commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/dotnet/java-interop/commit/c6c487b62dab4ffec45e61b09dd43afc89898caf/hovercard" href="https://github.com/dotnet/java-interop/commit/c6c487b62dab4ffec45e61b09dd43afc89898caf">c6c487b Context: 312fbf4 Context: 2197579 Context: dotnet/android#7276 There is a desire to remove the "marshal-ilgen" component from .NET Android, which is responsible for all non-blittable type marshaling within P/Invoke (and related) invocations. The largest source of such non-blittable parameter marshaling was with string marshaling: `JNIEnv::GetFieldID()` was "wrapped" by `java_interop_jnienv_get_field_id`: JI_API jfieldID java_interop_jnienv_get_field_id (JNIEnv *env, jthrowable *_thrown, jclass type, const char* name, const char* signature); which was P/Invoked within `JniEnvironment.g.cs`: partial class NativeMethods { internal static extern unsafe IntPtr java_interop_jnienv_get_field_id (IntPtr jnienv, out IntPtr thrown, jobject type, string name, string signature); } and `string` parameter marshaling is *not* blittable. Turns out™ that this particular usage of non-blittable parameter marshaling was fixed and rendered moot by: * 312fbf4: C#9 function pointer backend for `JNIEnv` invocations * c6c487b: "Standalone" build config to use C#9 function pointers * 2197579: Standalone build config is now the default That said, this code path felt slightly less than ideal: the "top-level abstraction" for member lookups is an "encoded member", a string containing the name of the member, a `.`, and the JNI signature of the member, e.g.: _members.InstanceFields.GetBooleanValue("propogateFinallyBlockExecuted.Z", this) The "encoded member" would need to be split on `.`, and with c6c487b the name and signature would be separately passed to `Marshal.StringToCoTaskMemUTF8()`, which performs a memory allocation and converts the UTF-16 string to UTF-8. Meanwhile, [C# 11 introduced UTF-8 string literals][0], which allows the compiler to deal with UTF-8 conversion and memory allocation. Enter `JniMemberInfoLookup``: public ref struct JniMemberInfoLookup { public string EncodedMember {get;} public ReadOnlySpan<byte> MemberName {get;} public ReadOnlySpan<byte> MemberSignature {get;} public JniMemberInfoLookup (string encodedMember, ReadOnlySpan<byte> memberName, ReadOnlySpan<byte> memberSignature); } `JniMemberInfoLookup` removes the need to call `Marshal.StringToCoTaskMemUTF8()` entirely, at the cost of a more complicated member invocation: // Old and busted: bool value = _members.InstanceFields.GetBooleanValue("propogateFinallyBlockExecuted.Z", this); // Eventual new hawtness: var lookup = new JniMemberInfoLookup ( "propogateFinallyBlockExecuted.Z", "propogateFinallyBlockExecuted"u8, "Z"u8); bool value = _members.InstanceFields.GetBooleanValue(lookup, this); Is It Worth It™? *Maybe*; see the new `JniFieldLookupTiming.FieldLookupTiming()` test, which allocates a new `JniPeerMembers` instance and invoke `members.InstanceFields.GetFieldInfo(string)` and `members.InstanceFields.GetFieldInfo(JniMemberInfoLookup)`. (A new `JniPeerMembers` instance is required because `GetFieldInfo()` caches the field lookup.) Using `JniMemberInfoLookup` is about 4% faster. # FieldLookupTiming Timing: looking up JavaTiming.instanceIntField 10000 times # .InstanceMethods.GetFieldInfo(string): 00:00:02.2780667 # .InstanceMethods.GetFieldInfo(JniMemberInfoLookup): 00:00:02.2016146 I'm not sure if this is *actually* worth it, especially as this will imply an increase in code size. TODO: * Update `JniPeerMembers.*.cs` to use `JniMemberInfoLookup`, so that e.g. the above `_members.InstanceFields.GetBooleanValue()` overload exists. * `generator` changes to use `JniMemberInfoLookup` [0]: https://learn.microsoft.com/dotnet/csharp/whats-new/csharp-11#utf-8-string-literals

[Java.Interop] Add JniMemberInfoLookup#1208jonpryor wants to merge 7 commits intomaindotnet/java-interop:mainfrom dev/jonp/jonp-zero-alloc-member-lookupdotnet/java-interop:dev/jonp/jonp-zero-alloc-member-lookupCopy head branch name to clipboard

Commits

Commits on Jul 5, 2024

[Java.Interop] Add JniMemberInfoLookup

Fix PublicAPI.Unshipped.txt errors.

Fix indentation

Flesh things out…

Commits on Jul 9, 2024

Flesh out method lookup

Merge remote-tracking branch 'origin/main' into dev/jonp/jonp-zero-alloc-member-lookup

JniMemberInfoLookup timing

[Java.Interop] Add JniMemberInfoLookup#1208
jonpryor wants to merge 7 commits intomainfrom
dev/jonp/jonp-zero-alloc-member-lookup