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 com.datastax.oss.driver.internal.core.os;
  
  import java.util.Locale;
  import java.util.Optional;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class GraalLibc implements Libc {
  
    private static final Logger LOG = LoggerFactory.getLogger(GraalLibc.class);
  
    private static final Locale LOCALE = Locale.ENGLISH;
  
    private static final String MAC_PLATFORM_STR = "mac".toLowerCase(LOCALE);
    private static final String DARWIN_PLATFORM_STR = "darwin".toLowerCase(LOCALE);
    private static final String LINUX_PLATFORM_STR = "linux".toLowerCase(LOCALE);
  
    private final boolean available = checkAvailability();
  
    /* This method is adapted from of jnr.ffi.Platform.determineOS() in jnr-ffi version 2.1.10. **/
    private boolean checkPlatform() {
  
      String osName = System.getProperty("os.name").split(" ", -1)[0];
      String compareStr = osName.toLowerCase(Locale.ENGLISH);
      return compareStr.startsWith(MAC_PLATFORM_STR)
          || compareStr.startsWith(DARWIN_PLATFORM_STR)
          || compareStr.startsWith(LINUX_PLATFORM_STR);
    }
  
    private boolean checkAvailability() {
  
      if (!checkPlatform()) {
        return false;
      }
  
      try {
        getpidRaw();
      } catch (Throwable t) {
  
        LOG.debug("Error calling getpid()", t);
        return false;
      }
  
      try {
        gettimeofdayRaw();
      } catch (Throwable t) {
  
        LOG.debug("Error calling gettimeofday()", t);
        return false;
      }
  
      return true;
    }
  
    @Override
    public boolean available() {
      return this.available;
    }
  
    /* Substrate includes a substitution for Linux + Darwin which redefines System.nanoTime() to use
     * gettimeofday() (unless platform-specific higher-res clocks are available, which is even better). */
    @Override
    public Optional<Long> gettimeofday() {
      return this.available ? Optional.of(gettimeofdayRaw()) : Optional.empty();
    }
  
    private long gettimeofdayRaw() {
      return Math.round(System.nanoTime() / 1_000d);
    }
  
    @Override
    public Optional<Integer> getpid() {
      return this.available ? Optional.of(getpidRaw()) : Optional.empty();
    }
  
    private int getpidRaw() {
      return GraalGetpid.getpid();
    }
  }
  