try to unmap files when done

core/src/main/groovy/com/muwire/core/download/DownloadSession.groovy

@@ -198,6 +198,7 @@ class DownloadSession {
 
                 mapped.clear()
                 digest.update(mapped)
+                DataUtil.tryUnmap(mapped)
                 byte [] hash = digest.digest()
                 byte [] expected = new byte[32]
                 System.arraycopy(infoHash.getHashList(), piece * 32, expected, 0, 32)

core/src/main/groovy/com/muwire/core/files/FileHasher.groovy

@@ -1,6 +1,7 @@
 package com.muwire.core.files
 
 import com.muwire.core.InfoHash
+import com.muwire.core.util.DataUtil
 
 import net.i2p.data.Base64
 
@@ -59,6 +60,7 @@ class FileHasher {
 			for (int i = 0; i < numPieces - 1; i++) {
 				buf = raf.getChannel().map(MapMode.READ_ONLY, ((long)size) * i, size)
 				digest.update buf
+                DataUtil.tryUnmap(buf)
 				output.write(digest.digest(), 0, 32)
 			}
 			def lastPieceLength = length - (numPieces - 1) * ((long)size)

core/src/main/groovy/com/muwire/core/upload/ContentUploader.groovy

@@ -56,7 +56,7 @@ class ContentUploader extends Uploader {
         writeMesh(request.downloader)
         os.write("\r\n".getBytes(StandardCharsets.US_ASCII))
         
-        FileChannel channel
+        FileChannel channel = null
         try {
             channel = Files.newByteChannel(file.toPath(), EnumSet.of(StandardOpenOption.READ))
             mapped = channel.map(FileChannel.MapMode.READ_ONLY, range.start, range.end - range.start + 1)
@@ -72,6 +72,10 @@ class ContentUploader extends Uploader {
         } finally {
             try {channel?.close() } catch (IOException ignored) {}
             endpoint.getOutputStream().flush()
+            synchronized(this) {
+                DataUtil.tryUnmap(mapped)
+                mapped = null
+            }
         }
     }
     

core/src/main/groovy/com/muwire/core/util/DataUtil.groovy

@@ -1,5 +1,8 @@
 package com.muwire.core.util
 
+import java.lang.reflect.Field
+import java.lang.reflect.Method
+import java.nio.ByteBuffer
 import java.nio.charset.StandardCharsets
 
 import com.muwire.core.Constants
@@ -115,4 +118,39 @@ class DataUtil {
             e = e.getCause()
         e
     }
+    
+    public static void tryUnmap(ByteBuffer cb) {
+        if (cb==null || !cb.isDirect()) return;
+        // we could use this type cast and call functions without reflection code,
+        // but static import from sun.* package is risky for non-SUN virtual machine.
+        //try { ((sun.nio.ch.DirectBuffer)cb).cleaner().clean(); } catch (Exception ex) { }
+    
+        // JavaSpecVer: 1.6, 1.7, 1.8, 9, 10
+        boolean isOldJDK = System.getProperty("java.specification.version","99").startsWith("1.");
+        try {
+            if (isOldJDK) {
+                Method cleaner = cb.getClass().getMethod("cleaner");
+                cleaner.setAccessible(true);
+                Method clean = Class.forName("sun.misc.Cleaner").getMethod("clean");
+                clean.setAccessible(true);
+                clean.invoke(cleaner.invoke(cb));
+            } else {
+                Class unsafeClass;
+                try {
+                    unsafeClass = Class.forName("sun.misc.Unsafe");
+                } catch(Exception ex) {
+                    // jdk.internal.misc.Unsafe doesn't yet have an invokeCleaner() method,
+                    // but that method should be added if sun.misc.Unsafe is removed.
+                    unsafeClass = Class.forName("jdk.internal.misc.Unsafe");
+                }
+                Method clean = unsafeClass.getMethod("invokeCleaner", ByteBuffer.class);
+                clean.setAccessible(true);
+                Field theUnsafeField = unsafeClass.getDeclaredField("theUnsafe");
+                theUnsafeField.setAccessible(true);
+                Object theUnsafe = theUnsafeField.get(null);
+                clean.invoke(theUnsafe, cb);
+            }
+        } catch(Exception ex) { }
+        cb = null;
+    }
 }