HADOOP-19072. S3A: expand optimisations on stores with "fs.s3a.performance.flags" for mkdir (#6543)

If the flag list in fs.s3a.performance.flags includes "mkdir"
then the safety check of a walk up the tree to look for a parent directory,
-done to verify a directory isn't being created under a file- are skipped.

This saves the cost of multiple list operations.

Contributed by Viraj Jasani

Author: virajjasani

hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdataoutputstreambuilder.md

@@ -200,8 +200,8 @@ Prioritize file creation performance over safety checks for filesystem consisten
 This:
 1. Skips the `LIST` call which makes sure a file is being created over a directory.
    Risk: a file is created over a directory.
-1. Ignores the overwrite flag.
-1. Never issues a `DELETE` call to delete parent directory markers.
+2. Ignores the overwrite flag.
+3. Never issues a `DELETE` call to delete parent directory markers.
 
 It is possible to probe an S3A Filesystem instance for this capability through
 the `hasPathCapability(path, "fs.s3a.create.performance")` check.

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/FileContextCreateMkdirBaseTest.java

@@ -27,6 +27,7 @@
 import static org.apache.hadoop.fs.FileContextTestHelper.*;
 import static org.apache.hadoop.fs.contract.ContractTestUtils.assertIsDirectory;
 import static org.apache.hadoop.fs.contract.ContractTestUtils.assertIsFile;
+import static org.apache.hadoop.test.LambdaTestUtils.intercept;
 
 import org.apache.hadoop.test.GenericTestUtils;
 import org.slf4j.event.Level;
@@ -55,7 +56,10 @@ public abstract class FileContextCreateMkdirBaseTest {
 
   protected final FileContextTestHelper fileContextTestHelper;
   protected static FileContext fc;
-      
+
+  public static final String MKDIR_FILE_PRESENT_ERROR =
+      " should have failed as a file was present";
+
   static {
     GenericTestUtils.setLogLevel(FileSystem.LOG, Level.DEBUG);
   }
@@ -128,7 +132,7 @@ public void testMkdirsRecursiveWithExistingDir() throws IOException {
   }
 
   @Test
-  public void testMkdirRecursiveWithExistingFile() throws IOException {
+  public void testMkdirRecursiveWithExistingFile() throws Exception {
     Path f = getTestRootPath(fc, "NonExistant3/aDir");
     fc.mkdir(f, FileContext.DEFAULT_PERM, true);
     assertIsDirectory(fc.getFileStatus(f));
@@ -141,13 +145,12 @@ public void testMkdirRecursiveWithExistingFile() throws IOException {
 
     // try creating another folder which conflicts with filePath
     Path dirPath = new Path(filePath, "bDir/cDir");
-    try {
-      fc.mkdir(dirPath, FileContext.DEFAULT_PERM, true);
-      Assert.fail("Mkdir for " + dirPath
-          + " should have failed as a file was present");
-    } catch(IOException e) {
-      // failed as expected
-    }
+    intercept(
+        IOException.class,
+        null,
+        "Mkdir for " + dirPath + MKDIR_FILE_PRESENT_ERROR,
+        () -> fc.mkdir(dirPath, FileContext.DEFAULT_PERM, true)
+    );
   }
 
   @Test

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractMkdirTest.java

@@ -35,6 +35,9 @@
  */
 public abstract class AbstractContractMkdirTest extends AbstractFSContractTestBase {
 
+  public static final String MKDIRS_NOT_FAILED_OVER_FILE =
+      "mkdirs did not fail over a file but returned ";
+
   @Test
   public void testMkDirRmDir() throws Throwable {
     FileSystem fs = getFileSystem();
@@ -66,7 +69,7 @@ public void testNoMkdirOverFile() throws Throwable {
     createFile(getFileSystem(), path, false, dataset);
     try {
       boolean made = fs.mkdirs(path);
-      fail("mkdirs did not fail over a file but returned " + made
+      fail(MKDIRS_NOT_FAILED_OVER_FILE + made
             + "; " + ls(path));
     } catch (ParentNotDirectoryException | FileAlreadyExistsException e) {
       //parent is a directory
@@ -93,7 +96,7 @@ public void testMkdirOverParentFile() throws Throwable {
     Path child = new Path(path,"child-to-mkdir");
     try {
       boolean made = fs.mkdirs(child);
-      fail("mkdirs did not fail over a file but returned " + made
+      fail(MKDIRS_NOT_FAILED_OVER_FILE + made
            + "; " + ls(path));
     } catch (ParentNotDirectoryException | FileAlreadyExistsException e) {
       //parent is a directory

