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[Microsoft.Android.Runtime.NativeAOT] Parse debug.dotnet.log (#9824)
Context: https://github.com/dotnet/java-interop/blob/9dea87dc1f3052ed0f9499c9858b27c83e7d139e/samples/Hello-NativeAOTFromAndroid/README.md The NativeAOT sample and related `Microsoft.Android.Runtime.NativeAOT` assembly is based in part on the `Hello-NativeAOTFromAndroid` sample in dotnet/java-interop, which contains this comment about Logging: > The (very!) extensive logging around JNI Global and Local > references mean that this sample should not be used as-is for > startup timing comparison. …because `adb logcat` is absolutely *spammed* by LREF and GREF logs. The "solution" in .NET for Android "proper" is to use the `debug.mono.log` system property to control logging. By default, LREF and GREF logs are disabled, but can be enabled by setting the `debug.mono.log` system property property: adb shell setprop debug.mono.log gref # only grefs adb shell setprop debug.mono.log lref,gref # lrefs & grefs adb shell setprop debug.mono.log all # EVERYTHING Begin plumbing similar support for a new `debug.dotnet.log` system property into `JavaInteropRuntime` via a new `DiagnosticSettings` type. This allows us to e.g. have LREF and GREF logging *disabled by default*, allowing for (somewhat) more representative startup timing comparisons, while allowing these logs to be enabled when needed. adb shell setprop debug.dotnet.log gref # only grefs adb shell setprop debug.dotnet.log lref,gref # only grefs adb shell setprop debug.dotnet.log lref,gref # both, right now Additionally, `=PATH` can be appended to redirect gref or lref logs to the file `PATH`. Note that `PATH` must be writable by the app, and that the value of `debug.dotnet.log` must be shorter than 92 bytes: adb shell mkdir -p /sdcard/Documents/jonp adb shell chmod 777 /sdcard/Documents/jonp adb shell setprop debug.dotnet.log gref=/sdcard/Documents/jonp/jni.txt,lref=/sdcard/Documents/jonp/jni.txt Note that in the above example on a Pixel 8 with Android 15, `/sdcard/Documents/jonp/jni.txt` can only be written to *once*; subsequent attempts to write to the file will error out, so we'll fallback to writing to `adb logcat`: E NativeAot: Failed to open log file `/sdcard/Documents/jonp/jni.txt`: System.UnauthorizedAccessException: UnauthorizedAccess_IODenied_Path, /sdcard/Documents/jonp/jni.txt E NativeAot: ---> System.IO.IOException: Permission denied … D NativeAot:LREF: +l+ lrefc 1 handle 0x723ff2501d/L from thread ''(1) …
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‎src/Microsoft.Android.Runtime.NativeAOT/Android.Runtime.NativeAOT/DiagnosticSettings.cs

