br.com.insula.log4j.sns.SNSAppender.java Source code

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Here is the source code for br.com.insula.log4j.sns.SNSAppender.java

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/*
 *  (C) Copyright 2012 Insula Tecnologia da Informacao Ltda.
 *
 *  This file is part of log4j-sns.
 *
 *  log4j-sns is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  log4j-sns is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with log4j-sns.  If not, see <http://www.gnu.org/licenses/>.
 */
package br.com.insula.log4j.sns;

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.TriggeringEventEvaluator;

import com.amazonaws.AmazonClientException;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.sns.AmazonSNSAsync;
import com.amazonaws.services.sns.AmazonSNSAsyncClient;
import com.amazonaws.services.sns.model.CreateTopicRequest;
import com.amazonaws.services.sns.model.PublishRequest;

public class SNSAppender extends AppenderSkeleton {

    private static final int SNS_MAXIMUM_MESSAGE_SIZE = 64 * 1024;

    private TriggeringEventEvaluator evaluator;

    private AmazonSNSAsync amazonSNSAsync;

    private String topicArn;

    private String accessKey;

    private String secretKey;

    private String topic;

    private String subject;

    public SNSAppender() {
    }

    public SNSAppender(AmazonSNSAsync amazonSNSAsync) {
        this.amazonSNSAsync = amazonSNSAsync;
    }

    @Override
    public void activateOptions() {
        createEvaluatorIfNeeded();
        createAmazonSNSAsyncIfNeeded();
        createTopicArn();
    }

    public boolean checkEntryConditions() {
        if (this.amazonSNSAsync == null) {
            errorHandler.error(String.format("AmazonSNSAsync object not configured for appender [%s].", name));
            return false;
        }
        if (this.evaluator == null) {
            errorHandler.error(String.format("No TriggeringEventEvaluator is set for appender [%s].", name));
            return false;
        }
        if (this.layout == null) {
            errorHandler.error(String.format("No layout set for appender named [%s].", name));
            return false;
        }
        if (this.topic == null) {
            errorHandler.error(String.format("No topic set for appender named [%s].", name));
            return false;
        }
        if (this.subject == null) {
            errorHandler.error(String.format("No subject set for appender named [%s].", name));
            return false;
        }
        return true;
    }

    @Override
    public void close() {
    }

    @Override
    public boolean requiresLayout() {
        return true;
    }

    @Override
    protected void append(LoggingEvent event) {
        if (!checkEntryConditions()) {
            return;
        }
        if (evaluator.isTriggeringEvent(event)) {
            publishMessage(createMessage(event));
        }
    }

    private void createEvaluatorIfNeeded() {
        if (this.evaluator == null) {
            this.evaluator = new QuietPeriodTriggeringEventEvaluator();
        }
    }

    private void createAmazonSNSAsyncIfNeeded() {
        if (this.amazonSNSAsync == null) {
            this.amazonSNSAsync = new AmazonSNSAsyncClient(new BasicAWSCredentials(accessKey, secretKey));
        }
    }

    private void createTopicArn() {
        this.topicArn = amazonSNSAsync.createTopic(new CreateTopicRequest(topic)).getTopicArn();
    }

    private String createMessage(LoggingEvent event) {
        StringBuilder sb = new StringBuilder();
        appendMessageHeader(sb);
        appendMessageEvent(sb, event);
        appendThrowableMessageBody(sb, event);
        appendMessageFooter(sb);
        return cutMessageTextIfExceedsMaximum(sb);
    }

    private void appendMessageHeader(StringBuilder sb) {
        String header = layout.getHeader();
        if (header != null) {
            sb.append(header);
        }
    }

    private void appendMessageEvent(StringBuilder sb, LoggingEvent event) {
        sb.append(layout.format(event));
    }

    private void appendThrowableMessageBody(StringBuilder sb, LoggingEvent event) {
        if (layout.ignoresThrowable()) {
            String[] throwableStrRep = event.getThrowableStrRep();
            if (throwableStrRep != null) {
                for (String line : throwableStrRep) {
                    sb.append(line);
                    sb.append(Layout.LINE_SEP);
                }
            }
        }
    }

    private void appendMessageFooter(StringBuilder sb) {
        String footer = layout.getFooter();
        if (footer != null) {
            sb.append(footer);
        }
    }

    private String cutMessageTextIfExceedsMaximum(StringBuilder sb) {
        if (sb.length() > SNS_MAXIMUM_MESSAGE_SIZE) {
            return sb.substring(0, SNS_MAXIMUM_MESSAGE_SIZE);
        }
        return sb.toString();
    }

    private void publishMessage(String message) {
        try {
            amazonSNSAsync.publishAsync(new PublishRequest(topicArn, message, subject));
        } catch (AmazonClientException ex) {
            errorHandler.error("Unable to publish log message to SNS.");
        }
    }

    public void setEvaluatorClass(String value) {
        this.evaluator = (TriggeringEventEvaluator) OptionConverter.instantiateByClassName(value,
                TriggeringEventEvaluator.class, evaluator);
    }

    public void setAccessKey(String accessKey) {
        this.accessKey = accessKey;
    }

    public void setSecretKey(String secretKey) {
        this.secretKey = secretKey;
    }

    public void setTopic(String topic) {
        this.topic = topic;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

}