid-glue.cc

@@ -205,6 +205,11 @@ Logger::init_logging_categories (char*& mono_log_mask, char*& mono_log_level) no
 			continue;
 		}
 
+		if (param.starts_with ("native-tracing")) {
+			_native_tracing_enabled = true;
+			continue;
+		}
+
 		if (param.starts_with ("timing=fast-bare")) {
 			log_categories |= LOG_TIMING;
 			_log_timing_categories |= LogTimingCategories::FastBare;

src/native/runtime-base/logger.cc

@@ -18,6 +18,11 @@ namespace xamarin::android {
 			return _log_timing_categories;
 		}
 
+		static bool native_tracing_enabled () noexcept
+		{
+			return _native_tracing_enabled;
+		}
+
 #if defined(DEBUG)
 		static void set_debugger_log_level (const char *level) noexcept;
 
@@ -46,7 +51,8 @@ namespace xamarin::android {
 		static bool set_category (std::string_view const& name, internal::string_segment& arg, unsigned int entry, bool arg_starts_with_name = false) noexcept;
 
 	private:
-		static inline LogTimingCategories _log_timing_categories;
+		static inline LogTimingCategories _log_timing_categories = LogTimingCategories::Default;
+		static inline bool _native_tracing_enabled = false;
 #if defined(DEBUG)
 		static inline bool _got_debugger_log_level = false;
 		static inline int _debugger_log_level = 0;

src/native/runtime-base/logger.hh

@@ -61,6 +61,7 @@ namespace xamarin::android::internal
 		static inline constexpr std::string_view DEBUG_MONO_SOFT_BREAKPOINTS      { "debug.mono.soft_breakpoints" };
 		static inline constexpr std::string_view DEBUG_MONO_TRACE_PROPERTY        { "debug.mono.trace" };
 		static inline constexpr std::string_view DEBUG_MONO_WREF_PROPERTY         { "debug.mono.wref" };
+		static inline constexpr std::string_view DEBUG_MONO_NATIVE_TRACING        { "debug.mono.native-tracing" };
 
 #if __arm__
 		static constexpr std::string_view android_abi        { "armeabi_v7a" };

src/native/runtime-base/shared-constants.hh

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <cstdint>
+
+namespace xamarin::android {
+	enum class TracingAutoStartMode
+	{
+		None,
+
+		// Start tracing as soon as possible at the application startup
+		Startup,
+
+		// Start after an initial delay, counting from the application startup
+		Delay,
+
+		// At the application startup, prepare for tracing at a later point. This is to avoid
+		// unnecessary delays to load the tracing shared library and initialize everything.
+		// Tracing itself will need to be started by a p/invoke or an intent.
+		JustInit,
+	};
+
+	enum class TracingAutoStopMode
+	{
+		None,
+
+		// Stop tracing after the designated delay, counted from the moment tracing was started
+		DelayFromStart,
+
+		// Stop tracing after the designated delay, counting from application startup
+		AbsoluteDelay,
+	};
+
+	class TracingConstants
+	{
+	public:
+		static inline constexpr size_t DEFAULT_STOP_DELAY_MS = 2000; // 2s
+		static inline constexpr size_t DEFAULT_START_DELAY_MS = 0;
+	};
+}