Replace generated cleaner code with concrete implementation (elastic#…

…13430)

* Replace generated cleaner code with concrete implementation

No need to to perform codegen to create JDK specific compatible classes to
call the ByteBuffer cleaner, as we are dropping support for Java 8.

* Remove dead/redundant java 8 code from LogstashJavaCompat

Removes setupByteBuffer, specific test for Java9 and above and updates memory monitor
unit test to only test for values relevant to Java>1.8

* Renamed version utility class to reflect use after removal of methods

Also fixed some dead imports

logstash-core/src/main/java/org/logstash/JavaVersionUtils.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.logstash;
+
+/**
+ * Helper Class for dealing with Java versions
+ */
+public final class JavaVersionUtils {
+
+    /**
+     * Identifies whether we are running on a version greater than or equal to the version parameter specified.
+     * @param version The version to test against. This must be the Major version of Java
+     * @return True if running on Java whose major version is greater than or equal to the
+     *         specified version.
+     */
+    public static boolean isJavaAtLeast(int version) {
+        final String value = System.getProperty("java.specification.version");
+        final int actualVersion;
+        // Java specification version prior to Java 9 were of the format `1.X`, and after the format `X`
+        // See https://openjdk.java.net/jeps/223
+        if (value.startsWith("1.")) {
+            actualVersion = Integer.parseInt(value.split("\\.")[1]);
+        } else {
+            actualVersion = Integer.parseInt(value);
+        }
+        return actualVersion >= version;
+    }
+}

logstash-core/src/main/java/org/logstash/ackedqueue/io/ByteBufferCleanerImpl.java

@@ -0,0 +1,26 @@
+package org.logstash.ackedqueue.io;
+
+import java.nio.MappedByteBuffer;
+
+import sun.misc.Unsafe;
+import java.lang.reflect.Field;
+
+public class ByteBufferCleanerImpl implements ByteBufferCleaner {
+
+    private final Unsafe unsafe;
+
+    public ByteBufferCleanerImpl() {
+        try {
+            Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
+            unsafeField.setAccessible(true);
+            unsafe = (Unsafe) unsafeField.get(null);
+        }catch (Exception e){
+            throw new IllegalStateException(e);
+        }
+    }
+
+    @Override
+    public void clean(MappedByteBuffer buffer) {
+        unsafe.invokeCleaner(buffer);
+    }
+}

logstash-core/src/main/java/org/logstash/ackedqueue/io/MmapPageIOV1.java

@@ -29,7 +29,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.zip.CRC32;
-import org.logstash.LogstashJavaCompat;
+
 import org.logstash.ackedqueue.SequencedList;
 
 /**
@@ -43,8 +43,7 @@ public final class MmapPageIOV1 implements PageIO {
     /**
      * Cleaner function for forcing unmapping of backing {@link MmapPageIOV1#buffer}.
      */
-    private static final ByteBufferCleaner BUFFER_CLEANER =
-        LogstashJavaCompat.setupBytebufferCleaner();
+    private static final ByteBufferCleaner BUFFER_CLEANER = new ByteBufferCleanerImpl();
 
     private final File file;
 

logstash-core/src/main/java/org/logstash/ackedqueue/io/MmapPageIOV2.java

@@ -32,7 +32,6 @@
 import java.util.zip.CRC32;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.logstash.LogstashJavaCompat;
 import org.logstash.ackedqueue.SequencedList;
 
 /**
@@ -54,8 +53,7 @@ public final class MmapPageIOV2 implements PageIO {
     /**
      * Cleaner function for forcing unmapping of backing {@link MmapPageIOV2#buffer}.
      */
-    private static final ByteBufferCleaner BUFFER_CLEANER =
-        LogstashJavaCompat.setupBytebufferCleaner();
+    private static final ByteBufferCleaner BUFFER_CLEANER = new ByteBufferCleanerImpl();
 
     private final File file;
 

logstash-core/src/main/java/org/logstash/instrument/monitors/ProcessMonitor.java

@@ -30,8 +30,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.logstash.Logstash;
-import org.logstash.LogstashJavaCompat;
+import org.logstash.JavaVersionUtils;
 
 public class ProcessMonitor {
 
@@ -119,7 +118,7 @@ private short getSystemCpuLoad() {
      */
     private static Method getCpuLoadMethod(){
         try{
-            String methodName = (LogstashJavaCompat.isJavaAtLeast(14)) ? "getCpuLoad" : "getSystemCpuLoad";
+            String methodName = (JavaVersionUtils.isJavaAtLeast(14)) ? "getCpuLoad" : "getSystemCpuLoad";
             return Class.forName("com.sun.management.OperatingSystemMXBean").getMethod(methodName);
         } catch (ReflectiveOperationException e){
             LOGGER.warn("OperatingSystemMXBean CPU load method not available, CPU load will not be measured", e);

logstash-core/src/test/java/org/logstash/instruments/monitors/MemoryMonitorTest.java

@@ -21,7 +21,6 @@
 package org.logstash.instruments.monitors;
 
 import org.junit.Test;
-import org.logstash.LogstashJavaCompat;
 import org.logstash.instrument.monitors.MemoryMonitor;
 
 import java.util.Map;
@@ -38,11 +37,7 @@ public class MemoryMonitorTest {
     public void testEachHeapSpaceRepresented() {
         Map<String, Map<String, Object>> heap = MemoryMonitor.detect(MemoryMonitor.Type.All).getHeap();
         assertThat(heap, notNullValue());
-        if (LogstashJavaCompat.IS_JAVA_9_OR_GREATER) {
-            assertThat(heap.keySet(), hasItems("G1 Old Gen", "G1 Survivor Space", "G1 Eden Space"));
-        } else {
-            assertThat(heap.keySet(), hasItems("PS Survivor Space", "PS Old Gen", "PS Eden Space"));
-        }
+        assertThat(heap.keySet(), hasItems("G1 Old Gen", "G1 Survivor Space", "G1 Eden Space"));
     }
 
     @Test

logstash-core/src/test/java/org/logstash/secret/store/backend/JavaKeyStoreTest.java

@@ -27,7 +27,6 @@
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
-import org.logstash.LogstashJavaCompat;
 import org.logstash.secret.SecretIdentifier;
 import org.logstash.secret.store.SecretStore;
 import org.logstash.secret.store.SecretStoreException;
@@ -48,7 +47,6 @@
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.*;
 import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;