RDBOutputStream.java

package com.splout.db.engine;

/*
 * #%L
 * Splout SQL commons
 * %%
 * Copyright (C) 2012 - 2014 Datasalt Systems S.L.
 * %%
 * Licensed 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.
 * #L%
 */

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class RDBOutputStream {
  OutputStream out;

  public RDBOutputStream(OutputStream out) {
    this.out = out;
  }

  public void close() throws IOException {
    out.flush();
    out.close();
  }

  public void writeHeader() throws IOException {
    out.write("REDIS".getBytes());
    out.write("0001".getBytes());
  }

  public void writeFooter() throws IOException {
    out.write(0xFF);
  }

  public void writeDatabaseSelector(long db) throws IOException {
    out.write(0xFE);
    writeLength(db);
  }

  public void writeString(RDBString key, RDBString value) throws IOException {
    out.write(0x00);
    write(key);
    write(value);
  }

  public void writeList(RDBString key, RDBString[] values) throws IOException {
    out.write(0x01);
    write(key);
    writeLength(values.length);
    for (int i = 0; i < values.length; i++)
      write(values[i]);
  }

  public void writeSet(RDBString key, RDBString[] values) throws IOException {
    out.write(0x02);
    write(key);
    writeLength(values.length);
    for (int i = 0; i < values.length; i++)
      write(values[i]);
  }

  public void writeHash(RDBString key, RDBString[] hashKeys, RDBString[] values) throws IOException {
    if (hashKeys.length != values.length)
      throw new RuntimeException("Must have same number of keys and values");

    out.write(0x04);
    write(key);
    writeLength(hashKeys.length);
    for (int i = 0; i < hashKeys.length; i++) {
      write(hashKeys[i]);
      write(values[i]);
    }
  }

  void write(int b) throws IOException {
    out.write(b);
  }

  void write(byte[] bytes) throws IOException {
    out.write(bytes);
  }

  void write(RDBString string) throws IOException {
    string.write(this);
  }

  void writeLength(long len) throws IOException {
    if (len < (1 << 6)) {
      out.write((int) (len & 0xFF));
    } else if (len < (1 << 14)) {
      out.write((int) (((len >> 8) & 0xFF) | 0x40));
      out.write((int) (len & 0xFF));
    } else if (len < (1L << 32)) {
      out.write(0x80);
      out.write((int) ((len >> 24) & 0xFF));
      out.write((int) ((len >> 16) & 0xFF));
      out.write((int) ((len >> 8) & 0xFF));
      out.write((int) (len & 0xFF));
    } else {
      throw new RuntimeException("length is too long");
    }
  }

  public static void main(String[] args) throws FileNotFoundException, IOException {
    RDBOutputStream rdb = new RDBOutputStream(new FileOutputStream(args[0]));
    rdb.writeHeader();
    rdb.writeDatabaseSelector(0);
    rdb.writeString(
        RDBString.create("foo"),
        RDBString
            .create("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"));
    rdb.writeFooter();
    rdb.close();
  }
}