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AFileSystem.java

@@ -3828,7 +3828,8 @@ public boolean mkdirs(Path p, FsPermission permission) throws IOException,
             createStoreContext(),
             path,
             createMkdirOperationCallbacks(),
-            isMagicCommitPath(path)));
+            isMagicCommitPath(path),
+            performanceFlags.enabled(PerformanceFlagEnum.Mkdir)));
   }
 
   /**
@@ -4281,7 +4282,9 @@ public boolean createEmptyDir(Path path, StoreContext storeContext)
           new MkdirOperation(
               storeContext,
               path,
-              createMkdirOperationCallbacks(), false));
+              createMkdirOperationCallbacks(),
+              false,
+              performanceFlags.enabled(PerformanceFlagEnum.Mkdir)));
     }
   }
 

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/impl/MkdirOperation.java

@@ -26,6 +26,8 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.FileAlreadyExistsException;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Path;
@@ -54,30 +56,54 @@
  *   <li>If needed, one PUT</li>
  * </ol>
  */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
 public class MkdirOperation extends ExecutingStoreOperation<Boolean> {
 
   private static final Logger LOG = LoggerFactory.getLogger(
       MkdirOperation.class);
 
+  /**
+   * Path of the directory to be created.
+   */
   private final Path dir;
 
+  /**
+   * Mkdir Callbacks object to be used by the Mkdir operation.
+   */
   private final MkdirCallbacks callbacks;
 
   /**
-   * Should checks for ancestors existing be skipped?
-   * This flag is set when working with magic directories.
+   * Whether to skip the validation of the parent directory.
+   */
+  private final boolean performanceMkdir;
+
+  /**
+   * Whether the path is magic commit path.
    */
   private final boolean isMagicPath;
 
+  /**
+   * Initialize Mkdir Operation context for S3A.
+   *
+   * @param storeContext Store context.
+   * @param dir Dir path of the directory.
+   * @param callbacks MkdirCallbacks object used by the Mkdir operation.
+   * @param isMagicPath True if the path is magic commit path.
+   * @param performanceMkdir If true, skip validation of the parent directory
+   * structure.
+   */
   public MkdirOperation(
       final StoreContext storeContext,
       final Path dir,
       final MkdirCallbacks callbacks,
-      final boolean isMagicPath) {
+      final boolean isMagicPath,
+      final boolean performanceMkdir) {
     super(storeContext);
     this.dir = dir;
     this.callbacks = callbacks;
     this.isMagicPath = isMagicPath;
+    this.performanceMkdir = performanceMkdir;
   }
 
   /**
@@ -124,7 +150,32 @@ public Boolean execute() throws IOException {
       return true;
     }
 
-    // Walk path to root, ensuring closest ancestor is a directory, not file
+    // if performance creation mode is set, no need to check
+    // whether the closest ancestor is dir.
+    if (!performanceMkdir) {
+      verifyFileStatusOfClosestAncestor();
+    }
+
+    // if we get here there is no directory at the destination.
+    // so create one.
+
+    // Create the marker file, delete the parent entries
+    // if the filesystem isn't configured to retain them
+    callbacks.createFakeDirectory(dir, false);
+    return true;
+  }
+
+  /**
+   * Verify the file status of the closest ancestor, if it is
+   * dir, the mkdir operation should proceed. If it is file,
+   * the mkdir operation should throw error.
+   *
+   * @throws IOException If either file status could not be retrieved,
+   * or if the closest ancestor is a file.
+   */
+  private void verifyFileStatusOfClosestAncestor() throws IOException {
+    FileStatus fileStatus;
+    // Walk path to root, ensuring the closest ancestor is a directory, not file
     Path fPart = dir.getParent();
     try {
       while (fPart != null && !fPart.isRoot()) {
@@ -140,24 +191,18 @@ public Boolean execute() throws IOException {
         }
 
         // there's a file at the parent entry
-        throw new FileAlreadyExistsException(String.format(
-            "Can't make directory for path '%s' since it is a file.",
-            fPart));
+        throw new FileAlreadyExistsException(
+            String.format(
+                "Can't make directory for path '%s' since it is a file.",
+                fPart));
       }
     } catch (AccessDeniedException e) {
       LOG.info("mkdirs({}}: Access denied when looking"
               + " for parent directory {}; skipping checks",
-          dir, fPart);
+          dir,
+          fPart);
       LOG.debug("{}", e, e);
     }
-
-    // if we get here there is no directory at the destination.
-    // so create one.
-
-    // Create the marker file, delete the parent entries
-    // if the filesystem isn't configured to retain them
-    callbacks.createFakeDirectory(dir, false);
-    return true;
   }
 
   /**

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/performance.md

@@ -299,8 +299,11 @@ understands the risks.
 | *Option* | *Meaning*          | Since |
 |----------|--------------------|:------|
 | `create` | Create Performance | 3.4.1 |
+| `mkdir`  | Mkdir Performance  | 3.4.1 |
 
-The `create` flag has the same semantics as [`fs.s3a.create.performance`](#create-performance)
+
+* The `create` flag has the same semantics as [`fs.s3a.create.performance`](#create-performance)
+* The `mkdir` flag semantics are explained in [Mkdir Performance](#mkdir-performance)
 
 
 ### <a name="create-performance"></a> Create Performance `fs.s3a.create.performance`
@@ -321,6 +324,22 @@ It may however result in
 
 Use with care, and, ideally, enable versioning on the S3 store.
 
