src/org/objectweb/cjdbc/controller/loadbalancer/policies/createtable/CreateTableRandom.java

説明を見る。

package org.objectweb.cjdbc.controller.loadbalancer.policies.createtable;

import java.util.ArrayList;
import java.util.Random;

import org.objectweb.cjdbc.controller.backend.DatabaseBackend;

public class CreateTableRandom extends CreateTableRule
{
  private Random random = new Random();

  public CreateTableRandom()
  {
    super(CreateTablePolicy.RANDOM);
  }

  public CreateTableRandom(ArrayList backendList)
  {
    super(CreateTablePolicy.RANDOM, backendList);
  }

  public ArrayList getBackends(ArrayList backends) throws CreateTableException
  {
    int size = backends.size();

    if (nbOfNodes == 0)
      return null;
    else if (nbOfNodes == size)
      return backends;

    ArrayList result = new ArrayList(nbOfNodes);
    ArrayList clonedList;

    if (backendList.size() > 0)
    { // Keep only the backends that are affected by this rule
      clonedList = new ArrayList(nbOfNodes);
      for (int i = 0; i < size; i++)
      {
        DatabaseBackend db = (DatabaseBackend) backends.get(i);
        if (db.isWriteEnabled() && backendList.contains(db.getName()))
          clonedList.add(db);
      }
    }
    else
    { // Take all enabled backends
      clonedList = new ArrayList(size);
      for (int i = 0; i < size; i++)
      {
        DatabaseBackend db = (DatabaseBackend) backends.get(i);
        if (db.isWriteEnabled())
          clonedList.add(db);
      }
    }

    int clonedSize = clonedList.size();

    if (nbOfNodes == clonedSize)
      return backends;
    else if (nbOfNodes > clonedSize)
      throw new CreateTableException(
        "Asking for more backends ("
          + nbOfNodes
          + ") than available ("
          + clonedSize
          + ")");

    for (int i = 0; i < nbOfNodes; i++)
      result.add(clonedList.remove(random.nextInt(clonedSize)));

    return result;
  }

  public String getInformation()
  {
    String s;
    if (tableName == null)
      s = "Default rule create table on ";
    else
      s = "Rule for table " + tableName + " create table on ";

    return s + nbOfNodes + " node(s) randomly from " + backendList;
  }
}

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