Re: [PR] IGNITE-20515 Fix MappedFile.map for JDK 14 and newer. [ignite]

["NSAmelchev (via GitHub)" <gi...@apache.org>]

NSAmelchev commented on code in PR #10961:
URL: https://github.com/apache/ignite/pull/10961#discussion_r1342507741


##########
modules/core/src/main/java/org/apache/ignite/internal/mem/file/MappedFile.java:
##########
@@ -141,14 +134,166 @@ public static long map(RandomAccessFile f, int mode, long start, long size) thro
      * @param size Size of the mapped file.
      */
     public static void unmap(long addr, long size) {
-        try {
-            unmap0.invoke(null, addr, size);
+        mapper.unmap(addr, size);
+    }
+
+    /** */
+    private static Mapper pickMapper() {
+        int javaVersion = majorJavaVersion(jdkVersion());
+
+        if (javaVersion >= 19)
+            return new JDK19Mapper();
+
+        if (javaVersion >= 14)
+            return new JDK14Mapper();
+
+        return new LegacyMapper();
+    }
+
+    /** */
+    private interface Mapper {
+        /** */
+        long map(RandomAccessFile f, int mode, long start, long size) throws IOException;
+
+        /** */
+        void unmap(long addr, long size);
+    }
+
+    /** */
+    private static class LegacyMapper implements Mapper {
+        /** */
+        private static final Method map0 = U.findNonPublicMethod(FileChannelImpl.class, "map0", int.class, long.class, long.class);
+
+        /** */
+        private static final Method unmap0 = U.findNonPublicMethod(FileChannelImpl.class, "unmap0", long.class, long.class);
+
+
+        /** {@inheritDoc} */
+        @Override public long map(RandomAccessFile f, int mode, long start, long size) throws IOException {
+            try {
+                return (Long)map0.invoke(f.getChannel(), mode, start, size);
+            }
+            catch (IllegalAccessException e) {
+                throw new IllegalStateException(e);
+            }
+            catch (InvocationTargetException e) {
+                Throwable target = e.getTargetException();
+                throw (target instanceof IOException) ? (IOException)target : new IOException(target);
+            }
+        }
+
+        /** {@inheritDoc} */
+        @Override public void unmap(long addr, long size) {
+            try {
+                unmap0.invoke(null, addr, size);
+            }
+            catch (IllegalAccessException e) {
+                throw new IllegalStateException(e);
+            }
+            catch (InvocationTargetException e) {
+                throw new IllegalStateException(e.getTargetException());
+            }
         }
-        catch (IllegalAccessException e) {
-            throw new IllegalStateException(e);
+    }
+
+    /** */
+    private static class JDK14Mapper extends LegacyMapper {
+        /** Method {@link FileChannelImpl#map0} has additional parameter since JDK 14, isSync, {@code false} by default. */
+        private static final Method map0 = U.findNonPublicMethod(FileChannelImpl.class, "map0", int.class, long.class,
+                long.class, boolean.class);
+
+        /** {@inheritDoc} */
+        @Override public long map(RandomAccessFile f, int mode, long start, long size) throws IOException {
+            try {
+                return (Long)map0.invoke(f.getChannel(), mode, start, size, false);
+            }
+            catch (IllegalAccessException e) {
+                throw new IllegalStateException(e);
+            }
+            catch (InvocationTargetException e) {
+                Throwable target = e.getTargetException();
+                throw (target instanceof IOException) ? (IOException)target : new IOException(target);
+            }
         }
-        catch (InvocationTargetException e) {
-            throw new IllegalStateException(e.getTargetException());
+    }
+
+    /** */
+    private static class JDK19Mapper implements Mapper {
+        /**  */
+        private static final Method map;
+
+        /** */
+        private static final Method unmap;
+
+        /** */
+        private static final Object dispatcher;
+
+        static {
+            try {
+                // These methods are still in {@link FileChannelImpl} class in JDK 19.
+                Method map0 = U.findNonPublicMethod(FileChannelImpl.class, "map0", FileDescriptor.class, int.class,
+                        long.class, long.class, boolean.class);
+
+                Method unmap0 = U.findNonPublicMethod(FileChannelImpl.class, "unmap0", long.class, long.class);
+
+                if (map0 != null && unmap0 != null) {
+                    map = map0;
+                    unmap = unmap0;
+                    dispatcher = null;
+                }
+                else {
+                    // That methods are moved to {@link sun.nio.ch.FileDispatcher}.
+                    Class<?> fileDispatcherCls = Class.forName("sun.nio.ch.FileDispatcher");
+
+                    dispatcher = U.staticField(FileChannelImpl.class, "nd");
+
+                    map = U.findNonPublicMethod(fileDispatcherCls, "map", FileDescriptor.class, int.class,
+                            long.class, long.class, boolean.class);
+
+                    unmap = U.findNonPublicMethod(fileDispatcherCls, "unmap", long.class, long.class);
+
+                }
+            }
+            catch (ClassNotFoundException | IgniteCheckedException e) {
+                throw new ExceptionInInitializerError(e);
+            }
+        }
+
+        /** {@inheritDoc} */
+        @Override public long map(RandomAccessFile f, int mode, long start, long size) throws IOException {
+            try {
+                Object fd = U.field(f.getChannel(), "fd");
+
+                if (dispatcher != null) {
+                    return (Long)map.invoke(dispatcher, fd, mode, start, size, false);
+                }
+                else
+                    return (Long)map.invoke(f.getChannel(), fd, mode, start, size, false);
+

Review Comment:
   Unnecessary line break



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