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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * 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. See accompanying
 * LICENSE file.
 */

package com.gemstone.gemfire.internal;

import com.gemstone.gemfire.internal.i18n.LocalizedStrings;
import com.gemstone.gemfire.InternalGemFireError;

/**
 * Support for correctness assertions.
 * "An assertion is a statement containing a boolean expression that the
 *  programmer believes to be true at the time the statement is executed.
 * For example, after unmarshalling all of the arguments from a data
 * buffer, a programmer might assert that the number of bytes of data
 * remaining in the buffer is zero. The system executes the assertion by
 * evaluating the boolean expression and reporting an error if it evaluates to
 * false. By verifying that the boolean expression is indeed true, the system
 * corroborates the programmer's knowledge of the program and increases his
 * confidence that the program is free of bugs.Assertion checking may be
 * disabled for increased performance. Typically, assertion-checking is enabled
 * during program development and testing, and disabled during deployment."
 *     - from http://java.sun.com/aboutJava/communityprocess/jsr/asrt_prop.html
 *
 * This class does not provide a way to disable assertions for increased performance,
 * since we cannot prevent the arguments from being evaluated in any case without
 * changes to the Java language itself.
 *
 * The interface to this class was designed for easy migration to the new assert
 * facility that is currently proposed for the Java language in JSR-000041
 *
 * @see JSR-000041 A Simple Assertion Facility
 * @see Proposal: A Simple Assertion Facility For the Java[tm] Programming Language
 */

public class Assert {
  /**
   * Assert that a boolean value is true.
   * @param b the boolean value to check
   * @throws InternalGemFireError if false
   */
  public static void assertTrue(boolean b) {
    if (!b) {
      throwError(null);
    }
  }

  private static boolean debug = Boolean.getBoolean("gemfire.haltOnAssertFailure");

  public static boolean waitForDebuggerOnError() { return debug; }

  public static void fail(Object message) {
    throwError(message);
  }

  private static void throwError(Object message) {
    if (debug) { 
      System.out.flush();
      System.err.println("Assertion failure: " + message);
      try {
        throw new Exception(LocalizedStrings.Assert_GET_STACK_TRACE.toLocalizedString());
      } catch (Exception ex) {
        ex.printStackTrace();
      }
      System.out.println();
      System.out.flush();
      System.err.println("Waiting for debugger to attach"); 
      System.err.flush();
      while (true) {
        try { Thread.sleep(1000); }
        catch (InterruptedException ignore) { 
          Thread.currentThread().interrupt();
        }
      }
    } else {
      InternalGemFireError ex = null;
      if (message != null) {
        ex = new InternalGemFireError(message);
      } else {
        ex = new InternalGemFireError();
      }
//       com.gemstone.gemfire.internal.cache.GemFireCache gfc
//         = com.gemstone.gemfire.internal.cache.GemFireCache.getInstance();
//       if (gfc != null) {
//         gfc.getLogger().info("DEBUG", ex);
//       }
      throw ex;
    }
  }

  /**
   * Assert that a boolean value is true.The
   * message object will be sent toString()
   * and used for an error message.
   *
   * @param b the boolean value to check
   * @param message used for error message
   * @throws InternalGemFireError if false
   */
  public static void assertTrue(boolean b, Object message) {
    if (!b) {
      throwError(message);
    }
  }
  
  public static void assertTrue(boolean b, boolean message) {
    if (!b) {
      throwError(Boolean.valueOf(message));
    }
  }
  
  public static void assertTrue(boolean b, char message) {
    if (!b) {
      throwError(Character.valueOf(message));
    }
  }
  
  public static void assertTrue(boolean b, int message) {
    if (!b) {
      throwError(Integer.valueOf(message));
    }
  }
  
  public static void assertTrue(boolean b, long message) {
    if (!b) {
      throwError(Long.valueOf(message));
    }
  }
  
  public static void assertTrue(boolean b, float message) {
    if (!b) {
      throwError(new Float(message));
    }
  }
  
  public static void assertTrue(boolean b, double message) {
    if (!b) {
      throwError(Double.valueOf(message));
    }
  }
  
  /**
   * This is a workaround for X bug 38288. JRockit can throw a NullPointerException
   * from Thread.holdsLock, so we catch the NullPointerException if it happens.
   * 
   * This method returns true, unless it throws an exception. This is so we can disable
   * these tests for performance reasons with a java assertion, eg
   * assert Assert.assertHoldLock(lock, true);
   * @param lock The lock to test
   * @param shouldBeHeld true if this thread should hold this lock.
   * @return true, unless the method throws an exception. 
   */
  public static boolean assertHoldsLock(Object lock, boolean shouldBeHeld) {
    try {
      if(Thread.holdsLock(lock) != shouldBeHeld) {
        throwError(null);
      }
    } catch (NullPointerException jrockitSucks) {
      assertTrue(lock != null);
    }
    
    return true;
  }
}