HDDS-12383. Fix spotbugs warnings in hdds-common & httpfsgateway.

hadoop-hdds/common/dev-support/findbugsExcludeFile.xml

@@ -18,10 +18,6 @@
   <Match>
     <Package name="org.apache.hadoop.hdds.protocol.proto"/>
   </Match>
-  <Match>
-    <Class name="org.apache.hadoop.hdds.cli.GenericCli"></Class>
-    <Bug pattern="DM_EXIT" />
-  </Match>
   <Match>
     <Class name="org.apache.hadoop.ozone.OzoneConsts"/>
     <Bug pattern="DMI_HARDCODED_ABSOLUTE_FILENAME" />

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/cli/GenericCli.java

@@ -29,6 +29,7 @@
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdds.conf.OzoneConfiguration;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.ratis.util.ExitUtils;
 import picocli.CommandLine;
 import picocli.CommandLine.ExitCode;
 import picocli.CommandLine.Option;
@@ -78,7 +79,7 @@ public void run(String[] argv) {
     int exitCode = execute(argv);
 
     if (exitCode != ExitCode.OK) {
-      System.exit(exitCode);
+      ExitUtils.terminate(exitCode, null, null);
     }
   }
 

hadoop-ozone/httpfsgateway/dev-support/findbugsExcludeFile.xml

@@ -15,24 +15,4 @@
    limitations under the License.
 -->
 <FindBugsFilter>
-  <Match>
-    <Class name="org.apache.ozone.lib.service.instrumentation.InstrumentationService" />
-    <Method name="getToAdd" />
-    <Bug pattern="UL_UNRELEASED_LOCK" />
-  </Match>
-  <Match>
-    <Class name="org.apache.ozone.fs.http.server.HttpFSServerWebApp" />
-    <Method name="destroy" />
-    <Bug pattern="ST_WRITE_TO_STATIC_FROM_INSTANCE_METHOD" />
-  </Match>
-  <Match>
-    <Class name="org.apache.ozone.lib.servlet.ServerWebApp" />
-    <Field name="authority" />
-    <Bug pattern="IS2_INCONSISTENT_SYNC" />
-  </Match>
-  <Match>
-    <Class name="org.apache.ozone.lib.service.hadoop.FileSystemAccessService" />
-    <Method name="closeFileSystem" />
-    <Bug pattern="NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE" />
-  </Match>
 </FindBugsFilter>

hadoop-ozone/httpfsgateway/src/main/java/org/apache/ozone/fs/http/server/HttpFSServerWebApp.java

@@ -18,6 +18,7 @@
 package org.apache.ozone.fs.http.server;
 
 import java.io.IOException;
+import java.util.concurrent.atomic.AtomicReference;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.hdds.annotation.InterfaceAudience;
@@ -36,7 +37,7 @@
  * </code> implementation that is wired in HttpFSServer's WAR
  * <code>WEB-INF/web.xml</code>.
  * <p>
- * It provides acces to the server context via the singleton {@link #get}.
+ * It provides access to the server context via the singleton {@link #get}.
  * <p>
  * All the configuration is loaded from configuration properties prefixed
  * with <code>httpfs.</code>.
@@ -56,8 +57,8 @@ public class HttpFSServerWebApp extends ServerWebApp {
    */
   public static final String CONF_ADMIN_GROUP = "admin.group";
 
-  private static HttpFSServerWebApp server;
-  private static HttpFSServerMetrics metrics;
+  private static final AtomicReference<HttpFSServerWebApp> SERVER = new AtomicReference<>();
+  private static final AtomicReference<HttpFSServerMetrics> METRICS = new AtomicReference<>();
 
   private String adminGroup;
 
