[Mono.Android] avoid System.Reflection.Emit usage for common calls #6657
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jonpryor
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Jan 26, 2022
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Context: https://github.com/xamarin/xamarin-android/wiki/Blueprint#java-type-registration
Context: b7a368a27667c69117f64be81050403f2d5c8560
Context: https://github.com/xamarin/xamarin-android/pull/4877
Context: https://github.com/xamarin/xamarin-android/pull/4927#issuecomment-875864999
In order for Java code to call C# code,
[`JNIEnv::RegisterNatives()][0] must be invoked, providing an array
of `JNINativeMethod` structures, each of which contains a function
pointer to invoke, kept in `JNINativeMethod::fnPtr`.
Fortunately, delegates marshal as function pointers, and there is a
bunch of `generator`-emitted infrastructure and coordination with
Java Callable Wrappers to eventually obtain a Delegate instance to
provide `JNIEnv::RegisterNatives()`.
There is one deficiency in the `generator`-emitted infrastructure:
it doesn't deal with C# exceptions. However, exceptions "can't"
cross the JNI boundary (see b7a368a2 for an example of the breakage
that results when exceptions do cross the boundary!), except when we
*do* want exceptions to cross the JNI boundary ("improved" IDE first
chance exception experience; see xamarin/xamarin-android#4877).
This "we want to catch exceptions, except when we don't" scenario has
existed since the very beginning. As "the very beginning" predates
[C# 4 exception filters][1], there wasn't a way for `generator`
output to "selectively `catch` exceptions".
We squared this circle by using `System.Reflection.Emit`:
1. During Java Callable Wrapper registration, we lookup the
"marshal method getter" as provided to the `Runtime.register()`
invocation, e.g.
`Android.App.Activity.GetOnCreate_Landroid_os_Bundle_Handler()`.
2. `GetOnCreate_Landroid_os_Bundle_Handler()` is `generator` output,
and contains a `JNINativeWrapper.CreateDelegate()` invocation:
cb_onCreate_Landroid_os_Bundle_ = JNINativeWrapper.CreateDelegate ((_JniMarshal_PPL_V) n_OnCreate_Landroid_os_Bundle_);
3. `JNINativeWrapper.CreateDelegate()` uses `System.Reflection.Emit`
to create a new delegate instance which *wraps* the marshal
method `Activity.n_OnCreate_Landroid_os_Bundle()` in a
`try`/*filtered* `catch` block and marshals the exception to Java;
`JNINativeWrapper.CreateDelegate()` effectively returns:
bool _run_catch_if_debugger_not_attached (Exception e)
{
if (Debugger.IsAttached || !JNIEnv.PropagateExceptions) {
JNIEnv.mono_unhandled_exception (e);
return false;
}
return true;
}
_JniMarshal_PPL_V result = (jnienv, native__this, native_savedInstanceState) => {
JNIEnv.WaitForBridgeProcessing ();
try {
Activity.n_OnCreate_Landroid_os_Bundle_ (jnienv, native__this, native_savedInstanceState);
} catch (Exception e) when (_run_catch_if_debugger_not_attached (e)) {
AndroidEnvironment.UnhandledException (e);
if (Debugger.IsAttached || !JNIEnv.PropagateExceptions)
throw;
}
};
return result;
Again, this was C# 2.0 at the time, so C# 4 exception filters
couldn't be used, thus the need for `System.Reflection.Emit`, so
that [`ILGenerator.BeginExceptionFilterBLock()`][2] could be used
(the support for which is a Mono extension).
After this point, use of `System.Reflection.Emit` was part of the
implicit ABI between Xamarin.Android and binding assemblies. While
`generator` *could* be updated to *itself* emit the `try`/`catch`
block with exception filters, that would only work for binding
assemblies released *after* that `generator` fix.
The `System.Reflection.Emit` wrapper *can't* be skipped without
breaking semantic compatibility, *or* without allowing C# exceptions
to always pass through a JNI boundary, which would be Bad™.
The use of `System.Refleciton.Emit` is a Known Problem™, and
something we'd *like* to remove.
(Hence the [`jnimarshalmethod-gen`][3] explorations…)
With that background out of the way…
Let us turn our attention to the `dotnet new maui` template.
The default MAUI template hits `JNINativeWrapper.CreateDelegate()`
58 times during process startup, and we were wondering if we could
selectively improve these particular invocations, without needing to
re-think the entire "marshal method" infrastructure.
