content: /*
   * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.javac.file;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.attribute.BasicFileAttributes;
  import java.util.List;
  import java.util.Optional;
  import java.util.concurrent.ConcurrentHashMap;
  
  import openjdk.tools.javac.util.Context;
  import openjdk.tools.javac.util.Context.Factory;
  
  /**
   * Caching implementation of FSInfo.
   *
   * <p><b>This is NOT part of any supported API.
   * If you write code that depends on this, you do so at your own risk.
   * This code and its internal interfaces are subject to change or
   * deletion without notice.</b>
   */
  public class CacheFSInfo extends FSInfo {
  
      protected final ConcurrentHashMap<Path, Path> canonicalPathCache = new ConcurrentHashMap<>();
      protected final ConcurrentHashMap<Path, Optional<BasicFileAttributes>> attributeCache =
              new ConcurrentHashMap<>();
      protected final ConcurrentHashMap<Path, List<Path>> jarClassPathCache =
              new ConcurrentHashMap<>();
  
      /**
       * Register a Context.Factory to create a CacheFSInfo.
       */
      public static void preRegister(Context context) {
          context.put(FSInfo.class, (Factory<FSInfo>)c -> {
                  FSInfo instance = new CacheFSInfo();
                  c.put(FSInfo.class, instance);
                  return instance;
              });
      }
  
      public void clearCache() {
          canonicalPathCache.clear();
          attributeCache.clear();
          jarClassPathCache.clear();
      }
  
      @Override
      public Path getCanonicalFile(Path file) {
          return canonicalPathCache.computeIfAbsent(file, super::getCanonicalFile);
      }
  
      @Override
      public boolean exists(Path file) {
          return getAttributes(file).isPresent();
      }
  
      @Override
      public boolean isDirectory(Path file) {
          return getAttributes(file).map(BasicFileAttributes::isDirectory).orElse(false);
      }
  
      @Override
      public boolean isFile(Path file) {
          return getAttributes(file).map(BasicFileAttributes::isRegularFile).orElse(false);
      }
  
      @Override
      public List<Path> getJarClassPath(Path file) throws IOException {
          synchronized (jarClassPathCache) {
              List<Path> jarClassPath = jarClassPathCache.get(file);
              if (jarClassPath == null) {
                  jarClassPath = super.getJarClassPath(file);
                  jarClassPathCache.put(file, jarClassPath);
              }
              return jarClassPath;
          }
      }
  
      protected Optional<BasicFileAttributes> getAttributes(Path file) {
          return attributeCache.computeIfAbsent(file, this::maybeReadAttributes);
      }
  
      protected Optional<BasicFileAttributes> maybeReadAttributes(Path file) {
          try {
              return Optional.of(Files.readAttributes(file, BasicFileAttributes.class));
          } catch (IOException e) {
              // Ignore; means file not found
              return Optional.empty();
          }
      }
  }
  