HDFS-15720 namenode audit async logger should add some log4j config (#2532)

(cherry picked from commit 9bd3c9bc50)
(cherry picked from commit bc5458bbd4)
(cherry picked from commit 9123f9245c)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -597,6 +597,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final boolean DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_DEFAULT = false;
   public static final String  DFS_NAMENODE_AUDIT_LOG_ASYNC_KEY = "dfs.namenode.audit.log.async";
   public static final boolean DFS_NAMENODE_AUDIT_LOG_ASYNC_DEFAULT = false;
+  public static final String  DFS_NAMENODE_AUDIT_LOG_ASYNC_BLOCKING_KEY = "dfs.namenode.audit.log.async.blocking";
+  public static final boolean DFS_NAMENODE_AUDIT_LOG_ASYNC_BLOCKING_DEFAULT = true;
+  public static final String  DFS_NAMENODE_AUDIT_LOG_ASYNC_BUFFER_SIZE_KEY = "dfs.namenode.audit.log.async.buffer.size";
+  public static final int     DFS_NAMENODE_AUDIT_LOG_ASYNC_BUFFER_SIZE_DEFAULT = 128;
   public static final String  DFS_NAMENODE_AUDIT_LOG_DEBUG_CMDLIST = "dfs.namenode.audit.log.debug.cmdlist";
   public static final String  DFS_NAMENODE_METRICS_LOGGER_PERIOD_SECONDS_KEY =
       "dfs.namenode.metrics.logger.period.seconds";

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -783,7 +783,7 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     if (conf.getBoolean(DFS_NAMENODE_AUDIT_LOG_ASYNC_KEY,
                         DFS_NAMENODE_AUDIT_LOG_ASYNC_DEFAULT)) {
       LOG.info("Enabling async auditlog");
-      enableAsyncAuditLog();
+      enableAsyncAuditLog(conf);
     }
     fsLock = new FSNamesystemLock(conf, detailedLockHoldTimeMetrics);
     cond = fsLock.newWriteLockCondition();
@@ -8019,7 +8019,7 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     }
   }
 
-  private static void enableAsyncAuditLog() {
+  private static void enableAsyncAuditLog(Configuration conf) {
     if (!(auditLog instanceof Log4JLogger)) {
       LOG.warn("Log4j is required to enable async auditlog");
       return;
@@ -8030,6 +8030,14 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     // failsafe against trying to async it more than once
     if (!appenders.isEmpty() && !(appenders.get(0) instanceof AsyncAppender)) {
       AsyncAppender asyncAppender = new AsyncAppender();
+      asyncAppender.setBlocking(conf.getBoolean(
+          DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_BLOCKING_KEY,
+          DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_BLOCKING_DEFAULT
+      ));
+      asyncAppender.setBufferSize(conf.getInt(
+          DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_BUFFER_SIZE_KEY,
+          DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_BUFFER_SIZE_DEFAULT
+      ));
       // change logger to have an async appender containing all the
       // previously configured appenders
       for (Appender appender : appenders) {

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -4339,6 +4339,27 @@
   </description>
 </property>
 
+<property>
+  <name>dfs.namenode.audit.log.async.blocking</name>
+  <value>true</value>
+  <description>
+    Only used when enables asynchronous audit log. Sets whether audit log async
+    appender should wait if there is no space available in the event buffer or
+    immediately return. Default value is true.
+  </description>
+</property>
+
+<property>
+  <name>dfs.namenode.audit.log.async.buffer.size</name>
+  <value>128</value>
+  <description>
+    Only used when enables asynchronous audit log. Sets the number of audit
+    logs allowed in the event buffer before the calling thread is blocked
+    (if dfs.namenode.audit.log.async.blocking is true) or until logs are
+    summarized and discarded. Default value is 128.
+  </description>
+</property>
+
 <property>
   <name>dfs.namenode.audit.log.token.tracking.id</name>
   <value>false</value>