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 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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.                                           *
 ****************************************************************/


package org.apache.james.util.watchdog;

import java.io.IOException;
import java.io.InputStream;

/**
 * This will reset the Watchdog each time a certain amount of data has
 * been transferred.  This allows us to keep the timeout settings low, while
 * not timing out during large data transfers.
 */
public class BytesReadResetInputStream extends InputStream {

    /**
     * The wrapped InputStream
     */
    private InputStream in = null;

    /**
     * The Watchdog to be reset every lengthReset bytes
     */
    private Watchdog watchdog;

    /**
     * The number of bytes that need to be read before the counter is reset.
     */
    private int lengthReset = 0;

    /**
     * The number of bytes read since the counter was last reset
     */
    int readCounter = 0;

    /**
     * @param in the InputStream to be wrapped by this stream
     * @param watchdog the watchdog to be reset
     * @param lengthReset the number of bytes to be read in between trigger resets
     */
    public BytesReadResetInputStream(InputStream in,
                                     Watchdog watchdog, 
                                     int lengthReset) {
        this.in = in;
        this.watchdog = watchdog;
        this.lengthReset = lengthReset;

        readCounter = 0;
    }

    /**
     * Read an array of bytes from the stream
     *
     * @param b the array of bytes to read from the stream
     * @param off the index in the array where we start writing
     * @param len the number of bytes of the array to read
     *
     * @return the number of bytes read
     *
     * @throws IOException if an exception is encountered when reading
     */
    public int read(byte[] b, int off, int len) throws IOException {
        int l = in.read(b, off, len);
        readCounter += l;

        if (readCounter > lengthReset) {
            readCounter = 0;
            watchdog.reset();
        }

        return l;
    }

    /**
     * Read a byte from the stream
     *
     * @return the byte read from the stream
     * @throws IOException if an exception is encountered when reading
     */
    public int read() throws IOException {
        int b = in.read();
        readCounter++;

        if (readCounter > lengthReset) {
            readCounter = 0;
            watchdog.reset();
        }

        return b;
    }

    /**
     * Close the stream
     *
     * @throws IOException if an exception is encountered when closing
     */
    public void close() throws IOException {
        in.close();
    }
}