content: /*
   *
   * 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.bookkeeper.common.util.affinity.impl;
  
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.Paths;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeMap;
  import java.util.TreeSet;
  import org.apache.commons.lang3.StringUtils;
  
  /**
   * Discover the list of processors from /proc/cpuinfo.
   */
  class ProcessorsInfo {
  
      private static final Charset ENCODING = StandardCharsets.US_ASCII;
  
      /**
       * Given one cpu id, return all CPUs that are sharing the same core.
       */
      public Set<Integer> getCpusOnSameCore(int targetCpu) {
          Set<Integer> result = new TreeSet<>();
          int targetCore = cpus.get(targetCpu);
  
          cpus.forEach((cpu, core) -> {
              if (core == targetCore) {
                  result.add(cpu);
              }
          });
  
          return result;
      }
  
      private final Map<Integer, Integer> cpus = new TreeMap<>();
  
      static ProcessorsInfo parseCpuInfo(String cpuInfoString) {
          ProcessorsInfo pi = new ProcessorsInfo();
  
          for (String cpu : cpuInfoString.split("\n\n")) {
              int cpuId = -1;
              int coreId = -1;
  
              for (String line : cpu.split("\n")) {
                  String[] parts = line.split(":", 2);
                  String key = StringUtils.trim(parts[0]);
                  String value = StringUtils.trim(parts[1]);
  
                  if (key.equals("core id")) {
                      coreId = Integer.parseInt(value);
                  } else if (key.equals("processor")) {
                      cpuId = Integer.parseInt(value);
                  } else {
                      // ignore
                  }
              }
  
              com.google.common.base.Preconditions.checkArgument(cpuId >= 0);
              com.google.common.base.Preconditions.checkArgument(coreId >= 0);
              pi.cpus.put(cpuId, coreId);
          }
  
          return pi;
      }
  
      static ProcessorsInfo parseCpuInfo() {
          try {
              return parseCpuInfo(new String(Files.readAllBytes(Paths.get("/proc/cpuinfo")), ENCODING));
          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }
  }
  