A persistent multi-version map: move to the main source tree

h2/src/tools/org/h2/dev/store/cache/FilePathCache.java

-/*
- * Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
- * Version 1.0, and under the Eclipse Public License, Version 1.0
- * (http://h2database.com/html/license.html).
- * Initial Developer: H2 Group
- */
-package org.h2.dev.store.cache;
-
-import java.io.IOException;
-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.FilePathWrapper;
-
-/**
- * A file with a read cache.
- */
-public class FilePathCache extends FilePathWrapper {
-
-    public static FileChannel wrap(FileChannel f) {
-        return new FileCache(f);
-    }
-
-    public FileChannel open(String mode) throws IOException {
-        return new FileCache(getBase().open(mode));
-    }
-
-    public String getScheme() {
-        return "cache";
-    }
-
-    /**
-     * A file with a read cache.
-     */
-    public static class FileCache extends FileBase {
-
-        private static final int CACHE_BLOCK_SIZE = 4 * 1024;
-        private final FileChannel base;
-        // 1 MB (256 * 4 * 1024)
-        private final CacheLongKeyLIRS<ByteBuffer> cache =
-                CacheLongKeyLIRS.newInstance(256);
-
-        FileCache(FileChannel base) {
-            this.base = base;
-        }
-
-        protected void implCloseChannel() throws IOException {
-            base.close();
-        }
-
-        public FileChannel position(long newPosition) throws IOException {
-            base.position(newPosition);
-            return this;
-        }
-
-        public long position() throws IOException {
-            return base.position();
-        }
-
-        public int read(ByteBuffer dst) throws IOException {
-            return base.read(dst);
-        }
-
-        public int read(ByteBuffer dst, long position) throws IOException {
-            long cachePos = getCachePos(position);
-            int off = (int) (position - cachePos);
-            int len = CACHE_BLOCK_SIZE - off;
-            ByteBuffer buff = cache.get(cachePos);
-            if (buff == null) {
-                buff = ByteBuffer.allocate(CACHE_BLOCK_SIZE);
-                int read = base.read(buff, cachePos);
-                if (read == CACHE_BLOCK_SIZE) {
-                    cache.put(cachePos, buff);
-                } else {
-                    if (read < 0) {
-                        return -1;
-                    }
-                    len = Math.min(len, read);
-                }
-            }
-            len = Math.min(len, dst.remaining());
-            System.arraycopy(buff.array(), off, dst.array(), dst.position(), len);
-            dst.position(dst.position() + len);
-            return len;
-        }
-
-        private static long getCachePos(long pos) {
-            return (pos / CACHE_BLOCK_SIZE) * CACHE_BLOCK_SIZE;
-        }
-
-        public long size() throws IOException {
-            return base.size();
-        }
-
-        public FileChannel truncate(long newSize) throws IOException {
-            cache.clear();
-            base.truncate(newSize);
-            return this;
-        }
-
-        public int write(ByteBuffer src, long position) throws IOException {
-            if (cache.size() > 0) {
-                int len = src.remaining();
-                long p = getCachePos(position);
-                while (len > 0) {
-                    cache.remove(p);
-                    p += CACHE_BLOCK_SIZE;
-                    len -= CACHE_BLOCK_SIZE;
-                }
-            }
-            return base.write(src, position);
-        }
-
-        public int write(ByteBuffer src) throws IOException {
-            throw new UnsupportedOperationException();
-            // return base.write(src);
-        }
-
-        public void force(boolean metaData) throws IOException {
-            base.force(metaData);
-        }
-
-        public FileLock tryLock(long position, long size, boolean shared) throws IOException {
-            return base.tryLock(position, size, shared);
-        }
-
-        public String toString() {
-            return "cache:" + base.toString();
-        }
-
-    }
-
-}

h2/src/tools/org/h2/dev/store/cache/package.html

-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
-<!--
-Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License, Version 1.0,
-and under the Eclipse Public License, Version 1.0
-(http://h2database.com/html/license.html).
-Initial Developer: H2 Group
--->
-<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
-<head><meta http-equiv="Content-Type" content="text/html;charset=utf-8" /><title>
-Javadoc package documentation
-</title></head><body style="font: 9pt/130% Tahoma, Arial, Helvetica, sans-serif; font-weight: normal;"><p>
-
-Classes related to caching.
-
-</p></body></html>
\ No newline at end of file