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/*
 * @test
 * @bug 8249719
 * @summary ResolvedMethodTable hash function should take method class into account
 * @requires vm.flagless
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 *          java.management
 * @run driver ResolvedMethodTableHash
 */

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;

// The test generates a thousand MethodHandles to the methods of the same name
// and the same signature. The rehash warning shouldn't be returned, unless Method hash
// function takes only the name and the signature as an input.
public class ResolvedMethodTableHash {

    public static class ResolvedMethodTableHashTest extends ClassLoader {
        // Generate a MethodHandle for ClassName.m()
        private MethodHandle generate(String className) throws ReflectiveOperationException {
            byte[] buf = new byte[100];
            int size = writeClass(buf, className);
            Class<?> cls = defineClass(null, buf, 0, size);
            return MethodHandles.publicLookup().findStatic(cls, "m", MethodType.methodType(void.class));
        }

        private MethodHandle generateWithSameName() throws ReflectiveOperationException {
            byte[] buf = new byte[100];
            int size = writeClass(buf, "MH$$");
            // use different classloader instances to load the classes with the same name
            Class<?> cls = new ResolvedMethodTableHashTest().defineClass(null, buf, 0, size);
            return MethodHandles.publicLookup().findStatic(cls, "m", MethodType.methodType(void.class));
        }

        // Produce a class file with the given name and a single method:
        //         public static native void m();
        private int writeClass(byte[] buf, String className) {
            return ByteBuffer.wrap(buf)
                .putInt(0xCAFEBABE)           // magic
                .putInt(50)                           // version: 50
                .putShort((short) 7)          // constant_pool_count: 7
                .put((byte) 7).putShort((short) 2)
                .put((byte) 1).putShort((short) className.length()).put(className.getBytes())
                .put((byte) 7).putShort((short) 4)
                .put((byte) 1).putShort((short) 16).put("java/lang/Object".getBytes())
                .put((byte) 1).putShort((short) 1).put("m".getBytes())
                .put((byte) 1).putShort((short) 3).put("()V".getBytes())
                .putShort((short) 0x21)   // access_flags: public super
                .putShort((short) 1)          // this_class: #1
                .putShort((short) 3)          // super_class: #3
                .putShort((short) 0)          // interfaces_count: 0
                .putShort((short) 0)          // fields_count: 0
                .putShort((short) 1)          // methods_count: 1
                .putShort((short) 0x109)  //   access_flags: public static native
                .putShort((short) 5)          //   name_index: #5
                .putShort((short) 6)          //   descriptor_index: #6
                .putShort((short) 0)          //   attributes_count: 0
                .putShort((short) 0)          // attributes_count: 0
                .position();
        }

        public static void main(String[] args) throws Exception {

            ResolvedMethodTableHashTest generator = new ResolvedMethodTableHashTest();
            List<MethodHandle> handles = new ArrayList<>();

            int count = 1001;

            for (int i = 0; i < count; i++) {
                // prevents metaspace oom
                if (i % 20 != 0) {
                    handles.add(generator.generate("MH$" + i));
                } else {
                    handles.add(generator.generateWithSameName());
                }
                if (i % 1000 == 0) {
                    System.out.println("Generated " + i + " handles");
                }
            }

            System.out.println("Test passed");
        }
    }

    public static void main(String[] args) throws Exception {

        // Running the table with only 1000 entries should not provoke a needs rehash warning, unless the hash code is bad.
        ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder("-Xlog:membername+table",
                                                                             ResolvedMethodTableHashTest.class.getName());
        OutputAnalyzer output = new OutputAnalyzer(pb.start());
        output.shouldNotContain("[membername,table] Rehash warning, load factor");
        output.shouldContain("Generated 1000 handles");
        output.shouldHaveExitValue(0);
    }
}