hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3GuardEmptyDirs.java

/*
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 * distributed with this work for additional information
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 * 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
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 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.hadoop.fs.s3a;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.s3a.s3guard.MetadataStore;
import org.apache.hadoop.fs.s3a.s3guard.NullMetadataStore;
import org.junit.Assume;
import org.junit.Test;

import static org.apache.hadoop.fs.contract.ContractTestUtils.touch;

/**
 * Test logic around whether or not a directory is empty, with S3Guard enabled.
 * The fact that S3AFileStatus has an isEmptyDirectory flag in it makes caching
 * S3AFileStatus's really tricky, as the flag can change as a side effect of
 * changes to other paths.
 * After S3Guard is merged to trunk, we should try to remove the
 * isEmptyDirectory flag from S3AFileStatus, or maintain it outside
 * of the MetadataStore.
 */
public class ITestS3GuardEmptyDirs extends AbstractS3ATestBase {

  @Test
  public void testEmptyDirs() throws Exception {
    S3AFileSystem fs = getFileSystem();
    Assume.assumeTrue(fs.hasMetadataStore());
    MetadataStore configuredMs = fs.getMetadataStore();
    Path existingDir = path("existing-dir");
    Path existingFile = path("existing-dir/existing-file");
    try {
      // 1. Simulate files already existing in the bucket before we started our
      // cluster.  Temporarily disable the MetadataStore so it doesn't witness
      // us creating these files.

      fs.setMetadataStore(new NullMetadataStore());
      assertTrue(fs.mkdirs(existingDir));
      touch(fs, existingFile);


      // 2. Simulate (from MetadataStore's perspective) starting our cluster and
      // creating a file in an existing directory.
      fs.setMetadataStore(configuredMs);  // "start cluster"
      Path newFile = path("existing-dir/new-file");
      touch(fs, newFile);

      S3AFileStatus status = fs.innerGetFileStatus(existingDir, true);
      assertEquals("Should not be empty dir", Tristate.FALSE,
          status.isEmptyDirectory());

      // 3. Assert that removing the only file the MetadataStore witnessed
      // being created doesn't cause it to think the directory is now empty.
      fs.delete(newFile, false);
      status = fs.innerGetFileStatus(existingDir, true);
      assertEquals("Should not be empty dir", Tristate.FALSE,
          status.isEmptyDirectory());

      // 4. Assert that removing the final file, that existed "before"
      // MetadataStore started, *does* cause the directory to be marked empty.
      fs.delete(existingFile, false);
      status = fs.innerGetFileStatus(existingDir, true);
      assertEquals("Should be empty dir now", Tristate.TRUE,
          status.isEmptyDirectory());
    } finally {
      configuredMs.forgetMetadata(existingFile);
      configuredMs.forgetMetadata(existingDir);
    }
  }
}