안정 빌드와 프리뷰 빌드를 CI에서 나누기

import java.nio.ByteBuffer;
import java.nio.file.Files;
import java.nio.file.Path;
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;

public final class PreviewArtifactLeakBug {
    static boolean preview(byte[] bytes) {
        ByteBuffer buffer = ByteBuffer.wrap(bytes);
        if (buffer.getInt() != 0xCAFEBABE) {
            throw new IllegalArgumentException("class magic");
        }
        return Short.toUnsignedInt(buffer.getShort()) == 0xFFFF;
    }

    public static void main(String[] args) throws Exception {
        Path root = Files.createTempDirectory("artifact-leak");
        Path previewOutput = Files.createDirectories(root.resolve("preview"));
        Path stableOutput = Files.createDirectories(root.resolve("stable"));
        Path source = root.resolve("PreviewOnly.java");
        Files.writeString(source, """
                public class PreviewOnly {
                    static String show(long value) {
                        return switch (value) { case long number -> "n=" + number; };
                    }
                }
                """);

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        int exit = compiler.run(null, null, null,
                "--enable-preview", "--release", "25",
                "-d", previewOutput.toString(), source.toString());
        if (exit != 0) {
            throw new IllegalStateException("compile exit=" + exit);
        }

        Path previewClass = previewOutput.resolve("PreviewOnly.class");
        Path leakedClass = stableOutput.resolve("PreviewOnly.class");
        Files.copy(previewClass, leakedClass);
        System.out.println("wrong-preview-in-stable=" + preview(Files.readAllBytes(leakedClass)));
    }
}

wrong-preview-in-stable=true

import java.nio.file.Path;
import java.util.List;

public final class SeparatedPreviewPipelines {
    private record Pipeline(
            String name,
            Path sourceRoot,
            Path output,
            List<String> compileFlags,
            List<String> runtimeFlags,
            boolean publishable) {}

    public static void main(String[] args) {
        Pipeline stable = new Pipeline(
                "stable",
                Path.of("src/main/java"),
                Path.of("build/classes/stable"),
                List.of("--release", "25", "-Xlint:all"),
                List.of(),
                true);
        Pipeline preview = new Pipeline(
                "preview",
                Path.of("src/preview/java"),
                Path.of("build/classes/preview"),
                List.of("--enable-preview", "--release", "25", "-Xlint:preview"),
                List.of("--enable-preview"),
                false);
        System.out.println(stable);
        System.out.println(preview);
    }
}

Pipeline[name=stable, sourceRoot=src/main/java, output=build/classes/stable, compileFlags=[--release, 25, -Xlint:all], runtimeFlags=[], publishable=true]
Pipeline[name=preview, sourceRoot=src/preview/java, output=build/classes/preview, compileFlags=[--enable-preview, --release, 25, -Xlint:preview], runtimeFlags=[--enable-preview], publishable=false]

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.HexFormat;
import java.util.List;

public final class PreviewBuildCacheKey {
    static String key(String sourceHash, boolean preview, List<String> flags) throws Exception {
        String input = String.join(
                "|",
                sourceHash,
                System.getProperty("java.vendor"),
                Runtime.version().toString(),
                Boolean.toString(preview),
                String.join(",", flags));
        byte[] digest =
                MessageDigest.getInstance("SHA-256").digest(input.getBytes(StandardCharsets.UTF_8));
        return HexFormat.of().formatHex(digest);
    }

    public static void main(String[] args) throws Exception {
        String stable = key("abc123", false, List.of("--release", "25"));
        String preview = key("abc123", true, List.of("--enable-preview", "--release", "25"));
        System.out.println("different=" + !stable.equals(preview));
        System.out.println("stable=" + stable.substring(0, 12));
        System.out.println("preview=" + preview.substring(0, 12));
    }
}

import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;

public final class PreviewRuntimeCommand {
    static List<String> command(Path java, Path classes, String mainClass, boolean preview) {
        List<String> values = new ArrayList<>();
        values.add(java.toString());
        if (preview) {
            values.add("--enable-preview");
        }
        values.add("-cp");
        values.add(classes.toString());
        values.add(mainClass);
        return List.copyOf(values);
    }

    public static void main(String[] args) {
        Path java = Path.of(System.getProperty("java.home"), "bin", "java");
        System.out.println(command(java, Path.of("build/classes/stable"), "App", false));
        System.out.println(command(java, Path.of("build/classes/preview"), "PreviewLab", true));
    }
}

[.../bin/java, -cp, build/classes/stable, App]
[.../bin/java, --enable-preview, -cp, build/classes/preview, PreviewLab]

import java.nio.ByteBuffer;
import java.util.List;

public final class PreviewArtifactScanner {
    static boolean isPreview(byte[] bytes) {
        if (bytes.length < 8) {
            return false;
        }
        ByteBuffer header = ByteBuffer.wrap(bytes);
        return header.getInt() == 0xCAFEBABE && Short.toUnsignedInt(header.getShort()) == 0xFFFF;
    }

    static long count(List<byte[]> classes) {
        return classes.stream().filter(PreviewArtifactScanner::isPreview).count();
    }

    public static void main(String[] args) {
        byte[] stable = {(byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE, 0x00, 0x00, 0x00, 0x45};
        byte[] preview = {(byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE, (byte) 0xFF, (byte) 0xFF, 0x00, 0x45};
        System.out.println("preview-count=" + count(List.of(stable, preview, preview)));
    }
}

preview-count=2