001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.core.appender;
018    
019    import org.apache.logging.log4j.core.Layout;
020    
021    import java.io.IOException;
022    import java.io.OutputStream;
023    
024    /**
025     * Manage an OutputStream so that it can be shared by multiple Appenders and will
026     * allow appenders to reconfigure without requiring a new stream.
027     */
028    public class OutputStreamManager extends AbstractManager {
029    
030        private volatile OutputStream os;
031    
032        private final byte[] footer;
033        private final byte[] header;
034    
035        protected OutputStreamManager(final OutputStream os, final String streamName, final Layout layout) {
036            super(streamName);
037            this.os = os;
038            if (layout != null) {
039                this.footer = layout.getFooter();
040                this.header = layout.getHeader();
041                if (this.header != null) {
042                    try {
043                        this.os.write(header, 0, header.length);
044                    } catch (final IOException ioe) {
045                        LOGGER.error("Unable to write header", ioe);
046                    }
047                }
048            } else {
049                this.footer = null;
050                this.header = null;
051            }
052        }
053    
054        /**
055         * Create a Manager.
056         *
057         * @param name The name of the stream to manage.
058         * @param data The data to pass to the Manager.
059         * @param factory The factory to use to create the Manager.
060         * @param <T> The type of the OutputStreamManager.
061         * @return An OutputStreamManager.
062         */
063        public static <T> OutputStreamManager getManager(final String name, final T data,
064                                                     final ManagerFactory<? extends OutputStreamManager, T> factory) {
065            return AbstractManager.getManager(name, factory, data);
066        }
067    
068        /**
069         * Default hook to write footer during close.
070         */
071        @Override
072        public void releaseSub() {
073            if (footer != null) {
074                write(footer);
075            }
076            close();
077        }
078    
079        /**
080         * Returns the status of the stream.
081         * @return true if the stream is open, false if it is not.
082         */
083        public boolean isOpen() {
084            return getCount() > 0;
085        }
086    
087        protected OutputStream getOutputStream() {
088            return os;
089        }
090    
091        protected void setOutputStream(final OutputStream os) {
092            if (header != null) {
093                try {
094                    os.write(header, 0, header.length);
095                    this.os = os; // only update field if os.write() succeeded
096                } catch (final IOException ioe) {
097                    LOGGER.error("Unable to write header", ioe);
098                }
099            } else {
100                this.os = os;
101            }
102        }
103    
104        /**
105         * Some output streams synchronize writes while others do not. Synchronizing here insures that
106         * log events won't be intertwined.
107         * @param bytes The serialized Log event.
108         * @param offset The offset into the byte array.
109         * @param length The number of bytes to write.
110         * @throws AppenderRuntimeException if an error occurs.
111         */
112        protected synchronized void write(final byte[] bytes, final int offset, final int length)  {
113            //System.out.println("write " + count);
114            try {
115                os.write(bytes, offset, length);
116            } catch (final IOException ex) {
117                final String msg = "Error writing to stream " + getName();
118                throw new AppenderRuntimeException(msg, ex);
119            }
120        }
121    
122        /**
123         * Some output streams synchronize writes while others do not. Synchronizing here insures that
124         * log events won't be intertwined.
125         * @param bytes The serialized Log event.
126         * @throws AppenderRuntimeException if an error occurs.
127         */
128        protected void write(final byte[] bytes)  {
129            write(bytes, 0, bytes.length);
130        }
131    
132        protected void close() {
133            OutputStream stream = os; // access volatile field only once per method
134            if (stream == System.out || stream == System.err) {
135                return;
136            }
137            try {
138                stream.close();
139            } catch (final IOException ex) {
140                LOGGER.error("Unable to close stream " + getName() + ". " + ex);
141            }
142        }
143    
144        /**
145         * Flush any buffers.
146         */
147        public void flush() {
148            try {
149                os.flush();
150            } catch (final IOException ex) {
151                final String msg = "Error flushing stream " + getName();
152                throw new AppenderRuntimeException(msg, ex);
153            }
154        }
155    }