*Partially specialize* `JNINativeWrapper.CreateDelegate()` for the
following delegate types:
* `_JniMarshal_PP_V`
* `_JniMarshal_PPI_V`
* `_JniMarshal_PPL_L`
* `_JniMarshal_PPL_V`
* `_JniMarshal_PPL_Z`
* `_JniMarshal_PPII_V`
* `_JniMarshal_PPLI_V`
* `_JniMarshal_PPLL_V`
* `_JniMarshal_PPLL_Z`
* `_JniMarshal_PPIIL_V`
* `_JniMarshal_PPILL_V`
* `_JniMarshal_PPLIL_Z`
* `_JniMarshal_PPLLL_L`
* `_JniMarshal_PPLLL_Z`
* `_JniMarshal_PPIIII_V`
* `_JniMarshal_PPLLLL_V`
* `_JniMarshal_PPLIIII_V`
* `_JniMarshal_PPZIIII_V`
* `_JniMarshal_PPLIIIIIIII_V`
This is done via use of a T4 template, which generates
`JNINativeWrapper.CreateBuiltInDelegate()`, and
`JNINativeWrapper.CreateDelegate()` is updated to call
`CreateBuiltInDelegate()`:
partial class JNINativeWrapper {
static Delegate? CreateBuiltInDelegate (Delegate dlg, Type delegateType)
{
switch (delegateType.Name) {
case "_JniMarshal_PP_V": return …
case "_JniMarshal_PPI_V": return …
…
}
return null;
}
public static Delegate CreateDelegate (Delegate dlg)
{
…
var builtin = CreateBuiltInDelegate (dlg, dlg.GetType ();
if (builtin != null)
return builtin;
…
}
}
This avoids use of `System.Reflection.Emit` for the specified types.
Other changes:
* Update `TypeManager.GetActivateHandler()` to use
`_JniMarshal_PPLLLL_V` instead of
`Action<IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr>`, so the
fast path can be used.
* Added a log message for `adb shell septprop debug.mono.log assembly`:
Falling back to System.Reflection.Emit for delegate type '{delegateType}': {dlg.Method}
* I was also able to remove `mono_unhandled_exception_method` from
`JNINativeWrapper` as we already has this value in `JNIEnv`.
~~ Results ~~
Testing `dotnet new maui` with version:
msbuild Xamarin.Android.sln -t:InstallMaui -bl -p:MauiVersion=6.0.200-preview.13.2536
A `Release` build on a Pixel 5 device, total startup time:
| Startup | Average (ms) | Std Err (ms) | Std Dev (ms) |
| --------- | ------------: | ------------: | ------------: |
| Before | 1106.3 | 6.919 | 21.879 |
| After | 1070.8 | 5.686 | 17.980 |
This might save ~35ms on average?
If I time the message for one call, [such as][4]:
I monodroid-timing: Runtime.register: registering type `Microsoft.Maui.MauiApplication, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null`
I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::794845
The result is:
| One Call | Average (ms) | Std Err (ms) | Std Dev (ms) |
| --------- | ------------: | ------------: | ------------: |
| Before | 23.925 | 0.050 | 0.159 |
| After | 18.101 | 0.107 | 0.339 |
Saving ~5.8ms for this one call.
`.apk` size difference for `dotnet new android`:
% apkdiff -f before.apk after.apk
Size difference in bytes ([*1] apk1 only, [*2] apk2 only):Context: https://github.com/xamarin/xamarin-android/wiki/Blueprint#java-type-registration
Context: b7a368a27667c69117f64be81050403f2d5c8560
Context: https://github.com/xamarin/xamarin-android/pull/4877
Context: https://github.com/xamarin/xamarin-android/pull/4927#issuecomment-875864999
In order for Java code to call C# code,
[`JNIEnv::RegisterNatives()][0] must be invoked, providing an array
of `JNINativeMethod` structures, each of which contains a function
pointer to invoke, kept in `JNINativeMethod::fnPtr`.
Fortunately, delegates marshal as function pointers, and there is a
bunch of `generator`-emitted infrastructure and coordination with
Java Callable Wrappers to eventually obtain a Delegate instance to
provide `JNIEnv::RegisterNatives()`.
