[browser] Support AppContext switches on runtime

[maraf]

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

[ghost]

Tagging subscribers to 'arch-wasm': @lewing
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Issue Details

---

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

Author:	maraf
Assignees:	-
Labels:	arch-wasm, area-Build-mono, os-browser
Milestone:	9.0.0

[lewing]

AppContext switches defined in csproj are not available on runtime

<ItemGroup>
    ...
    <RuntimeHostConfigurationOption Include="System.Runtime.OptionalFeatureBehavior"
                                    Condition="'$(UnoptimizedUserFacingBehavior)' != ''"
                                    Value="$(UnoptimizedUserFacingBehavior)"
                                    Link="false" />
    ...
</ItemGroup>

On other platforms, they end up in runtime.config.json. We should put them into blazor.boot.json as that's the only config required (for both wasmbrowser and blazor experience)

That works for browser but we will have the same issue in wasi where there is no json parser.

[maraf]

That works for browser but we will have the same issue in wasi where there is no json parser.

That's true. We can use the binary format for WASI and we bundle it into wasm file even for browser, but I would like to avoid distributing it as a separate file for browser scenario

[lambdageek]

Mono has a task that converts rutnimeconfig.json files into a binary blob at build time so you don't need to do JSON parsing at execution time
https://github.com/dotnet/runtime/blob/main/src/tasks/MonoTargetsTasks/RuntimeConfigParser/RuntimeConfigParser.cs

the binary blob can be passed by the driver to monovm_runtimeconfig_initialize:

runtime/src/native/public/mono/jit/details/mono-private-unstable-functions.h

Line 21 in 77fd98c

MONO_API_FUNCTION(int, monovm_runtimeconfig_initialize, (MonovmRuntimeConfigArguments *arg, MonovmRuntimeConfigArgumentsCleanup cleanup_fn, void *user_data))

runtime/src/native/public/mono/jit/details/mono-private-unstable-types.h

Lines 21 to 34 in 77fd98c

	typedef struct {
	uint32_t kind; // 0 = Path of runtimeconfig.blob, 1 = pointer to image data, >= 2 undefined
	union {
	struct {
	const char *path;
	} name;
	struct {
	const char *data;
	uint32_t data_len;
	} data;
	} runtimeconfig;
	} MonovmRuntimeConfigArguments;
	typedef void (*MonovmRuntimeConfigArgumentsCleanup) (MonovmRuntimeConfigArguments *args, void *user_data);

This is used by xamarin-android, for example:

https://github.com/xamarin/xamarin-android/blob/e67afc7d7ae848da6b33026b80973d30713b98ad/src/monodroid/jni/monodroid-glue.cc#L846-L848

[pavelsavara]

I need this to work in order to implement #111680 and it's P1 goal

After discussion with @maraf I learned that

• There is RuntimeConfigParser which translates the JSON to .bin file on multiple Mono platforms. In order to avoid managed JSON deserialization during app startup.
• we are able to load runtimeconfig.bin from VFS and parse it, also in "demo" mode
• but the file is only being produced with workload installed
• and with now obsolete tooling _WasmGenerateRuntimeConfig which is only triggered for WasmGenerateAppBundle
• Blazor prevents downloading runtimeconfig.bin anyway.
• .bin doesn't have great MIME type configured in most places
• I dislike using VFS for anything
• Blazor is full of managed reflection based JSON deserialization anyway

runtime/src/tasks/MonoTargetsTasks/RuntimeConfigParser/RuntimeConfigParser.cs

Lines 110 to 120 in b9adf8d

	private static void ConvertDictionaryToBlob(Dictionary<string, string> properties, BlobBuilder builder)
	{
	int count = properties.Count;
	builder.WriteCompressedInteger(count);
	foreach (var kvp in properties)
	{
	builder.WriteSerializedString(kvp.Key);
	builder.WriteSerializedString(kvp.Value);
	}
	}

runtime/src/mono/browser/runtime/driver.c

Lines 205 to 220 in b9adf8d

	char *file_name = RUNTIMECONFIG_BIN_FILE;
	int str_len = strlen (file_name) + 1; // +1 is for the "/"
	char *file_path = (char *)malloc (sizeof (char) * (str_len +1)); // +1 is for the terminating null character
	int num_char = snprintf (file_path, (str_len + 1), "/%s", file_name);
	struct stat buffer;
	assert (num_char > 0 && num_char == str_len);
	if (stat (file_path, &buffer) == 0) {
	MonovmRuntimeConfigArguments *arg = (MonovmRuntimeConfigArguments *)malloc (sizeof (MonovmRuntimeConfigArguments));
	arg->kind = 0;
	arg->runtimeconfig.name.path = file_path;
	monovm_runtimeconfig_initialize (arg, cleanup_runtime_config, file_path);
	} else {
	free (file_path);
	}

runtime/src/libraries/System.Private.CoreLib/src/System/AppContext.cs

Lines 145 to 153 in b9adf8d

	internal static unsafe void Setup(char** pNames, uint* pNameLengths, char** pValues, uint* pValueLengths, int count)
	{
	Debug.Assert(s_dataStore == null, "s_dataStore is not expected to be inited before Setup is called");
	s_dataStore = new Dictionary<string, object?>(count);
	for (int i = 0; i < count; i++)
	{
	s_dataStore.Add(new string(pNames[i], 0, (int)pNameLengths[i]), new string(pValues[i], 0, (int)pValueLengths[i]));
	}
	}

That gives us following implementation options
A) add any runtimeconfig.json as subset of dotnet.boot.json via GenerateWasmBootJson.
Only process the string->string dictionary, same as current AppContext.Setup
But do the JSON parsing in JavaScript for free.
Remove support for .bin file from wasm build
This will also work without workload installed.
This would NOT work for WASI

B) For consistency with other Mono platforms, fix runtimeconfig.bin
Lift RuntimeConfigParser into Microsoft.NET.Sdk.WebAssembly.Pack.Tasks, so that we could use it outside of workload.
Include it in VFS also for Blazor.
Have one extra file to download.
Deal with MIME type.

I prefer A) at this time