hadoop S3AInputPolicy 源码

haddop S3AInputPolicy 代码

文件路径：/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AInputPolicy.java

/*
 * 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.s3a;

import javax.annotation.Nullable;
import java.util.Collection;
import java.util.Locale;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_ADAPTIVE;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_DEFAULT;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_RANDOM;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_SEQUENTIAL;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_VECTOR;
import static org.apache.hadoop.fs.Options.OpenFileOptions.FS_OPTION_OPENFILE_READ_POLICY_WHOLE_FILE;

/**
 * Stream input policy.
 */
@InterfaceAudience.Private
@InterfaceStability.Unstable
public enum S3AInputPolicy {

  Normal(FS_OPTION_OPENFILE_READ_POLICY_DEFAULT, false, true),
  Random(FS_OPTION_OPENFILE_READ_POLICY_RANDOM, true, false),
  Sequential(FS_OPTION_OPENFILE_READ_POLICY_SEQUENTIAL, false, false);

  /** Policy name. */
  private final String policy;

  /** Is this random IO? */
  private final boolean randomIO;

  /** Is this an adaptive policy? */
  private final boolean adaptive;

  S3AInputPolicy(String policy,
      boolean randomIO,
      boolean adaptive) {
    this.policy = policy;
    this.randomIO = randomIO;
    this.adaptive = adaptive;
  }

  @Override
  public String toString() {
    return policy;
  }

  String getPolicy() {
    return policy;
  }

  boolean isRandomIO() {
    return randomIO;
  }

  boolean isAdaptive() {
    return adaptive;
  }

  /**
   * Choose an access policy.
   * @param name strategy name from a configuration option, etc.
   * @param defaultPolicy default policy to fall back to.
   * @return the chosen strategy
   */
  public static S3AInputPolicy getPolicy(
      String name,
      @Nullable S3AInputPolicy defaultPolicy) {
    String trimmed = name.trim().toLowerCase(Locale.ENGLISH);
    switch (trimmed) {
    case FS_OPTION_OPENFILE_READ_POLICY_ADAPTIVE:
    case FS_OPTION_OPENFILE_READ_POLICY_DEFAULT:
    case Constants.INPUT_FADV_NORMAL:
      return Normal;

    // all these options currently map to random IO.
    case FS_OPTION_OPENFILE_READ_POLICY_RANDOM:
    case FS_OPTION_OPENFILE_READ_POLICY_VECTOR:
      return Random;

    case FS_OPTION_OPENFILE_READ_POLICY_SEQUENTIAL:
    case FS_OPTION_OPENFILE_READ_POLICY_WHOLE_FILE:
      return Sequential;
    default:
      return defaultPolicy;
    }
  }

  /**
   * Scan the list of input policies, returning the first one supported.
   * @param policies list of policies.
   * @param defaultPolicy fallback
   * @return a policy or the defaultPolicy, which may be null
   */
  public static S3AInputPolicy getFirstSupportedPolicy(
      Collection<String> policies,
      @Nullable S3AInputPolicy defaultPolicy) {
    for (String s : policies) {
      S3AInputPolicy nextPolicy = S3AInputPolicy.getPolicy(s, null);
      if (nextPolicy != null) {
        return nextPolicy;
      }
    }
    return defaultPolicy;
  }

}

相关信息

hadoop 源码目录

相关文章

hadoop AWSBadRequestException 源码

hadoop AWSClientIOException 源码

hadoop AWSCredentialProviderList 源码

hadoop AWSNoResponseException 源码

hadoop AWSRedirectException 源码

hadoop AWSS3IOException 源码

hadoop AWSServiceIOException 源码

hadoop AWSServiceThrottledException 源码

hadoop AWSStatus500Exception 源码

hadoop AnonymousAWSCredentialsProvider 源码