com.intuit.cto.selfservice.service.RollingLogOutputStream.java Source code

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Here is the source code for com.intuit.cto.selfservice.service.RollingLogOutputStream.java

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/*
 * Copyright (c) 2012 Michael Vorburger
 * All rights reserved.
 *
 * 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.
 *
 * See also http://www.apache.org/licenses/LICENSE-2.0.html for an
 * explanation of the license and how it is applied.
 */
package com.intuit.cto.selfservice.service;

import java.util.Collection;

import org.apache.commons.collections.buffer.CircularFifoBuffer;
import org.apache.commons.exec.LogOutputStream;

/**
 * Rolling Process Output Buffer.
 * 
 * @author Michael Vorburger
 */
// intentionally package local for now
class RollingLogOutputStream extends LogOutputStream {

    private final Collection<String> ringBuffer;

    @SuppressWarnings("unchecked")
    RollingLogOutputStream(int maxLines) {
        ringBuffer = new CircularFifoBuffer(maxLines);
    }

    @Override
    protected void processLine(String line, @SuppressWarnings("unused") int level) {
        ringBuffer.add(line);
    }

    /**
     * Returns recent lines (up to maxLines from constructor).
     * 
     * The implementation is relatively expensive here;
     * the design is intended for many processLine() calls
     * and few getRecentLines().
     * 
     * @return recent Console output
     */
    public String getRecentLines() {
        StringBuilder sb = new StringBuilder();
        for (String line : ringBuffer) {
            if (sb.length() > 0)
                sb.append('\n');
            sb.append(line);
        }
        return sb.toString();
    }

}