LatchSupport.java

package com.sleepycat.je.latch;
import com.sleepycat.je.dbi.EnvironmentImpl;
import de.ovgu.cide.jakutil.*;
/** 
 * Various constructs to support Latches.  Switch hitting for 1.4 vs Java 5
 * JVM latch implementation (i.e. our's vs the JVM's), and assert-based
 * latch counting code.
 */
public class LatchSupport {
  private static String DISABLE_JAVA5_LATCHES="je.disable.java5.latches";
  private static Class JAVA5_LATCH_CLASS=null;
  private static Class JAVA5_SHARED_LATCH_CLASS=null;
static {
    try {
      if (System.getProperty(DISABLE_JAVA5_LATCHES) == null) {
        Class.forName("java.util.concurrent.locks.ReentrantLock");
        JAVA5_LATCH_CLASS=Class.forName("com.sleepycat.je.latch.Java5LatchImpl");
      }
    }
 catch (    ClassNotFoundException CNFE) {
    }
  }
static {
    try {
      if (System.getProperty(DISABLE_JAVA5_LATCHES) == null) {
        Class.forName("java.util.concurrent.locks.ReentrantReadWriteLock");
        JAVA5_SHARED_LATCH_CLASS=Class.forName("com.sleepycat.je.latch.Java5SharedLatchImpl");
      }
    }
 catch (    ClassNotFoundException CNFE) {
    }
  }
  public static Class getJava5LatchClass(){
    return JAVA5_LATCH_CLASS;
  }
  public static Latch makeLatch(  String name,  EnvironmentImpl env){
    if (JAVA5_LATCH_CLASS == null) {
      return new LatchImpl(name,env);
    }
 else {
      try {
        Latch ret=(Latch)JAVA5_LATCH_CLASS.newInstance();
        ret.setName(name);
        return ret;
      }
 catch (      InstantiationException IE) {
      }
catch (      IllegalAccessException IAE) {
      }
      JAVA5_LATCH_CLASS=null;
      return new LatchImpl(name,env);
    }
  }
  public static Latch makeLatch(  EnvironmentImpl env){
    if (JAVA5_LATCH_CLASS == null) {
      return new LatchImpl(env);
    }
 else {
      try {
        return (Latch)JAVA5_LATCH_CLASS.newInstance();
      }
 catch (      InstantiationException IE) {
      }
catch (      IllegalAccessException IAE) {
      }
      JAVA5_LATCH_CLASS=null;
      return new LatchImpl(env);
    }
  }
  public static SharedLatch makeSharedLatch(  String name,  EnvironmentImpl env){
    if (JAVA5_SHARED_LATCH_CLASS == null) {
      return new SharedLatchImpl(name,env);
    }
 else {
      try {
        SharedLatch ret=(SharedLatch)JAVA5_SHARED_LATCH_CLASS.newInstance();
        ret.setName(name);
        return ret;
      }
 catch (      InstantiationException IE) {
      }
catch (      IllegalAccessException IAE) {
      }
      JAVA5_SHARED_LATCH_CLASS=null;
      return new SharedLatchImpl(name,env);
    }
  }
  static LatchTable latchTable=new LatchTable("LatchImpl");
  /** 
 * Only call under the assert system. This records and counts held latches.
 */
  static public int countLatchesHeld(){
    return latchTable.countLatchesHeld();
  }
  static public void dumpLatchesHeld(){
    System.out.println(latchesHeldToString());
  }
  static public String latchesHeldToString(){
    return latchTable.latchesHeldToString();
  }
  static public void clearNotes(){
    latchTable.clearNotes();
  }
}