WIP: Graal native-image build of Java Schnorr Example

[msgilligan]

To build native image use:

./gradlew secp-examples-java:nativeCompile

Currently requires Graal JDK 25-ea

[msgilligan]

It also looks like some additional build configuration will be required:
https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/ForeignInterface.md

Update: The PR now includes this work (a somewhat rushed job of it, I must admit) but should build and run on AMD64 machines.

[schildbach]

As already mentioned elsewhere, I was able to build and run this successfully:

$ LD_LIBRARY_PATH=/nix/store/1c403w3lffz5p21lqqcvryh56ib0i28q-secp256k1-0.4.1/lib time -v secp256k1-examples-java/build/schnorrRunning secp256k1-jdk Schnorr example...
Is the signature valid? true
Secret Key: c6bf161b6530f588451b3790140722eb6de756164efc49baa1387f16b9089dac
Public Key (as ECPoint): 70176dcf4283032d089003785fce826ed7fa8e58c6a6a82ac27db4378d46ce50
Signature: 7ec2637314505842493670018a2e9b67ac0f63faf207640da4c206c2b2e89dcdaf0349608d40bec4c9f18ea2028eee70defd2e5bae1b7cada886ae88cfa7badd
	Command being timed: "secp256k1-examples-java/build/schnorr"
	User time (seconds): 0.00
	System time (seconds): 0.00
	Percent of CPU this job got: 100%
	Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
	Average shared text size (kbytes): 0
	Average unshared data size (kbytes): 0
	Average stack size (kbytes): 0
	Average total size (kbytes): 0
	Maximum resident set size (kbytes): 19520
	Average resident set size (kbytes): 0
	Major (requiring I/O) page faults: 0
	Minor (reclaiming a frame) page faults: 1225
	Voluntary context switches: 12
	Involuntary context switches: 1
	Swaps: 0
	File system inputs: 0
	File system outputs: 0
	Socket messages sent: 0
	Socket messages received: 0
	Signals delivered: 0
	Page size (bytes): 4096
	Exit status: 0

[msgilligan]

Looks like Graal JDK 25 will be the one: oracle/graal#8113 (comment)

Once we have a JDK 25-ea and a Gradle that can build for it, we should rebase and update this PR.

Update: The build can be done under JDK 23/24 with only native-image running under JDK 25 (-ea)

[msgilligan]

Current error on aarch64-darwin and aarch64-linux is:

$ ./secp-examples-java/build/schnorr 
Running secp256k1-jdk Schnorr example...
Exception in thread "main" java.util.NoSuchElementException: Default Provider not found.
	at org.bitcoinj.secp.api.Secp256k1Provider.lambda$find$2(Secp256k1Provider.java:59)
	at java.base@25/java.util.Optional.orElseThrow(Optional.java:403)
	at org.bitcoinj.secp.api.Secp256k1Provider.find(Secp256k1Provider.java:59)
	at org.bitcoinj.secp.api.Secp256k1.get(Secp256k1.java:84)
	at org.bitcoinj.secp.examples.Schnorr.main(Schnorr.java:37)
	at java.base@25/java.lang.invoke.LambdaForm$DMH/sa346b79c.invokeStaticInit(LambdaForm$DMH)

I suspect the native-image command needs to be updated to use --module-path (or similar) properly.

I haven't tested on x86_64.

[schildbach]

I removed myself from the reviewers because I already commented, and I want to clear my list of pending code reviews. Feel free to re-request if desired.