+136
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,136 @@
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using System.IO;
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using System.Text;
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using System.Runtime.InteropServices;
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using Java.Interop;
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namespace Microsoft.Android.Runtime;
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struct DiagnosticSettings {
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public bool LogJniLocalReferences;
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private string? LrefPath;
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public bool LogJniGlobalReferences;
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private string? GrefPath;
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private TextWriter? GrefLrefLog;
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public TextWriter? GrefLog {
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get {
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if (!LogJniGlobalReferences) {
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return null;
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}
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return ((LrefPath != null && LrefPath == GrefPath)
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? GrefLrefLog ??= CreateWriter (LrefPath)
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: null)
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??
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((GrefPath != null)
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? CreateWriter (GrefPath)
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: null)
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??
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new LogcatTextWriter (AndroidLogLevel.Debug, "NativeAot:GREF");
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}
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}
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public TextWriter? LrefLog {
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get {
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if (!LogJniLocalReferences) {
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return null;
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}
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return ((LrefPath != null && LrefPath == GrefPath)
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? GrefLrefLog ??= CreateWriter (LrefPath)
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: null)
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??
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((LrefPath != null)
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? CreateWriter (LrefPath)
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: null)
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??
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new LogcatTextWriter (AndroidLogLevel.Debug, "NativeAot:LREF");
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}
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}
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TextWriter? CreateWriter (string path)
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{
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try {
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return File.CreateText (path);
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}
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catch (Exception e) {
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AndroidLog.Print (AndroidLogLevel.Error, "NativeAot", $"Failed to open log file `{path}`: {e}");
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return null;
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}
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}
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public void AddDebugDotnetLog ()
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{
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Span<byte> value = stackalloc byte [RuntimeNativeMethods.PROP_VALUE_MAX];
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if (!RuntimeNativeMethods.TryGetSystemProperty ("debug.dotnet.log"u8, ref value)) {
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return;
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}
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AddParse (value);
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}
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void AddParse (ReadOnlySpan<byte> value)
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{
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while (TryGetNextValue (ref value, out var v)) {
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if (v.SequenceEqual ("lref"u8)) {
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LogJniLocalReferences = true;
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}
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else if (v.StartsWith ("lref="u8)) {
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LogJniLocalReferences = true;
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var path = v.Slice ("lref=".Length);
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LrefPath = Encoding.UTF8.GetString (path);
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}
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else if (v.SequenceEqual ("gref"u8)) {
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LogJniGlobalReferences = true;
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}
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else if (v.StartsWith ("gref="u8)) {
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LogJniGlobalReferences = true;
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var path = v.Slice ("gref=".Length);
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GrefPath = Encoding.UTF8.GetString (path);
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}
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else if (v.SequenceEqual ("all"u8)) {
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LogJniLocalReferences = true;
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LogJniGlobalReferences = true;
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}
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}
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bool TryGetNextValue (ref ReadOnlySpan<byte> value, out ReadOnlySpan<byte> next)
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{
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if (value.Length == 0) {
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next = default;
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return false;
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}
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int c = value.IndexOf ((byte) ',');
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if (c >= 0) {
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next = value.Slice (0, c);
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value = value.Slice (c + 1);
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}
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else {
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next = value;
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value = default;
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}
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return true;
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}
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}
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}
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static partial class RuntimeNativeMethods {
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[LibraryImport ("c", EntryPoint="__system_property_get")]
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static private partial int system_property_get (ReadOnlySpan<byte> name, Span<byte> value);
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internal const int PROP_VALUE_MAX = 92;
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internal static bool TryGetSystemProperty (ReadOnlySpan<byte> name, ref Span<byte> value)
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{
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int len = system_property_get (name, value);
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if (len <= 0) {
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return false;
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}
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value = value.Slice (0, len);
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return true;
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}
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}

‎src/Microsoft.Android.Runtime.NativeAOT/Android.Runtime.NativeAOT/JavaInteropRuntime.cs

+6-3
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44

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namespace Microsoft.Android.Runtime;
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static class JavaInteropRuntime
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static partial class JavaInteropRuntime
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{
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static JniRuntime? runtime;
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@@ -34,14 +34,17 @@ static void JNI_OnUnload (IntPtr vm, IntPtr reserved)
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static void init (IntPtr jnienv, IntPtr klass)
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{
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try {
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var settings = new DiagnosticSettings ();
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settings.AddDebugDotnetLog ();
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var typeManager = new NativeAotTypeManager ();
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var options = new NativeAotRuntimeOptions {
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EnvironmentPointer = jnienv,
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TypeManager = typeManager,
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ValueManager = new NativeAotValueManager (typeManager),
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UseMarshalMemberBuilder = false,
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JniGlobalReferenceLogWriter = new LogcatTextWriter (AndroidLogLevel.Debug, "NativeAot:GREF"),
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JniLocalReferenceLogWriter = new LogcatTextWriter (AndroidLogLevel.Debug, "NativeAot:LREF"),
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JniGlobalReferenceLogWriter = settings.GrefLog,
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JniLocalReferenceLogWriter = settings.LrefLog,
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};
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runtime = options.CreateJreVM ();
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‎src/Microsoft.Android.Runtime.NativeAOT/Microsoft.Android.Runtime.NativeAOT.csproj

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<SignAssembly>true</SignAssembly>
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<OutputPath>$(_MonoAndroidNETDefaultOutDir)</OutputPath>
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<RootNamespace>Microsoft.Android.Runtime</RootNamespace>
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<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
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</PropertyGroup>
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<ItemGroup>

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