There is one deficiency in the `generator`-emitted infrastructure:
it doesn't deal with C# exceptions. However, exceptions "can't"
cross the JNI boundary (see b7a368a2 for an example of the breakage
that results when exceptions do cross the boundary!), except when we
*do* want exceptions to cross the JNI boundary ("improved" IDE first
chance exception experience; see xamarin/xamarin-android#4877).
This "we want to catch exceptions, except when we don't" scenario has
existed since the very beginning. As "the very beginning" predates
[C# 4 exception filters][1], there wasn't a way for `generator`
output to "selectively `catch` exceptions".
We squared this circle by using `System.Reflection.Emit`:
1. During Java Callable Wrapper registration, we lookup the
"marshal method getter" as provided to the `Runtime.register()`
invocation, e.g.
`Android.App.Activity.GetOnCreate_Landroid_os_Bundle_Handler()`.
2. `GetOnCreate_Landroid_os_Bundle_Handler()` is `generator` output,
and contains a `JNINativeWrapper.CreateDelegate()` invocation:
cb_onCreate_Landroid_os_Bundle_ = JNINativeWrapper.CreateDelegate ((_JniMarshal_PPL_V) n_OnCreate_Landroid_os_Bundle_);
3. `JNINativeWrapper.CreateDelegate()` uses `System.Reflection.Emit`
to create a new delegate instance which *wraps* the marshal
method `Activity.n_OnCreate_Landroid_os_Bundle()` in a
`try`/*filtered* `catch` block and marshals the exception to Java;
`JNINativeWrapper.CreateDelegate()` effectively returns:
bool _run_catch_if_debugger_not_attached (Exception e)
{
if (Debugger.IsAttached || !JNIEnv.PropagateExceptions) {
JNIEnv.mono_unhandled_exception (e);
return false;
}
return true;
}
_JniMarshal_PPL_V result = (jnienv, native__this, native_savedInstanceState) => {
JNIEnv.WaitForBridgeProcessing ();
try {
Activity.n_OnCreate_Landroid_os_Bundle_ (jnienv, native__this, native_savedInstanceState);
} catch (Exception e) when (_run_catch_if_debugger_not_attached (e)) {
AndroidEnvironment.UnhandledException (e);
if (Debugger.IsAttached || !JNIEnv.PropagateExceptions)
throw;
}
};
return result;
Again, this was C# 2.0 at the time, so C# 4 exception filters
couldn't be used, thus the need for `System.Reflection.Emit`, so
that [`ILGenerator.BeginExceptionFilterBLock()`][2] could be used
(the support for which is a Mono extension).
After this point, use of `System.Reflection.Emit` was part of the
implicit ABI between Xamarin.Android and binding assemblies. While
`generator` *could* be updated to *itself* emit the `try`/`catch`
block with exception filters, that would only work for binding
assemblies released *after* that `generator` fix.
The `System.Reflection.Emit` wrapper *can't* be skipped without
breaking semantic compatibility, *or* without allowing C# exceptions
to always pass through a JNI boundary, which would be Bad™.
The use of `System.Refleciton.Emit` is a Known Problem™, and
something we'd *like* to remove.
(Hence the [`jnimarshalmethod-gen`][3] explorations…)
With that background out of the way…
Let us turn our attention to the `dotnet new maui` template.
The default MAUI template hits `JNINativeWrapper.CreateDelegate()`
58 times during process startup, and we were wondering if we could
selectively improve these particular invocations, without needing to
re-think the entire "marshal method" infrastructure.
*Partially specialize* `JNINativeWrapper.CreateDelegate()` for the
following delegate types:
* `_JniMarshal_PP_V`
* `_JniMarshal_PPI_V`
* `_JniMarshal_PPL_L`
* `_JniMarshal_PPL_V`
* `_JniMarshal_PPL_Z`
* `_JniMarshal_PPII_V`
* `_JniMarshal_PPLI_V`
* `_JniMarshal_PPLL_V`
* `_JniMarshal_PPLL_Z`
* `_JniMarshal_PPIIL_V`
* `_JniMarshal_PPILL_V`
* `_JniMarshal_PPLIL_Z`
* `_JniMarshal_PPLLL_L`
* `_JniMarshal_PPLLL_Z`
* `_JniMarshal_PPIIII_V`
* `_JniMarshal_PPLLLL_V`
* `_JniMarshal_PPLIIII_V`
* `_JniMarshal_PPZIIII_V`
* `_JniMarshal_PPLIIIIIIII_V`
This is done via use of a T4 template, which generates
`JNINativeWrapper.CreateBuiltInDelegate()`, and
`JNINativeWrapper.CreateDelegate()` is updated to call
`CreateBuiltInDelegate()`:
partial class JNINativeWrapper {
static Delegate? CreateBuiltInDelegate (Delegate dlg, Type delegateType)
{
switch (delegateType.Name) {
case "_JniMarshal_PP_V": return …
case "_JniMarshal_PPI_V": return …
…
}
return null;
}
public static Delegate CreateDelegate (Delegate dlg)
{
…
var builtin = CreateBuiltInDelegate (dlg, dlg.GetType ();
if (builtin != null)
return builtin;
…
}
}
This avoids use of `System.Reflection.Emit` for the specified types.
