HADOOP-16578 : Avoid FileSystem API calls when FileSystem already exists

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AzureBlobFileSystem.java

@@ -55,6 +55,7 @@ import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.PathIOException;
+import org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants;
 import org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations;
 import org.apache.hadoop.fs.azurebfs.constants.FileSystemUriSchemes;
 import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AbfsRestOperationException;
@@ -107,7 +108,7 @@ public class AzureBlobFileSystem extends FileSystem {
     this.setWorkingDirectory(this.getHomeDirectory());
 
     if (abfsConfiguration.getCreateRemoteFileSystemDuringInitialization()) {
-      if (!this.fileSystemExists()) {
+      if (this.tryGetFileStatus(new Path(AbfsHttpConstants.ROOT_PATH)) == null) {
         try {
           this.createFileSystem();
         } catch (AzureBlobFileSystemException ex) {

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/ITestGetNameSpaceEnabled.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.fs.azurebfs;
 
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.UUID;
 
@@ -25,6 +26,7 @@ import org.junit.Assume;
 import org.junit.Test;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.azurebfs.contracts.exceptions.AbfsRestOperationException;
 import org.apache.hadoop.fs.azurebfs.services.AuthType;
 
@@ -68,12 +70,12 @@ public class ITestGetNameSpaceEnabled extends AbstractAbfsIntegrationTest {
             + testUri.substring(testUri.indexOf("@"));
     final AzureBlobFileSystem fs = this.getFileSystem(nonExistingFsUrl);
 
-    intercept(AbfsRestOperationException.class,
+    intercept(FileNotFoundException.class,
             "\"The specified filesystem does not exist.\", 404",
         new LambdaTestUtils.VoidCallable() {
           @Override
           public void call() throws Exception {
-            fs.getIsNamespaceEnabled();
+            fs.getFileStatus(new Path("/")); // Run a dummy FS call
           }
         });
   }