@@ -80,13 +81,12 @@ public HttpFSServerWebApp() throws IOException {
    */
   @Override
   public void init() throws ServerException {
-    if (server != null) {
+    if (!SERVER.compareAndSet(null, this)) {
       throw new RuntimeException("HttpFSServer server already initialized");
     }
-    server = this;
     super.init();
     adminGroup = getConfig().get(getPrefixedName(CONF_ADMIN_GROUP), "admin");
-    LOG.info("Connects to Namenode [{}]",
+    LOG.info("Connects to FileSystem [{}]",
              get().get(FileSystemAccess.class).getFileSystemConfiguration().
                get(CommonConfigurationKeysPublic.FS_DEFAULT_NAME_KEY));
     setMetrics(getConfig());
@@ -97,7 +97,8 @@ public void init() throws ServerException {
    */
   @Override
   public void destroy() {
-    server = null;
+    SERVER.set(null);
+    HttpFSServerMetrics metrics = METRICS.getAndSet(null);
     if (metrics != null) {
       metrics.shutdown();
     }
@@ -106,11 +107,11 @@ public void destroy() {
 
   private static void setMetrics(Configuration config) {
     LOG.info("Initializing HttpFSServerMetrics");
-    metrics = HttpFSServerMetrics.create(config, "HttpFSServer");
+    METRICS.updateAndGet(prev -> prev != null ? prev : HttpFSServerMetrics.create(config, "HttpFSServer"));
     JvmPauseMonitor pauseMonitor = new JvmPauseMonitor();
     pauseMonitor.init(config);
     pauseMonitor.start();
-    metrics.getJvmMetrics().setPauseMonitor(pauseMonitor);
+    METRICS.get().getJvmMetrics().setPauseMonitor(pauseMonitor);
     FSOperations.setBufferSize(config);
     DefaultMetricsSystem.initialize("HttpFSServer");
   }
@@ -121,15 +122,15 @@ private static void setMetrics(Configuration config) {
    * @return the HttpFSServer server singleton.
    */
   public static HttpFSServerWebApp get() {
-    return server;
+    return SERVER.get();
   }
 
   /**
    * gets the HttpFSServerMetrics instance.
    * @return the HttpFSServerMetrics singleton.
    */
   public static HttpFSServerMetrics getMetrics() {
-    return metrics;
+    return METRICS.get();
   }
 
   /**

hadoop-ozone/httpfsgateway/src/main/java/org/apache/ozone/lib/service/instrumentation/InstrumentationService.java

@@ -129,43 +129,23 @@ private <T> T getToAdd(String group,
                          Class<T> klass,
                          Lock lock,
                          Map<String, Map<String, T>> map) {
-    boolean locked = false;
+    lock.lock();
     try {
-      Map<String, T> groupMap = map.get(group);
-      if (groupMap == null) {
-        lock.lock();
-        locked = true;
-        groupMap = map.get(group);
-        if (groupMap == null) {
-          groupMap = new ConcurrentHashMap<String, T>();
-          map.put(group, groupMap);
-        }
-      }
-      T element = groupMap.get(name);
-      if (element == null) {
-        if (!locked) {
-          lock.lock();
-          locked = true;
-        }
-        element = groupMap.get(name);
-        if (element == null) {
-          try {
-            if (klass == Timer.class) {
-              element = (T) new Timer(timersSize);
-            } else {
-              element = klass.newInstance();
+      return map
+          .computeIfAbsent(group, k -> new ConcurrentHashMap<>())
+          .computeIfAbsent(name, k -> {
+            try {
+              if (klass == Timer.class) {
+                return (T) new Timer(timersSize);
+              } else {
+                return klass.newInstance();
+              }
+            } catch (Exception ex) {
+              throw new RuntimeException(ex);
             }
-          } catch (Exception ex) {
-            throw new RuntimeException(ex);
-          }
-          groupMap.put(name, element);
-        }
-      }
-      return element;
+          });
     } finally {
-      if (locked) {
-        lock.unlock();
-      }
+      lock.unlock();
     }
   }
 

hadoop-ozone/httpfsgateway/src/main/java/org/apache/ozone/lib/servlet/ServerWebApp.java

@@ -191,7 +191,7 @@ public InetSocketAddress getAuthority() throws ServerException {
       if (authority == null) {
         authority = resolveAuthority();
       }
+      return authority;
     }
-    return authority;
   }
 }