Other changes:
* Update `TypeManager.GetActivateHandler()` to use
`_JniMarshal_PPLLLL_V` instead of
`Action<IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr>`, so the
fast path can be used.
* Added a log message for `adb shell septprop debug.mono.log assembly`:
Falling back to System.Reflection.Emit for delegate type '{delegateType}': {dlg.Method}
* I was also able to remove `mono_unhandled_exception_method` from
`JNINativeWrapper` as we already has this value in `JNIEnv`.
~~ Results ~~
Testing `dotnet new maui` with version:
msbuild Xamarin.Android.sln -t:InstallMaui -bl -p:MauiVersion=6.0.200-preview.13.2536
A `Release` build on a Pixel 5 device, total startup time:
| Startup | Average (ms) | Std Err (ms) | Std Dev (ms) |
| --------- | ------------: | ------------: | ------------: |
| Before | 1106.3 | 6.919 | 21.879 |
| After | 1078.8 | 5.438 | 17.197 |
This might save ~35ms on average?
If I time the message for one call, [such as][4]:
I monodroid-timing: Runtime.register: registering type `Microsoft.Maui.MauiApplication, Microsoft.Maui, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null`
I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::794845
The result is:
| One Call | Average (ms) | Std Err (ms) | Std Dev (ms) |
| --------- | ------------: | ------------: | ------------: |
| Before | 23.925 | 0.050 | 0.159 |
| After | 18.723 | 0.094 | 0.298 |
Saving ~5.8ms for this one call.
`.apk` size difference for `dotnet new android`:
% apkdiff -f before.apk after.apk
Size difference in bytes ([*1] apk1 only, [*2] apk2 only):
+ 3,390 assemblies/assemblies.blob
+ 54 assemblies/assemblies.x86_64.blob
- 4 assemblies/assemblies.arm64_v8a.blob
- 15 assemblies/assemblies.x86.blob
- 65 assemblies/assemblies.armeabi_v7a.blob
Summary:
+ 3,360 Other entries 0.03% (of 10,526,432)
+ 0 Dalvik executables 0.00% (of 7,816,392)
+ 0 Shared libraries 0.00% (of 18,414,404)
+ 4,096 Package size difference 0.02% (of 21,006,128)
We're looking at a ~4KB size increase for this partial specialization.
[0]: https://docs.oracle.com/javase/8/docs/technotes/guides/jni/spec/functions.html#RegisterNatives
[1]: https://docs.microsoft.com/en-us/dotnet/csharp/fundamentals/exceptions/exception-handling#catch-blocks
[2]: https://docs.microsoft.com/is-is/dotnet/api/system.reflection.emit.ilgenerator.beginexceptfilterblock?view=net-6.0
[3]: http://github.com/xamarin/Java.Interop/commit/c8f3e51a6cfd78bdce89e2429efae4495481f57b
[4]: https://github.com/dotnet/maui/blob/bfba62ed796d3416c4fcaa7cfbea86dc8d5e04c2/src/Compatibility/ControlGallery/src/Android/MainApplication.cs |
`dotnet new android` calls `JNINativeWrapper.CreateDelegate()` twice,
while `dotnet new maui` ends up calling it 58 times during startup.
