Github user cakofony commented on a diff in the pull request:
https://github.com/apache/logging-log4j2/pull/206#discussion_r210293489
--- Diff:
log4j-redis/src/main/java/org/apache/logging/log4j/redis/appender/RedisAppender.java
---
@@ -0,0 +1,244 @@
+/*
+ * 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.logging.log4j.redis.appender;
+
+import org.apache.logging.log4j.core.*;
+import org.apache.logging.log4j.core.appender.AbstractAppender;
+import org.apache.logging.log4j.core.appender.AppenderLoggingException;
+import org.apache.logging.log4j.core.config.Node;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginBuilderAttribute;
+import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
+import
org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
+import org.apache.logging.log4j.core.net.ssl.SslConfiguration;
+import org.apache.logging.log4j.spi.AbstractLogger;
+
+import java.io.Serializable;
+import java.util.Objects;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Sends log events to a Redis Queue. All logs are appended to Redis lists
via the RPUSH command at keys defined
+ * in the configuration.
+ */
+@Plugin(name = "Redis", category = Node.CATEGORY, elementType =
Appender.ELEMENT_TYPE, printObject = true)
+public final class RedisAppender extends AbstractAppender {
+
+ private final RedisManager manager;
+ private final LinkedBlockingQueue<String> logQueue;
+ private final boolean immediateFlush;
+ private final int queueCapacity;
+
+ private RedisAppender(final String name, final Layout<? extends
Serializable> layout, final Filter filter,
+ final boolean ignoreExceptions, boolean
immediateFlush, final int queueCapacity, final RedisManager manager) {
+ super(name, filter, layout, ignoreExceptions);
+ this.manager = Objects.requireNonNull(manager, "Redis Manager");
+ this.immediateFlush = immediateFlush;
+ this.queueCapacity = queueCapacity;
+ this.logQueue = new LinkedBlockingQueue<>(queueCapacity);
+ }
+
+ /**
+ * Builds RedisAppender instances.
+ * @param <B> The type to build
+ */
+ public static class Builder<B extends Builder<B>> extends
AbstractAppender.Builder<B>
+ implements
org.apache.logging.log4j.core.util.Builder<RedisAppender> {
+
+ private final String KEY_SEPARATOR = ",";
+
+ @PluginBuilderAttribute("host")
+ @Required(message = "No Redis hostname provided")
+ private String host;
+
+ @PluginBuilderAttribute("keys")
+ private String keys = "logEvents";
+
+ @PluginBuilderAttribute("port")
+ private int port = 6379;
+
+ @PluginBuilderAttribute("immediateFlush")
+ private boolean immediateFlush = true;
+
+ @PluginBuilderAttribute("queueCapacity")
+ private int queueCapacity = 20;
+
+ @PluginElement("SslConfiguration")
+ private SslConfiguration sslConfiguration;
+
+ @PluginElement("PoolConfiguration")
+ private LoggingJedisPoolConfiguration poolConfiguration =
LoggingJedisPoolConfiguration.defaultConfiguration();
+
+ @SuppressWarnings("resource")
+ @Override
+ public RedisAppender build() {
+ return new RedisAppender(
+ getName(),
+ getLayout(),
+ getFilter(),
+ isIgnoreExceptions(),
+ isImmediateFlush(),
+ getQueueCapacity(),
+ getRedisManager()
+ );
+ }
+
+ String getKeys() {
+ return keys;
+ }
+
+ String getHost() {
+ return host;
+ }
+
+ int getQueueCapacity() {
+ return queueCapacity;
+ }
+
+ boolean isImmediateFlush() {
+ return immediateFlush;
+ }
+
+ SslConfiguration getSslConfiguration() {
+ return sslConfiguration;
+ }
+
+ LoggingJedisPoolConfiguration getPoolConfiguration() {
+ return poolConfiguration;
+ }
+
+ int getPort() {
+ return port;
+ }
+
+ public B setKeys(final String keys) {
+ this.keys = keys;
+ return asBuilder();
+ }
+
+ public B setHost(final String host) {
+ this.host = host;
+ return asBuilder();
+ }
+
+ public B setPort(final int port) {
+ this.port = port;
+ return asBuilder();
+ }
+
+ public B setQueueCapacity(final int queueCapacity) {
+ this.queueCapacity = queueCapacity;
+ return asBuilder();
+ }
+
+ public B setPoolConfiguration(final LoggingJedisPoolConfiguration
poolConfiguration) {
+ this.poolConfiguration = poolConfiguration;
+ return asBuilder();
+ }
+
+ public B setSslConfiguration(final SslConfiguration ssl) {
+ this.sslConfiguration = ssl;
+ return asBuilder();
+ }
+
+ public B setImmediateFlush(final boolean immediateFlush) {
+ this.immediateFlush = immediateFlush;
+ return asBuilder();
+ }
+
+ RedisManager getRedisManager() {
+ return new RedisManager(
+ getConfiguration().getLoggerContext(),
+ getName(),
+ getKeys().split(KEY_SEPARATOR),
+ getHost(),
+ getPort(),
+ getSslConfiguration(),
+ getPoolConfiguration()
+ );
+ }
+ }
+
+ /**
+ * Creates a builder for a RedisAppender.
+ * @return a builder for a RedisAppender.
+ */
+ @PluginBuilderFactory
+ public static <B extends Builder<B>> B newBuilder() {
+ return new Builder<B>().asBuilder();
+ }
+
+ @Override
+ public void append(final LogEvent event) {
+ final Layout<? extends Serializable> layout = getLayout();
+ if (event.getLoggerName() != null &&
AbstractLogger.getRecursionDepth() > 1) {
+ LOGGER.warn("Recursive logging from [{}] for appender [{}].",
event.getLoggerName(), getName());
+ } else if (layout instanceof StringLayout) {
+ logQueue.add(((StringLayout)layout).toSerializable(event));
+ if (shouldFlushLogQueue(event.isEndOfBatch())) {
--- End diff --
There's a race here. Appenders may be used concurrently by multiple
threads, if two events are logged at the same time, one invocation of
`logQueue.add` will throw.
There's a helpful table on this page:
https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingQueue.html
I think we want to use offer, if that fails, we can fall back to flushing
and try again.
---
