Java performance improvements from Apache Lucene

compiler/generator_java.c

@@ -272,7 +272,7 @@ static void generate_AE(struct generator * g, struct node * p) {
             break;
         case c_len: /* Same as size() for Java. */
         case c_size:
-            w(g, "current.length()");
+            w(g, "length");
             break;
     }
 }
@@ -977,9 +977,12 @@ static void generate_define(struct generator * g, struct node * p) {
      * be required to allow the SnowballProgram base class to invoke them.
      * FIXME: Is this avoidable?
      */
-    if (q->type == t_routine && !q->used_in_among) {
+    if (q->used_in_among) {
+        g->S[0] = "public";
+    } else if (q->type == t_routine) {
         g->S[0] = "private";
     } else {
+        w(g, "~N~M@Override");
         g->S[0] = "public";
     }
     g->V[0] = q;
@@ -1192,6 +1195,7 @@ static void generate_class_begin(struct generator * g) {
     w(g, " {~+~N"
          "~N"
          "~Mprivate static final long serialVersionUID = 1L;~N"
+         "~Mprivate static final java.lang.invoke.MethodHandles.Lookup methodObject = java.lang.invoke.MethodHandles.lookup();~N"
          "~N");
 }
 
@@ -1238,7 +1242,7 @@ static void generate_among_table(struct generator * g, struct among * x) {
             if (v->function != 0) {
                 w(g, ", \"");
                 write_varname(g, v->function);
-                w(g, "\", ~n.class");
+                w(g, "\", methodObject");
             }
             w(g, ")~S0~N");
             v++;

java/org/tartarus/snowball/Among.java

@@ -1,7 +1,13 @@
 package org.tartarus.snowball;
 
-import java.lang.reflect.Method;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.util.Locale;
 
+/**
+ * Internal class used by Snowball stemmers
+ */
 public class Among {
     public Among (String s, int substring_i, int result) {
         this.s = s.toCharArray();
@@ -11,19 +17,30 @@ public Among (String s, int substring_i, int result) {
     }
 
     public Among (String s, int substring_i, int result, String methodname,
-		  Class<? extends SnowballProgram> programclass) {
+		  MethodHandles.Lookup methodobject) {
         this.s = s.toCharArray();
         this.substring_i = substring_i;
 	this.result = result;
-	try {
-	    this.method = programclass.getDeclaredMethod(methodname);
-	} catch (NoSuchMethodException e) {
-	    throw new RuntimeException(e);
-	}
+	final Class<? extends SnowballProgram> clazz = methodobject.lookupClass().asSubclass(SnowballProgram.class);
+	if (methodname.length() > 0) {
+	    try {
+	        this.method = methodobject.findVirtual(clazz, methodname, MethodType.methodType(boolean.class))
+	            .asType(MethodType.methodType(boolean.class, SnowballProgram.class));
+	    } catch (NoSuchMethodException | IllegalAccessException e) {
+	        throw new RuntimeException(String.format(Locale.ENGLISH,
+	            "Snowball program '%s' is broken, cannot access method: boolean %s()",
+	            clazz.getSimpleName(), methodname
+	        ), e);
+	    }
+	} else {
+	    this.method = null;
+        }
     }
 
-    public final char[] s; /* search string */
-    public final int substring_i; /* index to longest matching substring */
-    public final int result; /* result of the lookup */
-    public final Method method; /* method to use if substring matches */
+    final char[] s; /* search string */
+    final int substring_i; /* index to longest matching substring */
+    final int result; /* result of the lookup */
+
+    // Make sure this is not accessible outside package for Java security reasons!
+    final MethodHandle method; /* method to use if substring matches */
 };