This code path calls System.Reflection.Emit to generate a
`System.Delegate` at runtime to be invoked. After some thought, it is
possible to "hard code" common delegate types and avoid SRE:
private static Delegate CreateBuiltInDelegate (Delegate dlg, Type delegateType)
{
switch (delegateType.Name) {
case nameof (_JniMarshal_PP_V): {
_JniMarshal_PP_V callback = (_JniMarshal_PP_V) Delegate.CreateDelegate (typeof (_JniMarshal_PP_V), dlg.Target, dlg.Method);
_JniMarshal_PP_V result = (jnienv, klazz) => {
JNIEnv.WaitForBridgeProcessing ();
try {
callback (jnienv, klazz);
} catch (Exception e) {
bool filter = Debugger.IsAttached || !JNIEnv.PropagateExceptions;
if (filter && JNIEnv.mono_unhandled_exception != null) {
JNIEnv.mono_unhandled_exception (e);
}
AndroidEnvironment.UnhandledException (e);
if (filter)
throw;
}
};
return result;
}
// etc.
`dotnet new maui`'s startup can be covered if we hardcoded:
_JniMarshal_PP_V
_JniMarshal_PPI_V
_JniMarshal_PPL_L
_JniMarshal_PPL_V
_JniMarshal_PPL_Z
_JniMarshal_PPII_V
_JniMarshal_PPLI_V
_JniMarshal_PPLL_V
_JniMarshal_PPLL_Z
_JniMarshal_PPIIL_V
_JniMarshal_PPILL_V
_JniMarshal_PPLIL_Z
_JniMarshal_PPLLL_L
_JniMarshal_PPLLL_Z
_JniMarshal_PPIIII_V
_JniMarshal_PPLLLL_V
_JniMarshal_PPLIIII_V
_JniMarshal_PPZIIII_V
_JniMarshal_PPLIIIIIIII_V
Then System.Reflection.Emit isn't used at all.
Other changes:
* `TypeManager.GetActivateHandler()` needs to use
`_JniMarshal_PPLLLL_V` instead of `Action<IntPtr, IntPtr, IntPtr,
IntPtr, IntPtr, IntPtr>`, so the fast path can be used.
* Added a log message for `debug.mono.log assembly`:
Falling back to System.Reflection.Emit for delegate type '{delegateType}': {dlg.Method}
* I was also able to remove `mono_unhandled_exception_method` from
`JNINativeWrapper` as we already has this value in `JNIEnv`.
~~ Results ~~
Testing `dotnet new maui` with version:
msbuild Xamarin.Android.sln -t:InstallMaui -bl -p:MauiVersion=6.0.200-preview.13.2536
A `Release` build on a Pixel 5 device, total startup time:
Before:
01-21 11:58:39.030 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s83ms
01-21 11:58:41.297 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s127ms
01-21 11:58:43.429 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s68ms
01-21 11:58:45.702 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s113ms
01-21 11:58:47.906 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s125ms
01-21 11:58:50.082 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s92ms
01-21 11:58:52.297 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s133ms
01-21 11:58:54.465 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s102ms
01-21 11:58:56.673 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s126ms
01-21 11:58:58.848 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s94ms
Average(ms): 1106.3
Std Err(ms): 6.91865433287267
Std Dev(ms): 21.8787060352704
After:
01-21 12:00:33.312 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s61ms
01-21 12:00:35.513 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s79ms
01-21 12:00:37.724 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s85ms
01-21 12:00:39.928 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s83ms
01-21 12:00:42.117 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s60ms
01-21 12:00:44.337 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s59ms
01-21 12:00:46.612 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s106ms
01-21 12:00:48.782 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s47ms
01-21 12:00:51.018 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s75ms
01-21 12:00:53.200 1867 2226 I ActivityTaskManager: Displayed com.companyname.bar/crc6474063b540de74d1e.MainActivity: +1s53ms
Average(ms): 1070.8
Std Err(ms): 5.68584988272544
Std Dev(ms): 17.9802360632137
This might save ~35ms on average?
