MVStore: disabled the file system cache by default, because it limits concurrency

h2/src/docsrc/html/changelog.html

@@ -83,6 +83,10 @@ Change Log
 </li>
 <li>MVStore / transaction store: opening a store in read-only mode does no longer loop.
 </li>
+<li>MVStore: disabled the file system cache by default, because it limits concurrency
+    when using larger databases and many threads.
+    To re-enable, use the file name prefix "cache:".
+</li>
 </ul>
 
 <h2>Version 1.4.192 Beta (2016-05-26)</h2>

h2/src/main/org/h2/mvstore/FileStore.java

@@ -129,6 +129,8 @@ public class FileStore {
             return;
         }
         if (fileName != null) {
+            // ensure the Cache file system is registered
+            FilePathCache.INSTANCE.getScheme();
             FilePath p = FilePath.get(fileName);
             // if no explicit scheme was specified, NIO is used
             if (p instanceof FilePathDisk &&
@@ -156,7 +158,6 @@ public class FileStore {
                 encryptedFile = file;
                 file = new FilePathEncrypt.FileEncrypt(fileName, key, file);
             }
-            file = FilePathCache.wrap(file);
             try {
                 if (readOnly) {
                     fileLock = file.tryLock(0, Long.MAX_VALUE, true);

h2/src/main/org/h2/mvstore/cache/FilePathCache.java

@@ -10,6 +10,7 @@ import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
 import org.h2.store.fs.FileBase;
+import org.h2.store.fs.FilePath;
 import org.h2.store.fs.FilePathWrapper;
 
 /**
@@ -17,6 +18,15 @@ import org.h2.store.fs.FilePathWrapper;
  */
 public class FilePathCache extends FilePathWrapper {
 
+    public static final FilePathCache INSTANCE = new FilePathCache();
+
+    /**
+     * Register the file system.
+     */
+    static {
+        FilePath.register(INSTANCE);
+    }
+
     public static FileChannel wrap(FileChannel f) {
         return new FileCache(f);
     }