+
+### <a name="mkdir-performance"></a> Mkdir Performance
+
+`fs.s3a.performance.flag` flag option `mkdir`:
+
+* Mkdir does not check whether the parent is directory or file.
+
+This avoids the verification of the file status of the parent file
+or the closest ancestor. Unlike the default mkdir operation, if the
+parent is not a directory, the mkdir operation does not throw any
+error.
+
+This option can help with mkdir performance improvement but must be used
+only if the person setting them understands the above-mentioned risk.
+
+
 ### <a name="threads"></a> Thread and connection pool settings.
 
 Each S3A client interacting with a single bucket, as a single user, has its

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/contract/s3a/ITestS3AContractMkdir.java

@@ -22,11 +22,22 @@
 import org.apache.hadoop.fs.contract.AbstractContractMkdirTest;
 import org.apache.hadoop.fs.contract.AbstractFSContract;
 
+import static org.apache.hadoop.fs.s3a.Constants.FS_S3A_CREATE_PERFORMANCE;
+import static org.apache.hadoop.fs.s3a.S3ATestUtils.removeBaseAndBucketOverrides;
+
 /**
  * Test dir operations on S3A.
  */
 public class ITestS3AContractMkdir extends AbstractContractMkdirTest {
 
+  @Override
+  protected Configuration createConfiguration() {
+    Configuration conf = super.createConfiguration();
+    removeBaseAndBucketOverrides(conf,
+        FS_S3A_CREATE_PERFORMANCE);
+    return conf;
+  }
+
   @Override
   protected AbstractFSContract createContract(Configuration conf) {
     return new S3AContract(conf);

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/contract/s3a/ITestS3AContractMkdirWithCreatePerf.java

@@ -0,0 +1,75 @@
+/*
+ * 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.hadoop.fs.contract.s3a;
+
+import org.junit.Test;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.contract.AbstractContractMkdirTest;
+import org.apache.hadoop.fs.contract.AbstractFSContract;
+import org.apache.hadoop.fs.contract.ContractTestUtils;
+
+import static org.apache.hadoop.fs.contract.ContractTestUtils.createFile;
+import static org.apache.hadoop.fs.contract.ContractTestUtils.dataset;
+import static org.apache.hadoop.fs.s3a.Constants.FS_S3A_CREATE_PERFORMANCE;
+import static org.apache.hadoop.fs.s3a.Constants.FS_S3A_PERFORMANCE_FLAGS;
+import static org.apache.hadoop.fs.s3a.S3ATestUtils.removeBaseAndBucketOverrides;
+
+/**
+ * Test mkdir operations on S3A with create performance mode.
+ */
+public class ITestS3AContractMkdirWithCreatePerf extends AbstractContractMkdirTest {
+
+  @Override
+  protected Configuration createConfiguration() {
+    Configuration conf = super.createConfiguration();
+    removeBaseAndBucketOverrides(
+        conf,
+        FS_S3A_CREATE_PERFORMANCE,
+        FS_S3A_PERFORMANCE_FLAGS);
+    conf.setStrings(FS_S3A_PERFORMANCE_FLAGS,
+        "create,mkdir");
+    return conf;
+  }
+
+  @Override
+  protected AbstractFSContract createContract(Configuration conf) {
+    return new S3AContract(conf);
+  }
+
+  @Test
+  public void testMkdirOverParentFile() throws Throwable {
+    describe("try to mkdir where a parent is a file, should pass");
+    FileSystem fs = getFileSystem();
+    Path path = methodPath();
+    byte[] dataset = dataset(1024, ' ', 'z');
+    createFile(getFileSystem(), path, false, dataset);
+    Path child = new Path(path, "child-to-mkdir");
+    boolean childCreated = fs.mkdirs(child);
+    assertTrue("Child dir is created", childCreated);
+    assertIsFile(path);
+    byte[] bytes = ContractTestUtils.readDataset(getFileSystem(), path, dataset.length);
+    ContractTestUtils.compareByteArrays(dataset, bytes, dataset.length);
+    assertPathExists("mkdir failed", child);
+    assertDeleted(child, true);
+  }
+
+}