If I time the message for one call, such as:
01-21 12:14:01.132 29819 29819 I monodroid-timing: Runtime.register: registering type `Microsoft.Maui.MauiApplication, Microsoft.Maui, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null`
01-21 12:14:01.150 29819 29819 I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::794845
https://github.com/dotnet/maui/blob/bfba62ed796d3416c4fcaa7cfbea86dc8d5e04c2/src/Compatibility/ControlGallery/src/Android/MainApplication.cs
The result is:
Before:
01-21 13:21:22.261 9359 9359 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::868440
01-21 13:21:24.446 9424 9424 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::875159
01-21 13:21:26.639 9497 9497 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::829742
01-21 13:21:28.842 9570 9570 I monodroid-timing: Runtime.register: end time; elapsed: 0s:24::165211
01-21 13:21:31.021 9631 9631 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::976721
01-21 13:21:33.221 9697 9697 I monodroid-timing: Runtime.register: end time; elapsed: 0s:24::237034
01-21 13:21:35.418 9759 9759 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::857346
01-21 13:21:37.585 9821 9821 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::872138
01-21 13:21:39.805 9884 9884 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::840107
01-21 13:21:42.014 9952 9952 I monodroid-timing: Runtime.register: end time; elapsed: 0s:23::723805
Average(ms): 23.9245703
Std Err(ms): 0.0502830551065224
Std Dev(ms): 0.159008981848371
After:
01-21 13:22:28.004 10226 10226 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::12345
01-21 13:22:30.261 10298 10298 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::338022
01-21 13:22:32.443 10362 10362 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::56251
01-21 13:22:34.664 10427 10427 I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::997397
01-21 13:22:36.902 10497 10497 I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::787554
01-21 13:22:39.117 10563 10563 I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::801772
01-21 13:22:41.306 10630 10630 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::28752
01-21 13:22:43.552 10695 10695 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::75522
01-21 13:22:45.761 10759 10759 I monodroid-timing: Runtime.register: end time; elapsed: 0s:17::958075
01-21 13:22:47.978 10823 10823 I monodroid-timing: Runtime.register: end time; elapsed: 0s:18::961773
Average(ms): 18.1017463
Std Err(ms): 0.107071213504746
Std Dev(ms): 0.338588906513177
Saving ~5.8ms for this one call.
`.apk` size difference for `dotnet new android`:
> apkdiff -f before.apk after.apk
Size difference in bytes ([*1] apk1 only, [*2] apk2 only):
+ 3,390 assemblies/assemblies.blob
+ 54 assemblies/assemblies.x86_64.blob
- 4 assemblies/assemblies.arm64_v8a.blob
- 15 assemblies/assemblies.x86.blob
- 65 assemblies/assemblies.armeabi_v7a.blob
Summary:
+ 3,360 Other entries 0.03% (of 10,526,432)
+ 0 Dalvik executables 0.00% (of 7,816,392)
+ 0 Shared libraries 0.00% (of 18,414,404)
+ 4,096 Package size difference 0.02% (of 21,006,128)
Co-authored-by: Jonathan Pryor <jonpryor@vt.edu>
jonpryor
reviewed
Jan 28, 2022
jonpryor
reviewed
Jan 28, 2022
| JNIEnv.WaitForBridgeProcessing (); | ||
| try { | ||
| <#= info.Return ? "return " : "" #>callback <#= info.Signature #>; | ||
| } catch (Exception e) { |
Contributor
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This catch should be updated to:
catch (Exception e) when (_unhandled_exception (e)) {
AndroidEnvironment.UnhandledException (e);
if (Debugger.IsAttached || !JNIEnv.PropagateExceptions)
throw;
}
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I think the performance with the latest changes is still probably the same (or very close): Then full displayed: |
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dotnet new androidcallsJNINativeWrapper.CreateDelegate()twice,while
dotnet new mauiends up calling it 58 times during startup.This code path calls System.Reflection.Emit to generate a
System.Delegateat runtime to be invoked. After some thought, it ispossible to "hard code" common delegate types and avoid SRE:
dotnet new maui's startup can be covered if we hardcoded:Then System.Reflection.Emit isn't used at all.
Other changes:
TypeManager.GetActivateHandler()needs to use_JniMarshal_PPLLLL_Vinstead ofAction<IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, IntPtr>, so the fast path can be used.Added a log message for
debug.mono.log assembly:Falling back to System.Reflection.Emit for delegate type '{delegateType}': {dlg.Method}
I was also able to remove
mono_unhandled_exception_methodfromJNINativeWrapperas we already has this value inJNIEnv.Results
Testing
dotnet new mauiwith version:A
Releasebuild on a Pixel 5 device, total startup time:This might save ~35ms on average?
If I time the message for one call, such as:
https://github.com/dotnet/maui/blob/bfba62ed796d3416c4fcaa7cfbea86dc8d5e04c2/src/Compatibility/ControlGallery/src/Android/MainApplication.cs
The result is:
Saving ~5.8ms for this one call.
.apksize difference fordotnet new android: