content: /*
   * Copyright (C) 2016 The Android Open Source Project
   *
   * Licensed 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.android.server.pm;
  
  import android.content.pm.PackageParser;
  import android.os.Process;
  import android.os.Trace;
  import android.util.DisplayMetrics;
  
  import com.android.internal.annotations.VisibleForTesting;
  import com.android.internal.util.ConcurrentUtils;
  
  import java.io.File;
  import java.util.List;
  import java.util.concurrent.ArrayBlockingQueue;
  import java.util.concurrent.BlockingQueue;
  import java.util.concurrent.ExecutorService;
  
  import static android.os.Trace.TRACE_TAG_PACKAGE_MANAGER;
  
  /**
   * Helper class for parallel parsing of packages using {@link PackageParser}.
   * <p>Parsing requests are processed by a thread-pool of {@link #MAX_THREADS}.
   * At any time, at most {@link #QUEUE_CAPACITY} results are kept in RAM</p>
   */
  class ParallelPackageParser implements AutoCloseable {
  
      private static final int QUEUE_CAPACITY = 10;
      private static final int MAX_THREADS = 4;
  
      private final String[] mSeparateProcesses;
      private final boolean mOnlyCore;
      private final DisplayMetrics mMetrics;
      private final File mCacheDir;
      private final PackageParser.Callback mPackageParserCallback;
      private volatile String mInterruptedInThread;
  
      private final BlockingQueue<ParseResult> mQueue = new ArrayBlockingQueue<>(QUEUE_CAPACITY);
  
      private final ExecutorService mService = ConcurrentUtils.newFixedThreadPool(MAX_THREADS,
              "package-parsing-thread", Process.THREAD_PRIORITY_FOREGROUND);
  
      ParallelPackageParser(String[] separateProcesses, boolean onlyCoreApps,
              DisplayMetrics metrics, File cacheDir, PackageParser.Callback callback) {
          mSeparateProcesses = separateProcesses;
          mOnlyCore = onlyCoreApps;
          mMetrics = metrics;
          mCacheDir = cacheDir;
          mPackageParserCallback = callback;
      }
  
      static class ParseResult {
  
          PackageParser.Package pkg; // Parsed package
          File scanFile; // File that was parsed
          Throwable throwable; // Set if an error occurs during parsing
  
          @Override
          public String toString() {
              return "ParseResult{" +
                      "pkg=" + pkg +
                      ", scanFile=" + scanFile +
                      ", throwable=" + throwable +
                      '}';
          }
      }
  
      /**
       * Take the parsed package from the parsing queue, waiting if necessary until the element
       * appears in the queue.
       * @return parsed package
       */
      public ParseResult take() {
          try {
              if (mInterruptedInThread != null) {
                  throw new InterruptedException("Interrupted in " + mInterruptedInThread);
              }
              return mQueue.take();
          } catch (InterruptedException e) {
              // We cannot recover from interrupt here
              Thread.currentThread().interrupt();
              throw new IllegalStateException(e);
          }
      }
  
      /**
       * Submits the file for parsing
       * @param scanFile file to scan
       * @param parseFlags parse falgs
       */
      public void submit(File scanFile, int parseFlags) {
          mService.submit(() -> {
              ParseResult pr = new ParseResult();
              Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "parallel parsePackage [" + scanFile + "]");
              try {
                  PackageParser pp = new PackageParser();
                  pp.setSeparateProcesses(mSeparateProcesses);
                  pp.setOnlyCoreApps(mOnlyCore);
                  pp.setDisplayMetrics(mMetrics);
                  pp.setCacheDir(mCacheDir);
                  pp.setCallback(mPackageParserCallback);
                  pr.scanFile = scanFile;
                  pr.pkg = parsePackage(pp, scanFile, parseFlags);
              } catch (Throwable e) {
                  pr.throwable = e;
              } finally {
                  Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
              }
              try {
                  mQueue.put(pr);
              } catch (InterruptedException e) {
                  Thread.currentThread().interrupt();
                  // Propagate result to callers of take().
                  // This is helpful to prevent main thread from getting stuck waiting on
                  // ParallelPackageParser to finish in case of interruption
                  mInterruptedInThread = Thread.currentThread().getName();
              }
          });
      }
  
      @VisibleForTesting
      protected PackageParser.Package parsePackage(PackageParser packageParser, File scanFile,
              int parseFlags) throws PackageParser.PackageParserException {
          return packageParser.parsePackage(scanFile, parseFlags, true /* useCaches */);
      }
  
      @Override
      public void close() {
          List<Runnable> unfinishedTasks = mService.shutdownNow();
          if (!unfinishedTasks.isEmpty()) {
              throw new IllegalStateException("Not all tasks finished before calling close: "
                      + unfinishedTasks);
          }
      }
  }
  