ChrisHegarty commented on code in PR #12311:
URL: https://github.com/apache/lucene/pull/12311#discussion_r1198189573
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lucene/core/src/java/org/apache/lucene/util/VectorUtil.java:
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@@ -270,4 +216,134 @@ public static float dotProductScore(byte[] a, byte[] b) {
float denom = (float) (a.length * (1 << 15));
return 0.5f + dotProduct(a, b) / denom;
}
+
+ interface VectorUtilProvider {
+
+ // just dot product for now
+ float dotProduct(float[] a, float[] b);
+ }
+
+ private static VectorUtilProvider lookupProvider() {
+ // TODO: add a check
+ final int runtimeVersion = Runtime.version().feature();
+ if (runtimeVersion == 20) { // TODO: do we want JDK 19?
+ try {
+ ensureReadability();
+ final var lookup = MethodHandles.lookup();
+ final var cls =
lookup.findClass("org.apache.lucene.util.JDKVectorUtilProvider");
+ // we use method handles, so we do not need to deal with setAccessible
as we have private
+ // access through the lookup:
+ final var constr = lookup.findConstructor(cls,
MethodType.methodType(void.class));
+ try {
+ return (VectorUtilProvider) constr.invoke();
+ } catch (RuntimeException | Error e) {
+ throw e;
+ } catch (Throwable th) {
+ throw new AssertionError(th);
+ }
+ } catch (NoSuchMethodException | IllegalAccessException e) {
+ throw new LinkageError("JDKVectorUtilProvider is missing correctly
typed constructor", e);
+ } catch (ClassNotFoundException cnfe) {
+ throw new LinkageError("JDKVectorUtilProvider is missing in Lucene JAR
file", cnfe);
+ }
+ } else if (runtimeVersion >= 21) {
+ LOG.warning(
+ "You are running with Java 21 or later. To make full use of the
Vector API, please update Apache Lucene.");
+ }
+ return new LuceneVectorUtilProvider();
+ }
+
+ // Extracted to a method to be able to apply the SuppressForbidden annotation
+ @SuppressWarnings("removal")
+ @SuppressForbidden(reason = "security manager")
+ private static <T> T doPrivileged(PrivilegedAction<T> action) {
+ return AccessController.doPrivileged(action);
+ }
+
+ static void ensureReadability() {
+ ModuleLayer.boot().modules().stream()
+ .filter(m -> m.getName().equals("jdk.incubator.vector"))
+ .findFirst()
+ .ifPresentOrElse(
+ vecMod -> VectorUtilProvider.class.getModule().addReads(vecMod),
+ () -> LOG.warning("vector incubator module not present"));
+ }
+
+ static {
+ PROVIDER =
Review Comment:
I’ll refactor to minimise the privileged block.
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