content: /*
   * Copyright (C) 2018 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;
  
  import android.util.Log;
  import android.util.LogWriter;
  import android.util.Slog;
  
  import com.android.internal.annotations.VisibleForTesting;
  import com.android.server.Watchdog.HandlerChecker;
  
  import dalvik.system.AnnotatedStackTraceElement;
  import dalvik.system.VMStack;
  
  import java.io.PrintWriter;
  import java.util.List;
  
  /**
   * Class to give diagnostic messages for Watchdogs.
   */
  class WatchdogDiagnostics {
      private static String getBlockedOnString(Object blockedOn) {
          return String.format("- waiting to lock <0x%08x> (a %s)",
                  System.identityHashCode(blockedOn), blockedOn.getClass().getName());
      }
  
      private static String getLockedString(Object heldLock) {
          return String.format("- locked <0x%08x> (a %s)", System.identityHashCode(heldLock),
                  heldLock.getClass().getName());
      }
  
      /**
       * Print the annotated stack for the given thread. If the annotated stack cannot be retrieved,
       * returns false.
       */
      @VisibleForTesting
      public static boolean printAnnotatedStack(Thread thread, PrintWriter out) {
          AnnotatedStackTraceElement stack[] = VMStack.getAnnotatedThreadStackTrace(thread);
          if (stack == null) {
              return false;
          }
          out.println(thread.getName() + " annotated stack trace:");
          for (AnnotatedStackTraceElement element : stack) {
              out.println("    at " + element.getStackTraceElement());
              if (element.getBlockedOn() != null) {
                  out.println("    " + getBlockedOnString(element.getBlockedOn()));
              }
              if (element.getHeldLocks() != null) {
                  for (Object held : element.getHeldLocks()) {
                      out.println("    " + getLockedString(held));
                  }
              }
          }
          return true;
      }
  
      public static void diagnoseCheckers(final List<HandlerChecker> blockedCheckers) {
          PrintWriter out = new PrintWriter(new LogWriter(Log.WARN, Watchdog.TAG, Log.LOG_ID_SYSTEM),
                  true);
          for (int i=0; i<blockedCheckers.size(); i++) {
              Thread blockedThread = blockedCheckers.get(i).getThread();
              if (printAnnotatedStack(blockedThread, out)) {
                  continue;
              }
  
              // Fall back to "regular" stack trace, if necessary.
              Slog.w(Watchdog.TAG, blockedThread.getName() + " stack trace:");
              StackTraceElement[] stackTrace = blockedThread.getStackTrace();
              for (StackTraceElement element : stackTrace) {
                  Slog.w(Watchdog.TAG, "    at " + element);
              }
          }
      }
  }
  