Class Wasmtime

src/main/java/net/bluejekyll/wasmtime/Wasmtime.java:14–105

Wasmtime A wrapper over the FFI of the Rust wasmtime library, which uses Wasmtime for the WASM runtime

 * the WASM runtime
 */
public class Wasmtime {
    private static final String NATIVE_LIB = "wasmtime_jni";
    private static volatile boolean libraryLoaded = false;

    private static void loadNative() {
        if (Wasmtime.libraryLoaded) {
            return;
        }

        try {
            System.loadLibrary(NATIVE_LIB);
            System.out.printf("loadLibrary succeeded for %s%n", NATIVE_LIB);
            libraryLoaded = true;
            return;
        } catch (UnsatisfiedLinkError e) {
            System.out.printf("Failed to loadLibrary %s, will try from classpath%n", NATIVE_LIB);
        }

        String osName = System.getProperty("os.name");
        String osArch = System.getProperty("os.arch");

        if (osName.contains("Mac OS X")) {
            osName = "Darwin";
        }
        if (osArch.contains("amd64")) {
            osArch = "x86_64";
        }

        final String libName = System.mapLibraryName(NATIVE_LIB);
        final String libPath = String.format("NATIVE/%s/%s/%s", osName, osArch, libName);

        // open a temporary file for the native_lib
        final String tmpDir = System.getProperty("java.io.tmpdir");

        if (tmpDir == null) {
            throw new RuntimeException("java.io.tmpdir is null?");
        }

        final File libFile = new File(tmpDir, libName);
        final String path = libFile.getAbsolutePath();

        // FIXME: add back...
        // if (libFile.exists()) {
        // System.out.printf("Temporary library already exists %s, did not replace%n",
        // libFile);
        // loadLibrary(path);
        // return;
        // }

        try (OutputStream os = new FileOutputStream(libFile, false);
                InputStream in = ClassLoader.getSystemResourceAsStream(libPath);) {
            if (in == null)
                throw new RuntimeException(String.format("could not find %s in classpath", libPath));
            long length = in.transferTo(os);
            System.out.printf("Created temporary library sized %d at %s%n", length, libFile);
            os.flush();
        } catch (Exception e) {
            System.err.printf("Failed to write %s to %s library: %s%n", libPath, libFile, e.getMessage());